Journal articles: 'Volcanisme effusif'

1

Kröchert, Jörg Buchner, Martin Schmieder, Holger Maurer, Marco Walter, Annette Strasser, and Marcel Strasser. "Effusive melilititic volcanism on the Swabian Alb the Sternberg volcano (Gomadingen)." Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 160, no. 4 (December 1, 2009): 315–23. http://dx.doi.org/10.1127/1860-1804/2009/0160-0315.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Smellie, John L. "Chapter 1.2 Antarctic volcanism: volcanology and palaeoenvironmental overview." Geological Society, London, Memoirs 55, no. 1 (2021): 19–42. http://dx.doi.org/10.1144/m55-2020-1.

Full text

Abstract:

AbstractSince Jurassic time (c.200 Ma), Antarctica has had a greater diversity of volcanism than other southern continents. It includes: (1) voluminous mafic and felsic volcanism associated with the break-up of Gondwana; (2) a long-lived continental margin volcanic arc, including back-arc alkaline volcanism linked to slab rollback; (3) small-volume mafic alkaline volcanism associated with slab-window formation; and (4) one of Earth's major continental rift zones, the West Antarctic Rift System (WARS), with its numerous large alkaline central volcanoes. Several of Antarctica's volcanoes are still active. This chapter is a review of the major volcanic episodes and their principal characteristics, in their tectonic, volcanological and palaeoenvironmental contexts. Jurassic Gondwana break-up was associated with large-scale volcanism that caused global environmental changes and associated mass extinctions. The volcanic arc was a major extensional arc characterized by alternating volcanic flare-ups and lulls. The Neogene rift-related alkaline volcanism is dominated by effusive glaciovolcanic eruptions, overwhelmingly as both pāhoehoe- and ‘a‘ā-sourced lava-fed deltas. The rift is conspicuously poor in pyroclastic rocks due to the advection and removal of tephra erupted during glacial intervals. Volcanological investigations of the Neogene volcanism have also significantly increased our knowledge of the critical parameters and development of the Antarctic Ice Sheet.

APA, Harvard, Vancouver, ISO, and other styles

3

DeWolfe, Y. M., H. L. Gibson, B. Lafrance, and A. H. Bailes. "Volcanic reconstruction of Paleoproterozoic arc volcanoes: the Hidden and Louis formations, Flin Flon, Manitoba, CanadaThis is a companion paper to DeWolfe, Y.M., Gibson, H.L., and Piercey, S.J. 2009. Petrogenesis of the 1.9 Ga mafic hanging wall sequence to the Flin Flon, Callinan, and Triple 7 massive sulphide deposits, Flin Flon, Manitoba, Canada. Canadian Journal of Earth Sciences, 46: this issue." Canadian Journal of Earth Sciences 46, no. 7 (July 2009): 481–508. http://dx.doi.org/10.1139/e09-031.

Full text

Abstract:

The hanging wall to the Flin Flon, Callinan, and Triple 7 volcanogenic massive sulphide deposits of the Flin Flon district is composed of the Hidden and Louis formations. The contact between these formations is marked by mafic tuff that represents a hiatus in effusive volcanism. The formations form a composite volcanic edifice that was erupted and grew within a large, volcanic–tectonic subsidence structure (hosting the deposits) that developed within a rifted-arc environment. The formations are evidence of resurgent effusive volcanism and subsidence following a hiatus in volcanism marked by ore formation since they consist of dominantly basaltic flows, sills, and volcaniclastic rocks with subordinate basaltic andesite and rhyodacitic flows and volcaniclastic rocks. The Hidden formation is interpreted to represent a small shield volcano and the Louis formation a separate shield volcano that developed on its flank. Both the Hidden and Louis volcanic edifices were constructed by continuous, low-volume eruptions of pillow lava. A gradual change from a dominantly extensional environment during the formation of the footwall Flin Flon formation to a progressively more dominant convergent environment during the emplacement of the hanging wall suggests that the Hidden and Louis formations are unlikely to host significant volcanogenic massive sulphide-type mineralization. However, synvolcanic structures in the formations define structural corridors that project downwards into the footwall where they encompass massive sulphide mineralization, indicating their control on ore formation, longevity,and reactivation as magma and fluid pathways during the growth of the Hidden and Louis volcanoes.

APA, Harvard, Vancouver, ISO, and other styles

4

Inza, Coulibaly, Kouamelan Alain Nicaise, Djro Sagbrou Chérubin, and Coulibaly Yacouba. "Petrographie Des Volcanites Et Plutonites De La Partie Sud Du Sillon Volcano-Sedimentaire De Toumodi-Fetekro (Cote D’ivoire)." European Scientific Journal, ESJ 13, no. 30 (October 31, 2017): 199. http://dx.doi.org/10.19044/esj.2017.v13n30p199.

Full text

Abstract:

The southern part of Toumodi-Fètêkro greenstone belt is located in the Center - Southeast of Ivory Coast. Petrographic study of volcanic and plutonic rocks shows three units. The first unit is composed of basaltic to rhyolitic lavas which imply effusive character. Then we have volcanosedimentary unit composed of pyroclastic formations (lapilli tuff, breccia, ash deposit and ignimbrites) and the pillow-lavas. Indeed, the presence of this last shows clearly that an explosive volcanism and a submarine effusive volcanism have occurred during during the setting of Toumodi-Fètêkro belt. Plutonic unit is constituted of gabbroic to granitic rocks. Sericite, chlorite, epidote observed in these rocks are consistent with the impacts of greenschist facies metamorphism. The rocks of the southern part of the Toumodi-Fètêkro greenstone belt are formed in a subduction context rather than in oceanic plateaus context because of the old inheritance, sometimes of Archean age, found somewhere in theBirimiandomain. The lithologies of the southern part of Toumodi-Fètêkro meet elsewhere in the other Birimian greenstone belts. Also, these lithologies are affected by a hydrothermal alteration due to the abundant veins of quartz, carbonates, sericite, chlorite, epidote, sulphides and oxides. However, volcanic show in some places amphibolit facies metamorphism.

APA, Harvard, Vancouver, ISO, and other styles

5

Filipovich, Ruben, Walter Báez, Emilce Bustos, Agustina Villagrán, Agostina Chiodi, and Jose Viramonte. "Estilos eruptivos asociados al volcanismo monogenético máfico de la región de Pasto Ventura, Puna Austral, Argentina." Andean Geology 46, no. 2 (May 31, 2019): 300. http://dx.doi.org/10.5027/andgeov46n2-3091.

Full text

Abstract:

One of the most outstanding features of the Southern Puna is the occurrence of a widespread monogenetic mafic volcanism during Neogene-Quaternary. Despite a number of published papers focusing on the petrogenesis of this back-arc volcanism, works aimed on its physical volcanology are scarce. This paper presents the characterization of the monogenetic mafic volcanism in the Pasto Ventura region, located in the southeast edge of the Southern Puna. The results show that in the Pasto Ventura region there is a low density of small-volume eruptive centers aligned with regional tectonic structures and a significant variability in eruptive styles (effusive, strombolian, hawaiian, violent strombolian and phreatomagmatic) and typology of volcanic structures (domes, scoria cones, maars and tuff rings). The first of these features is explained by a limited magma flow rate from the deep source and the use of favorable tectonic structures (oriented obliquely to the regional maximum compression direction) for the ascent of small volumes of magma through the upper crust. The variability of eruptive styles responds to the complex interaction of different endogenous and exogenous factors. The occurrence of effusive or explosive eruptions depends on the differences in magma ascent rates including periods of stagnation in the upper crust, which in turn control the efficiency of degassing and ultimately the occurrence of fragmentation. On the other hand, the more humid local climatic conditions (~150 mm/year), which are related to the geographical position of the Pasto Ventura region in the eastern edge of the Puna, favor the occurrence of phreatomagmatic activity. Phreatomagmatic activity also varies according to the topography, substrate typology and depth at which water-magma interaction occurs.

APA, Harvard, Vancouver, ISO, and other styles

6

Mahoney, J. Brian, Richard M. Friedman, and Sean D. McKinley. "Evolution of a Middle Jurassic volcanic arc: stratigraphic, isotopic, and geochemical characteristics of the Harrison Lake Formation, southwestern British Columbia." Canadian Journal of Earth Sciences 32, no. 10 (October 1, 1995): 1759–76. http://dx.doi.org/10.1139/e95-137.

