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1
Dooley, Tim P., and Michael R. Hudec. "Extension and inversion of salt-bearing rift systems." Solid Earth 11, no. 4 (July 6, 2020): 1187–204. http://dx.doi.org/10.5194/se-11-1187-2020.
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Abstract. We used physical models to investigate the structural evolution of segmented extensional rifts containing syn-rift evaporites and their subsequent inversion. An early stage of extension generated structural topography consisting of a series of en-échelon graben. Our salt analog filled these graben and the surroundings before continued extension and, finally, inversion. During post-salt extension, deformation in the subsalt section remained focused on the graben-bounding fault systems, whereas deformation in suprasalt sediments was mostly detached, forming a sigmoidal extensional minibasin system across the original segmented graben array. Little brittle deformation was observed in the post-salt section. Sedimentary loading from the minibasins drove salt up onto the footwalls of the subsalt faults, forming diapirs and salt-ridge networks on the intra-rift high blocks. Salt remobilization and expulsion from beneath the extensional minibasins was enhanced along and up the major relay or transfer zones that separated the original sub-salt grabens, forming major diapirs in these locations. Inversion of this salt-bearing rift system produced strongly decoupled shortening belts in basement and suprasalt sequences. Suprasalt deformation geometries and orientations are strongly controlled by the salt diapir and ridge network produced during extension and subsequent downbuilding. Thrusts are typically localized at minibasin margins where the overburden was thinnest, and salt had risen diapirically on the horst blocks. In the subsalt section, shortening strongly inverted sub-salt grabens, which uplifted the suprasalt minibasins. New pop-up structures also formed in the subsalt section. Primary welds formed as suprasalt minibasins touched down onto inverted graben. Model geometries compare favorably to natural examples such as those in the Moroccan High Atlas.
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Tari, Gábor, Didier Arbouille, Zsolt Schléder, and Tamás Tóth. "Inversion tectonics: a brief petroleum industry perspective." Solid Earth 11, no. 5 (October 21, 2020): 1865–89. http://dx.doi.org/10.5194/se-11-1865-2020.
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Abstract. Inverted structures provide traps for petroleum exploration, typically four-way structural closures. As to the degree of inversion, based on a large number of worldwide examples seen in various basins, the most preferred petroleum exploration targets are mild to moderate inversion structures, defined by the location of the null points. In these instances, the closures have a relatively small vertical amplitude but are simple in a map-view sense and well imaged on seismic reflection data. Also, the closures typically cluster above the extensional depocenters which tend to contain source rocks providing petroleum charge during and after the inversion. Cases for strong or total inversion are generally not that common and typically are not considered as ideal exploration prospects, mostly due to breaching and seismic imaging challenges associated with the trap(s) formed early on in the process of inversion. Also, migration may become tortuous due to the structural complexity or the source rock units may be uplifted above the hydrocarbon generation window, effectively terminating the charge once the inversion has occurred. Cases of inversion tectonics can be grouped into two main modes. A structure develops in Mode I inversion if the syn-rift succession in the preexisting extensional basin unit is thicker than its post-rift cover including the pre- and syn-inversion part of it. In contrast, a structure evolves in Mode II inversion if the opposite syn- versus post-rift sequence thickness ratio can be observed. These two modes have different impacts on the petroleum system elements in any given inversion structure. Mode I inversion tends to develop in failed intracontinental rifts and proximal passive margins, and Mode II structures are associated with back-arc basins and distal parts of passive margins. For any particular structure the evidence for inversion is typically provided by subsurface data sets such as reflection seismic and well data. However, in many cases the deeper segments of the structure are either poorly imaged by the seismic data and/or have not been penetrated by exploration wells. In these cases the interpretation in terms of inversion has to rely on the regional understanding of the basin evolution with evidence for an early phase of crustal extension by normal faulting.
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Huang, Lei, Chi-yang Liu, Jun-feng Zhao, and Dong-dong Zhang. "Synrift basin inversion: Significant role of synchronous strike-slip motion in a rift basin." GSA Bulletin 132, no. 11-12 (April 17, 2020): 2572–86. http://dx.doi.org/10.1130/b35435.1.
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Abstract In rift basins with superposed strike-slip deformation, the structural style of wrench elements and the roles they play in synrift architecture and evolution are important, poorly understood issues for basin analysis and hydrocarbon exploration. The NE-SW–striking Tan-Lu fault zone, located in eastern China, runs through the Liaodong Bay subbasin within the Cenozoic Bohai Bay Basin and experienced dextral strike-slip motion during the later synrift stage of the basin (ca. 40 Ma to 23 Ma). Investigations of the Liaodong Bay subbasin indicate that rift-fault reactivation and wrench-fault development during strike-slip reactivation were strongly controlled by the distribution and geometry of preexisting rift faults, and local synrift basin inversion, induced by strike-slip reactivation of a preexisting graben during a later synrift stage, was a significant manifestation of synchronous strike-slip motion modifying synrift architecture and evolution. Moreover, synrift basin inversion within the Liaodong Bay subbasin manifested in two ways. First, stronger inversion occurred along the restraining bends of preexisting extensional faults. This induced uplift of the footwalls of graben-controlling faults, leading to deformation characterized by abundant shortcut thrusts and folds. The Liaodong uplift formed via this mechanism, triggered by strike-slip movement along the Tan-Lu fault zone at ca. 40 Ma. Second, weaker inversion induced by newly formed, subvertical, strike-slip faults occurred near the central part of the graben, with the characteristics of positive flower structures. Although inversion was limited to a very local area along a narrow fault zone, it substantially modified the basin’s physiography. In this rift system, coincident with local inversion-induced uplift, large-scale, rift-related subsidence occurred beyond the inversion belt within the flanking graben, leading to complexity and variety in intrabasinal structural deformation and filling, and exerting a complex influence on hydrocarbon prospects. This model of synrift basin inversion has profound implications for the interpretation of inversion structures and basin dynamics in any rift basin with superposed strike-slip deformation.
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Bosworth, William, and Gábor Tari. "Hydrocarbon accumulation in basins with multiple phases of extension and inversion: examples from the Western Desert (Egypt) and the western Black Sea." Solid Earth 12, no. 1 (January 14, 2021): 59–77. http://dx.doi.org/10.5194/se-12-59-2021.
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Abstract. Folds associated with inverted extensional faults are important exploration targets in many basins across our planet. A common cause for failure to trap hydrocarbons in inversion structures is crestal breaching or erosion of top seal. The likelihood of failure increases as the intensity of inversion grows. Inversion also decreases the amount of overburden, which can adversely affect maturation of source rocks within the underlying syn-extensional stratigraphic section. However, many rift basins are multi-phase in origin, and in some cases the various syn-rift and post-rift events are separated by multiple phases of shortening. When an inversion event is followed by a later phase of extension and subsidence, new top seals can be deposited and hydrocarbon maturation enhanced or reinitiated. These more complex rift histories can result in intra-basinal folds that have higher chances of success than single-phase inversion-related targets. In other basins, repeated inversion events can occur without significant intervening extension. This can also produce more complicated hydrocarbon maturation histories and trap geometries. Multiple phases of rifting and inversion affected numerous basins in North Africa and the Black Sea region and produced some structures that are now prolific hydrocarbon producing fields and others that failed. Understanding a basin's sequence of extensional and contractional events and the resulting complex interactions is essential to formulating successful exploration strategies in these settings.
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Wald, Reli, Amit Segev, Zvi Ben-Avraham, and Uri Schattner. "Structural expression of a fading rift front: a case study from the Oligo-Miocene Irbid rift of northwest Arabia." Solid Earth 10, no. 1 (January 31, 2019): 225–50. http://dx.doi.org/10.5194/se-10-225-2019.
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Abstract. Not all continental rifts mature to form a young ocean. The mechanism and duration of their cessation depend on the crustal structure, modifications in plate kinematics, lithospheric thermal response, or the intensity of subcrustal flow (e.g., plume activity). The cessation is recorded in the structure and stratigraphy of the basins that develop during the rifting process. This architecture is lost due to younger tectonic inversion, severe erosion, or even burial into greater depths that forces their detection by low-resolution geophysical imaging. The current study focuses on a uniquely preserved Oligo-Miocene rift that was subsequently taken over by a crossing transform fault system and, mostly due to that, died out. We integrate all geological, geophysical, and previous study results from across the southern Galilee to unravel the structural development of the Irbid failing rift in northwest Arabia. Despite tectonic, magmatic, and geomorphologic activity postdating the rifting, its subsurface structure northwest of the Dead Sea fault is preserved at depths of up to 1 km. Our results show that a series of basins subsided at the rift front, i.e., rift termination, across the southern Galilee. We constrain the timing and extent of their subsidence into two main stages based on facies analysis and chronology of magmatism. Between 20 and 9 Ma grabens and half-grabens subsided within a larger releasing jog, following a NW direction of a deeper presumed principal displacement zone. The basins continued to subside until a transition from the transtensional Red Sea to the transpressional Dead Sea stress regime occurred. With the transition, the basins ceased to subside as a rift, while the Dead Sea fault split the jog structure. Between 9 and 5 Ma basin subsidence accentuated and an uplift of their margins accompanied their overall elongation to the NNE. Our study provides for the first time a structural as well as tectonic context for the southern Galilee basins. Based on this case study we suggest that the rift did not fail but rather faded and was taken over by a more dominant stress regime. Otherwise, these basins of a failing rift could have simply died out peacefully.
