The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Jiangfeng Chen - One of the best experts on this subject based on the ideXlab platform.
-
Crustal Evolution of southeastern china nd and sr isotopic evidence
Tectonophysics, 1998Co-Authors: Jiangfeng Chen, Borming JahnAbstract:We present a synthesis of Crustal Evolution in SE China based on extensive Nd and Sr isotopic data compiled from the literature for intrusive granitoids, volcanic, sedimentary and metamorphic rocks from three major tectonic units of SE China: Dabie, Yangtze and Cathaysia. Overall, igneous rocks of Phanerozoic ages possess initial eNd(T) values from −21 to +5 and depleted-mantle model ages (TDM) from 2.3 to 0.5 Ga. Sedimentary and metamorphic rocks have a TDM range of 3.3 to 1.1 Ga. The model age data indicate that the most important Crustal formation took place in the Proterozoic, possibly with a very minor proportion produced in the late Archaean. This finding clearly suggests that the Crustal Evolution in SE China, including the Yangtze craton and Cathaysia, is distinctly different from the Archaean-dominated North China Block. The Dabie terrane, due to its lack of clear indication of Archaean Crustal signal, might belong more logically to the Yangtze Block. The large database shows an oceanward younging of TDM for Phanerozoic igneous rocks in SE China, with the oldest ages found in Cathaysia Interior and the youngest in coastal Fujian and Taiwan. eNd(T) values show parallel systematic variations. Two NE-striking low-TDM zones characterized by high-REE granites in the middle of SE China are identified, but their tectonic significance is not yet clear. Within SE China, timing of the Yangtze-Cathaysia collision (Proterozoic vs. Mesozoic) has been controversial for many years. While the Mesozoic thrust model may be supported by a recent 40Ar/39Ar age study that reveals Triassic to Early Jurassic ages for mylonitic rocks from the same fracture zone, a Proterozoic collision model seems to be favoured because (1) abundant Neoproterozoic ages have been obtained recently for a variety of rocks occurring along the Jiangshan-Shaoxing fracture zone and for ophiolite suites of the Banxi Group, and (2) many lines of evidence have been found to argue against the Banxi Group as a melange complex and a long displaced thrust sheet. This issue is not yet resolved by geochronological means, but the present synthesis of Nd isotopic data and model ages and recent palaeomagnetic studies of Lower to Middle Triassic rocks appear to refute the hypothesis of Mesozoic collision.
Suzanne Y Oreilly - One of the best experts on this subject based on the ideXlab platform.
-
precambrian Crustal Evolution of the yangtze block tracked by detrital zircons from neoproterozoic sedimentary rocks
Precambrian Research, 2010Co-Authors: W L Griffin, Lijuan Wang, Jinhai Yu, Suzanne Y OreillyAbstract:Abstract Integrated U–Pb dating, Hf-isotope and trace-element analysis of detrital zircons from the Fanjingshan and Xiajiang sediments in the southeastern part of the Yangtze Block has been used to identify ancient Crustal remnants and the provenance of clastic sediments, and to provide an overview of Crustal Evolution in the now-covered parts of the Yangtze Block. The zircon dating indicates that the Fanjingshan Group, which previously was regarded as 870 Ma old, actually was deposited in a ∼800 Ma rift basin similar to other contemporaneous basins in the Yangtze Block; the regional unconformity separating the Fanjingshan Group from the overlying Xiajing Group is dated to 800–740 Ma. Differences in clast compositions and the trace-element and Hf-isotope signatures of zircons between the Fanjingshan Group and the Xiajiang Group suggest changes in the source areas within the Yangtze Block. The combined ages and Hf-isotope data for each group show different histories of Crustal Evolution in their source areas. In the Yangtze Block, a previously unrecognized source (∼4.3 Ga) is suggested by the Hf model ages of the oldest zircons. Both recycling of ancient Crustal materials and minor addition of juvenile material took place in the time intervals 2.5–2.4 Ga, 2.0–1.7 Ga and 0.85–0.8 Ga. The most important generation of juvenile crust appears to have occurred at 1.6–1.4 Ga in the source area of the Fanjingshan Group, and at 0.95–0.85 Ga and 0.78–0.74 Ga in the source area of the Xiajiang Group. This is the first documentation of early Mesoproterozoic (1.6–1.4 Ga) juvenile crust in South China.