Full text

Abstract:

The Harrison Lake Formation is an Early to Middle Jurassic volcanic-arc assemblage unconformably overlying Triassic oceanic basement in the eastern Coast Belt of southwestern British Columbia. The formation is subdivided into four members including, in ascending order, the Celia Cove Member (conglomerate), the Francis Lake Member (fine-grained strata), the Weaver Lake Member (flows and breccias), and the Echo Island Member (pyroclastic and epiclastic strata). New biostratigraphic constraints pinpoint the initiation of volcanism to late early Toarcian. U–Pb geochronology demonstrates the arc was active until at least late Bajocian–early Bathonian time (166.0 ± 0.4 Ma), and that the timing of arc volcanism strongly overlaps emplacement of both hypabyssal intrusions (Hemlock Valley stock) and deep-seated plutons (Mount Jasper pluton) within and adjacent to the arc. Geochemical data indicate the arc is of medium- to high-K calc-alkaline affinity, and is strongly light rare earth element enriched (LaN/YbN = 1.5 – 2.5). Nd and Sr isotopic data from primary volcanic rocks demonstrate the juvenile nature of the magmatic system, but isotopic data from associated fine-grained sedimentary rocks suggest temporally controlled variations in isotopic composition interpreted to represent two-component mixing between juvenile volcanic detritus and a more evolved detrital component. The succession of facies in the Harrison Lake Formation records initial basin subsidence in the Early Jurassic, initiation of explosive volcanism in the late early Toarcian, a change to effusive volcanism in the early Aalenian, and late-stage explosive volcanism in the late Bajocian. The Harrison Lake Formation contains mesoscopic folds and overturned bedding that are absent in the overlying Callovian Mysterious Creek Formation, strongly suggesting the existence of a regional Bathonian deformational event in the southern Coast Belt.

APA, Harvard, Vancouver, ISO, and other styles

7

Wright, Robert. "MODVOLC: 14 years of autonomous observations of effusive volcanism from space." Geological Society, London, Special Publications 426, no. 1 (August 27, 2015): 23–53. http://dx.doi.org/10.1144/sp426.12.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Byrne, Paul K., Lillian R. Ostrach, Caleb I. Fassett, Clark R. Chapman, Brett W. Denevi, Alexander J. Evans, Christian Klimczak, Maria E. Banks, James W. Head, and Sean C. Solomon. "Widespread effusive volcanism on Mercury likely ended by about 3.5 Ga." Geophysical Research Letters 43, no. 14 (July 21, 2016): 7408–16. http://dx.doi.org/10.1002/2016gl069412.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Fink, Jonathan H., Steven W. Anderson, and Curtis R. Manley. "Textural constraints on effusive silicic volcanism: Beyond the permeable foam model." Journal of Geophysical Research 97, B6 (1992): 9073. http://dx.doi.org/10.1029/92jb00416.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Busby, Cathy. "Possible distinguishing characteristics of very deepwater explosive and effusive silicic volcanism." Geology 33, no. 11 (2005): 845. http://dx.doi.org/10.1130/g21216.1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Stelten, Mark E., Drew T. Downs, Duane E. Champion, Hannah R. Dietterich, Andrew T. Calvert, Thomas W. Sisson, Gail A. Mahood, and Hani Zahran. "The timing and compositional evolution of volcanism within northern Harrat Rahat, Kingdom of Saudi Arabia." GSA Bulletin 132, no. 7-8 (November 4, 2019): 1381–403. http://dx.doi.org/10.1130/b35337.1.

Full text

Abstract:

Abstract Harrat Rahat, one of several large, basalt-dominated volcanic fields in western Saudi Arabia, is a prime example of continental, intraplate volcanism. Excellent exposure makes this an outstanding site to investigate changing volcanic flux and composition through time. We present 93 40Ar/39Ar ages and six 36Cl surface-exposure ages for volcanic deposits throughout northern Harrat Rahat that, when integrated with a new geologic map, define 12 eruptive stages. Exposed volcanic deposits in the study area erupted <1.2 Ma, and 214 of 234 eruptions occurred <570 ka. Two eruptions occurred in the Holocene, including a historically described basalt eruption in 1256 C.E. and a trachyte eruption newly recognized as Holocene (4.2 ± 5.2 ka). An estimated ∼82 km3 (dense rock equivalent) of volcanic product have erupted since 1.2 Ma, though this is a lower limit due to concealment of deposits >570 ka. Over the past 570 k.y., the average eruption rate was 0.14 km3/k.y., but volcanism was episodic with periods alternating between low (0.04–0.06 km3/k.y.) and high (0.1–0.3 km3/k.y.) effusion rates. Before 180 ka, eruptions vented from the volcanic field’s dominant eastern vent axis and from a subsidiary, diffuse, western vent axis. After 180 ka, volcanism focused along the eastern vent axis, and the composition of volcanism varied systematically along its length from basalt dominated in the north to trachyte dominated in the south. We hypothesize that these compositional variations <180 ka reflect the growth of a mafic intrusive complex beneath the southern portion of the vent axis, which led to the development of evolved magmas.

APA, Harvard, Vancouver, ISO, and other styles

12

Jerram, Dougal A., Henrik H. Svensen, Sverre Planke, Alexander G. Polozov, and Trond H. Torsvik. "The onset of flood volcanism in the north-western part of the Siberian Traps: Explosive volcanism versus effusive lava flows." Palaeogeography, Palaeoclimatology, Palaeoecology 441 (January 2016): 38–50. http://dx.doi.org/10.1016/j.palaeo.2015.04.022.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Hamilton, Christopher W., Peter J. Mouginis-Mark, Michael M. Sori, Stephen P. Scheidt, and Ali M. Bramson. "Episodes of Aqueous Flooding and Effusive Volcanism Associated With Hrad Vallis, Mars." Journal of Geophysical Research: Planets 123, no. 6 (June 2018): 1484–510. http://dx.doi.org/10.1029/2018je005543.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Pontbriand, Claire W., S. Adam Soule, Robert A. Sohn, Susan E. Humphris, Clayton Kunz, Hanumant Singh, Ko-ichi Nakamura, Martin Jakobsson, and Timothy Shank. "Effusive and explosive volcanism on the ultraslow-spreading Gakkel Ridge, 85°E." Geochemistry, Geophysics, Geosystems 13, no. 10 (October 2012): n/a. http://dx.doi.org/10.1029/2012gc004187.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Torres-Orozco, R., J. L. Arce, P. W. Layer, and J. A. Benowitz. "The Quaternary history of effusive volcanism of the Nevado de Toluca area, Central Mexico." Journal of South American Earth Sciences 79 (November 2017): 12–39. http://dx.doi.org/10.1016/j.jsames.2017.07.008.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Hwang, Sang Koo, So Jin Lee, and Young-In Hwang. "The latest volcanism in Nari Caldera, Ulleung Island: Transition from explosive to effusive eruption." Journal of the Geological Society of Korea 56, no. 5 (October 31, 2020): 539–53. http://dx.doi.org/10.14770/jgsk.2020.56.5.539.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Richardson, Jacob A., James A. Wilson, Charles B. Connor, Jacob E. Bleacher, and Koji Kiyosugi. "Recurrence rate and magma effusion rate for the latest volcanism on Arsia Mons, Mars." Earth and Planetary Science Letters 458 (January 2017): 170–78. http://dx.doi.org/10.1016/j.epsl.2016.10.040.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Zellmer, G. F. "Style of effusive arc volcanism, links to subduction velocity, and implications for magma transfer." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A732. http://dx.doi.org/10.1016/j.gca.2006.06.1317.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Sager, W. W., T. Sano, and J. Geldmacher. "IODP Expedition 324: Ocean Drilling at Shatsky Rise Gives Clues about Oceanic Plateau Formation." Scientific Drilling 12 (September 1, 2011): 24–31. http://dx.doi.org/10.5194/sd-12-24-2011.