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Cruz, Simone C. P., and Fernando F. Alkmim. "The Tectonic interaction between the Paramirim Aulacogen and the Araçuaí Belt, São Francisco craton region, Eastern Brazil." Anais da Academia Brasileira de Ciências 78, no. 1 (March 2006): 151–73. http://dx.doi.org/10.1590/s0001-37652006000100014.
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The Paramirim aulacogen, hosted in the northern part of the São Francisco craton, corresponds to two superimposed and partially inverted rifts of Paleo and Neoproterozoic ages. The Rio Pardo salient of the Araçuaí belt defines the local limit of the craton and interferes with the aulacogen structures. In order to understand the mechanism and timing of the tectonic interaction between these tectonic features during the inversion processes, a structural analysis was undertaken in the southern Paramirim aulacogen and along the Rio Pardo salient. The results obtained indicate that the Rio Pardo salient formed during an early stage of closure of the Neoproterozoic Macaúbas rift system and consequent initiation of the Araçuaí orogen. The orogenic front propagated further northwards into the craton, causing a first stage of inversion in the southern terminus of the aulacogen trough. Subsequently, the Paramirim aulacogen experienced the main stage of inversion, which led to the development of a NNW-oriented basement involved fold-thrust system. These fabric elements overprint the Rio Pardo salient, and the structures of both the first and second stages of inversion affect the Salitre Formation, the youngestNeoproterozoic unit of the area, clearly indicating a Late Neoproterozoic maximum age for all the inversion stages of the Paramirim aulacogen.
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Feng, Xuliang, Wanyin Wang, and Bingqiang Yuan. "3D gravity inversion of basement relief for a rift basin based on combined multinorm and normalized vertical derivative of the total horizontal derivative techniques." GEOPHYSICS 83, no. 5 (September 1, 2018): G107—G118. http://dx.doi.org/10.1190/geo2017-0678.1.
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The basement of a rift sedimentary basin, often possessing smooth and nonsmooth shapes, is not easily recovered from gravity data by current inversion methods. We have developed a new 3D gravity inversion method to estimate the basement relief of a rift basin. In the inversion process, we have established the objective function by combining the gravity data misfit function, the known depth constraint function, and the model constraint function composed of the [Formula: see text]-norm and [Formula: see text]-norm, respectively. An edge recognition technology based on the normalized vertical derivative of the total horizontal derivative for gravity data is adopted to recognize the discontinuous and continuous parts of the basin and combine the two inputs to form the final model constraint function. The inversion is conducted by minimizing the objective function by the nonlinear conjugate gradient algorithm. We have developed two applications using synthetic gravity anomalies produced from two synthetic rift basins, one with a single graben and one with six differently sized grabens. The test results indicate that the inversion method is a feasible technique to delineate the basement relief of a rift basin. The inversion method is also tested on field data from the Xi’an depression in the middle of the Weihe Basin, Shaanxi Province, China, and the result illustrates its effectiveness.
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Lescoutre, Rodolphe, and Gianreto Manatschal. "Role of rift-inheritance and segmentation for orogenic evolution: example from the Pyrenean-Cantabrian system." BSGF - Earth Sciences Bulletin 191 (2020): 18. http://dx.doi.org/10.1051/bsgf/2020021.
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The Basque-Cantabrian junction corresponds to an inverted rift accommodation zone at the limit between the former hyperextended Pyrenean and Cantabrian rift segments. The recognition of an inherited rift segment boundary allows to investigate the reactivation associated with large-scale rift segmentation in an orogenic system. We use criteria from published field observations and seismic data to propose a new map of rift domains for the Basque-Cantabrian junction. We also provide balanced cross-sections that allow to define the along-strike architecture associated with segmentation during rifting and subsequent Alpine reactivation. Based on these results, this study aims to characterize and identify reactivated and newly formed structures during inversion of two rift segments and its intermitted segment boundary. It also aims to describe the timing of thin-skinned and thick-skinned deformation associated with the inversion of segmented rift systems. During convergence, two phases have been recognized within the rift segment (eastern Mauléon basin). The Late Cretaceous to Paleocene underthrusting/subduction phase was mostly governed by thin-skinned deformation that reactivated the former hyperextended domains and the supra-salt sedimentary cover. The Eocene to Miocene collisional phase, controlled by thick-skinned deformation that took place once necking domains collided and formed an orogenic wedge. At the rift segment boundary, the underthrusting/subduction phase was already controlled by thick-skinned deformation due to the formation of shortcutting thrust faults at the termination of overlapping V-shaped rift segments. This led to the formation of a proto-wedge composed of the Basque massifs. We suggest that this proto-wedge is responsible for the preservation of pre-Alpine structures in the Basque massifs and for the emplacement of subcontinental mantle rocks at a crustal level beneath the western Mauléon basin. These results argue for a first order cylindrical orogenic architecture from the Central Pyrenean segment to the Cantabrian segment (up to the Santander transfer zone) despite rift segmentation. They also highlight the control of 3D rift-inheritance for the initial phase of orogenic evolution and for the local architecture of mountain belts.
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Salem, Ahmed, Chris Green, Matthew Stewart, and Davide De Lerma. "Inversion of gravity data with isostatic constraints." GEOPHYSICS 79, no. 6 (November 1, 2014): A45—A50. http://dx.doi.org/10.1190/geo2014-0220.1.
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We have developed a simple iterative gravity-inversion approach to map the basement and Moho surfaces of a rift basin simultaneously. Gravity anomalies in rift basins commonly consist of interfering broad, positive crustal-thinning anomalies and narrow, negative sedimentary-basin anomalies. In our model, we assumed that the Moho and basement surfaces are in Airy isostatic equilibrium. An initial plane-layered model was iterated to fit the gravity data. We applied the process to a model in which the inverted basement and Moho surfaces matched the model surfaces well and to a gravity profile across the Kosti Basin in Sudan.
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Ramos, Adrià, Berta Lopez-Mir, Elisabeth P. Wilson, Pablo Granado, and Josep Anton Muñoz. "3D reconstruction of syn-tectonic strata in a salt-related orogen: learnings from the Llert syncline (South-central Pyrenees)." Geologica Acta 18 (December 11, 2020): 1–19. http://dx.doi.org/10.1344/geologicaacta2020.18.20.
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The Llert syncline is located in the South-central Pyrenees, between the eastern termination of the EW-trending Cotiella Basin and the north-western limb of the NS-trending Turbón-Serrado fold system. The Cotiella Basin is an inverted upper Coniacian-lower Santonian salt-floored post-rift extensional basin developed along the northern Iberian rift system. The Turbón-Serrado fold system consists of upper Santonian – Maastrichtian contractional salt-cored anticlines developed along an inverted transfer zone of the Pyrenean rift system. Based on field research, this paper presents a 3D reconstruction of the Llert syncline in order to further constrain the transition between these oblique salt-related structures. Our results suggest that the evolution of the Llert syncline was mainly controlled by tectonic shortening related to the tectonic inversion of the Cotiella Basin synchronously to the growth of the Turbón-Serrado detachment anticline, and by the pre-compressional structural framework of the Pyrenean rift system. Our contribution provides new insight into the geometric and kinematic relationships of structures developed during the inversion of passive margins involving salt.
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Cheng, Jong E. "PETROLEUM SYSTEM OF SHOUSHAN BASIN, WESTERN DESERT, EGYPT." Geological Behavior 4, no. 1 (February 28, 2020): 01–08. http://dx.doi.org/10.26480/gbr.01.2020.01.08.
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The Western Desert is located in Egypt and it consists of a few extensional coastal rift-basins. It started as rifts and was formed during the Jurassic time in association with the opening of the Tethys Sea. There were three major tectonic events that occurred in Western Desert within Jurassic to Eocene time and resulted in NE-SW trend and NW-SE trend normal fault, and inversion of Western Desert basin due to rifting of Neo-Tethys followed by South America & Africa Atlantic rifting and Transpressional Syrian Arc event which had contributed to the formation of hydrocarbon trap. The generation, migration and accumulation of hydrocarbon started in the Late Cretaceous (95–90 Ma) and it continues to the present time. There is proven petroleum system named as Khatatba-Khatatba petroleum system within the Western Desert. The source of hydrocarbons is the Middle Jurassic Khatatba organicz-rich shales which contains type II- III and type III kerogen source migrated into Khatatba sandstones reservoir rock. Khatatba sandstones are mostly quartz arenite, which composed mainly of more than 95 % quartz. These sandstones have high porosity and high permeability with well sorted and are mostly subangular to subrounded grains. Masajid carbonate acts as regional seal within the basin. Hence, the Western Desert of Egypt has a significant hydrocarbon potential for exploration or development targeting on inversion structure.
