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Artículos de revistas sobre el tema "ΕNd"

Autor: Grafiati
Publicado: 14 de diciembre de 2024
Última modificación: 31 de julio de 2025

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1

Kerr, Andrew, George A. Jenner, and Brian J. Fryer. "Sm–Nd isotopic geochemistry of Precambrian to Paleozoic granitoid suites and the deep-crustal structure of the southeast margin of the Newfoundland Appalachians." Canadian Journal of Earth Sciences 32, no. 2 (1995): 224–45. http://dx.doi.org/10.1139/e95-019.

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In the Eastern Central Mobile Belt of the Newfoundland Appalachians, late Precambrian basement inliers have εNd from −3 to +2, but Cambro-Ordovician metasedimentary rocks have initial εNd below −7. This region is inferred to have an "inverted" crustal residence structure, which influenced subsequent Appalachian-cycle magmatism. Ordovician and Silurian granitoid suites have εNd of −8 to −2, bracketing both basement and cover, but peraluminous, "S-type" granites have the lowest εNd. Devonian granites have initial εNd values from −5 to +1, and low εNd is associated with peraluminous character. Th
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2

Arsouze, T., J. C. Dutay, M. Kageyama, et al. "A modeling sensitivity study of the influence of the Atlantic meridional overturning circulation on neodymium isotopic composition at the Last Glacial Maximum." Climate of the Past 4, no. 3 (2008): 191–203. http://dx.doi.org/10.5194/cp-4-191-2008.

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Abstract. Using a simple parameterisation that resolves the first order global Nd isotopic composition (hereafter expressed as εNd in an Ocean Global Circulation Model, we have tested the impact of different circulation scenarios on the εNd in the Atlantic for the Last Glacial Maximum (LGM), relative to a modern control run. Three different LGM freshwater forcing experiments are performed to test for variability in the εNd oceanic distribution as a function of ocean circulation. Highly distinct representations of the ocean circulation are generated in the three simulations, which drive signifi
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3

Mikhailik, P. E., I. A. Vishnevskaya, E. V. Mikhailik, et al. "Genesis and Nd Isotope Composition of Ferromanganese Deposits of the Sea of Okhotsk and the Kuril Island Arc." Russian Geology and Geophysics 62, no. 9 (2021): 1074–87. http://dx.doi.org/10.2113/rgg20194142.

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Abstract —The Nd isotope composition of ferromanganese deposits (FMD) from the central part of the Sea of Okhotsk and the Kuril island arc has been studied. The results showed that diagenetic samples from the Deryugin Basin have a heterogeneous Nd isotope composition. The positive εNd values here might be both due to the input of a terrigenous impurity and due to diffuse endogenetic element supply. The FMD samples from the Sonne underwater ridge show a εNd value specific to seawater (–3.2). The εNd value of hydrogenetic FMD from Volcano 7.14 is –3.4, which corresponds to the εNd value of the P
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4

Bock, B., S. M. McLennan, and G. N. Hanson. "The Taconian orogeny in southern New England: Nd-isotope evidence against addition of juvenile components." Canadian Journal of Earth Sciences 33, no. 12 (1996): 1612–27. http://dx.doi.org/10.1139/e96-122.

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Nd-isotope data for pre-Taconian (meta)sedimentary and igneous rocks, syn-Taconian (meta)sedimentary rocks, and Late Ordovician–Silurian plutonic rocks indicate that the Ordovician Taconian orogeny did not add significant amounts of juvenile crust to the Laurentian margin in southern New England. Nd-isotope compositions of Grenvillian crust and Late Proterozoic to Early Cambrian rift sediments range from εNd of −3.1 to −6.6 at 450 Ma. Sedimentary rocks deposited during the Cambrian and the early Middle Ordovician, which represent the drift stage of Laurentia, and earliest Taconian sedimentary
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5

Khim, Boo-Keun, Keiji Horikawa, Yoshihiro Asahara, Ji-Eun Kim, and Minoru Ikehara. "Detrital Sr–Nd isotopes, sediment provenances and depositional processes in the Laxmi Basin of the Arabian Sea during the last 800 ka." Geological Magazine 157, no. 6 (2018): 895–907. http://dx.doi.org/10.1017/s0016756818000596.

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Abstract87Sr/86Sr ratios and εNd values of detrital particles at International Ocean Discovery Program (IODP) Site U1456 in the Laxmi Basin of the Arabian Sea were measured to trace changes in sediment provenance over glacial–interglacial cycles. Based on the correlation of planktonic foraminiferal (Globigerinoides ruber) δ18O fluctuations with the LR04 stack of benthic foraminifera δ18O values, combined with shipboard biostratigraphic and palaeomagnetic data, the studied interval spans ∼1.2 Ma. Over the past 800 ka, 87Sr/86Sr values ranged from 0.711 to 0.726 while εNd values ranged between −
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6

Dubois-Dauphin, Quentin, Paolo Montagna, Giuseppe Siani, et al. "Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals." Climate of the Past 13, no. 1 (2017): 17–37. http://dx.doi.org/10.5194/cp-13-17-2017.

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Abstract. We present the neodymium isotopic composition (εNd) of mixed planktonic foraminifera species from a sediment core collected at 622 m water depth in the Balearic Sea, as well as εNd of scleractinian cold-water corals (CWC; Madrepora oculata, Lophelia pertusa) retrieved between 280 and 442 m water depth in the Alboran Sea and at 414 m depth in the southern Sardinian continental margin. The aim is to constrain hydrological variations at intermediate depths in the western Mediterranean Sea during the last 20 kyr. Planktonic (Globigerina bulloides) and benthic (Cibicidoides pachyderma) fo
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7

Samson, Scott D., Sandra M. Barr, and Chris E. White. "Nd isotopic characteristics of terranes within the Avalon Zone, southern New Brunswick." Canadian Journal of Earth Sciences 37, no. 7 (2000): 1039–52. http://dx.doi.org/10.1139/e00-015.