Full text

Abstract:

Integrated Ocean Drilling Program (IODP) Expedition 324 cored Shatsky Rise at five sites (U1346–U1350) to study processes of oceanic plateau formation and evolution. Site penetrations ranged from 191.8 m to 324.1 m with coring of 52.6 m to 172.7 m into igneous basement at four of the sites. Average recovery in basement was 38.7%–67.4%. Cored igneous sections consist mainly of variably evolved tholeiitic basalts emplaced as pillows or massive flows. Massive flows are thickest and make up the largest percentage of section on the largest and oldest volcano, late Jurassic age Tamu Massif; thus, it may have formed at high effusion rates. Such massive flows are characteristic of flood basalts, and similar flows were cored at Ontong Java Plateau. Indeed, the similarity of igneous sections at Site U1347 with that cored on Ontong Java Plateau implies similar volcanic styles for these two plateaus. On younger, smaller Shatsky Rise volcanoes, pillow flows are common and massive flows thinner and fewer, which might mean volcanism waned with time. Cored sediments from summit sites contain fossils and structures implying shallow water depths or emergence at the time of eruption and normal subsidence since. Summit sites also show pervasive alteration that could be due to high fluid fluxes. A thick section of volcaniclastics cored on Tamu Massif suggests that shallow, explosive submarine volcanism played a significant role in the geologic development of the plateau summit. Expedition 324 results imply that Shatsky Rise began with massive eruptions forming a huge volcano and that subsequent eruptions waned in intensity, forming volcanoes that are large, but which did not erupt with unusually high effusion rates. Similarities of cored sections on Tamu Massif with those of Ontong Java Plateau indicate that these oceanic plateaus formed in similar fashion. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.12.03.2011" target="_blank">10.2204/iodp.sd.12.03.2011</a>

APA, Harvard, Vancouver, ISO, and other styles

20

Ouarhache, Driss, André Charriere, Françoise Chalot-prat, and Mohamed EL Wartiti. "Triassic to early Liassic continental rifting chronology and process at the southwest margin of the Alpine Tethys (Middle Atlas and High Moulouya, Morocco); correlations with the Atlantic rifting, synchronous and diachronous." Bulletin de la Société Géologique de France 183, no. 3 (May 1, 2012): 233–49. http://dx.doi.org/10.2113/gssgfbull.183.3.233.

Full text

Abstract:

AbstractApparu à l’est du rift continental atlantique, un rift continental téthysien s’est développé sur le domaine atlasique du Maroc au cours du Trias et du début du Jurassique. Dans le transect étudié du Moyen Atlas et de la Haute Moulouya (MAHM), ce début du rifting téthysien, le « rifting initial », comporta 3 étapes majeures.Au Trias supérieur, apparut une première génération de bassins syn-rift (sr1) continentaux et détritiques, associés au rejeu extensif de certaines sutures hercyniennes ; cette phase se poursuivit avec une transgression laguno-marine généralisée dans un stade post-rift (pr1) au Carnien supérieur-Norien.Au voisinage de la limite Trias-Lias, se produisit une effusion de trapps basaltiques aériens à subaquatiques ; la région subit ensuite une phase d’érosion.Au début du Lias, se différencia une deuxième génération de bassins syn-rift (sr2) continentaux ou laguno-marins, extensifs ou transtensifs, associés à un volcanisme explosif localisé sur quatre zones faillées (faille d’Adarouch, accident du Tizi n’Trettène, accident Sud Moyen atlasique, faille de Ksabi-Ahouli) ; cette phase se clôtura avec l’arrivée de la mer dans un stade post-rift (pr2) débutant au Sinémurien supérieur-Carixien inférieur.La zone du MAHM eut une histoire différente des régions occidentales du domaine atlasique, qu’il s’agisse d’un autre segment du rift atlasique (Haut Atlas de Marrakech) ou d’une bordure du rift atlantique (Haut Atlas occidental).Pendant le rifting ante-trapp, alors que ces bassins occidentaux ont été structurés par plusieurs séquences tectono-sédimentaires successives étagées du Permien supérieur au Trias supérieur, les bassins du MAHM n’enregistrèrent qu’une seule mégaséquence sédimentaire triasique. Ainsi, les rifts continentaux atlantique et Ouest atlasique furent initiés, simultanément (?), dès le Permien supérieur, tandis que le rift continental de l’Atlas central et oriental n’apparut vraisemblablement qu’au Trias supérieur. La déchirure du rift atlasique migra ainsi vers l’est de la fin du Primaire au début du Secondaire.Durant la période post-trapp, alors que les bassins occidentaux étaient le siège d’un calme tectonique relatif, une fracturation majeure affecta le MAHM, générant de nouveaux bassins sédimentaires associés à un second épisode volcanique, de nature explosive cette fois. Cette poursuite du rifting, après les dernières effusions basaltiques et avant l’arrivée de la mer jurassique, préfigura les découpages tectoniques qui continuèrent de se manifester dans les parties centrale et orientale du rift atlasique jusqu’au Jurassique moyen.

APA, Harvard, Vancouver, ISO, and other styles

21

Lebedeva, E. V. "Impact of volcanic and post volcanic activity on fluvial relief." Geomorphology RAS, no. 4 (November 8, 2019): 49–66. http://dx.doi.org/10.31857/s0435-42812019449-66.

Full text

Abstract:

The characteristic features of the river network, the structure and functioning of the valleys affected by effusive and explosive volcanism, volcano-tectonic phenomena, gas hydrothermal activity and mud volcanism are revealed. It has been established that within flows and covers of effusives, the formation of new streams channels can occur not only due to backward erosion, but also as a result of the collapse of the roof of the near-surface lava tubes, which are actively used by underground runoff. A high erosion rate, a large volume of solid runoff, and a significant role of deflation in the transformation of the fluvial relief are characteristic for regions of domination of explosive activity. There valleys become zones of accumulation of volcanic material, which is gradually processed by mudflow, alluvial, aeolian and other processes. Volcanic-tectonic activity changes the rivers position, direction of streams and morphology of the valleys, leading to numerous reorganizations of the river network, as a result of which the valleys of modern watercourses often consist of uneven-age fragments. Valleys of hydrothermal zones are characterized by the active development of slope processes, which leads to the formation in them not only of sinter terraces, but also numerous landslide ones. Mud volcanic processes periodically lead to the filling and blocking of the valleys with mud breccia flows, which affects both the composition of the alluvium of watercourses and the morphology of the valleys.

APA, Harvard, Vancouver, ISO, and other styles

22

Ivanov, K. S., and Yu V. Erokhin. "On time of the triassic rifts system origin in West Siberia." Доклады Академии наук 486, no. 1 (May 10, 2019): 88–92. http://dx.doi.org/10.31857/s0869-5652486188-92.

Full text

Abstract:

It is commonly supposed that a very substantial volume of early basalt magmatism effused synchronously on Siberia platform and West Siberia in a very short time interval at 249.4 ± 0.5 Ma (Reichow et al., 2002, etc.). This magmatism and induced climate change are considered as a main reason of the most catastrophic in the Earth history extinction at the border of Permian and Triassic time. But these conclusions were based on incomplete and unrepresentative data on West Siberia. We have obtained by analysis of pyroxenes monofraction from kainotype basalts of Guslinskaya P-430 well Ar-Ar age 268.4 ± 7.5 Ma. In Taurovskaya 503 well this age is 268.1 ± 7.5 Ma. Hence, volcanism in axial rift zones of the basement of West Siberia plate began earlier than that considered before and significantly earlier than on Siberia platform.

APA, Harvard, Vancouver, ISO, and other styles

23

Bailey, D. K., and S. Kearns. "New forms of abundant carbonatite–silicate volcanism: recognition criteria and further target locations." Mineralogical Magazine 76, no. 2 (April 2012): 271–84. http://dx.doi.org/10.1180/minmag.2012.076.2.03.