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Hansen, Torsten Hundebøl, Ole Rønø Clausen, and Katrine Juul Andresen. "Thick- and thin-skinned basin inversion in the Danish Central Graben, North Sea – the role of deep evaporites and basement kinematics." Solid Earth 12, no. 8 (August 4, 2021): 1719–47. http://dx.doi.org/10.5194/se-12-1719-2021.
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Abstract. Using borehole-constrained 3D reflection seismic data, we analyse the importance of sub-salt, salt, and supra-salt deformation in controlling the geometries and the kinematics of inverted structures in the Danish Central Graben. The Danish Central Graben is part of the failed Late Jurassic North Sea rift. Later tectonic shortening caused mild basin inversion during the Late Cretaceous and Paleogene. Where mobile Zechstein evaporites are present, they have played a significant role in the structural evolution of the Danish Central Graben since the Triassic. Within the study area, Jurassic rifting generated two major W- to SW-dipping basement faults (the Coffee Soil Fault and the Gorm–Tyra Fault) with several kilometres of normal offset and associated block rotation. The Coffee Soil Fault system delineates the eastern boundary of the rift basins, and within its hanging wall a broad zone is characterized by late Mesozoic to early Paleogene shortening and relative uplift. Buttressed growth folds in the immediate hanging wall of the Coffee Soil Fault indicate thick-skinned inversion, i.e. coupled deformation between the basement and cover units. The western boundary of the inverted zone follows the westward pinch-out of the Zechstein salt. Here, thin-skinned folds and faults sole out into Zechstein units dipping into the half-graben. The most pronounced inversion structures occur directly above and in prolongation of salt anticlines and rollers that localized shortening in the cover above. With no physical links to underlying basement faults (if present), we balance thin-skinned shortening to the sub-salt basement via a triangle zone concept. This implies that thin Zechstein units on the dipping half-graben floor formed thrust detachments during inversion while basement shortening was mainly accommodated by reactivation of the major rift faults further east. Disseminated deformation (i.e. “ductile” at seismic scales) accounts for thin-skinned shortening of the cover units where such a detachment did not develop. The observed structural styles are discussed in relation to those found in other inverted basins in the North Sea Basin and to those produced from physical model experiments. Our results indicate that Zechstein units imposed a strong control on structural styles and kinematics not only during rift-related extension but also during basin inversion in large parts of the Danish Central Graben. Reactivated thin-skinned faults soling out into thin Triassic evaporite units within the carapace above Zechstein salt structures illustrate that even thin evaporite units may contribute to defining structures during tectonic extension and shortening. We thus provide an updated and dedicated case study of post-rift basin inversion, which takes into account the mechanical heterogeneity of sub-salt basement, salt, and supra-salt cover, including multiple evaporite units of which the Zechstein is the most important.
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Holford, Simon, Richard Hillis, Ian Duddy, Paul Green, Martyn Stoker, Adrian Tuitt, Guillaume Backé, David Tassone, and Justin MacDonald. "Cenozoic post-breakup compressional deformation and exhumation of the southern Australian margin." APPEA Journal 51, no. 1 (2011): 613. http://dx.doi.org/10.1071/aj10044.
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We present results from a margin-wide analysis of the history of post-breakup Cenozoic compressional deformation and related exhumation along the passive southern margin of Australia, based on a regional synthesis of seismic, stratigraphic and thermochronological data. The Cenozoic sedimentary record of the southern margin contains regional unconformities of intra-Lutetian and late Miocene–Pliocene age, which coincide with reconfigurations of the boundaries of the Indo-Australian Plate. Seismic data show that post-breakup compressional deformation and sedimentary basin inversion—characterised by reactivation of syn-rift faults and folding of post-rift sediments—is pervasive from the Gulf St Vincent to Gippsland basins, and occurred almost continually since the early- to mid-Eocene. Inversion structures are absent from the Bight Basin, which we interpret to be the result of both the unsuitable orientation of faults for reactivation with respect to post-breakup stress fields, and the colder, stronger lithosphere that underlies that part of the margin. Compressional deformation along the southeastern margin has mainly been accommodated by reactivation of syn-rift faults, resulting in folds with varying ages and amplitudes in the post-rift Cenozoic succession. Many hydrocarbon fields in the Otway and Gippsland basins are located in these folds, the largest of which are often associated with substantial localised exhumation. Our results emphasise the importance of constraining the timing of Cenozoic compression and exhumation in defining hydrocarbon prospectivity of the southern margin.
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Hinsch, Ralph, Chloé Asmar, Muhammad Nasim, Muhammad Asif Abbas, and Shaista Sultan. "Linked thick- to thin-skinned inversion in the central Kirthar Fold Belt of Pakistan." Solid Earth 10, no. 2 (March 22, 2019): 425–46. http://dx.doi.org/10.5194/se-10-425-2019.
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Abstract. The Kirthar Fold Belt is part of the transpressive transfer zone in Pakistan linking the Makran accretionary wedge with the Himalaya orogeny. The region is deforming very obliquely, nearly parallel to the regional S–N plate motion vector, indicating strong strain partitioning. In the central Kirthar Fold Belt, folds trend roughly N–S and their structural control is poorly understood. In this study, we use newly acquired 2-D seismic data with pre-stack depth migration, published focal mechanisms, surface and subsurface geological data, and structural modelling with restoration and balancing to constrain the structural architecture and kinematics of the Kirthar Fold Belt. The central Kirthar Fold Belt is controlled by Pliocene to recent linked thick-skinned to thin-skinned deformation. The thick-skinned faults are most likely partially inverting rift-related normal faults. Focal mechanisms indicate dip-slip faulting on roughly N–S-trending faults with some dip angles exceeding 40∘, which are considered too steep for newly initiated thrust faults. The hinterland of the study area is primarily dominated by strike-slip faulting. The inverting faults do not break straight through the thick sedimentary column of the post-rift and flexural foreland; rather, the inversion movements link with a series of detachment horizons in the sedimentary cover. Large-scale folding and layer-parallel shortening has been observed in the northern study area. In the southern study area progressive imbrication of the former footwall of the normal fault is inferred. Due to the presence of a thick incompetent upper unit (Eocene Ghazij shales) these imbricates develop as passive roof duplexes. In both sectors the youngest footwall shortcut links with a major detachment and the deformation propagates to the deformation front, forming a large fault-propagation fold. Shortening within the studied sections is calculated to be 18 %–20 %. The central Kirthar Fold Belt is a genuine example of a hybrid thick- and thin-skinned system in which the paleogeography controls the deformation. The locations and sizes of the former rift faults control the location and orientation of the major folds. The complex tectonostratigraphy (rift, post-rift, flexural foreland) and strong E–W gradients define the mechanical stratigraphy, which in turn controls the complex thin-skinned deformation.
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Giambiagi, L., S. Spagnotto, S. M. Moreiras, G. Gómez, E. Stahlschmidt, and J. Mescua. "Three-dimensional approach to understanding the relationship between the Plio–Quaternary stress field and tectonic inversion in the Triassic Cuyo Basin, Argentina." Solid Earth 6, no. 2 (June 19, 2015): 747–63. http://dx.doi.org/10.5194/se-6-747-2015.
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Abstract. The Cacheuta sub-basin of the Triassic Cuyo Basin is an example of rift basin inversion contemporaneous to the advance of the Andean thrust front, during the Plio–Quaternary. This basin is one of the most important sedimentary basins in a much larger Triassic NNW-trending depositional system along the southwestern margin of the Pangea supercontinent. The amount and structural style of inversion is provided in this paper by a three-dimensional approach to the relationship between inversion of rift-related structures and spatial variations in late Cenozoic stress fields. The Plio–Quaternary stress field exhibits important N–S variations in the foreland area of the southern Central Andes, between 33 and 34° S, with a southward gradual change from pure compression, with σ1 and σ2 being horizontal, to a strike-slip type stress field, with σ2 being vertical. We present a 3-D approach for studying the tectonic inversion of the sub-basin master fault associated with strike-slip–reverse to strike-slip faulting stress regimes. We suggest that the inversion of Triassic extensional structures, striking NNW to WNW, occurred during the Plio–Pleistocene in those areas with strike-slip–reverse to strike-slip faulting stress regime, while in the reverse faulting stress regime domain they remain fossilized. Our example demonstrates the impact of the stress regime on the reactivation pattern along the faults.
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Giambiagi, L., S. Spagnotto, S. M. Moreiras, G. Gómez, E. Stahlschmidt, and J. Mescua. "Three-dimensional approach to understanding the relationship between the Plio-Quaternary stress field and tectonic inversion in the Triassic Cuyo Basin, Argentina." Solid Earth Discussions 7, no. 1 (January 30, 2015): 459–94. http://dx.doi.org/10.5194/sed-7-459-2015.