-
archaean and proterozoic Crustal Evolution in the eastern succession of the mt isa district australia u pb and hf isotope studies of detrital zircons
Australian Journal of Earth Sciences, 2006Co-Authors: W L Griffin, E A Belousova, Steve Walters, Suzanne Y OreillyAbstract:Over 500 zircon grains separated from modern sediments in 10 drainages covering the Eastern Succession of the Mt Isa Inlier have been analysed for U – Pb ages, Hf isotopes, and trace elements, using in situ LAM-ICPMS techniques, to evaluate the efficacy of this approach in characterising large-scale Crustal Evolution. U – Pb age spectra are used to estimate the timing of terrane-scale events, primarily magmatic episodes; Hf isotopes provide information on the relative contributions of juvenile material and reworked older crust at each stage of Crustal Evolution; trace-element patterns of zircons are used to characterise original magma types. The integration of these data for individual zircon grains produces an event signature that provides more information than that gained from U – Pb dating alone. The data define four major stages of Crustal Evolution in the area: 2550 – 2330 Ma, 1950 – 1825 Ma, 1800 – 1600 Ma, and 1590 – 1420 Ma. Each stage, except the last, involved Crustal extension, and ended with a...
-
archean Crustal Evolution in the northern yilgarn craton u pb and hf isotope evidence from detrital zircons
Precambrian Research, 2004Co-Authors: W L Griffin, E A Belousova, S R Shee, Norman J Pearson, Suzanne Y OreillyAbstract:The integrated application of U–Pb dating, Hf-isotope analysis and trace-element analysis to detrital zircon populations offers a rapid means of assessing the geochronology and Crustal Evolution history of different terranes within a composite craton. In situ U–Pb and Hf-isotope analyses of 550 zircons from 21 modern drainages across the northern part of the Yilgarn Craton and the adjacent Capricorn Orogen provide a broad view of Crustal Evolution in Archean and Proterozoic time. The oldest Crustal components (3.7 Ga) are identified in the Yeelirrie geophysical domain [A.J. Whitaker, Proceedings of Fourth International Archaean Symposium Ext. Abstracts AGSO-Geoscience Australia Record, vol. 37, 2001, p. 536] that runs N–S down the middle of the craton; these components are represented by ancient zircons and also are reflected in the Hf model ages of younger magmas. Ancient (>3.4 Ga) crust contributed to the generation of younger magmas in the Narryer Province, and the proportion of ancient recycled material increases from east to west across the Murchison Province. In contrast, the Hf-isotope data provide no evidence for crust older than 2.9–3.0 Ga in the Southern Cross or Eastern Goldfields (including the Marymia Inlier) domains. The Yeelirrie domain and the composite Narryer–Murchison block are interpreted as ancient microcontinents, sandwiched with the juvenile terranes of the Southern Cross and Eastern Goldfields domains. There is little evidence for the existence of a Depleted Mantle reservoir beneath the Yilgarn Craton prior to 3.1–3.2 Ga, but this reservoir is a major contributor to Crustal generation from 3.1 to 2.6 Ga; this suggests that much of the continental crust in the craton was generated after ca. 3.2 Ga. 1.8–2.3 Ga magmatism, associated with the Capricorn Orogen, involved the recycling of older crust with little obvious contribution from the Depleted Mantle. A significant (and previously unrecognised) 540 Ma episode in the NE part of the craton involved metamorphism or remelting of the 2.7–3.0 Ga crust of the Eastern Goldfields Province.
W L Griffin - One of the best experts on this subject based on the ideXlab platform.