Full text

Abstract:

AbstractIn the Calatrava province of central Spain, numerous Quaternary pyroclastic vents have erupted carbonatite magmas carrying silicate melt fragments, mantle debris and megacrysts. Lava flows are rare. Maar and scoria deposits have carbonate matrices and pass into tuff sheets with carbonate contents >50%, which are spread widely away from the eruptive centres and constitute the most abundant form of effusive carbonate. Immense quantities of mantle debris are present in the erupted material. The tuffs have a distinctive fabric, which consists of a pale matrix carrying black silicate glass clasts that contain globules of immiscible carbonate and carbonate phenocrysts. There is evidence of similar volcanism in the Limagne province of central France and in other intra-continental provinces in Europe and Africa. About 500 vents have been identified in France and Spain: all the vents examined to date have erupted carbonatite magma. Such eruptions are not generally recognized in classical volcanology. As pyroclastic carbonatite was not previously recognized in Spain and France, a detailed examination of other mafic and ultramafic alkaline provinces, where research has traditionally concentrated on lava flows, is vital. For any search to be successful, evidence from the pyroclastic rocks will be required.

APA, Harvard, Vancouver, ISO, and other styles

24

Aalto, Kenneth. "A Natural Order of Volcanic Succession: Midnineteenth-Century Field-based Models of Von Richthofen, King, and Dutton." Earth Sciences History 27, no. 1 (January 1, 2008): 59–77. http://dx.doi.org/10.17704/eshi.27.1.n6682008250q2315.

Full text

Abstract:

During the latter half of the nineteenth century, pioneering studies of volcanic rocks were undertaken by Ferdinand von Richthofen, Clarence King, and Clarence Dutton in the Great Basin and California Cascades. They developed hypotheses on the petrogenesis of magmas in order to explain what they deemed to be a regular progression of volcanic rock types through time during the Cenozoic Era. There was general agreement that effusive volcanism resulted in an orderly sequence of magmas: propylitic, andesitic, trachytic, rhyolitic, and basaltic. Von Richthofen related this phenomenon to the tapping of magma sources at ever-greater depths during orogenic activity, the basic magmas being denser and occupying a lower level within the Earth. King felt that so-called ‘lakes of fusion’ developed within the Earth as a result of erosional unloading of its crust; and that within such lakes gravity separation resulted in silicic magmas floating upon basic. In the secular refrigeration of the globe these temporary lakes would necessarily occur successively at greater and greater depths and the secular changes that recorded themselves in the subtle petrographical distinctions by which the various acidic and basic members could be distinguished were in each case an expression of depth. Dutton, by contrast, saw no connection between unloading and volcanism and established a modified model for the genesis of magma, emphasizing the importance of magma provenance being controlled by the fusion of variable source rocks. All felt that such temporal changes in magma type were universal and provided a basis for a natural classification of volcanic rocks.

APA, Harvard, Vancouver, ISO, and other styles

25

Hanson, Richard E., and David H. Elliot. "Rift-related Jurassic basaltic phreatomagmatic volcanism in the central Transantarctic Mountains: precursory stage to flood-basalt effusion." Bulletin of Volcanology 58, no. 5 (1996): 327. http://dx.doi.org/10.1007/s004450050143.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Koloskov, A. V., M. Yu Davydova, D. V. Kovalenko, and V. V. Ananyev. "New data on age, material composition and geological structure of the Central Kamchatka depression (CKD). Part 1. Rocks types. Age, petrological and isotopo-geochemical characteristicsн." Вулканология и сейсмология, no. 3 (May 14, 2019): 3–24. http://dx.doi.org/10.31857/s0203-0306201933-24.

Full text

Abstract:

The paper presents new age and isotope geochemical characteristics for plateau effusive rocks from the Central Kamchatka Depression (CKD) and Nikolka Volcano. We compared these data with the data on rocks from the Klyuchevskoy group of volcanoes and also Sheveluch, Kharchinsky, Zarechny, Nachikinsky, Bakening volcanoes and NEB-adakites from Pliocene shield volcano between the Ozernaya Kamchatka and Pravaya Kamchatka rivers. It is shown that the evolutionally advanced (often more alkaline) rock from Nachikinsky, Bakening, Nikolka volcanoes and the Pliocene shield volcanoe significantly differ in isotope-geochemical characteristics from the Klyuchevskoy group of volcanoes rocks. Exactly this type of rocks is characteristic for CKD as rift structure. The Klyuchevskoy group of volcanoes rock are not typomorphic for this structure and manifest the usual orogenic volcanism stage, typical for much larger area. Miocene plateau effusive rocks differ from rocks of this group only by slightly increased potassium alkalinity. The rift type rocks characteristic feature is not only their increased alkalinity, but also specific microcomponents ratios: Ti/V > 0.004, Nb/Y > 0.28, Dy/Yb > 2.00, La/Yb > 6.5, Sm/Yb > 2.4, Lu/Hf < 0.08. Along with isotopic characteristics, these ratios suggest the existence of the single deep asthenospheric mantle reservoir for initial melts. The Kurile-Kamchatka and Commander-Aleutian island-arc systems’ junction is marked by the increased fluid enrichment (Ce group of REE) of melts for rocks of certain volcanoes: Shiveluch, Kharchinsky, Zarechny.

APA, Harvard, Vancouver, ISO, and other styles

27

Koloskov, A. V., M. Yu Davydova, and D. V. Kovalenko. "New data on age, material composition and geological structure of the Central Kamchatka depression (CKD). Part 1. Rocks types. Age, petrological and isotopo-geochemical characteristicsн." Вулканология и сейсмология, no. 3 (May 14, 2019): 3–24. http://dx.doi.org/10.31857/s0205-9614201933-24.

Full text

Abstract:

The paper presents new age and isotope geochemical characteristics for plateau effusive rocks from the Central Kamchatka Depression (CKD) and Nikolka Volcano. We compared these data with the data on rocks from the Klyuchevskoy group of volcanoes and also Sheveluch, Kharchinsky, Zarechny, Nachikinsky, Bakening volcanoes and NEB-adakites from Pliocene shield volcano between the Ozernaya Kamchatka and Pravaya Kamchatka rivers. It is shown that the evolutionally advanced (often more alkaline) rock from Nachikinsky, Bakening, Nikolka volcanoes and the Pliocene shield volcanoe significantly differ in isotope-geochemical characteristics from the Klyuchevskoy group of volcanoes rocks. Exactly this type of rocks is characteristic for CKD as rift structure. The Klyuchevskoy group of volcanoes rock are not typomorphic for this structure and manifest the usual orogenic volcanism stage, typical for much larger area. Miocene plateau effusive rocks differ from rocks of this group only by slightly increased potassium alkalinity. The rift type rocks characteristic feature is not only their increased alkalinity, but also specific microcomponents ratios: Ti/V > 0.004, Nb/Y > 0.28, Dy/Yb > 2.00, La/Yb > 6.5, Sm/Yb > 2.4, Lu/Hf < 0.08. Along with isotopic characteristics, these ratios suggest the existence of the single deep asthenospheric mantle reservoir for initial melts. The Kurile-Kamchatka and Commander-Aleutian island-arc systems’ junction is marked by the increased fluid enrichment (Ce group of REE) of melts for rocks of certain volcanoes: Shiveluch, Kharchinsky, Zarechny.

APA, Harvard, Vancouver, ISO, and other styles

28

Altunkaynak, Şafak, Ercan Aldanmaz, Işıl Nur Güraslan, Ayşe Zeynep Çalışkanoğlu, Alp Ünal, and Daniel Nývlt. "Lithostratigraphy and petrology of Lachman Crags and Cape Lachman lava-fed deltas, Ulu Peninsula, James Ross Island, north-eastern Antarctic Peninsula: Preliminary results." Czech Polar Reports 8, no. 1 (January 1, 2018): 60–83. http://dx.doi.org/10.5817/cpr2018-1-5.

Full text

Abstract:

This paper presents the preliminary results regarding the lithostratigraphy, petrography and petrology of James Ross Island Volcanic Group dominating the Lachman Crags and Cape Lachman lava-fed deltas in the Ulu Peninsula, James Ross Island north-eastern Antarctic Peninsula. Studied lava-fed deltas were produced via Late Miocene to Pleistocene sub-marine and sub-glacial volcanism and made up four main lithofacies: a- bottomset pillow lavas, peperites and associated volcanoclastic/siliciclastic deposits; b- foreset-bedded hyaloclastite breccias; c- intrusions (feeder dykes, sills, and plugs) and d- topset subaerial lavas. Collectively these lithofacies record the transition from an effusive subaqueous to an effusive subaerial eruption environment. All lava samples and dykes from bottomset, foreset and topset lava-fed delta associations are olivine-phyric alkali basalts and are mineralogically and geochemically homogeneous. These eruptive products display significant enrichments in alkali contents and have ocean island basalt (OIB)-type, intra-plate geochemical signatures characterized by enrichments in all highly to moderately incompatible trace elements relative to basaltic rocks from ocean ridge settings. Volcanic products from a number of different eruptive periods display limited variations in major and trace element relative abundances, indicating derivation from a relatively homogeneous mantle source. The results of quantitative modelling of geochemical data is consistent with the view that the primary melts from which these mafic alkaline rocks were originated are the products of relatively small degrees (~3-7%) of partial melting of a volatile-bearing, metasomatized mantle source. The magmatism is likely the result of extension-driven mantle upwelling.