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Nd isotopic data are presented for rock units in four terranes within the traditional Avalon Zone of southern New Brunswick. Initial εNd values for igneous rocks within the Caledonia terrane range from -1.6 to +4.6, whereas values for sedimentary rocks range from -8.4 to +3.6. A granite within the Kingston terrane has εNd(438 Ma) = +4.0. Nd isotopic compositions for the Kingston and Caledonia terranes are similar to those of the Mira terrane in Cape Breton Island, the Antigonish Highlands of Nova Scotia, and plutonic rocks of eastern Newfoundland. Each of these regions may be a dismembered par
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8

Garzione, Carmala N., P. Jonathan Patchett, Gerald M. Ross, and JoAnne Nelson. "Provenance of Paleozoic sedimentary rocks in the Canadian Cordilleran miogeocline: a Nd isotopic study." Canadian Journal of Earth Sciences 34, no. 12 (1997): 1603–18. http://dx.doi.org/10.1139/e17-129.

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Nd isotopes and trace elements in sedimentary rocks of the Yukon, the Northwest Territories, and northern British Columbia are used to examine the source of sediments in the Canadian Cordilleran miogeocline. Previous Nd isotope studies in southern Alberta demonstrated that strata of Neoproterozoic to Late Ordovician age were derived from Archean and Proterozoic Canadian Shield sources, whereas by the Late Devonian, a shift of 6 εNd units to younger crustal sources (εNd (T) = −6 to −9) had occurred. In this study, we found that the shift to younger crustal Nd isotopic signatures in the Yukon an
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9

Chauvel, C., N. T. Arndt, S. Kielinzcuk, and A. Thom. "Formation of Canadian 1.9 Ga old continental crust. I: Nd isotopic data." Canadian Journal of Earth Sciences 24, no. 3 (1987): 396–406. http://dx.doi.org/10.1139/e87-042.

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A Nd isotopic study was carried out on 1.9−1.8 Ga rocks from two parts of the Trans-Hudson Orogen in northern Canada. The first part is the Reindeer Lake Zone in the Churchill Province in Saskatchewan, where a variety of volcanic, granitoid, and sedimentary rocks are preserved in several lithotectonic belts that border a reworked Archean craton to the northwest. The second area comprises the Ottawa and Belcher islands, in Hudson Bay, and the Fox River volcanics, in Manitoba. These form part of the Circum-Superior Belt, a band of basaltic volcanics and sedimentary rocks that overlies the Archea
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10

Fryer, Brian J., John D. Greenough, and J. Victor Owen. "Iapetus Ocean floor stuffed into a suture zone: xenolith Nd isotopic evidence for Dunnage-equivalent basement in central Newfoundland." Canadian Journal of Earth Sciences 34, no. 10 (1997): 1392–400. http://dx.doi.org/10.1139/e17-111.

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Granulite-facies xenoliths from Late Jurassic alkaline lamprophyres may represent basement to the Dunnage Zone in north-central Newfoundland (Notre Dame Bay area). At 143 Ma the xenoliths had positive εNd values between 0.9 and 4.7. They give Nd depleted mantle model ages around 700 Ma and have trace element and major element compositions reminiscent of oceanic arc-related intermediate volcanic and sedimentary rocks. Their positive εNd values and associated "young" Nd model ages argue against their representing Grenvillian crust. Similarly, Gander Zone basement to the east produced granitic ro
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11

Udoratina, O. V., K. V. Kulikova, A. S. Shuyskiy, et al. "GRANITOID MAGMATISM IN THE NORTH OF THE URALS: U–Pb AGE, EVOLUTION, SOURCES." Geodynamics & Tectonophysics 12, no. 2 (2021): 287–309. http://dx.doi.org/10.5800/gt-2021-12-2-0525.

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This work presents the summarization of U–Pb (SIMS, TIMS) zircon dates and petrogeochemical signatures of granitoids of the north of the Urals (Polar, Subpolar, and Northern Urals) obtained over the last decade. Granitе melts were formed from melting of different substrates, highly heterogeneous in composition and age, at all geodynamic stages distinguished in the studied area. Preuralides include island arc–accretionary (735–720 Ma, 670 Ma), collisional (650–520 Ma), and rift-related (520–480 Ma) granitoids. Uralides includes primitive island-arc granitoids (460–429 Ma), mature island-arc gra
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12

Stone, P., and J. A. Evans. "Silurian provenance variation in the Southern Uplands terrane, Scotland, assessed using neodymium isotopes and linked with regional tectonic evolution." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91, no. 3-4 (2000): 447–55. http://dx.doi.org/10.1017/s0263593300008294.

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ABSTRACTThe progressive changes in the provenance of Silurian greywacke turbidites in the Southern Uplands terrane reflect geotectonic events at the Laurentian continental margin during closure of the Iapetus Ocean. In the northern Gala Group, juvenile andesitic detritus in some beds gives εNd values no lower than −4·2; more commonly, quartzo-feldspathic greywackes have εNd values in the −5·5 to −6·7 range, produced by the mixing of juvenile plutonic and Proterozoic basement detritus during arc unroofing. In the southern (younger) Gala Group, Proterozoic εNd values range down from −7·7 to −11·
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13

Xu, Jianzhong, Guangming Yu, Shichang Kang, et al. "Sr-Nd isotope evidence for modern aeolian dust sources in mountain glaciers of western China." Journal of Glaciology 58, no. 211 (2012): 859–65. http://dx.doi.org/10.3189/2012jog12j006.