-
Precambrian Crustal Evolution of the Yangtze Block tracked by detrital zircons from Neoproterozoic sedimentary rocks
Precambrian Research, 2020Co-Authors: Lijuan Wang, W L Griffin, Jinhai Yu, S.y. O’reillyAbstract:Integrated U–Pb dating, Hf-isotope and trace-element analysis of detrital zircons from the Fanjingshan and Xiajiang sediments in the southeastern part of the Yangtze Block has been used to identify ancient Crustal remnants and the provenance of clastic sediments, and to provide an overview of Crustal Evolution in the now-covered parts of the Yangtze Block. The zircon dating indicates that the Fanjingshan Group, which previously was regarded as 870 Ma old, actually was deposited in a ~800 Ma rift basin similar to other contemporaneous basins in the Yangtze Block; the regional unconformity separating the Fanjingshan Group from the overlying Xiajing Group is dated to 800–740 Ma. Differences in clast compositions and the trace-element and Hf-isotope signatures of zircons between the Fanjingshan Group and the Xiajiang Group suggest changes in the source areas within the Yangtze Block. The combined ages and Hf-isotope data for each group show different histories of Crustal Evolution in their source areas. In the Yangtze Block, a previously unrecognized source (~4.3 Ga) is suggested by the Hf model ages of the oldest zircons. Both recycling of ancient Crustal materials and minor addition of juvenile material took place in the time intervals 2.5–2.4 Ga, 2.0–1.7 Ga and 0.85–0.8 Ga. The most important generation of juvenile crust appears to have occurred at 1.6–1.4 Ga in the source area of the Fanjingshan Group, and at 0.95–0.85 Ga and 0.78–0.74 Ga in the source area of the Xiajiang Group. This is the first documentation of early Mesoproterozoic (1.6–1.4 Ga) juvenile crust in South China.14 page(s
-
U–Pb and Hf-isotope analyses of zircon from the Kundelungu Kimberlites, D.R. Congo: Implications for Crustal Evolution
Precambrian Research, 2020Co-Authors: J.m. Batumike, W L Griffin, S.y. O’reilly, E.a. BelousovaAbstract:The Gungwania and Talala kimberlitic pipes on the Kundelungu Plateau (Katanga, SE Congo) have been used as drillholes, to obtain Crustal zircons for a study of Crustal Evolution in the region and to constrain the age of the basement and the sedimentary provenance of the Katangan Supergroup. Two hundred and twenty-nine zircon grains were analysed for U–Pb ages and Hf-isotope compositions. Juvenile Mesoarchean (~3.4–3.3 Ga) crust in the region underwent recycling during Neoarchean and Paleoproterozoic time. The Paleoproterozoic event involved little production of juvenile crust, and this Paleoproterozoic crust was recycled during Mesoproterozoic and Neoproterozoic time. Both the Mesoproterozoic and Neoproterozoic were characterised by bimodal magmatism reflecting extension, linked with the break up of Rodinia and the opening of the Katangan basin, and the development of juvenile crust. Detailed studies of the external morphology of the zircons in different age groups suggest that the basement beneath the Kundelungu region is predominantly Paleoproterozoic in age; other zircon populations may be derived from the Katangan sediments. The absence of any zircons younger than 560 Ma supports deposition of the Biano Subgroup, which hosts the kimberlites, during the Pan-African Lufilian orogeny. The Archean Congo and Zimbabwe cratons, the Paleoproterozoic Ubendian Belt (Bangweulu Block), the Paleo-to-Mesoproterozoic Irumide Belt, the Mesoproterozoic Kibaran Belt and the Choma Kalomo Block may all have contributed material to the sediments of the Katangan Supergroup.31 page(s
-
precambrian Crustal Evolution of the yangtze block tracked by detrital zircons from neoproterozoic sedimentary rocks
Precambrian Research, 2010Co-Authors: W L Griffin, Lijuan Wang, Jinhai Yu, Suzanne Y OreillyAbstract:Abstract Integrated U–Pb dating, Hf-isotope and trace-element analysis of detrital zircons from the Fanjingshan and Xiajiang sediments in the southeastern part of the Yangtze Block has been used to identify ancient Crustal remnants and the provenance of clastic sediments, and to provide an overview of Crustal Evolution in the now-covered parts of the Yangtze Block. The zircon dating indicates that the Fanjingshan Group, which previously was regarded as 870 Ma old, actually was deposited in a ∼800 Ma rift basin similar to other contemporaneous basins in the Yangtze Block; the regional unconformity separating the Fanjingshan Group from the overlying Xiajing Group is dated to 800–740 Ma. Differences in clast compositions and the trace-element and Hf-isotope signatures of zircons between the Fanjingshan Group and the Xiajiang Group suggest changes in the source areas within the Yangtze Block. The combined ages and Hf-isotope data for each group show different histories of Crustal Evolution in their source areas. In the Yangtze Block, a previously unrecognized source (∼4.3 Ga) is suggested by the Hf model ages of the oldest zircons. Both recycling of ancient Crustal materials and minor addition of juvenile material took place in the time intervals 2.5–2.4 Ga, 2.0–1.7 Ga and 0.85–0.8 Ga. The most important generation of juvenile crust appears to have occurred at 1.6–1.4 Ga in the source area of the Fanjingshan Group, and at 0.95–0.85 Ga and 0.78–0.74 Ga in the source area of the Xiajiang Group. This is the first documentation of early Mesoproterozoic (1.6–1.4 Ga) juvenile crust in South China.