APA, Harvard, Vancouver, ISO, and other styles

29

Doucet, P., W. Mueller, and F. Chartrand. "Archean, deep-marine, volcanic eruptive products associated with the Coniagas massive sulfide deposit, Quebec, Canada." Canadian Journal of Earth Sciences 31, no. 10 (October 1, 1994): 1569–84. http://dx.doi.org/10.1139/e94-139.

Full text

Abstract:

The mafic-dominated volcanic and related volcaniclastic sedimentary rocks, which host the Archean Coniagas Zn–Pb–Ag massive sulfide deposit, are inferred to be the result of submarine explosive and effusive eruptions at depths of approximately 1000 m, as suggested by the presence of volcaniclastic turbidites, the absence of wave-induced sedimentary structures, pillowed lava flows, the sulfide deposit itself, and the incipient arc setting. The rock assemblage includes massive, pillowed and brecciated, basaltic to andesitic flows, massive, andesitic to rhyodacitic lapilli tuffs, andesitic stratified lapilli tuffs, and bedded tuffs. Preserved fragments and delicate volcanic textures, such as angularity of clasts, chilled clast margins, and clast vesicularity, and sedimentary structures are consistent with a subaqueous hydroclastic origin for the volcaniclastic sedimentary rocks. Explosive degasification of magma and (or) lava, in conjunction with fragmentation due to the interaction of magma–water, or nonexplosive hydroclastic fragmentation can account for the observed characteristics in the volcaniclastic deposits.The 280 m thick Coniagas volcano-sedimentary succession, used to reconstruct the volcanic history of the deposit, records two explosive–effusive volcanic cycles. The initial stage of each cycle is envisaged to have commenced with a small fire fountain or boiling-over eruption. Transport and deposition of the fragmented debris along the flanks of the volcanic edifice is attributed to high-concentration particulate gravity flows. The massive lapilli tuffs are interpreted as laminar debris flows, whereas the stratified lapilli tuffs may reflect turbulent flow deposits. The bedded tuffs were produced during the waning eruptive stages or elutriated from high-concentration syneruption flows. Ingestion of water, causing hydroclastic fragmentation, occurred during the eruptive and (or) the transport process. Calm, effusive mafic volcanism, characterized by massive, pillowed and brecciated flows and reworked counterparts, terminates each volcanic cycle. The massive, felsic lapilli tuffs, which host the mineralization, are inferred to represent locally reworked hydroclastic products of explosive or nonexplosive origin. The Coniagas mine deposit may serve as a guide for future exploration of small Archean volcanic-hosted massive sulfide deposits with a restricted alteration halo.

APA, Harvard, Vancouver, ISO, and other styles

30

Samper, A., X. Quidelleur, P. Lahitte, and D. Mollex. "Timing of effusive volcanism and collapse events within an oceanic arc island: Basse-Terre, Guadeloupe archipelago (Lesser Antilles Arc)." Earth and Planetary Science Letters 258, no. 1-2 (June 2007): 175–91. http://dx.doi.org/10.1016/j.epsl.2007.03.030.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

de Silva, S. L., S. Self, P. W. Francis, R. E. Drake, and Ramirez R. Carlos. "Effusive silicic volcanism in the Central Andes: The Chao dacite and other young lavas of the Altiplano-Puna Volcanic Complex." Journal of Geophysical Research: Solid Earth 99, B9 (September 10, 1994): 17805–25. http://dx.doi.org/10.1029/94jb00652.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Álvaro, Jose Javier, Hassan Ezzouhairi, M. Luisa Ribeiro, J. Farinha Ramos, and A. Rita Solá. "Early Ordovician volcanism in the Iberian Chains (NE Spain) and its influence on the preservation of shell concentrations." Bulletin de la Société Géologique de France 179, no. 6 (November 1, 2008): 569–81. http://dx.doi.org/10.2113/gssgfbull.179.6.569.

Full text

Abstract:

Abstract Research is described to evaluate the influence of volcanic activity on studies of shell-concentration taphonomy and biodiversity patterns in strata that commonly display poor densities of skeletal debris. Two volcanic episodes are recorded in the Lower Ordovician of the Iberian Chains: (i) a succession of Tremadocian-earliest “Arenig”, eruptive felsic products, expelled explosively and characterized by the onset of rhyolitic and dacitic tuffs embedded in the Borrachón and Santed formations; and (ii) an “Arenig”, effusive basaltic volcanic episode, represented by a single lava flow embedded in the Armorican Quartzite. The volcanic activity reflects a change from sub-alkaline to alkaline geochemical affinities, related to the Early Ordovician magmatism recorded in southwestern Europe that is commonly attributed to the opening of the Rheic Ocean. The felsic explosive tuffs are associated with two ecosystem disturbance events: (i) a short-term colonization event of opportunistic linguliformean brachiopods that proliferated in the aftermath of a multi-event rhyolitic pyroclastic surge deposit; and (ii) several single-event mass-mortality horizons associated with dacitic pyroclastic flows responsible for the preservation of high-diverse allochthonous coquinas. Our knowledge of the biodiversity patterns achieved by the benthic communities preserved in the poorly fossiliferous, siliciclastic strata of the Iberian Chains is, as a result, strongly biased by the presence of skeletal tuffs, directly controlled by the onset of neighbouring eruptive explosions.

APA, Harvard, Vancouver, ISO, and other styles

33

Pierosan, Ronaldo, Evandro F. Lima, Lauro V. S. Nardi, Cristina P. de Campos, Artur C. Bastos Neto, José M. T. M. Ferron, and Maurício Prado. "Paleoproterozoic (~1.88Ga) felsic volcanism of the Iricoumé Group in the Pitinga Mining District area, Amazonian Craton, Brazil: insights in ancient volcanic processes from field and petrologic data." Anais da Academia Brasileira de Ciências 83, no. 3 (September 2011): 921–37. http://dx.doi.org/10.1590/s0001-37652011000300012.

Full text

Abstract:

The Iricoumé Group correspond to the most expressive Paleoproterozoic volcanism in the Guyana Shield, Amazonian craton. The volcanics are coeval with Mapuera granitoids, and belong to the Uatumã magmatism. They have U-Pb ages around 1880 Ma, and geochemical signatures of α-type magmas. Iricoumé volcanics consist of porphyritic trachyte to rhyolite, associated to crystal-rich ignimbrites and co-ignimbritic fall tuffs and surges. The amount and morphology of phenocrysts can be useful to distinguish lava (flow and dome) from hypabyssal units. The morphology of ignimbrite crystals allows the distinction between effusive units and ignimbrite, when pyroclasts are obliterated. Co-ignimbritic tuffs are massive, and some show stratifications that suggest deposition by current traction flow. Zircon and apatite saturation temperatures vary from 799°C to 980°C, are in agreement with most temperatures of α-type melts and can be interpreted as minimum liquidus temperature. The viscosities estimation for rhyolitic and trachytic compositions yield values close to experimentally determined melts, and show a typical exponential decay with water addition. The emplacement of Iricoumé volcanics and part of Mapuera granitoids was controlled by ring-faults in an intracratonic environment. A genesis related to the caldera complex setting can be assumed for the Iricoumé-Mapuera volcano-plutonic association in the Pitinga Mining District.

APA, Harvard, Vancouver, ISO, and other styles

34

Patrick, Matthew R., and John L. Smellie. "Synthesis A spaceborne inventory of volcanic activity in Antarctica and southern oceans, 2000–10." Antarctic Science 25, no. 4 (June 12, 2013): 475–500. http://dx.doi.org/10.1017/s0954102013000436.