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AbstractIn order to apportion the dust sources of mountain glaciers in western China, the Sr-Nd isotopic compositions of insoluble particles were determined in snow samples collected from 13 sites. The combined plot of 87Sr/86Sr and εNd(0) demonstrates a distinctive geographic pattern over western China, which can be classified into three regions from north to south. Samples from the Altai mountains show the lowest 87Sr/86Sr ratio and the highest εNd(0) value, similar to the data of deserts in the north of China such as the Gurbantunggut desert. Samples from the southern Tibetan Plateau (TP) a
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14

Myskova, T. А., A. S. Nikonova, K. А. Nikonov, I. А. Zhitnikova, and P. A. Lvov. "Kichan structure of the Archean Tiksheozero greenstone belt of the Fennoscandinavian shield in the light of new geochemical and geochronological data." Geohimiâ 69, no. 9 (2024): 831–56. https://doi.org/10.31857/s0016752524090029.

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New geological, geochemical, and geochronological (U-Pb zircon) data obtained on the greenstone rocks of the Kichany structure from the Archean Tiksheozero greenstone belt made it possible to clarify and supplement the previously proposed stratification schemes. The composition of the identified sequences, the order and duration of their formation have been specified. The Archean supracrustal rocks are divided into three sequences. The lower sequence (previously not identified) is represented by a bimodal series: tholeiitic metabasalts and felsic metavolcanics, with subordinate metagraywackes.
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15

Barr, Sandra M., and Ernst Hegner. "Nd isotopic compositions of felsic igneous rocks in Cape Breton Island, Nova Scotia." Canadian Journal of Earth Sciences 29, no. 4 (1992): 650–57. http://dx.doi.org/10.1139/e92-056.

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Nd isotopic data from 18 felsic plutonic and volcanic units in Cape Breton Island show variations consistent with other geological and geophysical evidence for at least three distinct terranes. A ca. 1.2 Ga syenite considered to be part of Grenvilleage basement exposed in the northwestern part of the island yields an initial εNd value of +0.4 and a depleted-mantle model age (TDM) of 1.66 Ga, suggesting substantial involvement of older (Archean or Early Proterozoic) crust in its petrogenesis. A TDM of 1.38 Ga indicated by Nd isotopic data for a Devonian granite spatially associated with the sye
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16

CHEN, BIN, and BOR-MING JAHN. "Geochemical and isotopic studies of the sedimentary and granitic rocks of the Altai orogen of northwest China and their tectonic implications." Geological Magazine 139, no. 1 (2002): 1–13. http://dx.doi.org/10.1017/s0016756801006100.

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The Altai orogen (northwest China) represents the southwestern margin of the Central Asian Orogenic Belt. Geochemical and Nd–Sr isotope analyses were carried out on the Palaeozoic sedimentary and granitic rocks in order to trace their sources and to evaluate the pattern of continental growth of the orogen. Nd isotopic data for both the granites and sediments suggest a significant proportion of middle Proterozoic crust beneath the Altai orogen. However, addition of juvenile material (arc/back-arc oceanic crust) during Palaeozoic times is also significant. Trace elements and isotopic data of sed
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17

Barrie, C. Tucker, and Steven B. Shirey. "Nd- and Sr-isotope systematics for the Kamiskotia–Montcalm area: implications for the formation of late Archean crust in the western Abitibi Subprovince, Canada." Canadian Journal of Earth Sciences 28, no. 1 (1991): 58–76. http://dx.doi.org/10.1139/e91-006.

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Geochemistry and Nd isotopic compositions are used to characterize mantle and crustal sources and to provide constraints on petrogenetic models for tholeiitic, calc-alkalic, and lamprophyric suites in the Kamiskotia–Montcalm area. The Kamiskotia gabbroic complex (KGC) and cogenetic, bimodal volcanic rocks have εNd(t) = +2.2 to +2.6, consistent with a direct derivation from a long-term, light rare-earth element (LREE)-depleted mantle. The Montcalm gabbroic complex has decreasing εNd(t) upsection from +2.8 to +1.0, consistent with contamination by long-term, LREE-enriched (with respect to the lo
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18

Nicholson, Suzanne W., Klaus J. Schulz, Steven B. Shirey, and John C. Green. "Rift-wide correlation of 1.1 Ga Midcontinent rift system basalts: implications for multiple mantle sources during rift development." Canadian Journal of Earth Sciences 34, no. 4 (1997): 504–20. http://dx.doi.org/10.1139/e17-041.

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Magmatism that accompanied the 1.1 Ga Midcontinent rift system (MRS) is attributed to the upwelling and decompression melting of a mantle plume beneath North America. Five distinctive flood-basalt compositions are recognized in the rift-related basalt succession along the south shore of western Lake Superior, based on stratigraphically correlated major element, trace element, and Nd isotopic analyses. These distinctive compositions can be correlated with equivalent basalt types in comparable stratigraphic positions in other MRS localities around western Lake Superior. Four of these composition
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19

Haynes, Shannon J., Kenneth G. MacLeod, Jean-Baptiste Ladant, et al. "Constraining sources and relative flow rates of bottom waters in the Late Cretaceous Pacific Ocean." Geology 48, no. 5 (2020): 509–13. http://dx.doi.org/10.1130/g47197.1.

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Abstract Geochemical data suggest that ocean circulation patterns changed over a period of long-term cooling during the last 10 m.y. of the Cretaceous (late Campanian–Maastrichtian). Proposed changes include enhanced deep-water formation in the South Atlantic and/or Indian sectors of the Southern Ocean, initiation or enhanced deep-water formation in the North Atlantic, and alternating regions of deep convection in the North and South Pacific. Existing geochemical data do not allow simple confirmation or rejection of any of these scenarios. To test Pacific circulation during the Maastrichtian,
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20

Ayache, Mohamed, Jean-Claude Dutay, Thomas Arsouze, Sidonie Révillon, Jonathan Beuvier та Catherine Jeandel. "High-resolution neodymium characterization along the Mediterranean margins and modelling of <i>ε</i><sub>Nd</sub> distribution in the Mediterranean basins". Biogeosciences 13, № 18 (2016): 5259–76. http://dx.doi.org/10.5194/bg-13-5259-2016.