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Abstract. The Cacheuta sub-basin of the Triassic Cuyo Basin is an example of rift basin inversion contemporaneous to the advance of the Andean thrust front, during the Plio-Quaternary. This basin is one of the most important sedimentary basins in a much larger Triassic NNW-trending depositional system along the southwestern margin of the Pangea supercontinent. The amount and structural style of inversion is provided in this paper by three-dimensional insights into the relationship between inversion of rift-related structures and spatial variations in late Cenozoic stress fields. The Plio-Quaternary stress field exhibits important N–S variations in the foreland area of the Southern Central Andes, between 33 and 34° S, with a southward gradually change from pure compression with σ1 and σ2 being horizontal, to a strike-slip type stress field with σ2 being vertical. We present a 3-D approach for studying the tectonic inversion of the sub-basin master fault associated with strike-slip/reverse to strike-slip faulting stress regimes. We suggest that the inversion of Triassic extensional structures, striking NNW to WNW, occurred during the Plio–Pleistocene in those areas with strike-slip/reverse to strike-slip faulting stress regime, while in the reverse faulting stress regime domain, they remain fossilized. Our example demonstrates the impact of the stress regime on the reactivation pattern along the faults.
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Lawrence, Sophie, Mark Thompson, Adrian Rankin, Joanna Alexander, Daniel Bishop, and Ben Boterhoven. "A new structural analysis of the Browse Basin, Australian North West Margin." APPEA Journal 54, no. 1 (2014): 1. http://dx.doi.org/10.1071/aj13001.
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A new structural analysis is presented for the Browse Basin of the Australian North West Margin, integrating new observations based on a regional 2D seismic data-set and potential field data. Previously published plate reconstructions and gravity inversion modelling were used to understand the mega-regional context of this interpretation and propose a new history of basin evolution. Key basin-forming northeast to southwest structural elements were developed during Carboniferous to Permian rifting, inherited fabrics from relaxed Proterozoic fold belts. Long-lived highs formed during this time delineated the structure of the basin through later Mesozoic rifting. Rifting was accommodated initially by inheritance of large basin-bounding Paleozoic listric faults and then development of new planar faults in the basin. This led to the formation of both rotated syn-rift sediment wedges and tilted fault block geometries. Structures related to several phases of inversion have been mapped, including a previously little-documented Early Cretaceous event. The influence of inherited structural trends and location of inversion structures is discussed. This work provides a new understanding of structural inheritance and rift architecture, and highlights the complexity of the inversion history of the Browse Basin. It has implications for petroleum systems development and the timing of potential hydrocarbon trap formation.
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Gómez, Manuel, Jaume Vergés, and Carlos Riaza. "Inversion tectonics of the northern margin of the Basque Cantabrian Basin." Bulletin de la Société Géologique de France 173, no. 5 (September 1, 2002): 449–59. http://dx.doi.org/10.2113/173.5.449.
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Abstract The northern margin of the Basque-Cantabrian Basin was analysed combining stratigraphic and structural data from both surface and subsurface together with reflectance of vitrinite data from oil wells. The use of cross-section balancing techniques in addition to thermal modelling enabled us to reconstruct the tectonic, burial and thermal evolutions of the basin margin as well as those of the Landes High to the N in two different periods. The section restoration at the end of the Cretaceous shows a northern basin margin structure influenced by evaporites related to south-dipping normal faults. The reconstruction in middle Eocene times yielded up to 1 800 m of Paleocene-middle Eocene deposits on top of the basin margin. Subsequent tectonic inversion related to the Pyrenean compression led to the north-directed thrusting of basement units and to the formation of thrust slices or inverted folds in the cover along the northern margin of the basin. Tectonic subsidence analysis together with maturity data provided evidence that oil was generated in the basin during the late syn-rift and post-rift stages in the Late Cretaceous and became overmature during the period of incipient inversion after 55 Ma. In the autochthonous Landes High, the oil was generated after the tectonic inversion period 37 Ma.
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O'Brien, G. W., R. Higgins, P. Symonds, P. Quaife, J. Colwell, and J. Blevin. "BASEMENT CONTROL ON THE DEVELOPMENT OF EXTENSIONAL SYSTEMS IN AUSTRALIA'S TIMOR SEA: AN EXAMPLE OF HYBRID HARD LINKED/SOFT LINKED FAULTING?" APPEA Journal 36, no. 1 (1996): 161. http://dx.doi.org/10.1071/aj95010.
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A series of rift models has been developed for basin systems in Australia's Timor Sea, via the interpretation of newly acquired deep crustal seismic and high resolution aeromagnetic data. These models, which incorporate observations on rift architecture, fault geometries, fault orientation, basement grain and composition, extensional transport direction and reactivation history, have then been iteratively tested by sophisticated analogue modelling experiments. This work has led to the development of a hybrid hard linked/soft linked (basement-involved/basement-detached) fault model. In this model, basement grain is the principal control on the rift architecture that develops, with pre-existing fracture systems acting to establish discrete offsets (hard linkages) between adjacent extensional faults. It is these basement features that produce the recti-linear features which are so common in aeromagnetic data around the Australian margin. With progressively greater extension, the basement-involved, hard linked system exerts no through-going (transfer fault-type) influence over the faulting within the overlying syn-rift phase, with the linkages between the syn-rift faults being 'soft' (via relay ramps, etc). However, as the hard links do act to relay the extensional faults or to flip their polarity (thereby typically producing cross-basinal highs), hard links strongly segment the extensional system into compartments of similar extensional style, and do control the relative positions of source rocks, fluid migration pathways and reservoirs within the rift. During basin reactivation (particularly inversion), the location and geometry of the underpinning, hard linked basement features closely control the locations of the traps that develop in the syn-and post-rift section, and the late-stage fluid flow history. When combined with aeromagnetic data, which define the location of the under-pinning, recti-linear, hard linked basement features, and some regional seismic data, these observations provide a first-pass predictive tool for determining where source depocentres, reservoirs and major structures are likely to be developed in a frontier basin, or where more subtle structural and/or stratigraphic traps might be found in a mature province.
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Shchetnikov, A. A. "Morphotectonic inversion in the Tunka rift basin ( southwestern Baikal region)." Russian Geology and Geophysics 58, no. 7 (July 2017): 778–86. http://dx.doi.org/10.1016/j.rgg.2016.10.014.
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Samson, C., and G. F. West. "Detailed basin structure and tectonic evolution of the Midcontinent Rift System in eastern Lake Superior from reprocessing of GLIMPCE deep reflection seismic data." Canadian Journal of Earth Sciences 31, no. 4 (April 1, 1994): 629–39. http://dx.doi.org/10.1139/e94-056.
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Line F of the GLIMPCE deep marine reflection seismic survey has been reprocessed according to a data-dependent strategy aimed at enhancing the fine structural features of the Midcontinent Rift System in eastern Lake Superior. The processing sequence was specially designed to attenuate first-order water reverberations and to reduce the excessive oscillatory character of the basic wavelet. A detailed examination of the final migrated stacked section reveals that, beneath line F, the Midcontinent Rift System is an almost perfectly symmetric syncline. The structure appears to have formed in the beginning by the extrusion of lavas on a horizontal platform subsiding without major deformation. The initial phase was followed by local crustal sagging in the centre. The transition is marked by a major reflector, which is hypothesized to correspond to the boundary between reverse- and normal-polarity volcanics in eastern Lake Superior. Integrating the results of several recent investigations, a five-stage evolutionary scenario is proposed for the Midcontinent Rift System in eastern Lake Superior: (1) onset of extrusive volcanism, (2) platform subsidence, (3) local crustal sagging, (4) deposition of postrift sediments, and (5) tectonic inversion.
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Belgarde, Catherine, Gianreto Manatschal, Nick Kusznir, Sonia Scarselli, and Michal Ruder. "Rift processes in the Westralian Superbasin, North West Shelf, Australia: insights from 2D deep reflection seismic interpretation and potential fields modelling." APPEA Journal 55, no. 2 (2015): 400. http://dx.doi.org/10.1071/aj14035.
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Acquisition of long-offset (8–10 km), long-record length (12–18 sec), 2D reflection seismic and ship-borne potential fields data (WestraliaSpan by Ion/GXT and New Dawn by PGS) on the North West Shelf of Australia provide the opportunity to study rift processes in the context of modern models for rifted margins (Manatschal, 2004). Basement and Moho surfaces were interpreted on seismic reflection data. Refraction models from Geoscience Australia constrain Moho depth and initial densities for gravity modelling through standard velocity-density transformation. 2D joint inversion of seismic reflection and gravity data for Moho depth and basement density constrain depth to basement on seismic. 2D gravity and magnetic intensity forward modelling of key seismic lines constrain basement thickness, type and density. Late Permian and Jurassic-Early Cretaceous rift zones were mapped on seismic reflection data and constrained further by inversion and forward modelling of potential fields data. The Westralian Superbasin formed as a marginal basin in Eastern Gondwana during the Late Permian rifting of the Sibumasu terrane. Crustal necking was localised along mechanically-weak Proterozoic suture belts or Early Paleozoic sedimentary basins (such as Paterson and Canning). Mechanically-strong cratons (such as Pilbara and Kimberley) remained intact, resulting in necking and hyper-extension at their edges. Late Permian hyper-extended areas (such as Exmouth Plateau) behaved as mechanically-strong blocks during the Jurassic to Early Cretaceous continental break-up. Late Permian necking zones were reactivated as failed-rift basins and localised the deposition of the Jurassic oil-prone source rocks that have generated much of the oil discovered on the North West Shelf.