Full text

Abstract:

AbstractOf the more than twenty historically active volcanoes in Antarctica and the sub-Antarctic region only two, to our knowledge, host any ground-based monitoring instruments. Moreover, because of their remoteness, most of the volcanoes are seldom visited, thus relegating the monitoring of volcanism in this region almost entirely to satellites. In this study, high temporal resolution satellite data from the Hawaii Institute of Geophysics and Planetology's MODVOLC system using MODIS (Moderate Resolution Imaging Spectroradiometer) are complemented with high spatial resolution data (ASTER, or Advanced Spaceborne Thermal Emission and Reflection Radiometer, and similar sensors) to document volcanic activity throughout the region during the period 2000–10. Five volcanoes were observed in eruption (Mount Erebus, Mount Belinda, Mount Michael, Heard Island and McDonald Island), which were predominantly low-level and effusive in nature. Mount Belinda produced tephra, building a cinder cone in addition to an extensive lava field. Five volcanoes exhibited detectable thermal, and presumed fumarolic, activity (Deception, Zavodovski, Candlemas, Bristol, and Bellingshausen islands). A minor eruption reported at Marion Island was not detected in our survey due to its small size. This study also discovered a new active vent on Mount Michael, tracked dramatic vent enlargement on Heard Island, and provides an improved picture of the morphology of some of the volcanoes.

APA, Harvard, Vancouver, ISO, and other styles

35

Dunbar, N. W., N. A. Iverson, J. L. Smellie, W. C. McIntosh, M. J. Zimmerer, and P. R. Kyle. "Chapter 7.4 Active volcanoes in Marie Byrd Land." Geological Society, London, Memoirs 55, no. 1 (2021): 759–83. http://dx.doi.org/10.1144/m55-2019-29.

Full text

Abstract:

AbstractTwo volcanoes in Marie Byrd Land, Mount Berlin and Mount Takahe, can be considered active, and a third, Mount Waesche, may be as well; although the chronology of activity is less well constrained. The records of explosive activity of these three volcanoes is well represented through deposits on the volcano flanks and tephra layers found in blue ice areas, as well as by the presence of cryptotephra layers found in West and East Antarctic ice cores. Records of effusive volcanism are found on the volcano flanks but some deposits may be obscured by pervasive glacerization of the edifices. Based on a compilation of tephra depths–ages in ice cores, the activity patterns of Mount Takahe and Mount Berlin are dramatically different. Mount Takahe has erupted infrequently over the past 100 kyr. Mount Berlin, by contrast, has erupted episodically during this time interval, with the number of eruptions being dramatically higher in the time interval betweenc.32 and 18 ka. Integration of the Mount Berlin tephra record from ice cores and blue ice areas over a 500 kyr time span reveals a pattern of geochemical evolution related to small batches of partial melt being progressively removed from a single source underlying Mount Berlin.

APA, Harvard, Vancouver, ISO, and other styles

36

Semenzato, Andrea, Matteo Massironi, Sabrina Ferrari, Valentina Galluzzi, David A. Rothery, David L. Pegg, Riccardo Pozzobon, and Simone Marchi. "An Integrated Geologic Map of the Rembrandt Basin, on Mercury, as a Starting Point for Stratigraphic Analysis." Remote Sensing 12, no. 19 (October 1, 2020): 3213. http://dx.doi.org/10.3390/rs12193213.

Full text

Abstract:

Planetary geologic maps are usually carried out following a morpho-stratigraphic approach where morphology is the dominant character guiding the remote sensing image interpretation. On the other hand, on Earth a more comprehensive stratigraphic approach is preferred, using lithology, overlapping relationship, genetic source, and ages as the main discriminants among the different geologic units. In this work we produced two different geologic maps of the Rembrandt basin of Mercury, following the morpho-stratigraphic methods and symbology adopted by many authors while mapping quadrangles on Mercury, and an integrated geo-stratigraphic approach, where geologic units were distinguished also on the basis of their false colors (derived by multispectral image data of the NASA MESSENGER mission), subsurface stratigraphic position (inferred by crater excavation) and model ages. We distinguished two different resurfacing events within the Rembrandt basin, after the impact event, and four other smooth plains units outside the basin itself. This provided the basis to estimate thicknesses, volumes, and ages of the smooth plains inside the basin. Results from thickness estimates obtained using different methodologies confirm the presence of two distinct volcanic events inside the Rembrandt basin, with a total thickness ranging between 1–1.5 km. Furthermore, model ages suggest that the volcanic infilling of the Rembrandt basin is among the ones that extended well into the mid-Calorian period, when Mercury’s effusive volcanism was previously thought to be largely over.

APA, Harvard, Vancouver, ISO, and other styles

37

Groves, John R., and Yue Wang. "Timing and size selectivity of the Guadalupian (Middle Permian) fusulinoidean extinction." Journal of Paleontology 87, no. 2 (March 2013): 183–96. http://dx.doi.org/10.1666/12-076r.1.

Full text

Abstract:

A comprehensive, high resolution stratigraphic database of fusulinoidean foraminifers reveals that this group of protists suffered extreme losses during the Guadalupian extinction. Most species (88%) were eliminated gradually over the course of 9 myr during the Wordian and Capitanian ages. A pulse of greatly elevated per capita extinction frequency occurred during the last million years of the Capitanian (260–259 Ma). Contrary to prevailing opinion, the end-Capitanian event did not preferentially eliminate large, morphologically complex species in the families Schwagerinidae and Neoschwagerinidae, because most species in those families were already extinct. Rather, 69 percent of the species eliminated at the end of the Capitanian were small, morphologically conservative representatives of the Ozawainellidae, Schubertellidae and Staffellidae. Survivors from these families comprised the low-diversity association of Wuchiapingian fusulinoideans. Schubertellids, and to a lesser extent ozawainellids, diversified in the late Wuchiapingian and Changhsingian ages before the final demise of fusulinoideans during the end-Permian mass extinction. The Wordian–Capitanian fusulinoidean attrition might have been caused by photosymbiont loss and habitat reduction stemming from an interval of global cooling termed the Kamura event (∼265–259.5 Ma), although the onset of fusulinoidean diversity decline predates geochemical evidence for the beginning of the Kamura event by ∼3 myr. The end-Capitanian extinction pulse might reflect environmental deterioration from the combined effects of global cooling, Emeishan effusive volcanism and sea-level lowstand.

APA, Harvard, Vancouver, ISO, and other styles

38

Polo, L. A., V. A. Janasi, D. Giordano, E. F. Lima, E. Cañon-Tapia, and M. Roverato. "Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: Evidence for locally-fed lava flows and domes from detailed field work." Journal of Volcanology and Geothermal Research 355 (April 2018): 204–18. http://dx.doi.org/10.1016/j.jvolgeores.2017.08.007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Ntarmouchant, A., H. Smaili, T. Bento dos Santos, M. Dahire, K. Sabri, M. L. Ribeiro, Y. Driouch, R. Santos, and R. Calvo. "New evidence of effusive and explosive volcanism in the Lower Carboniferous formations of the Moroccan Central Hercynian Massif: Geochemical data and geodynamic significance." Journal of African Earth Sciences 115 (March 2016): 218–33. http://dx.doi.org/10.1016/j.jafrearsci.2015.12.019.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Chauvet, François, Henriette Lapierre, Delphine Bosch, Stéphane Guillot, Georges Mascle, Jean-Claude Vannay, Jo Cotten, Pierre Brunet, and Francine Keller. "Geochemistry of the Panjal Traps basalts (NW Himalaya): records of the Pangea Permian break-up." Bulletin de la Société Géologique de France 179, no. 4 (July 1, 2008): 383–95. http://dx.doi.org/10.2113/gssgfbull.179.4.383.