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Abstract. An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (Nd IC) was realized in order to establish a new database and a map (using a high-resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done in order to improve this data set in key a
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21

Robinson, Suzanne, Ruza F. Ivanovic, Lauren J. Gregoire, et al. "Simulating marine neodymium isotope distributions using Nd v1.0 coupled to the ocean component of the FAMOUS–MOSES1 climate model: sensitivities to reversible scavenging efficiency and benthic source distributions." Geoscientific Model Development 16, no. 4 (2023): 1231–64. http://dx.doi.org/10.5194/gmd-16-1231-2023.

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Abstract. The neodymium (Nd) isotopic composition of seawater is a widely used ocean circulation tracer. However, uncertainty in quantifying the global ocean Nd budget, particularly constraining elusive non-conservative processes, remains a major challenge. A substantial increase in modern seawater Nd measurements from the GEOTRACES programme, coupled with recent hypotheses that a seafloor-wide benthic Nd flux to the ocean may govern global Nd isotope distributions (εNd), presents an opportunity to develop a new scheme specifically designed to test these paradigms. Here, we present the impleme
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22

Nosova, А. А., N. М. Lebedeva, А. А. Vozniak, L. V. Sazonova, Yu О. Larionova, and I. А. Kondrashev. "Nd-isotope effects through factional crystallisation-assimilation (AFC) processes in the continental crust, heterogeneous in age: the example of ferrobasalts from the Ladoga Graben (Karelia, Russia)." Doklady Rossijskoj akademii nauk. Nauki o Zemle 515, no. 1 (2024): 74–85. http://dx.doi.org/10.31857/s2686739724030106.

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Petrography, geochemistry and isotope geochemistry of the Mesoproterozoic volcanic rocks occurred as lava flows and the Valaam sill in the Ladoga rift, have been studied. The Ladoga rift is located in the area of thrusting of the Palaeoproterozoic Svekofennian orogenic complexes onto the Archean Karelian craton. Ferrobasites of close composition and geological position in lava flows and sill have different Nd isotopic composition, differing by 5 units εNd(t): –4…-5 in ferrobasalts of lava flows and a very low-radiogenic Nd isotopic composition in mafic rocks of the sill (εNd(t) to –11 for ferr
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23

Smith, Alan D., Alan D. Brandon, and Richard StJ Lambert. "Nd–Sr isotope systematics of Nicola Group volcanic rocks, Quesnel terrane." Canadian Journal of Earth Sciences 32, no. 4 (1995): 437–46. http://dx.doi.org/10.1139/e95-037.

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Volcanic rocks of the Nicola Group belong to an arc built on the western margin of the Quesnel terrane in the Late Triassic to Early Jurassic. Low-K – high-K compositional types define a Rb–Sr isochron of 222 ± 15 Ma with initial 87Sr/86Sr = 0.70367 ± 2. The corresponding Nd isotopic compositions of these samples (εNd(222 Ma) = +5.1 to +7.8) fall within the range for early Mesozoic island arcs. A comparable range of εNd(222 Ma) (+5.0 to +7.9) in picrite–shoshonite samples precludes generation of increasingly potassic magmas by progressive metasomatism of the mantle wedge alone. Source-region h
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24

Stevenson, R. K., and A. Turek. "An isotopic study of the Island Lake Greenstone Belt, Manitoba: crustal evolution and progressive cratonization in the late Archean." Canadian Journal of Earth Sciences 29, no. 10 (1992): 2200–2210. http://dx.doi.org/10.1139/e92-174.

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Three new U–Pb zircon ages are reported for units within the Island Lake Greenstone Belt in northern Manitoba: the Jubilee Island dacite (2761 ± 12 Ma), the Chapin Bay tonalite (2748 ± 3 Ma), and the Wassagomach tonalité (2778 ± 5 Ma). Rb–Sr data suggest a mild metamorphic event about 2736 ± 67 Ma ago. Basalts within the basal Hayes River Group (2860–2900 Ma) appear to be derived from a time-averaged, Nd-depleted mantle with εNd values between +0.78 and +2.1. Lower εNd values (&lt; +0.31) are found in volcanic and intrusive rocks of the same age, implying contamination by or remelting of preex
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25

Turkina, O. M. "Variation in Trace Element and Isotope Composition of Neoarchean Mafic Granulites of the Southwest Siberian Craton: A Consequence of Various Mantle Sources or Crustal Contamination." Петрология 31, no. 2 (2023): 182–201. http://dx.doi.org/10.31857/s0869590323020061.

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The paper presents geochemical and isotopic characteristics of Neoarchean (2.7–2.66 Ga) mafic granulites of the Sharyzhalgay uplift in the southwestern Siberian craton. Mafic and predominant felsic granulites compose fragments of the metamorphic complex among the Neoarchean and Paleoproterozoic granitoids. Mafic granulites are characterized by the mineral association Cpx + Pl ± Hbl ± Opx ± Qz and include two types with different major and immobile trace element contents. The dominant rocks of the first type have a wide range of Mg# and concetrations of TiO2 and immobile trace elements (REE, Zr
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26

Goulart, Luís Emanoel Alexandre, and Mauricio Antonio Carneiro. "Evolution of arc magmatism in the Carmópolis de Minas Layered Suite, Minas Gerais, Brazil: Sm-Nd and Rb-Sr isotope geochemistry." Rem: Revista Escola de Minas 66, no. 4 (2013): 447–54. http://dx.doi.org/10.1590/s0370-44672013000400007.