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Unger, A. V., A. M. Nikishin, M. A. Kuzlyapina, and A. P. Afanasenkov. "History of the inversion megaswells of the Yenisei-Khatanga basin development." Moscow University Bulletin. Series 4. Geology, no. 2 (April 28, 2017): 8–15. http://dx.doi.org/10.33623/0579-9406-2017-2-8-15.
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Paper presents description of Balakhninsky and Rassohinsky swells, which were located in the central part of the Yenisei-Khatanga Basin by seismic and drilling data, and the results of its geological structure comparative analysis. History of swells formation discussed in de- tails, including rift initiation in the Late Permian-Early Triassic time and stages of inversion structures growth intensification in the Middle Triassic, Late Jurassic, Early Cretaceous and Cenozoic time. Asynchronous development of these structures established on the base of paleoreconstruction analysis.
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Osorio Afanador, Diego, and Francisco Velandia. "Late Jurassic syn-extensional sedimentary deposition and Cenozoic basin inversion as recorded in The Girón Formation, northern Andes of Colombia." Andean Geology 48, no. 2 (May 31, 2021): 237. http://dx.doi.org/10.5027/andgeov48n2-3264.
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The Yariguíes Anticlinorium, a regional structure located at the western flank of the Eastern Cordillera of Colombia, includes the thickest record of continental sedimentary rocks accumulated near to the Jurassic-Cretaceous boundary. The sedimentary rocks are lithoarenites and feldspathic arenites, grouped in the Girón Formation, and deposited in a Late Jurassic extensional basin interpreted in this work as a rift basin. We analysed the sedimentologic and compositional characteristics of two sections that accumulated in a complex rift system. We identified important thickness variations, from 3,350 m in the type section to at least 525 m in a reference section in the Zapatoca area, as well as petrographic and lithofacies changes. This led us to confirm that the Girón Formation encompasses all the continental facies, whose source rock correspond mainly to the exhumed blocks of the Santander Massif during the Late Jurassic. The synrift successions were segmented by transverse structures and regional longitudinal faults of the rift-shoulder, as the Suárez Fault. The tectonic frame of the study area shows the relevance of the W-E compressional regimes, explaining the local kinematics as a heritage of the former configuration and tectonic inversion of the basins. However, clockwise rotation of the stress field was detected from the stress tensor analysis. The latest orientation of the stress tensors and shear joints are related to the effect of the transpressional Bucaramanga and Lebrija faults along the study area.
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Jentzsch, G., R. Mahatsente, and T. Jahr. "Three dimensional inversion of gravity data from the main ethiopian Rift." Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy 25, no. 4 (January 2000): 365–73. http://dx.doi.org/10.1016/s1464-1895(00)00058-2.
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Mahatsente, R., G. Jentzsch, and T. Jahr. "Three-dimensional inversion of gravity data from the Main Ethiopian Rift." Journal of African Earth Sciences 31, no. 2 (August 2000): 451–66. http://dx.doi.org/10.1016/s0899-5362(00)00099-3.
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de Castro, David Lopes, Nilo Costa Pedrosa, and Fernando Acácio Monteiro Santos. "Gravity–geoelectric joint inversion over the Potiguar rift basin, NE Brazil." Journal of Applied Geophysics 75, no. 3 (November 2011): 431–43. http://dx.doi.org/10.1016/j.jappgeo.2011.07.022.
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Fambrini, Gelson Luís, Wellington Ferreira da Silva-Filho, Diógenes Ribeiro de Lemos, Diego Da Cunha Silvestre, Jadson Trajano de Araújo, José Acioli Bezerra de Menezes-Filho, Sidney Tesser Junior, and Virginio Henrique De Miranda Lopes Neumann. "Análise tectonossedimentar das fases início de rifte e clímax de rifte da Bacia do Araripe, Nordeste do Brasil." Geologia USP. Série Científica 19, no. 3 (October 14, 2019): 205–36. http://dx.doi.org/10.11606/issn.2316-9095.v19-150526.
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Este trabalho objetivou a caracterização tectonossedimentar das fases início de rifte e clímax de rifte da Bacia do Araripe. As principais estruturas identificadas foram falhas normais, transcorrentes e inversas em ordem de importância. Esse grupo de falhas coloca lateralmente diferentes unidades litoestratigráficas como rochas de unidades início de rifte e clímax de rifte. Exemplo é o contato lateral das formações Missão Velho e Brejo Santo ao longo de falhas normais NNE. É de grande importância a integração entre análise geométrica e cinemática dessas falhas com a evolução estratigráfica para uma evolução global da evolução geológica da Bacia do Araripe. Principais afloramentos de campo utilizados neste trabalho consistem em exposições formadas durante as obras de construção da ferrovia Transnordestina e da transposição do Rio São Francisco. A análise tectônica realizada para este trabalho identificou dois conjuntos principais de falhas: falhas orientadas segundo a direção NE-SW (mais antigas) e falhas orientadas na direção NW-SE e WNW-ESE (mais jovens). Além disso, foram também analisadas falhas transcorrentes e inversas. A tectônica rifte que afetou a Bacia do Araripe (extensional) reativou falhas antigas do embasamento Pré-Cambriano e, por sua vez, forneceu falhas normais de direção NE-SW e também gerou falhas de orientação E-W e NW-SE.
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Almeida, Gisela Miranda de Souza, and Caroline Janette Souza Gomes. "Modelagem física da deformação pós-sal em bacias invertidas." Geologia USP. Série Científica 20, no. 2 (April 16, 2020): 3–17. http://dx.doi.org/10.11606/issn.2316-9095.v20-157870.
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Este estudo analisou, em modelos físicos, uma inversão tectônica positiva de bacias com uma camada de sal na sequência pós-rifte. O intuito foi examinar a influência da variação da resistência à deformação da camada dúctil sobre a estruturação da sobrecarga, variando-se as espessuras do silicone (simulando sal) e da sobrecarga, e a velocidade de inversão. Os ensaios foram montados em caixas de areia com dimensões de 35 × 23,4 cm (comprimento × largura), nos quais o embasamento (a sequência pré-rifte) foi simulado por um pacote de areia. Após a fase de distensão e subsequente preenchimento da bacia recém-formada, depositou-se a sequência pós-rifte: um substrato de areia, uma camada de silicone e uma sobrecarga, também de areia. Cortes efetuados nos modelos úmidos após a deformação final de inversão revelaram que o número de falhas na sobrecarga variou significativamente em decorrência da variação da resistência à deformação tanto da camada dúctil quanto da sobrecarga rúptil. No caso da camada dúctil, de silicone, a resistência à deformação cresceu com o aumento da velocidade de deformação, enquanto para a sequência rúptil, de areia, a resistência cresceu quando se elevou a espessura da sobrecarga. Por outro lado, o aumento da espessura da camada dúctil produziu um decréscimo em sua resistência à deformação e acomodou por fluxo a deformação, internamente. A formação de estruturas rúpteis na sobrecarga foi associada ao desenvolvimento de falhas compressivas no pré- e sin-rifte, nucleadas durante a inversão. A reativação de falhas normais somente gerou falhas na sobrecarga quando caracterizadas por alto rejeito. Feições similares ocorrem na Bacia de Tucumán (Argentina).
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Piana Agostinetti, Nicola, Francesca Martini, and Joe Mongan. "Sedimentary basin investigation using receiver function: an East African Rift case study." Geophysical Journal International 215, no. 3 (October 2, 2018): 2105–13. http://dx.doi.org/10.1093/gji/ggy405.
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SUMMARY We apply receiver function (RF) methodology to map the geometry of a sedimentary basin along a ∼10-km-long profile of broadband seismometers that recorded continuously for approximately 3 months. For a subset of the stations, we apply the Neighbourhood Algorithm inversion scheme, to quantify the geometry of basin bounding fault directly beneath the stations. We compare our results with active reflection seismic data and with the lithostratigraphy from a well located along the profile. We find that the P-to-s conversions from the sediments–basement interface (SBI), recorded in RF data sets together with information on intrabasin structures, are useful for obtaining high resolution images of the basin. The depth of the SBI derived from RF inversion is consistent (within ∼0.4 km) with the estimates from active reflection seismic and the well data. This study highlights that analysis of teleseismic waveforms can retrieve relevant information on the structure of a sedimentary basin.
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Anderson, Alan D., Murray S. Durham, and Andrew J. Sutherland. "THE INTEGRATION OF GEOLOGY AND GEOPHYSICS TO POST-WELL EVALUATIONS - EXAMPLE FROM BELUGA-I, OFFSHORE NORTHERN AUSTRALIA." APPEA Journal 33, no. 1 (1993): 15. http://dx.doi.org/10.1071/aj92002.
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The Beluga 1 well was drilled in May 1991 in Permit NT/P41 in the Arafura Sea to test a seismically identified stratigraphic trap in Late Jurassic - Early Cretaceous age syn-rift sediments on the southern flank of the Malita Graben. A continuous high amplitude seismic event defined a lithologic package prognosed as a rift infill sand prone fan sequence interpreted to have been sourced from the adjacent southern platform.The target section penetrated by the well was found to consist predominantly of a uniform sequence of bioturbated fine sandstones with poor porosity and almost nil permeability indicating distal deposition.Post well evaluation of Beluga 1, utilizing a variety of well and seismic measurements, showed evidence for several episodes of basin inversion within the juvenile Malita Graben. Reinterpretation resulted in a new structural and depositional model which accounted for the well result and has implications for future exploration in this area and lowstand fan studies in general.
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KOTHYARI, G. C., R. K. DUMKA, A. P. SINGH, G. CHAUHAN, M. G. THAKKAR, and S. K. BISWAS. "Tectonic evolution and stress pattern of South Wagad Fault at the Kachchh Rift Basin in western India." Geological Magazine 154, no. 4 (June 27, 2016): 875–87. http://dx.doi.org/10.1017/s0016756816000509.
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AbstractWe describe a study of the E–W-trending South Wagad Fault (SWF) complex at the eastern part of the Kachchh Rift Basin (KRB) in Western India. This basin was filled during Late Cretaceous time, and is presently undergoing tectonic inversion. During the late stage of the inversion cycle, all the principal rift faults were reactivated as transpressional strike-slip faults. The SWF complex shows wrench geometry of an anastomosing en échelon fault, where contractional and extensional segments and offsets alternate along the Principal Deformation Zone (PDZ). Geometric analysis of different segments of the SWF shows that several conjugate faults, which are a combination of R synthetic and R’ antithetic, propagate at a short distance along the PDZ and interact, generating significant fault slip partitioning. Surface morphology of the fault zone revealed three deformation zones: a 500 m to 1 km wide single fault zone; a 5–6 km wide double fault zone; and a c. 500 m wide diffuse fault zone. The single fault zone is represented by a higher stress accumulation which is located close to the epicentre of the 2001 Bhuj earthquake of Mw 7.7. The double fault zone represents moderate stress at releasing bends bounded by two fault branches. The diffuse fault zone represents a low-stress zone where several fault branches join together. Our findings are well corroborated with the available geological and seismological data.
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Manson, Matthew L., and Henry C. Halls. "Proterozoic reactivation of the southern Superior Province and its role in the evolution of the Midcontinent rift." Canadian Journal of Earth Sciences 34, no. 4 (April 1, 1997): 562–75. http://dx.doi.org/10.1139/e17-045.
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Major reverse faults associated with the late compressional phase of the 1.1 Ga Midcontinent rift in the western Lake Superior region appear to cut across the rift at the eastern end of the lake and join with reverse faults on the eastern shoreline, defined on the basis of geological and potential field data. The continuation of the faults across eastern Lake Superior is inferred on evidence drawn from nearshore shipborne magnetic surveys together with new interpretations of published bathymetric and GLIMPCE aeromagnetic data. In the Archean Superior Province about 100 km east of Lake Superior, paleomagnetic and petrographic data from the 2.45 Ga Matachewan dyke swarm show that the Kapuskasing Zone, a narrow belt of uplifted crust, can be extended to within 50 km of the Lake Superior shoreline and has bounding reverse faults that are almost continuous with two faults of similar dip and sense of displacement that define the inversion of the Midcontinent rift in the central and western parts of the lake. Since the Kapuskasing Zone is dominantly a Paleoproterozoic (about 1.9 Ga) structure, the continuity suggests that the Lake Superior faults, whose last major activity was during the Grenville Orogen, may represent reactivation of much older faults that were part of an extended Kapuskasing structure. Within the Superior Province to the north and east of Lake Superior, published radiometric data on biotites suggest a series of alternating crustal blocks of varying tectonic stability, separated by northeast-trending faults. The Lake Superior segment of the Midcontinent rift developed within the most unstable block, bounded by the Gravel River fault to the northwest and the Ivanhoe Lake fault (the eastern margin of the Kapuskasing Zone) to the southeast.
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El Hassan, Waleed Mohamed, Abdalla Gumaa Farwa, and Mohamed Zayed Awad. "Inversion tectonics in Central Africa Rift System: Evidence from the Heglig Field." Marine and Petroleum Geology 80 (February 2017): 293–306. http://dx.doi.org/10.1016/j.marpetgeo.2016.12.007.
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Dunham, C. K., J. P. O’Donnell, G. W. Stuart, A. M. Brisbourne, S. Rost, T. A. Jordan, A. A. Nyblade, D. A. Wiens, and R. C. Aster. "A joint inversion of receiver function and Rayleigh wave phase velocity dispersion data to estimate crustal structure in West Antarctica." Geophysical Journal International 223, no. 3 (August 22, 2020): 1644–57. http://dx.doi.org/10.1093/gji/ggaa398.
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SUMMARY We determine crustal shear wave velocity structure and crustal thickness at recently deployed seismic stations across West Antarctica, using a joint inversion of receiver functions and fundamental mode Rayleigh wave phase velocity dispersion. The stations are from both the UK Antarctic Network (UKANET) and Polar Earth Observing Network/Antarctic Network (POLENET/ANET). The former include, for the first time, four stations along the spine of the Antarctic Peninsula, three in the Ellsworth Land and five stations in the vicinity of the Pine Island Rift. Within the West Antarctic Rift System (WARS) we model a crustal thickness range of 18–28 km, and show that the thinnest crust (∼18 km) is in the vicinity of the Byrd Subglacial Basin and Bentley Subglacial Trench. In these regions we also find the highest ratio of fast (Vs = 4.0–4.3 km s–1, likely mafic) lower crust to felsic/intermediate upper crust. The thickest mafic lower crust we model is in Ellsworth Land, a critical area for constraining the eastern limits of the WARS. Although we find thinner crust in this region (∼30 km) than in the neighbouring Antarctic Peninsula and Haag-Ellsworth Whitmore block (HEW), the Ellsworth Land crust has not undergone as much extension as the central WARS. This suggests that the WARS does not link with the Weddell Sea Rift System through Ellsworth Land, and instead has progressed during its formation towards the Bellingshausen and Amundsen Sea Embayments. We also find that the thin WARS crust extends towards the Pine Island Rift, suggesting that the boundary between the WARS and the Thurston Island block lies in this region, ∼200 km north of its previously accepted position. The thickest crust (38–40 km) we model in this study is in the Ellsworth Mountain section of the HEW block. We find thinner crust (30–33 km) in the Whitmore Mountains and Haag Nunatak sectors of the HEW, consistent with the composite nature of the block. In the Antarctic Peninsula we find a crustal thickness range of 30–38 km and a likely dominantly felsic/intermediate crustal composition. By forward modelling high frequency receiver functions we also assess if any thick, low velocity subglacial sediment accumulations are present, and find a 0.1–0.8-km-thick layer at 10 stations within the WARS, Thurston Island and Ellsworth Land. We suggest that these units of subglacial sediment could provide a source region for the soft basal till layers found beneath numerous outlet glaciers, and may act to accelerate ice flow.
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Mariano, John, and William J. Hinze. "Gravity and magnetic models of the Midcontinent Rift in eastern Lake Superior." Canadian Journal of Earth Sciences 31, no. 4 (April 1, 1994): 661–74. http://dx.doi.org/10.1139/e94-059.
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Gravity and magnetic models of the Midcontinent Rift (MCR) in eastern Lake Superior supplement recent structural and stratigraphic interpretations based on the seismic reflection method. An algorithm developed to accommodate spatially varying direction and magnitude of magnetization within a magnetic source is used in both forward and inverse modeling procedures. Structural attitudes of rift-filling basalts derived from seismic reflection sections are used to rotate the Keweenawan remanent magnetization vectors in the direction of deformation. An iterative linear inversion routine calculates magnitudes of induced and remanent magnetizations, as well as normal and reversed polarity basalt flow distributions. The results indicate that the Koenigsberger ratios of these basalts generally range from 1 to 3, which is in agreement with values obtained from rock property measurements. The models also suggest that the greater volume of the Keweenawan basalt section in eastern Lake Superior is reversely polarized and that remanent magnetizations persist to depths of up to 20 km. Our results, supplemented by isotopic and paleomagnetic data, suggest that the vast majority of the basalts predate 1097 ± 1 Ma. A prominent positive magnetic anomaly and a corresponding gravity low strike west across the trend of the rift from the vicinity of Michipicoten Island. These anomalies may reflect a relatively strongly magnetized, felsic igneous body of late-middle to upper Keweenawan in age. Forward gravity models suggest clastic sedimentary rocks up to several kilometers thick overlay the volcanic rocks in localized depressions. Deep crustal seismic data used to constrain gravity models provide evidence of anomalously dense lower crust beneath the MCR.
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Tiberi, C., M. Diament, H. Lyon-Caen, and T. King. "Moho topography beneath the Corinth Rift area (Greece) from inversion of gravity data." Geophysical Journal International 145, no. 3 (June 2001): 797–808. http://dx.doi.org/10.1046/j.1365-246x.2001.01441.x.