-
archaean and proterozoic Crustal Evolution in the eastern succession of the mt isa district australia u pb and hf isotope studies of detrital zircons
Australian Journal of Earth Sciences, 2006Co-Authors: W L Griffin, E A Belousova, Steve Walters, Suzanne Y OreillyAbstract:Over 500 zircon grains separated from modern sediments in 10 drainages covering the Eastern Succession of the Mt Isa Inlier have been analysed for U – Pb ages, Hf isotopes, and trace elements, using in situ LAM-ICPMS techniques, to evaluate the efficacy of this approach in characterising large-scale Crustal Evolution. U – Pb age spectra are used to estimate the timing of terrane-scale events, primarily magmatic episodes; Hf isotopes provide information on the relative contributions of juvenile material and reworked older crust at each stage of Crustal Evolution; trace-element patterns of zircons are used to characterise original magma types. The integration of these data for individual zircon grains produces an event signature that provides more information than that gained from U – Pb dating alone. The data define four major stages of Crustal Evolution in the area: 2550 – 2330 Ma, 1950 – 1825 Ma, 1800 – 1600 Ma, and 1590 – 1420 Ma. Each stage, except the last, involved Crustal extension, and ended with a...
-
archean Crustal Evolution in the northern yilgarn craton u pb and hf isotope evidence from detrital zircons
Precambrian Research, 2004Co-Authors: W L Griffin, E A Belousova, S R Shee, Norman J Pearson, Suzanne Y OreillyAbstract:The integrated application of U–Pb dating, Hf-isotope analysis and trace-element analysis to detrital zircon populations offers a rapid means of assessing the geochronology and Crustal Evolution history of different terranes within a composite craton. In situ U–Pb and Hf-isotope analyses of 550 zircons from 21 modern drainages across the northern part of the Yilgarn Craton and the adjacent Capricorn Orogen provide a broad view of Crustal Evolution in Archean and Proterozoic time. The oldest Crustal components (3.7 Ga) are identified in the Yeelirrie geophysical domain [A.J. Whitaker, Proceedings of Fourth International Archaean Symposium Ext. Abstracts AGSO-Geoscience Australia Record, vol. 37, 2001, p. 536] that runs N–S down the middle of the craton; these components are represented by ancient zircons and also are reflected in the Hf model ages of younger magmas. Ancient (>3.4 Ga) crust contributed to the generation of younger magmas in the Narryer Province, and the proportion of ancient recycled material increases from east to west across the Murchison Province. In contrast, the Hf-isotope data provide no evidence for crust older than 2.9–3.0 Ga in the Southern Cross or Eastern Goldfields (including the Marymia Inlier) domains. The Yeelirrie domain and the composite Narryer–Murchison block are interpreted as ancient microcontinents, sandwiched with the juvenile terranes of the Southern Cross and Eastern Goldfields domains. There is little evidence for the existence of a Depleted Mantle reservoir beneath the Yilgarn Craton prior to 3.1–3.2 Ga, but this reservoir is a major contributor to Crustal generation from 3.1 to 2.6 Ga; this suggests that much of the continental crust in the craton was generated after ca. 3.2 Ga. 1.8–2.3 Ga magmatism, associated with the Capricorn Orogen, involved the recycling of older crust with little obvious contribution from the Depleted Mantle. A significant (and previously unrecognised) 540 Ma episode in the NE part of the craton involved metamorphism or remelting of the 2.7–3.0 Ga crust of the Eastern Goldfields Province.
Borming Jahn - One of the best experts on this subject based on the ideXlab platform.
-
Archean Crustal Evolution of the Aldan Shield, Siberia: geochemical and isotopic constraints
Precambrian Research, 1998Co-Authors: Borming Jahn, J. Cornichet, Gérard Gruau, Raymond Capdevila, Alexander A. Nemchin, Robert T. Pidgeon, V.a. RudnikAbstract:Abstract The relatively unknown Aldan Shield in eastern Siberia is made up of Archean granite–greenstone and high-grade gneiss terrains as commonly observed in many Precambrian shield areas. New results of geochemical and isotopic study on two terrains of contrasting metamorphic grades (Olekma Granite–Greenstone and West Aldan Granulite Gneiss terrains) are present with the following principal conclusions being reached: (1) the Crustal Evolution of the Aldan Shield started as early as 3.5 Ga as suggested by the TDM model ages of a few high-grade gneisses and a retrograded granulite enclave, but the most important crust-forming and tectonothermal event is firmly established at ca 3.0 Ga. (2) New SHRIMP and Pb evaporation analyses on zircons have confirmed the presence of Crustal rocks older than 3 Ga. However, the zircon U–Pb systems appear to have been disturbed by later thermal effects, and no components of ≥3.5 Ga have been identified. (3) Komatiitic and basaltic amphibolites form important supraCrustal sequences in the Olekma terrain. Both Group I and II komatiites occur and garnet (or majorite) fractionation in mantle melting processes is likely to have taken place during the genesis of group II komatiites. Overall, depleted mantle sources were involved in the geneses of basic and ultrabasic magmas as evidenced from LREE depletion and Nd isotopic compositions [ϵNd(T)=+2]. Crustal contamination was not significant as suggested by the low La/Nb ratios (=1) in komatiites and metabasalts. (4) As common to most Archean tonalite–trondhjemite–granodiorite (TTG) rocks, the Aldan granitic gneisses also show highly fractionated rare earth element (REE) patterns with heavy REE depletions, suggesting that separation of garnet and amphibole has occurred during melting of their mafic sources. (5) Although the Olekma and West Aldan terrains have undergone different metamorphic Evolution, there is no substantial difference in the time of major crust-forming events at ∼3.0 Ga and a strong Proterozoic thermal disturbance at ∼2 Ga. Furthermore, from the geochemical comparison of the two terrains it is concluded that the nature of mantle sources for basic–ultrabasic magmas and the process of TTG magma generation are similar in both terrains and that the granulite facies rocks cannot be considered as the restites of intraCrustal melting.
-
Crustal Evolution of southeastern china nd and sr isotopic evidence
Tectonophysics, 1998Co-Authors: Jiangfeng Chen, Borming JahnAbstract:We present a synthesis of Crustal Evolution in SE China based on extensive Nd and Sr isotopic data compiled from the literature for intrusive granitoids, volcanic, sedimentary and metamorphic rocks from three major tectonic units of SE China: Dabie, Yangtze and Cathaysia. Overall, igneous rocks of Phanerozoic ages possess initial eNd(T) values from −21 to +5 and depleted-mantle model ages (TDM) from 2.3 to 0.5 Ga. Sedimentary and metamorphic rocks have a TDM range of 3.3 to 1.1 Ga. The model age data indicate that the most important Crustal formation took place in the Proterozoic, possibly with a very minor proportion produced in the late Archaean. This finding clearly suggests that the Crustal Evolution in SE China, including the Yangtze craton and Cathaysia, is distinctly different from the Archaean-dominated North China Block. The Dabie terrane, due to its lack of clear indication of Archaean Crustal signal, might belong more logically to the Yangtze Block. The large database shows an oceanward younging of TDM for Phanerozoic igneous rocks in SE China, with the oldest ages found in Cathaysia Interior and the youngest in coastal Fujian and Taiwan. eNd(T) values show parallel systematic variations. Two NE-striking low-TDM zones characterized by high-REE granites in the middle of SE China are identified, but their tectonic significance is not yet clear. Within SE China, timing of the Yangtze-Cathaysia collision (Proterozoic vs. Mesozoic) has been controversial for many years. While the Mesozoic thrust model may be supported by a recent 40Ar/39Ar age study that reveals Triassic to Early Jurassic ages for mylonitic rocks from the same fracture zone, a Proterozoic collision model seems to be favoured because (1) abundant Neoproterozoic ages have been obtained recently for a variety of rocks occurring along the Jiangshan-Shaoxing fracture zone and for ophiolite suites of the Banxi Group, and (2) many lines of evidence have been found to argue against the Banxi Group as a melange complex and a long displaced thrust sheet. This issue is not yet resolved by geochronological means, but the present synthesis of Nd isotopic data and model ages and recent palaeomagnetic studies of Lower to Middle Triassic rocks appear to refute the hypothesis of Mesozoic collision.
Lijuan Wang - One of the best experts on this subject based on the ideXlab platform.
-
Precambrian Crustal Evolution of the Yangtze Block tracked by detrital zircons from Neoproterozoic sedimentary rocks
Precambrian Research, 2020Co-Authors: Lijuan Wang, W L Griffin, Jinhai Yu, S.y. O’reillyAbstract:Integrated U–Pb dating, Hf-isotope and trace-element analysis of detrital zircons from the Fanjingshan and Xiajiang sediments in the southeastern part of the Yangtze Block has been used to identify ancient Crustal remnants and the provenance of clastic sediments, and to provide an overview of Crustal Evolution in the now-covered parts of the Yangtze Block. The zircon dating indicates that the Fanjingshan Group, which previously was regarded as 870 Ma old, actually was deposited in a ~800 Ma rift basin similar to other contemporaneous basins in the Yangtze Block; the regional unconformity separating the Fanjingshan Group from the overlying Xiajing Group is dated to 800–740 Ma. Differences in clast compositions and the trace-element and Hf-isotope signatures of zircons between the Fanjingshan Group and the Xiajiang Group suggest changes in the source areas within the Yangtze Block. The combined ages and Hf-isotope data for each group show different histories of Crustal Evolution in their source areas. In the Yangtze Block, a previously unrecognized source (~4.3 Ga) is suggested by the Hf model ages of the oldest zircons. Both recycling of ancient Crustal materials and minor addition of juvenile material took place in the time intervals 2.5–2.4 Ga, 2.0–1.7 Ga and 0.85–0.8 Ga. The most important generation of juvenile crust appears to have occurred at 1.6–1.4 Ga in the source area of the Fanjingshan Group, and at 0.95–0.85 Ga and 0.78–0.74 Ga in the source area of the Xiajiang Group. This is the first documentation of early Mesoproterozoic (1.6–1.4 Ga) juvenile crust in South China.14 page(s
-
precambrian Crustal Evolution of the yangtze block tracked by detrital zircons from neoproterozoic sedimentary rocks
Precambrian Research, 2010Co-Authors: W L Griffin, Lijuan Wang, Jinhai Yu, Suzanne Y OreillyAbstract:Abstract Integrated U–Pb dating, Hf-isotope and trace-element analysis of detrital zircons from the Fanjingshan and Xiajiang sediments in the southeastern part of the Yangtze Block has been used to identify ancient Crustal remnants and the provenance of clastic sediments, and to provide an overview of Crustal Evolution in the now-covered parts of the Yangtze Block. The zircon dating indicates that the Fanjingshan Group, which previously was regarded as 870 Ma old, actually was deposited in a ∼800 Ma rift basin similar to other contemporaneous basins in the Yangtze Block; the regional unconformity separating the Fanjingshan Group from the overlying Xiajing Group is dated to 800–740 Ma. Differences in clast compositions and the trace-element and Hf-isotope signatures of zircons between the Fanjingshan Group and the Xiajiang Group suggest changes in the source areas within the Yangtze Block. The combined ages and Hf-isotope data for each group show different histories of Crustal Evolution in their source areas. In the Yangtze Block, a previously unrecognized source (∼4.3 Ga) is suggested by the Hf model ages of the oldest zircons. Both recycling of ancient Crustal materials and minor addition of juvenile material took place in the time intervals 2.5–2.4 Ga, 2.0–1.7 Ga and 0.85–0.8 Ga. The most important generation of juvenile crust appears to have occurred at 1.6–1.4 Ga in the source area of the Fanjingshan Group, and at 0.95–0.85 Ga and 0.78–0.74 Ga in the source area of the Xiajiang Group. This is the first documentation of early Mesoproterozoic (1.6–1.4 Ga) juvenile crust in South China.