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The Carmópolis de Minas Layered Suite (CMLS) is a Neoarchean Unit metamorphosed at amphibolite- to granulite-facies conditions, comprised of metaultramafic rocks, amphibolites and metarhyolites. The CMLS is marked by two distinct phases of tholeiitic and calc-alkaline magmatism. Previous geochemical data and regional constraints suggest that the CMLS is possibly a metamorphosed arc-tholeiitic suite of the type boninite-basalt-andesite-rhyolite, interpreted in this study as a dismembered remnant of the juvenile oceanic arc. The rocks of tholeiitic affinity record a signature of depleted to enri
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27

Kerr, Andrew, and Richard J. Wardle. "Definition of an Archean – Proterozoic crustal suture by isotopic studies of basement intersections from offshore wells in the southern Labrador Sea." Canadian Journal of Earth Sciences 34, no. 2 (1997): 209–14. http://dx.doi.org/10.1139/e17-017.

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Eight hydrocarbon exploration wells in the southern Labrador Sea penetrated Precambrian basement rocks, adjacent to the course of a Lithoprobe marine seismic reflection survey. The rock types are mostly Early Proterozoic (1870–1800 Ma) calc-alkaline plutonic rocks or their metamorphic derivatives, but one example is a Middle Proterozoic (1270 Ma) anorogenic intrusion. These samples of buried basement document a transition from juvenile Proterozoic crust in the southeast (shown by εNd from +0.8 to +2.2) to ancient Archean crust in the northwest (shown by εNd from −2.7 to −7.0). However, initial
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28

Xu, Wentao, Fulai Liu, Wang Xu, et al. "Geochemical and Geochronological Constraints of Permian-Triassic Magmatism on Oceanic Subduction and Continental Collision during the Eastern Paleo-Tethyan Evolution." Minerals 12, no. 5 (2022): 633. http://dx.doi.org/10.3390/min12050633.

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The Jinshajiang–Ailaoshan–Song Ma orogenic belt (JASB), as a vital segment of the eastern Paleo-Tethyan tectonic zone, is one of the most important zones in which to study the Paleo-Tethyan tectonic evolution. We have undertaken an integrated geochronological, petrological, and geochemical study of mafic rocks from the JASB to reveal the subduction and closure processes of the eastern Paleo-Tethyan Ocean during the Permian to Triassic. In conjunction with previous magmatic and metamorphic records in the JASB, three important tectonic stages are identified: (1) Early Permian to Early Triassic (
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29

Kiseleva, Olga, Pavel Serov, Evgenia Airiyants, et al. "Nd-Sr Isotopic Study of Magmatic Rocks and 40Ar/39Ar Dating of the Mafic Dike of the Proterozoic Ulan-Sar’dag Ophiolite Mélange (Southern Siberia, East Sayan, Middle Belt, Russia)." Minerals 12, no. 1 (2022): 92. http://dx.doi.org/10.3390/min12010092.

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We report the first radiogenic Nd-Sr isotope data in the magmatic rocks island-arc ophiolite assemblage from the middle branch of the East Sayan ophiolite complexes to better constrain geodynamic processes in this segment of the CAOB in southern central Siberia. The magmatic rocks belong to the following geochemical types: (1) Ensimatic island-arc boninites; (2) island-arc assemblage; (3) enriched basalts of mid-ocean ridges; and (4) oceanic island-like basalts. The boninites have a positive value εNd (T), which is generated from a depleted mantle source (N-MORB). The island-arc assemblage has
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30

Ladant, Jean-Baptiste, Christopher J. Poulsen, Frédéric Fluteau, et al. "Paleogeographic controls on the evolution of Late Cretaceous ocean circulation." Climate of the Past 16, no. 3 (2020): 973–1006. http://dx.doi.org/10.5194/cp-16-973-2020.

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Abstract. Understanding of the role of ocean circulation on climate during the Late Cretaceous is contingent on the ability to reconstruct its modes and evolution. Geochemical proxies used to infer modes of past circulation provide conflicting interpretations for the reorganization of the ocean circulation through the Late Cretaceous. Here, we present climate model simulations of the Cenomanian (100.5–93.9 Ma) and Maastrichtian (72.1–66.1 Ma) stages of the Cretaceous with the CCSM4 earth system model. We focus on intermediate (500–1500 m) and deep (&gt; 1500 m) ocean circulation and show that
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31

FELITSYN, SERGEI B., and ALEXANDER P. GUBANOV. "Nd isotope composition of early Cambrian discrete basins." Geological Magazine 139, no. 2 (2002): 159–69. http://dx.doi.org/10.1017/s0016756801006252.

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A Nd isotope map of early Cambrian epeiric basins has been inferred from the Nd isotopic signature recorded in phosphatic Small Shelly Fossils. The most radiogenic εNd(t) values characterize water reservoirs along the Avalonian and Cadomian belts, while εNd(t) values of −10 to −20 were obtained in Laurentia and East Gondwanan Australia and China. Such a distribution of Nd isotope signatures results from the different provenance of early Cambrian epeiric seas: juvenile magmatic arcs and/or cordilleran for Mongolia, Siberia, Iberia and adjacent terranes, and cratonic sources for Laurentia and Ea
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32

Pasquier, Benoît, Sophia K. V. Hines, Hengdi Liang, Yingzhe Wu, Steven L. Goldstein, and Seth G. John. "GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle." Geoscientific Model Development 15, no. 11 (2022): 4625–56. http://dx.doi.org/10.5194/gmd-15-4625-2022.

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Abstract. Spatially distant sources of neodymium (Nd) to the ocean that carry different isotopic signatures (εNd) have been shown to trace out major water masses and have thus been extensively used to study large-scale features of the ocean circulation both past and current. While the global marine Nd cycle is qualitatively well understood, a complete quantitative determination of all its components and mechanisms, such as the magnitude of its sources and the paradoxical conservative behavior of εNd, remains elusive. To make sense of the increasing collection of observational Nd and εNd data,
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33

Kim, Daeyeong, Sang-Bong Yi, Hyeoncheol Kim, Taehwan Kim, Taehoon Kim, and Jong Ik Lee. "Geochemistry and Geochronology of Early Paleozoic Intrusive Rocks in the Terra Nova Bay Area, Northern Victoria Land, Antarctica." Minerals 11, no. 7 (2021): 787. http://dx.doi.org/10.3390/min11070787.

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The Terra Nova Intrusive Complex (TNIC) in northern Victoria Land, Antarctica, results from widespread magmatism during the Early Paleozoic Ross Orogeny. According to field relationships, geochemistry, and geochronology data, the northern part of the TNIC comprises the Browning Intrusive Unit (BIU), which is associated with an arc crustal melting including migmatization of the Wilson Metamorphic Complex, and the later Campbell Intrusive Unit (CIU), which is attributed to the mantle and crustal melting processes. Zircon U-Pb ages suggest Late Neoproterozoic to Early Cambrian protolith with Late
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34

Seifert, Karl E., and James F. Olmsted. "Geochemistry of North Shore Hypabyssal dikes and sills in the Midcontinent Rift of Minnesota: an example — the 47th Avenue sill." Canadian Journal of Earth Sciences 41, no. 7 (2004): 829–42. http://dx.doi.org/10.1139/e04-038.

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This study presents geochemical data for several of the numerous small to large dikes and sills, including the 47th Avenue sill, exposed along the shore of Lake Superior in and north of Duluth, Minnesota. These intrusions are late magmatic features of the Proterozoic Midcontinent Rift System and together form the North Shore Hypabyssal Group. The dikes are geochemically distinct from the sills, and, when the two are exposed together, the younger dike intrudes the older sill. Dikes are primitive with Mg# up to 68, have positive εNd values, and are oriented approximately north–south with steep w
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35

Whalen, Joseph B., Leslie R. Fyffe, Frederick J. Longstaffe, and George A. Jenner. "The position and nature of the Gander–Avalon boundary, southern New Brunswick, based on geochemical and isotopic data from granitoid rocks." Canadian Journal of Earth Sciences 33, no. 2 (1996): 129–39. http://dx.doi.org/10.1139/e96-013.

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In southern New Brunswick, the Gander–Avalon boundary is obscured by boundary-parallel faults and various cover sequences. Siluro-Devonian granites, which intrude unequivocal Gander or Avalon rocks, display exclusively negative (−1.9 ± 1.0) and positive (+1.9 ± 0.7) εNd(T) signatures, respectively. Such contrasting Nd isotopic signatures, combined with other geochemical differences between plutons, are potentially valuable tools for terrane analysis. Nine small Devonian plutons intruding the boundary zone fall into contrasting geochemical groups with (La/Lu)N &lt;4 and &gt;4. The former are to
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36

Petrakova, M. E., A. B. Kuznetsov, Sh K. Baltybaev, V. M. Savatenkov, R. A. Terentiev, and K. A. Savko. "Sources of melts and genesis conditions of the Khokhol-Repyevka batholith granitoids in the Volga-Don orogen, Eastern European craton." Geohimiâ 69, no. 5 (2024): 437–60. https://doi.org/10.31857/s0016752524050024.

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The paper discusses the possible conditions and involvement of sources in genesis of the Khokhol-Repyevka batholith granitoids, that build up the Don terrane in the Volga-Don orogen of the East European Craton. In the batholith, three types of granitoids are distinguished – pavlovsk (quartz monzodiorite–granites, mainly pyroxene-free), potudan (quartz monzogabbro–granodiorites containing pyroxene) and hybrid (quartz monzodiorites, monzonites, quartz monzonites). These three types of rocks are spaсely co-located and have a similar age of formation 2050–2080 Ma, similar geochemical characteristi
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37

Nedosekova, Irina, Nikolay Vladykin, Oksana Udoratina, and Boris Belyatsky. "Ore and Geochemical Specialization and Substance Sources of the Ural and Timan Carbonatite Complexes (Russia): Insights from Trace Element, Rb–Sr, and Sm–Nd Isotope Data." Minerals 11, no. 7 (2021): 711. http://dx.doi.org/10.3390/min11070711.

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The Ilmeno–Vishnevogorsk (IVC), Buldym, and Chetlassky carbonatite complexes are localized in the folded regions of the Urals and Timan. These complexes differ in geochemical signatures and ore specialization: Nb-deposits of pyrochlore carbonatites are associated with the IVC, while Nb–REE-deposits with the Buldym complex and REE-deposits of bastnäsite carbonatites with the Chetlassky complex. A comparative study of these carbonatite complexes has been conducted in order to establish the reasons for their ore specialization and their sources. The IVC is characterized by low 87Sr/86Sri (0.70336
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38

JIA, Xiaohui, Xiaodi WANG, Xiaofei QIU, and Wenqiang YANG. "Petrogenesis and Tectonic Implications of the Kwangsian Orogen: Constraints from Geochemistry and Sr‐Nd‐Hf Isotopic Compositions of the Early Paleozoic Peraluminous and Aluminous Granitoids in Northern Guangdong, SE China." Acta Geologica Sinica - English Edition 99, no. 3 (2025): 707–24. https://doi.org/10.1111/1755-6724.15296.

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AbstractThis study presents whole‐rock major, trace elements and Sr‐Nd‐Hf isotopic compositions, as well as zircon U‐Pb geochronological data, for the peraluminous and aluminous granitoids in northern Guangdong Province, South China, in order to investigate their petrogenesis and tectonic implications. The Qingzhou granodiorites (458.5–455.4 Ma) are peraluminous (A/CNK = 1.05–1.96). They have relatively high initial 87Sr/86Sr ratios (ISr = 0.7087–0.7148), low εNd(t) values (–11.2 to –10.1) and a variety of zircon εHf(t) values in the range –13.4 to +4.81. By contrast, the Damaoshan granodiorit
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39

Bédard, L. Paul, and John N. Ludden. "Nd-isotope evolution of Archaean plutonic rocks in southeastern Superior Province." Canadian Journal of Earth Sciences 34, no. 3 (1997): 286–98. http://dx.doi.org/10.1139/e17-026.

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The Opatica plutonic belt, Abitibi greenstone belt, and Pontiac Subprovince represent a major proportion of the southeastern Superior Province, which was formed and accreted rapidly between approximately 2.9 and 2.8 Ga. Plutons in these belts are grouped into four types: (i) trondhjemite–tonalite–granodiorite (TTG) suite (2.82–2.69 Ga), (ii) monzodiorite (MZD) suite (2.697–2.669 Ga), (iii) late alkaline granitoid (ALK) suite (2.68–2.67 Ga), and (iv) anatectic granite and monzonite (ANA) suite (2.69–2.64 Ga). The four suites are represented in all belts and show similar petrography and geochemi
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40

Ayache, Mohamed, Jean-Claude Dutay, Kazuyo Tachikawa, Thomas Arsouze, and Catherine Jeandel. "Neodymium budget in the Mediterranean Sea: evaluating the role of atmospheric dusts using a high-resolution dynamical-biogeochemical model." Biogeosciences 20, no. 1 (2023): 205–27. http://dx.doi.org/10.5194/bg-20-205-2023.

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Abstract. The relative importance of river solid discharge, deposited sediment remobilisation, and atmospheric dust as sources of neodymium (Nd) to the ocean is the subject of ongoing debate, the magnitudes of these fluxes being associated with a significant uncertainty. The Mediterranean basin is a specific basin; it receives a vast amount of emissions from different sources and is surrounded by continental margins, with a significant input of dust as compared to the global ocean. Furthermore, it is largely impacted by the Atlantic water inflow via the Strait of Gibraltar. Here, we present th
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41

Villeneuve, M. E., R. J. Thériault, and G. M. Ross. "U–Pb ages and Sm–Nd signature of two subsurface granites from the Fort Simpson magnetic high, northwest Canada." Canadian Journal of Earth Sciences 28, no. 7 (1991): 1003–8. http://dx.doi.org/10.1139/e91-091.

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Two undeformed biotite granites recovered from exploratory hydrocarbon drill holes that penetrated basement in the Fort Simpson magnetic high were analyzed for U–Pb zircon geochronology and Sm–Nd isotopic composition. Both samples give crystallization ages of 1845 Ma, with errors of less than 5 Ma. This age overlaps with the waning stages of magmatism in the Great Bear magmatic zone of Wopmay Orogen, 200 km to the east. One sample has an initial εNd of +1.3 and a TDM of 2.14 Ga, whereas the other yielded an initial εNd of −2.1 and a TDM of 2.45 Ga. The latter sample indicates that Early Proter
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42

Liu, Guichun, Guangyan Chen, M. Santosh, et al. "Tracking Prototethyan assembly felsic magmatic suites in southern Yunnan (SW China): evidence for an Early Ordovician–Early Silurian arc–back-arc system." Journal of the Geological Society 178, no. 4 (2021): jgs2020–221. http://dx.doi.org/10.1144/jgs2020-221.

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Early Paleozoic trondhjemites, gneissic granites and alkali granites in southern Yunnan preserve important records of the tectonic evolution of the Prototethyan Ocean and regional correlations. Zircon ages suggest that these granitoids were emplaced from 476 to 436 Ma. The trondhjemites are characterized by high Na2O and low K2O contents, with εNd(t) values of −1.9 to −3.5 and εHf(t) values of −2.8 to +3.9. The trondhjemites were derived from an amphibolite source with a juvenile mafic component. The gneissic granites belong to the metaluminous low-K calc-alkaline series with an εNd(t) value o
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43

Mezger, Jochen E., Robert A. Creaser, Philippe Erdmer, and Stephen T. Johnston. "A Cretaceous back-arc basin in the Coast Belt of the northern Canadian Cordillera: evidence from geochemical and neodymium isotope characteristics of the Kluane metamorphic assemblage, southwest Yukon." Canadian Journal of Earth Sciences 38, no. 1 (2001): 91–103. http://dx.doi.org/10.1139/e00-076.

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The Coast Belt of the northern Cordillera in Canada is the locus of the boundary between accreted and ancient North American margin rocks. The largest exposure of metasedimentary rocks in the Coast Belt is the Kluane metamorphic assemblage (KMA), a northwest-striking belt 160 km long of graphitic mica–quartz schist and gneiss with minor interfoliated olivine serpentinite. The KMA does not appear to correlate with other sedimentary or metamorphic rock assemblages in the Canadian Cordillera. To determine its tectonic setting and protolith provenance, we analyzed trace element, rare earth element
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44

DeWolfe, Y. M., H. L. Gibson, and S. J. Piercey. "Petrogenesis of the 1.9 Ga mafic hanging wall sequence to the Flin Flon, Callinan, and Triple 7 massive sulphide deposits, Flin Flon, Manitoba, CanadaThis is a companion paper to DeWolfe, Y.M., Gibson, H.L., Lafrance , B., and Bailes, A.H. 2009. Volcanic reconstruction of Paleoproterozoic arc volcanoes: the Hidden and Louis formations, Flin Flon, Manitoba, Canada. Canadian Journal of Earth Sciences, 46: this issue." Canadian Journal of Earth Sciences 46, no. 7 (2009): 509–27. http://dx.doi.org/10.1139/e09-033.

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A detailed study of the geochemical and isotopic characteristics of the volcanic rocks of the Hidden and Louis formations, which make up the hanging wall to the volcanogenic massive sulphide deposits at Flin Flon, Manitoba, was carried out on a stratigraphically controlled set of samples. The stratigraphy consists of the lowermost, dominantly basaltic, Hidden formation, and the overlying, dominantly basaltic, Louis formation. Of importance petrogenetically, is the 1920 unit a basaltic andesite with Nb/Thmn = 0.54–0.62, εNd(1.9Ga) = +3.6–+5.9, εHf(1.9Ga) = +8.5–+9.6, and 204Pb/206Pb = 23.9. The
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45

Olive, Valérie, Réjean Hébert, and Michel Loubet. "Isotopic and trace element constraints on the genesis of a boninitic sequence in the Thetford Mines ophiolitic complex, Quebec, Canada." Canadian Journal of Earth Sciences 34, no. 9 (1997): 1258–71. http://dx.doi.org/10.1139/e17-100.

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The Mont Ham Massif (part of the Thetford Mines ophiolite, south Quebec) represents a magmatic sequence made up of tholeiitic and boninitic derived products. A geochemical study confirms the multicomponent mixing models that have been classically advanced for the source of boninites, with slab-derived components added to the main refractory harzburgitic peridotite. An isochron diagram of the boninitic rocks is interpreted as a mixing trend between two components: (i) a light rare earth element (LREE) enriched component (A), interpreted as slab-derived fluid–melts equilibrated with sedimentary
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46

Savko, K. A., A. V. Samsonov, and A. N. Larionov. "Mesoarchean silicic volcanics of the Kursk block, Voronezh crystalline massif: composition, age and correlation with the Ukrainian shield." Доклады Академии наук 486, no. 6 (2019): 718–22. http://dx.doi.org/10.31857/s0869-56524866718-722.

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Rhyolites and basite rocks are present in the Archaean greenstone belts of the Kursk Domain (KD) of the East Sarmatia. The rhyolite age is 3122 ± 9 Ma (zircons, SIMS). A positive εNd (3122) = + 0.9 for rhyolites and their Sm-Nd model age ТNd (DM) = 3300 Ma as well as the age of the inherited zircon (3250 Ma) testifies to the participation of the more ancient crust component in the formation of rhyolite magmas. In geochemistry, rhyolites are very close to the TTG of the KD with an age 2.96-3.03 Ga. In the Middle Dnieper granite - greenstone area there are rhyolites and dacites with an age of 3.
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47

THOMAS, ROBERT J., JOACHIM JACOBS, and BRUCE M. EGLINGTON. "Geochemistry and isotopic evolution of the Mesoproterozoic Cape Meredith Complex, West Falkland." Geological Magazine 137, no. 5 (2000): 537–53. http://dx.doi.org/10.1017/s0016756800004519.

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Whole-rock major and trace element geochemical and Rb–Sr/Sm–Nd isotopic data are presented for the Mesoproterozoic (∼1.0 Ga) metamorphic and igneous rocks of the Cape Meredith Complex, West Falkland. The data indicate that the oldest rocks, the ∼1.1 Ga supracrustal gneisses of the Big Cape Formation, which form three petrographic and geochemical groups (mafic amphibolite, quartz–plagioclase–biotite–hornblende intermediate gneiss and acid gneiss), probably represent a juvenile calc-alkaline, basalt–andesite–rhyolite volcanic sequence, with epsilon (εNdT) values and NdTDM ages of ∼+3 to +6 and ∼
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48

Smirnov, Yu V., and S. I. Dril. "SOURCES OF THE PALEOZOIC SEDIMENTARY ROCKS IN THE NORA-SUKHOTINO TERRANE: RESULTS OF Sm-Nd ISOTOPIC-GEOCHEMICAL STUDIES." Geodynamics & Tectonophysics 14, no. 6 (2023): 0730. http://dx.doi.org/10.5800/gt-2023-14-6-0730.

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The paper presents the first results on Sm-Nd isotopic-geochemical studies of the Paleozoic sedimentary rocks in the Nora-Sukhotino terrane at the northeastern flank of the South Mongolia-Khingan orogenic belt.According to the studies, the sedimentary rocks of the Zeya-Selemdzha and Amur fragments of the Nora-Sukhotino terrane are characterized by the two-stage Mesoproterozoic Nd-model age (TNd(DM2)=1.62–1.08 Ga) at negative εNd(0)=–9.5…–3.0 and εNd(T)=–5.8...–0.2. Based on previous geochemical and isotopic (U-Pb, Lu-Hf) studies of sedimentary rocks of the Nora-Sukhotino terrane, as well as on
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49

Clift, Peter D., Peng Zhou, Daniel F. Stockli, and Jerzy Blusztajn. "Regional Pliocene exhumation of the Lesser Himalaya in the Indus drainage." Solid Earth 10, no. 3 (2019): 647–61. http://dx.doi.org/10.5194/se-10-647-2019.

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Abstract. New bulk sediment Sr and Nd isotope data, coupled with U–Pb dating of detrital zircon grains from sediment cored by the International Ocean Discovery Program in the Arabian Sea, allow the reconstruction of erosion in the Indus catchment since ∼17 Ma. Increasing εNd values from 17 to 9.5 Ma imply relatively more erosion from the Karakoram and Kohistan, likely linked to slip on the Karakoram Fault and compression in the southern and eastern Karakoram. After a period of relative stability from 9.5 to 5.7 Ma, there is a long-term decrease in εNd values that corresponds with increasing re
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50

Yang, Xiangrong, Detian Yan, Tong Li, et al. "Oceanic environment changes caused the Late Ordovician extinction: evidence from geochemical and Nd isotopic composition in the Yangtze area, South China." Geological Magazine 157, no. 4 (2019): 651–65. http://dx.doi.org/10.1017/s0016756819001237.

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AbstractThe Ordovician–Silurian (O–S) transition was a critical interval in geological history. Multiple geochemical methods are used to explore the changes in oceanic environment. The Nd isotopic compositions in the Yangtze Sea are controlled by two sources: the continental erosion and the Panthalassa Ocean. High εNd(t) values during the Katian, late Hirnantian and Rhuddanian intervals are associated with the high sea level, which resulted in less terrestrial input based on the low Ti/Al and Zr/Al ratios. In contrast, low εNd(t) values during the early Hirnantian interval are related to the s
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