Full text

Abstract:

AbstractThe late Lower to Middle Permian Panjal Traps (NW Himalaya, India-Pakistan) represent the greatest magmatic province erupted on the northern Indian platform during the Neotethys opening. New geochemical and isotopic analyses were performed on basalts from the eastern borders of the traps (SE Zanskar-NW Spiti area) in order to characterize this volcanism, to discuss its compositional variations in comparison to Panjal counterparts and its relationships with the opening of Neotethys. Lavas show features of tholeiitic low-Ti (< 1.6%) continental flood basalts with LREE, Th enrichments and Nb-Ta negative anomalies. Trace element ratios combined with εNdi values (−3.6 to +0.9) and high Pb isotopic ratios suggest that these tholeiitic basalts were derived from an OIB-like mantle contaminated at various degrees by a continental crust component. Previous geochemical features are broadly similar to those of the coeval Panjal volcanic sequences identified westwards (Ladakh, Kashmir and Pakistan). Present geochemical constraints obtained for the Panjal Traps basalts suggest they originated from rapid effusion of tholeiitic melts during opening of the Neotethys Ocean. Similar magmatism implying an OIB-type reservoir is contemporaneously recognized on and along the adjacent Arabian platform. Both Indian and Arabian Permian volcanics were emplaced during coeval syn-rift to post rift transition. These Lower to Middle Permian south Neotethyan continental flood magmatism are regarded as associated to a passive rifting. In this scheme, OIB-type isotopic signature would be related either to a melting episode of syn-rift up-welling mantle plumes or to a melting of a regional abnormally hot and enriched mantle.

APA, Harvard, Vancouver, ISO, and other styles

41

Polo, L. A., D. Giordano, V. A. Janasi, and L. F. Guimarães. "Effusive silicic volcanism in the Paraná Magmatic Province, South Brazil: Physico-chemical conditions of storage and eruption and considerations on the rheological behavior during emplacement." Journal of Volcanology and Geothermal Research 355 (April 2018): 115–35. http://dx.doi.org/10.1016/j.jvolgeores.2017.05.027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Lebedev, V. A., G. T. Vashakidze, A. V. Parfenov, and A. I. Yakushev. "The origin of adakite-like magmas in the modern continental ollision zone: evidence from pliocene dacitic volcanism of the Akhalkalaki lava plateau (Javakheti highland, Lesser Kaucasus)." Петрология 27, no. 3 (May 19, 2019): 327–51. http://dx.doi.org/10.31857/s0869-5903273327-351.

Full text

Abstract:

The paper reports the isotope-geochronological and petrological-geochemical studies of the Pliocene moderately-acid volcanism of the Akhalkalaki Plateau in the central part of the Lesser Caucasus (Javakheti highland, Georgia). K-Ar dating showed that young dacitic lavas and pyroclastic rocks were formed in the Mid-Pliocene (3.28 ± 0.10 Ma) in relation with the explosive–effusive eruptions of small composite volcanic cones and formation of minor extrusive domes confined mainly to the eastern margin of the region. Isotope-geochronological data in the combination with results of structural drilling indicate that the considered short-term pulse of the volcanic activity occurred during a short gap between two phases of the Pliocene–Early Pleistocene mafic magmatism widespread within the Akhalkalaki plateau. The studied Pliocene dacites were erupted at the post-collisional stage of the evolution of the Lesser Caucasus, but bear petrological-geochemical affinity of adakitic series. They are characterized by the steady presence of amphibole phenocrysts, the elevated contents of Sr, Ba, LILE and the lowered contents of Y, Nb, Ta, and HREE, and have depleted Sr isotopic composition (87Sr/86Sr < 0.7045). Analysis of petrogenetic models earlier proposed to explain the generation of adakite-like magmas in the modern collision zones showed that the origin of the Pliocene dacitic lavas of the Akhlkalaki plateau is best described by the crystallization differentiation of watersaturated calc-alkaline basaltic melts with removal of common mafic rock-forming minerals (first of all, amphibole and pyroxene) and accessory phases (apatite, titanite, Ti-magnetite) as cumulus minerals. Crustal assimilation of evolved magmas only insignificantly contributed to the petrogenesis of the dacites.

APA, Harvard, Vancouver, ISO, and other styles

43

Faria, B., and J. F. B. D. Fonseca. "Investigating volcanic hazard in Cape Verde Islands through geophysical monitoring: network description and first results." Natural Hazards and Earth System Sciences 14, no. 2 (February 28, 2014): 485–99. http://dx.doi.org/10.5194/nhess-14-485-2014.

Full text

Abstract:

Abstract. We describe a new geophysical network deployed in the Cape Verde Archipelago for the assessment and monitoring of volcanic hazards as well as the first results from the network. Across the archipelago, the ages of volcanic activity range from ca. 20 Ma to present. In general, older islands are in the east and younger ones are in the west, but there is no clear age progression of eruptive activity as widely separated islands have erupted contemporaneously on geological timescales. The overall magmatic rate is low, and there are indications that eruptive activity is episodic, with intervals between episodes of intense activity ranging from 1 to 4 Ma. Although only Fogo Island has experienced eruptions (mainly effusive) in the historic period (last 550 yr), Brava and Santo Antão have experienced numerous geologically recent eruptions, including violent explosive eruptions, and show felt seismic activity and geothermal activity. Evidence for recent volcanism in the other islands is more limited and the emphasis has therefore been on monitoring of the three critical islands of Fogo, Brava and Santo Antão, where volcanic hazard levels are highest. Geophysical monitoring of all three islands is now in operation. The first results show that on Fogo, the seismic activity is dominated by hydrothermal events and volcano-tectonic events that may be related to settling of the edifice after the 1995 eruption; in Brava by volcano-tectonic events (mostly offshore), and in Santo Antão by volcano-tectonic events, medium-frequency events and harmonic tremor. Both in Brava and in Santo Antão, the recorded seismicity indicates that relatively shallow magmatic systems are present and causing deformation of the edifices that may include episodes of dike intrusion.

APA, Harvard, Vancouver, ISO, and other styles

44

Faria, B., and J. F. B. D. Fonseca. "Investigating volcanic hazard in Cape Verde Islands through geophysical monitoring: network description and first results." Natural Hazards and Earth System Sciences Discussions 1, no. 5 (September 25, 2013): 4997–5032. http://dx.doi.org/10.5194/nhessd-1-4997-2013.

Full text

Abstract:

Abstract. We describe a new geophysical network deployed in the Cape Verde archipelago for the assessment and monitoring of volcanic hazards, and the first results from the network. Across the archipelago, the ages of volcanic activity range from ca. 20 Ma to present. In general, older islands are in the east and younger ones are in the west, but there is no clear age progression and widely-separated islands have erupted contemporaneously on geological time scales. The overall magmatic rate is low, and there are indications that eruptive activity is episodic, with intervals between episodes of intense activity ranging from 1 to 4 Ma. Although only Fogo island has experienced eruptions (mainly effusive) in the historic period (last 550 yr), Brava and Santo Antão have experienced numerous geologically recent eruptions including violent explosive eruptions, and show felt seismic activity and geothermal activity. Evidence for recent volcanism in the other islands is more limited and the emphasis has therefore been on monitoring of the three critical islands of Fogo, Brava and Santo Antão, where volcanic hazard levels are highest. Geophysical monitoring of all three islands is now in operation. The first results show that in Fogo the seismic activity is dominated by hydrothermal events and volcano-tectonic events that may be related to settling of the edifice after the 1995 eruption; in Brava by volcano-tectonic events (mostly offshore), and in Santo Antão by volcano-tectonic events, medium frequency events and harmonic tremor. Both in Brava and in Santo Antão, the recorded seismicity indicates that relatively shallow magmatic systems are present and causing deformation of the edifices that may include episodes of dike intrusion.

APA, Harvard, Vancouver, ISO, and other styles

45

Abdel Motelib, A., E. A. Khalaf, and H. Al-Marzouki. "Growth, destruction and facies architecture of effusive and explosive volcanics in the Miocene Shama basin, southwest of Saudi Arabia: Subaqueous–subaerial volcanism in a lacustrine setting." Journal of Volcanology and Geothermal Research 309 (January 2016): 156–77. http://dx.doi.org/10.1016/j.jvolgeores.2015.10.011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Abdel Motelib, A., E. A. Khalaf, and H. Al-Marzouki. "WITHDRAWN: Growth, destruction and facies architecture of effusive and explosive volcanics in the Miocene Shama basin, southwest of Saudi Arabia: Subaqueous–subaerial volcanism in a lacustrine setting." Journal of Volcanology and Geothermal Research 277 (May 2014): 51–76. http://dx.doi.org/10.1016/j.jvolgeores.2014.03.007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Pécskay, Zoltán, Ioan Seghedi, Marinel Kovacs, Alexandru Szakács, and Alexandrina Fülöp. "Geochronology of the Neogene calc-alkaline intrusive magmatism in the "Subvolcanic Zone" of the Eastern Carpathians (Romania)." Geologica Carpathica 60, no. 2 (April 1, 2009): 181–90. http://dx.doi.org/10.2478/v10096-009-0012-5.