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O'Brien, G. W., M. Morse, D. Wilson, P. Quaife, J. Colwell, R. Higgins, and C. B. Foster. "MARGIN-SCALE, BASEMENT-INVOLVED COMPARTMENTALISATION OF AUSTRALIA'S NORTH WEST SHELF: A PRIMARY CONTROL ON BASIN-SCALE RIFT, DEPOSITION AL AND REACTIVATION HISTORIES." APPEA Journal 39, no. 1 (1999): 40. http://dx.doi.org/10.1071/aj98003.
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Australia's North West Shelf is segmented into four discrete margin-scale compartments which have distinct rift and reactivation histories. Two of the margin segments, the Carnarvon and Bonaparte compartments, are very wide (500–600 km), marginal plateau systems, whereas the other two segments, the Canning and Browse compartments, are narrower and steeper. The boundaries between individual rift compartments appear to be controlled by Proterozoic fracture systems.The Browse-Bonaparte transition zone is a major, northwest-trending Proterozoic fracture system which has a series of igneous intrusions along its length. These intrusions are located where the fracture system is cut by younger, northeast-trending extensional faults. This transition zone is a margin-scale fault relay zone, with intense fault overlap along the transition resulting in the zone being a long-lived, syn-rift high. Moreover, the transition zones between adjacent wide and narrow margins are prime locations for the entry point of siliciclastics into the rift or post-rift margin system. As a result, well-developed channel systems often cut through these boundaries and high quality reservoirs (particularly low-stand fans) are developed.Neogene fault reactivation, associated with convergence of the Australasian and Eurasian plates, is evident along the North West Shelf. The style of this reactivation is, however, closely controlled by the margin- scale architecture. In the Browse and Carnarvon basins, Neogene inversion is common, but at the leading edge of the collisional system, the Bonaparte compartment, the fault style is exclusively extensional. It appears that lithospheric flexure, associated with localised foreland development (i.e. the Timor Trough), has been the driving mechanism for the extensional faulting within the Bonaparte compartment. Crustal convergence seems to have been accommodated completely by thrusting on the northwestern margin of Timor and by foreland formation. In contrast, the Browse and Carnarvon compartments lacked a 'buffering' foreland system and, being adjacent to rigid and thin oceanic crust which transmits stress well over long distances, the inversional stresses were transmitted directly into these compartments.As a result of these margin-scale processes, the Bonaparte compartment is characterised by a thin regional seal (often 100 ms) on Neogene extensional faults—a combination which strongly favours fault seal failure and trap breach. In contrast, the Browse compartment is characterised by thick seals and small displacement Neogene faults, and thus the probability of fault seal failure is much less.
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LAFOSSE, MANFRED, ALEXANDRE BOUTOUX, NICOLAS BELLAHSEN, and LAETITIA LE POURHIET. "Role of tectonic burial and temperature on the inversion of inherited extensional basins during collision." Geological Magazine 153, no. 5-6 (June 28, 2016): 811–26. http://dx.doi.org/10.1017/s0016756816000510.
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AbstractThe style of inversion of inherited extensional basins in the Western Alps is investigated through thermo-mechanical modelling. Two-dimensional models consist of a half-graben embedded in a relatively strong crust (basement) and filled with weak syn-rift sediments (cover). We investigate the relative influence of the internal friction (µ) of the basin-bounding normal fault, tectonic burial (h) under an overlying nappe and the geothermal gradient. We use a viscoplastic model with symmetrical shortening. The inherited normal fault is implemented as a curved thin body with a variable friction coefficient (µ) ranging from 0.1 to 0.6. The style of basin inversion is controlled at shallow depth by the internal friction coefficient, whose influence decreases with the increase of both burial depth and geothermal gradient. With increasing burial and/or geothermal gradient, fault reactivation is inhibited and distributed deformation in the basement induces the vertical extrusion of the cover. The basin inversion is accompanied by distributed deformation in the cover and by the shearing of the basin and basement interface. The results are consistent with the style of inversion of inherited half-grabens in the external Western Alps, where no significant fault reactivation occurred owing to tectonic burial underneath the Alpine internal units during the early Alpine collision.
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Kahn, Daniel, Michael Lindenfeld, Georg Rumpke, and Kevin Aanyu. "Local inversion in rifts triggered by micro-plate rotation." Geotectonic Research 95 (June 1, 2008): 85–86. http://dx.doi.org/10.1127/1864-5658/08/9501-0085.
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Deng, Hongling, Hemin A. Koyi, and Jinjiang Zhang. "Modelling oblique inversion of pre-existing grabens." Geological Society, London, Special Publications 487, no. 1 (January 22, 2019): 263–90. http://dx.doi.org/10.1144/sp487.5.
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AbstractA series of analogue models were run to investigate oblique inversion of pre-existing grabens when overprinted by later shortening and the effect of these grabens on development of contractional structures. Obliquity angle (α) defining the initial trend of pre-existing grabens relative to the shortening direction, was systematically changed from 0°, 10°, 20°, 30°, 40°, 50°, 65° and 90°. Different structural styles are shown in different models and also in sections cutting across different parts of the models. Model results show that existence of multi-grabens enhances lateral discontinuity of overprinted thrusts in map view. With increasing the obliquity angle, more and longer lateral ramps developed sub-parallel to the graben trends. The pre-existing grabens were apparently rotated from their initial trends during shortening. Some of the normal faults bounding the grabens were partially inverted and resulted in bulging of the syn- and post-rift graben fill sediments. Most normal faults were displaced and rotated by thrusting, and provided relatively weak zones for propagation of thrusts. By comparing with observations from Qingxi graben in western China and from the SW Taiwan fold-and-thrust belt, where oblique inversion occurred, model results can be used to interpret unclear relationships between thrusts and pre-existing extensional structures during superimposed deformation.
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Gomes, Caroline J. S., Marcelo A. Martins-Neto, and Valéria E. Ribeiro. "Positive inversion of extensional footwalls in the southern Serra do Espinhaço, Brazil - insights from sandbox laboratory experiments." Anais da Academia Brasileira de Ciências 78, no. 2 (June 2006): 331–44. http://dx.doi.org/10.1590/s0001-37652006000200012.
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Analogue experiments were carried out to get insights into the processes governing positive inversion during the foreland propagating thrust tectonics in the southern Serra do Espinhaço, a Brasiliano/Panafrican foldthrust belt in southeast Brazil. In particular, model listric half-grabens were inverted by applying contractional displacement to the footwall blocks. We investigated two different inversion conditions in listric half-grabens: (i) extensional and contractional detachments at the same level and (ii) at different positions. The models revealed that the development of a forward-breaking thrust system occurs in the basin synrift deposits, by contractional translation of the extensional footwall block when the extensional and contractional master faults do not coincide. Our experiments show the tectonic imbrication between basement and synrift sequences which characterizes the southern Serra do Espinhaço, and support the location in the eastern mountain range domain of the Espinhaço rift master fault system, which is not exposed at the surface.
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Branquet, Y., A. Cheilletz, P. R. Cobbold, P. Baby, B. Laumonier, and G. Giuliani. "Andean deformation and rift inversion, eastern edge of Cordillera Oriental (Guateque–Medina area), Colombia." Journal of South American Earth Sciences 15, no. 4 (September 2002): 391–407. http://dx.doi.org/10.1016/s0895-9811(02)00063-9.
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Bannister, S., R. K. Snieder, and M. L. Passier. "Shear-wave velocities under the Transantarctic Mountains and terror rift from surface wave inversion." Geophysical Research Letters 27, no. 2 (January 15, 2000): 281–84. http://dx.doi.org/10.1029/1999gl010866.
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Eilon, Zachary, Geoffrey A. Abers, and James B. Gaherty. "A joint inversion for shear velocity and anisotropy: the Woodlark Rift, Papua New Guinea." Geophysical Journal International 206, no. 2 (May 1, 2016): 807–24. http://dx.doi.org/10.1093/gji/ggw177.
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Crémades, Antoine, Mary Ford, and Julien Charreau. "Evidence of decoupled deformation during Jurassic rifting and Cenozoic inversion phases in the salt-rich Corbières-Languedoc Transfer Zone (Pyreneo-Provençal orogen, France)." BSGF - Earth Sciences Bulletin 192 (2021): 37. http://dx.doi.org/10.1051/bsgf/2021022.
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A detailed field study of Jurassic tectono-stratigraphic architecture of the southwestern part of the Corbières-Languedoc Transfer Zone (CLTZ, NE-SW oriented), between the Pyrenean and Provençal orogenic segments (N110 oriented) in SE France, document for the first time variations in thickness and stratigraphic geometries in relation to oblique extensional cover structures (NE-SW and N110 oriented). These structures (low-dip normal faults, salt rollers, rollovers, forced folds) formed during a Jurassic extension phase with strong decoupling between basement and cover on the Keuper pre-rift salt (Carnian-Norian evaporites). Some of these structures such as the Treilles Fault, the Valdria and the Terres Noires fold pairs, were previously interpreted as compressional and Pyrenean in origin (Late Santonian-Bartonian). Our study instead shows that these are Jurassic extensional and salt related structures, which were later affected by Pyrenean compression and Oligo-Miocene extension. Evidence of Jurassic extension is still observable in the field despite later rectivations, making these good field analogs for gently inverted extensional salt structures. During the Jurassic the interference between oblique structures above Keuper, leads to the formation of three dimensional growth strata observable at kilometric scale. Despite the mechanical decoupling effect of Keuper, we infer that their formation was linked to a strong interaction between oblique basement structures (NE-SW and N110) as the area lies during the Jurassic at the intersection between the eastern part of the Pyrenean E-W trending rift system and the NE-SW trending European margin of the Alpine Tethys rift. The decoupled deformation and the strong segmentation above and below Keuper detachement are here identified as Jurassic structural inheritence for later tectonic events, notably for the Nappe des Corbières Orientales emplaced at the end of Pyrenean orogenesis. Associated to previous works, this study highlights that the CLTZ is a key area to better understand Pyreneo-Provençal system evolution along its whole Wilson cycle and to better understand the processes that govern the formation of a salt-rich transfer zone in a strongly pre-structured crust, its multiple reactivations and the decoupling role of salt.
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Fragoso-Irineo, Anaid, Javier Lazcano, Roberto S. Molina-Garza, and Alexander Iriondo. "Estimación gravimétrica del grosor cortical en el Golfo de California." Boletín de la Sociedad Geológica Mexicana 73, no. 1 (April 1, 2021): A270820. http://dx.doi.org/10.18268/bsgm2021v73n1a270820.
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En este estudio se implementa la inversión 3D de datos gravimétricos satelitales mediante el programa 3DINVER.M para modelar el grosor de la corteza en el rift del Golfo de California. Este rift oblicuo separa dextralmente la península de Baja California del continente de Norteamérica desde el Mioceno, periodo en el que se produjo el cambio desde un régimen tectónico fundamentalmente extensional al transtensional presente. A lo largo de su eje, el rift del Golfo de California se encuentra en una fase de oceanización incipiente en varias cuencas de su mitad meridional, mientras que al norte la presencia de corteza oceánica es controvertida. A consecuencia de esta particularidad, la corteza de la cuenca marina del Golfo y la de regiones terrestres adyacentes presentan importantes diferencias de densidad y grosor, siendo ambos parámetros fundamentales del método empleado, y, por ello, se realiza un modelo específico para cada dominio. Los modelos de grosor cortical generados se compararon con las estimaciones puntuales previas basadas en métodos sísmicos, obteniéndose que el 98% de los puntos confrontados del modelo marino y el 87% del terrestre se ajustan a un rango de ±6 km de diferencia, con diferencias promedio absolutas de 1.5 km y de 3.5 km respectivamente. La cuenca del Golfo en los modelos evoluciona a lo largo de su eje y desde el sur al norte desde una corteza híper-adelgazada (~8−12 km), característica de corteza oceánica a transicional, hasta una corteza continental moderadamente adelgazada (~12−18 km). En al área extendida circundante, que completa la denominada como Provincia Extensional del Golfo, la corteza continental varía habitualmente entre ~15 y ~28 km, mientras que en sus flancos la corteza llega a alcanzar los ~35−40 km en los dominios más engrosados (Sierra Madre Occidental y Meseta del Colorado). Asimismo, con base en las estimaciones del grosor cortical y la geología regional, se propone una nueva demarcación para la Provincia Extensional del Golfo.
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Hassan Aden, Abdek, Jasmin Raymond, Bernard Giroux, and Bernard Sanjuan. "New Insights into Hydrothermal Fluid Circulation Affected by Regional Groundwater Flow in the Asal Rift, Republic of Djibouti." Energies 14, no. 4 (February 22, 2021): 1166. http://dx.doi.org/10.3390/en14041166.
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The Asal Rift hosts a lake located in a depression at 150 m below sea level, where recharge is influenced by regional groundwater flow interacting with the Ghoubbet Sea along the coast of Djibouti. This regional groundwater flow is believed to influence hydrothermal fluid circulation, which we aim to better understand in this study, having the objective of developing concepts for geothermal exploration in the area. To this end, magnetotelluric data acquired in the Asal Rift were processed and analyzed. 1D inversion models of electrical conductivity were interpolated for interpretation. These data were then used to build a 2D hydrogeological model, allowing multiphase flow and heat transfer simulations to be performed, considering the regional groundwater flow near the surface and the site topography, in order to confirm the preferred path of fluid flow. Geophysical data analysis indicates the presence of normal faults, notably the H fault, which may act as a conduit for the circulation of hydrothermal fluids and where the hanging wall can be a hydrogeological barrier within the hydrothermal system of the Asal Rift. The results from the 2D numerical flow and heat transfer modelling show the importance of groundwater flow responsible for thermal springs located at the periphery of Asal Lake. Reservoir temperature inferred by means of geothermometry ranging from 200 to 270 °C was shown to correspond to simulated temperature at potential reservoir depth. Moreover, simulated temperature between 600 and 1700 m depth is close to the temperature profile measured in the geothermal well Asal 6 of the area, with less than 20 °C difference. Simulations indicate that hydrothermal fluid circulation is likely influenced by the regional groundwater flow controlled by the topography and the major water bodies, the Ghoubbet Sea and Asal Lake, feeding buoyant fluids interacting with a deep magmatic source and where tectonic activity created normal faults offering a preferred path for fluid circulation.
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Peace, Alexander, Edward Dempsey, Christian Schiffer, J. Welford, Ken McCaffrey, Jonathan Imber, and Jordan Phethean. "Evidence for Basement Reactivation during the Opening of the Labrador Sea from the Makkovik Province, Labrador, Canada: Insights from Field Data and Numerical Models." Geosciences 8, no. 8 (August 20, 2018): 308. http://dx.doi.org/10.3390/geosciences8080308.
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The onshore exposures adjacent to modern, offshore passive continental margins may preserve evidence of deformation from the pre-, syn-, and post-rift phases of continental breakup that allow us to investigate the processes associated with and controlling rifting and breakup. Here, we characterize onshore brittle deformation and pre-rift basement metamorphic mineral fabric from onshore Labrador in Eastern Canada in the Palaeoproterozoic Aillik Domain of the Makkovik Province. Stress inversion (1) was applied to these data and then compared to (2) numerical models of hybrid slip and dilation tendency, (3) independent calculations of the regional geopotential stress field, and (4) analyses of palaeo-stress in proximal regions from previous work. The stress inversion shows well-constrained extensional deformation perpendicular to the passive margin, likely related to pre-breakup rifting in the proto-Labrador Sea. Hybrid slip and dilatation analysis indicates that inherited basement structures were likely oriented in a favorable orientation to be reactivated during rifting. Reconstructed geopotential stresses illuminate changes of the ambient stress field over time and confirm the present paleo-stress estimates. The new results and numerical models provide a consistent picture of the late Mesozoic-Cenozoic lithospheric stress field evolution in the Labrador Sea region. The proto-Labrador Sea region was characterized by a persistent E–W (coast-perpendicular) extensional stress regime, which we interpret as the pre-breakup continental rifting that finally led to continental breakup. Later, the ridge push of the Labrador Sea spreading ridge maintained this general direction of extension. We see indications for anti-clockwise rotation of the direction of extension along some of the passive margins. However, extreme persistent N–S-oriented extension as indicated by studies further north in West Greenland cannot be confirmed.
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Winkler, Wilfried, Denise Bussien, Munktsengel Baatar, Chimedtseren Anaad, and Albrecht von Quadt. "Detrital Zircon Provenance Analysis in the Central Asian Orogenic Belt of Central and Southeastern Mongolia—A Palaeotectonic Model for the Mongolian Collage." Minerals 10, no. 10 (October 2, 2020): 880. http://dx.doi.org/10.3390/min10100880.
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Our study is aimed at reconstructing the Palaeozoic–early Mesozoic plate tectonic development of the Central Asian Orogenic Belt in central and southeast Mongolia (Gobi). We use sandstone provenance signatures including laser ablation U-Pb ages of detrital zircons, their epsilon hafnium isotope signatures, and detrital framework grain analyses. We adopt a well-established terran subdivision of central and southeastern Mongolia. However, according to their affinity and tectonic assemblage we group them into three larger units consisting of continental basement, rift-passive continental margin and arc elements, respectively. These are in today’s coordinates: (i) in the north the late Cambrian collage from which the later Mongol-Okhotsk and the Central Mongolia-Erguna mountain ranges resulted, (ii) in the south a heterogeneous block from which the South Mongolia-Xin’gan and Inner Mongolia-Xilin belts developed, and (iii) in between we still distinguish the intra-oceanic volcanic arc of the Gurvansayhan terrane. We present a model for paleotectonic development for the period from Cambrian to Jurassic, which also integrates findings from the Central Asian Orogenic Belt in China and Russia. This mobilistic model implies an interplay of rift and drift processes, ocean formation, oceanic subduction, basin inversion, collision and suture formation in space and time. The final assemblage of the Central Asian Orogenic Belt occurred in Early Jurassic.