Full text

Abstract:

Geochronology of the Neogene calc-alkaline intrusive magmatism in the "Subvolcanic Zone" of the Eastern Carpathians (Romania)The Poiana Botizei-Ţibleş-Toroiaga-Rodna-Bârgâu intrusive area (PBTTRB), northwest Romania, known as the "Subvolcanic Zone", is located between the Gutâi (NW) and Câlimani (SE) volcanic massifs. It consists of rocks displaying a wide range of compositions and textures: equigranular or porphyritic with holocrystalline groundmass (gabbro-diorites, diorites, monzodiorites and granodiorites), and/or porphyritic with fine holocrystalline or glassycryptocrystalline groundmass, similar with effusive rocks: basalts, basaltic andesites, andesites, dacites and rhyolites. The time-span of intrusive rocks emplacement is similar with the nearest calc-alkaline volcanic rocks from Gutâi (NW) and Câlimani (SE) massifs. They are represented by stocks, laccoliths, dykes and sills typical for an upper crustal intrusive environment. In the absence of biostratigraphic evidence, a comprehensive K-Ar study of intrusive rocks using whole rock samples, groundmass and monomineral fractions (biotite, hornblende) has been carried out in order to understand the magmatic evolution of the area. The oldest K-Ar ages recorded in the analysed rocks are close to 11.5 Ma and magmatism continued to develop until about 8.0 Ma. The inception of intrusion emplacement in the PBTTRB is coeval with intrusive activity spatially related to volcanism within the neighbouring Gutâi and Câlimani massifs. However, its culmination at ca. 8 Ma ago is younger than the interruption of this activity at ca. 9.2 Ma in Gutâi and Câlimani Mts where intrusive activity resumed for ca. 1 Myr. These circumstances strongly suggest that the geodynamic evolution of the area controlled the development of both volcanic and intrusive activity and their reciprocal relationships. The overall geological data suggest that in the PBTTRB intra-lithospheric transpressional-transtensional tectonic processes controlled the generation and emplacement of intrusive bodies between ca. 12-8 Ma.

APA, Harvard, Vancouver, ISO, and other styles

48

BRYAN, S. E., J. MARTÍ, and R. A. F. CAS. "Stratigraphy of the Bandas del Sur Formation: an extracaldera record of Quaternary phonolitic explosive eruptions from the Las Cañadas edifice, Tenerife (Canary Islands)." Geological Magazine 135, no. 5 (September 1998): 605–36. http://dx.doi.org/10.1017/s0016756897001258.

Full text

Abstract:

Explosive volcanism has dominated the large phonolitic shield volcano of Tenerife, the Las Cañadas edifice, for the last 1.5 m.y. Pyroclastic deposits of the Bandas del Sur Formation are exposed along the southern flanks, and record the last two of at least three long-term cycles of caldera-forming explosive eruptions. Each cycle began with flank fissure eruptions of alkali basalt lava, followed by minor eruptions of basanite to phonotephrite lavas. Minor phonotephritic to phonolitic lava effusions also occurred on the flanks of the edifice during the latter stages of the second explosive cycle. Non-welded plinian fall deposits and ignimbrites are the dominant explosive products preserved on the southern flanks. Of these, a significant volume has been dispersed offshore. Many pyroclastic units of the second explosive cycle exhibit compositional zonation. Banded pumice occurs in most units of the third (youngest) explosive cycle, and ignimbrites typically contain mixed phenocryst assemblages, indicating the role of magma mixing/mingling prior to eruption. At least four major eruptions of the third cycle began with phreatomagmatic activity, producing lithic-poor, accretionary lapilli-bearing fallout and/or surge deposits. The repeated, brief phase of phreatomagmatism at the onset of these eruptions is interpreted as reflecting an exhaustive water supply, probably a small caldera lake that was periodically established during the third cycle. Accidental syenite becomes an increasingly important lithic clast type in ignimbrites up-sequence, and is interpreted as recording the progressive development of a plutonic complex beneath the summit caldera.Successive eruptions during each explosive cycle increased in volume, with the largest eruption occurring at the end of the cycle. More than ten major explosive eruptions vented moderately large volumes (1−[ges ]10 km3) of phonolitic magma during the last two cycles. Culminating each explosive cycle was the emplacement of relatively large volume (>5−10 km3) ignimbrites with coarse, vent-derived lithic breccias, interpreted to record a major phase of caldera collapse. In the extracaldera record, explosive cycles are separated by ∼0.2 m.y. periods of non-explosive activity. Repose periods were characterized by erosion, remobilization of pyroclastic deposits by discharge events, and pedogenesis. The current period of non-explosive activity is characterized by the construction of the Teide-Pico Viejo stratovolcanic complex within the summit caldera. This suggests that eruptive hiatuses in the extracaldera record may reflect effusive activity and stratovolcano or shield-building phases within the summit caldera. Alternating effusive and explosive cycles have thus been important in the volcanic evolution of the Las Cañadas edifice.

APA, Harvard, Vancouver, ISO, and other styles

49

Spalletti, Luis A., and Carlos O. Limarino. "The Choiyoi magmatism in south western Gondwana: implications for the end-permian mass extinction - a review." Andean Geology 44, no. 3 (September 29, 2017): 328. http://dx.doi.org/10.5027/andgeov44n3-a05.

Full text

Abstract:

The end of the Permian period is marked by global warming and the biggest known mass extinction on Earth. The crisis is commonly attributed to the formation of large igneous provinces because continental volcanic emissions have the potential to control atmospheric carbon dioxide (CO2) levels and climate change. We propose that in southwestern Gondwana the long-term hothouse Permian environmental conditions were associated with the development of the Choiyoi magmatism. This large igneous province was developed between the Cisuralian and the early Triassic. It covers an area estimated at 1,680,000 km2 with an average thickness of 700 m, so that the volume of effusive and consanguineous rocks is estimated at 1,260,000 km3. Towards the western sector of the study region, a major overlap exists between the regional development of the Choiyoi magmatism and the Carboniferous sedimentary basins, which include paralic and continental deposits with intercalations of peat and coal beds. Commonly, these upper Palaeozoic deposits accumulated on a thick substrate composed of Cambro-Ordovician carbonates and Ordovician to Devonian terrigenous sedimentary rocks characterised by a large proportion of dark organic-rich shales and turbidite successions. While extensive volcanism released large masses of carbon dioxide into the Permian atmosphere, the heating of Palaeozoic organic-rich shales, peat and carbonates by ascending magma led to CO2 and CH4 gas generation in sufficient volumes to amplify the major climatic change. The analysis of the almost continuous record of Permian redbeds in the Paganzo basin, where the Choiyoi magmatism is not recorded, allowed us to recognize two main pulses of strong environmental desiccation, one at the Cisuralian and the second around the end-Permian. These two drastic climatic crisis are attributed to peaks of CO2 and CH4 outbursts to the atmosphere and related collateral effects, such as acid rain, impoverishment of soils and increase in forest-fire frequency. We propose that the combination of these multiple mechanisms triggered the decline of biodiversity in southwestern Gondwana and caused the end-Permian extinction of most of the Glossopteridales.

APA, Harvard, Vancouver, ISO, and other styles

50

Motelib, A. Abdel, E. A. Khalaf, and H. Al-Marzouki. "Corrigendum to “Growth, destruction and facies architecture of effusive and explosive volcanics in the Miocene Shama basin, South west of Saudi Arabia: Subaqueous–subaerial volcanism in a lacustrine setting” [J. Volcanol. Geotherm. Res. (1st May 2014) 51–76; 10.1016/j.jvolgeores.2014.03.007]." Journal of Volcanology and Geothermal Research 309 (January 2016): 178. http://dx.doi.org/10.1016/j.jvolgeores.2015.11.016.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Volcanisme effusif'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles