Pub Date : 2024-10-01DOI: 10.1016/j.precamres.2024.107580
Fang Song , Yaoyan He , Zhijun Niu , John Menzies , Wenqiang Yang , Zhihui An , Zhihong Wang
A better understanding of Ediacaran (Gaskiers) glaciations, including their ages, global distribution and types, is critical to our understanding of the Earth’s evolution following the Neoproterozoic “Snowball Earth”. The present study focuses on a diamictite that forms part of a continuous succession of Neoproterozoic clastic sedimentary rocks in the northwestern margin of the Cathaysia block in South China. Detailed sedimentary sequence established here shows that the diamictite, previously interpreted to be Cryogenian in age, is a part of the Ediacaran Aiqiling Formation. Detrital zircon U-Pb ages constrain its maximum deposition age to ca. 571 Ma, supporting its Ediacaran age. The macro sedimentary textures of the diamictite unit, including matrix-supported sediments with angular and randomly distributed clasts, combined with regional geochemical results, suggest a glaciogenic origin. The U-Pb detrital zircon age data also indicate an uplifting source area to the southeast that migrated northwestward since the Ediacaran.
{"title":"Ediacaran diamictite deposition in South China: Detrital zircon u-pb age evidence and macro sedimentary texture of the Aiqiling formation in southeastern Hunan Province","authors":"Fang Song , Yaoyan He , Zhijun Niu , John Menzies , Wenqiang Yang , Zhihui An , Zhihong Wang","doi":"10.1016/j.precamres.2024.107580","DOIUrl":"10.1016/j.precamres.2024.107580","url":null,"abstract":"<div><div>A better understanding of Ediacaran (Gaskiers) glaciations, including their ages, global distribution and types, is critical to our understanding of the Earth’s evolution following the Neoproterozoic “Snowball Earth”. The present study focuses on a diamictite that forms part of a continuous succession of Neoproterozoic clastic sedimentary rocks in the northwestern margin of the Cathaysia block in South China. Detailed sedimentary sequence established here shows that the diamictite, previously interpreted to be Cryogenian in age, is a part of the Ediacaran Aiqiling Formation. Detrital zircon U-Pb ages constrain its maximum deposition age to ca. 571 Ma, supporting its Ediacaran age. The macro sedimentary textures of the diamictite unit, including matrix-supported sediments with angular and randomly distributed clasts, combined with regional geochemical results, suggest a glaciogenic origin. The U-Pb detrital zircon age data also indicate an uplifting source area to the southeast that migrated northwestward since the Ediacaran.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107580"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.precamres.2024.107575
Renan F. dos Santos , Pierre Sansjofre , Afonso C.R. Nogueira , Peter W. Crockford , Gabriel J. Uhlein , Laurane Fogret , Fábio S. Pereira , Guilherme R. Romero , Stefan V. Lalonde
The extensive deglaciation linked to the Snowball Earth climate that elapsed in the terminal Neoproterozoic caused dramatic changes in ocean chemistry, exceptionally recorded in globally distributed cap carbonate successions. One of the most spectacular examples is the Puga cap carbonate (∼635 Ma), which is exposed in the Amazon Craton and associated with extensive sea level changes related to glacial-isostatic adjustment and local ice gravity, resulting in continuously mixed waters. This study meticulously evaluates complex post-Marinoan dynamics using a comprehensive multiproxy approach. The rare earth element + yttrium (REE+Y) patterns in the Puga cap carbonate do not accurately reflect the global ocean water composition; instead, they primarily fractionate in response to local expression of the post-Snowball Earth event, including alkalinity levels and freshwater mixing in the aftermath of the Marinoan glaciation. The flattened REE+Y pattern, accompanied by a positive Eu anomaly, may suggest the influence of continental weathering. Specifically, low Y/Ho ratios in the cap dolostone are consistent with seawater dilution due to meltwater influx (Y/Ho ∼ 29–32). Conversely, superchondritic Y/Ho ratios up to 71 in the basal cap dolostones suggest upwelling of hypersaline seawater in coastal areas. The shallow-water recurrence influenced by ice gravity resulted in continuous coastal uplift, forming isolated shelves and the deformation in diamicton, resulting in irregular substrate relief morphologies. This post-glaciation scenario was succeeded by significant landward shoreline migration concomitant with rapid recovery of primary productivity, with large microbial communities flourishing, inducing dolomite precipitation under restricted paleoenvironmental conditions on dolomitic platforms. The rapid rise in sea level led to the dilution of evaporative fluids, ultimately halting dolomicrite precipitation. Following the pos-tglacial transgression, the stratified waters gradually became more mixed, resulting in the termination of dolomitic platform deposition and coinciding with an increase in detrital components, as indicated by the increase of insoluble elements (e.g., REE, Zr, and Th), followed by abrupt replacement by CaCO3-oversaturated seas during the post-glacial transgression. These observations elucidate the interplay between post-glaciation and paleoceanographic dynamics during the Cryogenian-Ediacaran boundary.
{"title":"Rare earth elements as indicators of post-Marinoan (∼635 Ma) paleoceanographic changes from the Amazon Craton","authors":"Renan F. dos Santos , Pierre Sansjofre , Afonso C.R. Nogueira , Peter W. Crockford , Gabriel J. Uhlein , Laurane Fogret , Fábio S. Pereira , Guilherme R. Romero , Stefan V. Lalonde","doi":"10.1016/j.precamres.2024.107575","DOIUrl":"10.1016/j.precamres.2024.107575","url":null,"abstract":"<div><div>The extensive deglaciation linked to the Snowball Earth climate that elapsed in the terminal Neoproterozoic caused dramatic changes in ocean chemistry, exceptionally recorded in globally distributed cap carbonate successions. One of the most spectacular examples is the Puga cap carbonate (∼635 Ma), which is exposed in the Amazon Craton and associated with extensive sea level changes related to glacial-isostatic adjustment and local ice gravity, resulting in continuously mixed waters. This study meticulously evaluates complex post-Marinoan dynamics using a comprehensive multiproxy approach. The rare earth element + yttrium (REE+Y) patterns in the Puga cap carbonate do not accurately reflect the global ocean water composition; instead, they primarily fractionate in response to local expression of the post-Snowball Earth event, including alkalinity levels and freshwater mixing in the aftermath of the Marinoan glaciation. The flattened REE+Y pattern, accompanied by a positive Eu anomaly, may suggest the influence of continental weathering. Specifically, low Y/Ho ratios in the cap dolostone are consistent with seawater dilution due to meltwater influx (Y/Ho ∼ 29–32). Conversely, superchondritic Y/Ho ratios up to 71 in the basal cap dolostones suggest upwelling of hypersaline seawater in coastal areas. The shallow-water recurrence influenced by ice gravity resulted in continuous coastal uplift, forming isolated shelves and the deformation in diamicton, resulting in irregular substrate relief morphologies. This post-glaciation scenario was succeeded by significant landward shoreline migration concomitant with rapid recovery of primary productivity, with large microbial communities flourishing, inducing dolomite precipitation under restricted paleoenvironmental conditions on dolomitic platforms. The rapid rise in sea level led to the dilution of evaporative fluids, ultimately halting dolomicrite precipitation. Following the pos-tglacial transgression, the stratified waters gradually became more mixed, resulting in the termination of dolomitic platform deposition and coinciding with an increase in detrital components, as indicated by the increase of insoluble elements (e.g., REE, Zr, and Th), followed by abrupt replacement by CaCO<sub>3</sub>-oversaturated seas during the post-glacial transgression. These observations elucidate the interplay between post-glaciation and paleoceanographic dynamics during the Cryogenian-Ediacaran boundary.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107575"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.precamres.2024.107573
Samantha C. Russo , Alex J. McCoy-West , Paul Duuring
Pristine banded iron formations (BIF) are established paleo-environmental proxies for reconstructing the elemental and isotopic signatures of the ancient seawater that they precipitated from. Negligible changes in shale-normalised rare earth element patterns in BIF throughout Earth’s history, including features such as low La/Yb ratios, and positive La, Eu, Gd, and Y anomalies, and near- to super-chondritic Y/Ho ratios support the preservation of ancient seawater signatures. Nevertheless, limiting paleo-environmental reconstructions to pristine BIF imparts a significant sampling bias and restricts understanding of the temporal evolution of the oceans. However, altered BIF samples are problematic for paleo-environmental reconstructions due to the risk of disturbance of their primary signatures. Instead, mineral-/fraction-specific analysis potentially provides robust paleo-environmental reconstructions where primary mineral phases are preserved, with the three main mineral fractions in pristine and altered BIF including carbonates (e.g., siderite and ankerite), Fe oxides (e.g., magnetite, hematite, and goethite), and silicates (e.g., quartz and Fe-silicates). This study investigates samples from the ca. 2.7 Ga Weld Range BIF, located in the Youanmi Terrane, Yilgarn Craton, Western Australia. The lower-greenschist facies BIF varies from least-altered to progressively hypogene- and/or supergene-altered. Whole-rock analysis of these rocks revealed the preservation of seawater-like signatures despite significant alteration, such as positive La, Eu and Y anomalies. Additionally, sequential extraction techniques were performed on the least-altered and altered BIF samples to separately analyse the carbonate, Fe oxide, and silicate mineral fractions. In both the least- and hypogene-altered samples all fractions preserved evidence for seawater-like chemistry despite extensive precipitation of secondary hypogene carbonate and Fe oxide minerals in the latter. The seawater-like characteristics preserved in the hypogene carbonate and Fe oxide-fractions are the result of the seawater-magmatic fluid mixture that precipitated hypogene replacement minerals. Therefore, we interpret the silicate-fraction to be the most indicative of the primary seawater that precipitated the Weld Range BIF, where the quartz/chert reflects amorphous silica signatures that are unaffected by low-grade metamorphism and hypogene alteration. The preservation of primary mineral phases (i.e., silicates) and characteristic seawater signatures in the extensively altered Weld Range BIF, suggests that altered BIF should be more widely investigated to improve the breadth and representativeness of global paleo-environmental reconstructions.
原始带状铁地层（BIF）是重建其沉淀的古海水元素和同位素特征的公认古环境代用指标。在整个地球历史中，BIF 中页岩归一化稀土元素模式的变化微乎其微，包括低 La/Yb 比值、正 La、Eu、Gd 和 Y 异常等特征，以及接近于超软玉的 Y/Ho 比值，这些都支持古海水特征的保存。尽管如此，将古环境重建局限于原始的 BIF 会造成严重的取样偏差，限制对海洋时间演化的了解。然而，改变过的 BIF 样本由于其主要特征有可能受到干扰，因此在古环境重建方面存在问题。原始和蚀变 BIF 中的三种主要矿物组分包括碳酸盐（如菱铁矿和角闪石）、铁氧化物（如磁铁矿、赤铁矿和高铁铁矿）和硅酸盐（如石英和铁硅酸盐）。本研究调查了来自约2.7 Ga Weld Range B.C.的样品。2.7 Ga Weld Range BIF的样品。下绿泥石面BIF的变化程度从最轻微的改变到逐渐的低成因和/或超成因改变。对这些岩石的全岩分析表明，尽管发生了显著的蚀变，但仍保留了类似海水的特征，如 La、Eu 和 Y 阳性异常。此外，还对最少蚀变和蚀变的 BIF 样品进行了连续萃取技术，以分别分析碳酸盐、氧化铁和硅酸盐矿物组分。在最少蚀变和次生蚀变样品中，尽管次生蚀变样品中有大量次生碳酸盐和氧化铁矿物沉淀，但所有馏分都保留了类海水化学的证据。在次生碳酸盐和氧化铁馏分中保留的类海水特征是海水-岩浆流体混合物沉淀次生置换矿物的结果。因此，我们认为硅酸盐馏分最能体现沉淀 Weld Range BIF 的原生海水特征，而石英/白垩岩则反映了不受低级变质作用和次生蚀变影响的无定形二氧化硅特征。在广泛蚀变的韦尔德山脉 BIF 中保留了原生矿物相（即硅酸盐）和海水特征，这表明应更广泛地研究蚀变的 BIF，以提高全球古环境重建的广度和代表性。
{"title":"The potential for reconstructing primary ocean chemistry from hypogene and supergene altered banded iron formations: An example from Weld Range, Western Australia","authors":"Samantha C. Russo , Alex J. McCoy-West , Paul Duuring","doi":"10.1016/j.precamres.2024.107573","DOIUrl":"10.1016/j.precamres.2024.107573","url":null,"abstract":"<div><div>Pristine banded iron formations (BIF) are established paleo-environmental proxies for reconstructing the elemental and isotopic signatures of the ancient seawater that they precipitated from. Negligible changes in shale-normalised rare earth element patterns in BIF throughout Earth’s history, including features such as low La/Yb ratios, and positive La, Eu, Gd, and Y anomalies, and near- to super-chondritic Y/Ho ratios support the preservation of ancient seawater signatures. Nevertheless, limiting paleo-environmental reconstructions to pristine BIF imparts a significant sampling bias and restricts understanding of the temporal evolution of the oceans. However, altered BIF samples are problematic for paleo-environmental reconstructions due to the risk of disturbance of their primary signatures. Instead, mineral-/fraction-specific analysis potentially provides robust paleo-environmental reconstructions where primary mineral phases are preserved, with the three main mineral fractions in pristine and altered BIF including carbonates (e.g., siderite and ankerite), Fe oxides (e.g., magnetite, hematite, and goethite), and silicates (e.g., quartz and Fe-silicates). This study investigates samples from the ca. 2.7 Ga Weld Range BIF, located in the Youanmi Terrane, Yilgarn Craton, Western Australia. The lower-greenschist facies BIF varies from least-altered to progressively hypogene- and/or supergene-altered. Whole-rock analysis of these rocks revealed the preservation of seawater-like signatures despite significant alteration, such as positive La, Eu and Y anomalies. Additionally, sequential extraction techniques were performed on the least-altered and altered BIF samples to separately analyse the carbonate, Fe oxide, and silicate mineral fractions. In both the least- and hypogene-altered samples all fractions preserved evidence for seawater-like chemistry despite extensive precipitation of secondary hypogene carbonate and Fe oxide minerals in the latter. The seawater-like characteristics preserved in the hypogene carbonate and Fe oxide-fractions are the result of the seawater-magmatic fluid mixture that precipitated hypogene replacement minerals. Therefore, we interpret the silicate-fraction to be the most indicative of the primary seawater that precipitated the Weld Range BIF, where the quartz/chert reflects amorphous silica signatures that are unaffected by low-grade metamorphism and hypogene alteration. The preservation of primary mineral phases (i.e., silicates) and characteristic seawater signatures in the extensively altered Weld Range BIF, suggests that altered BIF should be more widely investigated to improve the breadth and representativeness of global paleo-environmental reconstructions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107573"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Iron (Fe) isotopic compositions of Iron formations (IFs) have the potential to constrain the oceanic redox environment and marine biosphere on the early Earth. However, the interpretation of Fe isotope ratios in IFs is controversial and related to various factors, such as Fe sources, mode of primary precipitation, and subsequent mineral transformations. This paper presents whole-rock Fe isotope data for ca. 3.2 Ga unweathered ferruginous siliciclastic sedimentary rocks deposited in a shallow ocean in the lower part (unit MdI1) of the Moodies Group, Barberton Greenstone Belt, South Africa. We also experimentally examined Fe isotope effects during the precipitation of Fe2+-silicates (e.g., greenalite), proposed as primary Fe minerals in IFs. The Fe isotope data show significant variation (δ56Fe = −0.58 ‰ to +0.60 ‰) for different lithologies (i.e., magnetite-rich siltstone, carbonate-rich siltstone, sandy siltstone, and jaspilite). The δ56Fe values (δ56Fe = −0.54 ‰ to +0.60 ‰) of the magnetite-rich siltstones tend to decrease with decreasing Fe2O3(T)/Al2O3 ratios and matrix ratios (the percentage of detrital grains with a size of <30 μm). Carbonate-rich siltstones also fall on the same Fe2O3(T)/Al2O3 – δ56Fe and matrix ratio – δ56Fe trends as magnetite-rich siltstone. The synthetic experiment showed that isotope fractionation during anoxygenic Fe2+-silicate precipitation from dissolved ferrous Fe (Fe2+(aq)) was much smaller (Δ56FeFe2+-silicate–Fe2+(aq) < +0.3 ‰) than that of oxidative precipitation. These results indicate that Fe isotopic variations in Fe-rich siltstones (magnetite- and carbonate-rich siltstones) are only explained by the oxidative precipitation of Fe2+(aq) supplied from the deep ocean following Rayleigh-type fractionation. Low carbonate-C isotope ratios (δ13Ccarb = −5.8 ‰ to −3.7 ‰) of the Fe-rich siltstones show that magnetite and ankerite or Mg-siderite formed from a primary Fe3+-bearing mineral by oxidation of organic C after Fe burial. The consistent Fe2O3(T)/Al2O3 – δ56Fe trends between the magnetite- and carbonate-rich siltstones suggest that Fe reduction during diagenetic and/or metamorphic transformation processes of Fe-bearing minerals caused negligible changes in the whole-rock Fe isotope composition, possibly because of limited mobility of Fe2+ in the sediment. Consequently, the Fe isotope compositions predominantly record the primary precipitation process that occurred in the water column of a 3.2 Ga shallow ocean environment.
{"title":"Primary Fe isotope signatures record oxidative precipitation in 3.2 Ga ferruginous siliciclastic sedimentary rocks deposited in a shallow ocean environment","authors":"Ryohei Suzumeji , Tsubasa Otake , Daizo Yamauchi , Yoko Ohtomo , Takeshi Kakegawa , Christoph Heubeck , Shin-ichi Yamasaki , Tsutomu Sato","doi":"10.1016/j.precamres.2024.107574","DOIUrl":"10.1016/j.precamres.2024.107574","url":null,"abstract":"<div><div>Iron (Fe) isotopic compositions of Iron formations (IFs) have the potential to constrain the oceanic redox environment and marine biosphere on the early Earth. However, the interpretation of Fe isotope ratios in IFs is controversial and related to various factors, such as Fe sources, mode of primary precipitation, and subsequent mineral transformations. This paper presents whole-rock Fe isotope data for <em>ca</em>. 3.2 Ga unweathered ferruginous siliciclastic sedimentary rocks deposited in a shallow ocean in the lower part (unit MdI1) of the Moodies Group, Barberton Greenstone Belt, South Africa. We also experimentally examined Fe isotope effects during the precipitation of Fe<sup>2+</sup>-silicates (e.g., greenalite), proposed as primary Fe minerals in IFs. The Fe isotope data show significant variation (δ<sup>56</sup>Fe = −0.58 ‰ to +0.60 ‰) for different lithologies (i.e., magnetite-rich siltstone, carbonate-rich siltstone, sandy siltstone, and jaspilite). The δ<sup>56</sup>Fe values (δ<sup>56</sup>Fe = −0.54 ‰ to +0.60 ‰) of the magnetite-rich siltstones tend to decrease with decreasing Fe<sub>2</sub>O<sub>3(T)</sub>/Al<sub>2</sub>O<sub>3</sub> ratios and matrix ratios (the percentage of detrital grains with a size of <30 μm). Carbonate-rich siltstones also fall on the same Fe<sub>2</sub>O<sub>3(T)</sub>/Al<sub>2</sub>O<sub>3</sub> – δ<sup>56</sup>Fe and matrix ratio – δ<sup>56</sup>Fe trends as magnetite-rich siltstone. The synthetic experiment showed that isotope fractionation during anoxygenic Fe<sup>2+</sup>-silicate precipitation from dissolved ferrous Fe (Fe<sup>2+</sup><sub>(aq)</sub>) was much smaller (Δ<sup>56</sup>Fe<sub>Fe2+-silicate–Fe2+(aq)</sub> < +0.3 ‰) than that of oxidative precipitation. These results indicate that Fe isotopic variations in Fe-rich siltstones (magnetite- and carbonate-rich siltstones) are only explained by the oxidative precipitation of Fe<sup>2+</sup><sub>(aq)</sub> supplied from the deep ocean following Rayleigh-type fractionation. Low carbonate-C isotope ratios (δ<sup>13</sup>C<sub>carb</sub> = −5.8 ‰ to −3.7 ‰) of the Fe-rich siltstones show that magnetite and ankerite or Mg-siderite formed from a primary Fe<sup>3+</sup>-bearing mineral by oxidation of organic C after Fe burial. The consistent Fe<sub>2</sub>O<sub>3(T)</sub>/Al<sub>2</sub>O<sub>3</sub> – δ<sup>56</sup>Fe trends between the magnetite- and carbonate-rich siltstones suggest that Fe reduction during diagenetic and/or metamorphic transformation processes of Fe-bearing minerals caused negligible changes in the whole-rock Fe isotope composition, possibly because of limited mobility of Fe<sup>2+</sup> in the sediment. Consequently, the Fe isotope compositions predominantly record the primary precipitation process that occurred in the water column of a 3.2 Ga shallow ocean environment.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107574"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.precamres.2024.107581
Liang Zhang , Shao-Bing Zhang , Zhen-Xin Li , Ting Liang , Zheng-Xiang Li , Xiang-Ping Zha
Ca. 2.1–1.9 Ga tectono-thermal events in the Yangtze Craton, South China, are coeval with global continental assembly in the dawn of supercontinent cycle. However, the tectonic regime for the ca. 2.0 Ga events there remains unresolved because magmatic rocks of both compressional and extensional environments have been reported. Here, we report the results of an integrated study of ca. 2.0 Ga granitic rocks in the Kongling Complex of the Yangtze Craton, including whole-rock major and trace element results, zircon U–Pb ages, and zircon Lu–Hf and oxygen isotope results. The 2.0 Ga granites are divided into two groups: Group 1 granites show highly depleted HREEs, HFSEs and positive Eu anomalies with relatively higher zircon εHf(t) values, whereas Group 2 granites have higher HREE and HFSE contents with lower Eu/Eu* and zircon εHf(t) values. Zircon Hf isotopic signatures indicate the source materials for the two types of granites were likely Archean tholeiite and Archean TTGs of the Kongling Complex, respectively. Thermodynamic modelling results suggest that magmas similar to the two groups of granites could be generated from partial melting of Mesoarchean Kongling Enriched Archean Tholeiite (kEAT) (Group 1 granites) and TTGs (Group 2 granites) under the same melting conditions of 800–900 °C, 10–12 kbar. Such a P–T condition is consistent with the peak metamorphic P–T estimates constrained from 2.0 Ga mafic granulites in the same area, indicating that the Archean crust was remelted at great depth (>1 GPa). Furthermore, the MgO/CaO ratios of the 2.1–1.9 Ga granitic rocks in northern Yangtze Craton shifted to higher values after ca. 2.0 Ga, likely caused by an increased melting temperature/pressure (T/P) ratio, i.e., the higher thermal gradient. Based on these results, we propose that the tectonic regime of the Yangtze Craton switched from compression to extension at ca. 2.0 Ga.
{"title":"Petrogenesis of ca. 2.0 Ga granites in the Kongling Complex: Implications for a tectonic transition of the Yangtze Craton from compression to extension","authors":"Liang Zhang , Shao-Bing Zhang , Zhen-Xin Li , Ting Liang , Zheng-Xiang Li , Xiang-Ping Zha","doi":"10.1016/j.precamres.2024.107581","DOIUrl":"10.1016/j.precamres.2024.107581","url":null,"abstract":"<div><div>Ca. 2.1–1.9 Ga tectono-thermal events in the Yangtze Craton, South China, are coeval with global continental assembly in the dawn of supercontinent cycle. However, the tectonic regime for the ca. 2.0 Ga events there remains unresolved because magmatic rocks of both compressional and extensional environments have been reported. Here, we report the results of an integrated study of ca. 2.0 Ga granitic rocks in the Kongling Complex of the Yangtze Craton, including whole-rock major and trace element results, zircon U–Pb ages, and zircon Lu–Hf and oxygen isotope results. The 2.0 Ga granites are divided into two groups: Group 1 granites show highly depleted HREEs, HFSEs and positive Eu anomalies with relatively higher zircon ε<sub>Hf</sub>(t) values, whereas Group 2 granites have higher HREE and HFSE contents with lower Eu/Eu* and zircon ε<sub>Hf</sub>(t) values. Zircon Hf isotopic signatures indicate the source materials for the two types of granites were likely Archean tholeiite and Archean TTGs of the Kongling Complex, respectively. Thermodynamic modelling results suggest that magmas similar to the two groups of granites could be generated from partial melting of Mesoarchean Kongling Enriched Archean Tholeiite (kEAT) (Group 1 granites) and TTGs (Group 2 granites) under the same melting conditions of 800–900 °C, 10–12 kbar. Such a <em>P</em>–<em>T</em> condition is consistent with the peak metamorphic <em>P</em>–<em>T</em> estimates constrained from 2.0 Ga mafic granulites in the same area, indicating that the Archean crust was remelted at great depth (>1 GPa). Furthermore, the MgO/CaO ratios of the 2.1–1.9 Ga granitic rocks in northern Yangtze Craton shifted to higher values after ca. 2.0 Ga, likely caused by an increased melting temperature/pressure (<em>T/P</em>) ratio, i.e., the higher thermal gradient. Based on these results, we propose that the tectonic regime of the Yangtze Craton switched from compression to extension at ca. 2.0 Ga.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107581"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-27DOI: 10.1016/j.precamres.2024.107577
Mario C. Campos Neto , Gabriella L. Frugis , Alice Westin , Renaud Caby , Augusto G. Nobre , Olivier Bruguier , Rômulo A. Ando
{"title":"Reply to “Comment on: Passive continental margin subducted to mantle depths: Coesite-bearing metasedimentary rocks from the Neoproterozoic Brasília Orogen, West Gondwana margin” by Schönig (2024)","authors":"Mario C. Campos Neto , Gabriella L. Frugis , Alice Westin , Renaud Caby , Augusto G. Nobre , Olivier Bruguier , Rômulo A. Ando","doi":"10.1016/j.precamres.2024.107577","DOIUrl":"10.1016/j.precamres.2024.107577","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107577"},"PeriodicalIF":3.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-27DOI: 10.1016/j.precamres.2024.107569
Jun Tang , Jian Wang , Guanghui Wu , Yinyu Wen , R. Damian Nance , Bing He , Chenghai Li , Yu Zou
Ediacaran continental rift basins in the Sichuan Basin (SW China) overlap in time with the breakup of Rodinia and the assembly of Gondwana, but whether the rifts occurred in response to a mantle plume or to a subduction-related mechanism at the outer margin of the supercontinent remains uncertain. In the absence of Ediacaran igneous rocks, we provide zircon LA-ICP-MS U-Pb age data and whole-rock geochemistry from exposed Ediacaran-Lower Cambrian siliciclastic rocks in the Sichuan Basin in an effort to decipher the origin of the Ediacaran rifting. Together with new seismic and drilling data, the Ediacaran period is characterized by a magma-poor rift succession deposited in a faulted depression within the basin. U-Pb ages of the Ediacaran detrital zircons are concentrated in the range of 850–630 Ma, which suggests a weak magmatic event during the Ediacaran rifting. Geochemically, the siliciclastic rocks are characterized by relatively flat rare earth elements (REE) with negative Eu* anomalies, enrichment in most high field strength elements (HFSE), but depletion in Nb, Ta, Sr and Ti. The geochemical data suggest that the Ediacaran sedimentary rocks formed in a continental island arc setting. Together with compiled zircon εHf(t) values, Ediacaran rifting in the Sichuan Basin is consistent with retreating subduction. We propose a weak, flat, retreating subduction-related intracontinental passive rift model for the Ediacaran South China Block. This case study suggests that the retreating subduction could not only trigger back-arc basin development, but could also lead to the magma-poor passive rift basin.
四川盆地（中国西南部）的埃迪卡拉纪大陆裂谷与罗迪尼亚的解体和冈瓦纳的形成在时间上重叠，但裂谷的发生是由于地幔羽流还是超大陆外缘与俯冲有关的机制仍不确定。在缺乏埃迪卡拉纪火成岩的情况下，我们提供了四川盆地出露的埃迪卡拉纪-下寒武纪硅质碎屑岩的锆石LA-ICP-MS U-Pb年龄数据和全岩地球化学数据，试图破解埃迪卡拉纪断裂的起源。结合新的地震和钻探数据，埃迪卡拉纪的特征是在盆地内的断层凹陷中沉积了岩浆贫乏的裂谷演替。埃迪卡拉纪碎屑锆石的 U-Pb 年龄集中在 850-630 Ma 之间，这表明埃迪卡拉纪断裂期间发生过一次微弱的岩浆活动。从地球化学角度看，硅质碎屑岩的稀土元素（REE）相对平坦，Eu*呈负异常，富含大多数高场强元素（HFSE），但Nb、Ta、Sr和Ti元素贫乏。地球化学数据表明，埃迪卡拉纪沉积岩形成于大陆岛弧环境中。结合已编制的锆石εHf（t）值，四川盆地埃迪卡拉纪的断裂与后退俯冲是一致的。我们为埃迪卡拉纪华南地块提出了一个弱的、平坦的、与后退俯冲相关的大陆内被动裂谷模型。这一案例研究表明，后退俯冲不仅可能引发弧后盆地发育，而且可能导致岩浆贫乏的被动裂谷盆地。
{"title":"Retreating subduction-related intracratonic rifting in the Ediacaran Sichuan Basin (SW China)","authors":"Jun Tang , Jian Wang , Guanghui Wu , Yinyu Wen , R. Damian Nance , Bing He , Chenghai Li , Yu Zou","doi":"10.1016/j.precamres.2024.107569","DOIUrl":"10.1016/j.precamres.2024.107569","url":null,"abstract":"<div><div>Ediacaran continental rift basins in the Sichuan Basin (SW China) overlap in time with the breakup of Rodinia and the assembly of Gondwana, but whether the rifts occurred in response to a mantle plume or to a subduction-related mechanism at the outer margin of the supercontinent remains uncertain. In the absence of Ediacaran igneous rocks, we provide zircon LA-ICP-MS U-Pb age data and whole-rock geochemistry from exposed Ediacaran-Lower Cambrian siliciclastic rocks in the Sichuan Basin in an effort to decipher the origin of the Ediacaran rifting. Together with new seismic and drilling data, the Ediacaran period is characterized by a magma-poor rift succession deposited in a faulted depression within the basin. U-Pb ages of the Ediacaran detrital zircons are concentrated in the range of 850–630 Ma, which suggests a weak magmatic event during the Ediacaran rifting. Geochemically, the siliciclastic rocks are characterized by relatively flat rare earth elements (REE) with negative Eu* anomalies, enrichment in most high field strength elements (HFSE), but depletion in Nb, Ta, Sr and Ti. The geochemical data suggest that the Ediacaran sedimentary rocks formed in a continental island arc setting. Together with compiled zircon εHf(t) values, Ediacaran rifting in the Sichuan Basin is consistent with retreating subduction. We propose a weak, flat, retreating subduction-related intracontinental passive rift model for the Ediacaran South China Block. This case study suggests that the retreating subduction could not only trigger back-arc basin development, but could also lead to the magma-poor passive rift basin.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107569"},"PeriodicalIF":3.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Interpretation of the deformation pattern of the western Reguibat Shield by integrating current geochronological knowledge allows deciphering the assembly and post-assembly tectonic history of the Awsard craton that became involved in the giant Eburnean (∼2 Ga) accretionary orogen. Final craton assembly took place along the newly recognized early Siderian (2.51–2.46 Ga) Tiris orogen. The eastern margin of the craton was then affected until 2.07–2.03 Ga by a west-verging (i.e., craton-ward) thrust system rooted in the collisional contact with the Eburnean orogen. Collision was controlled by thermal erosion and softening of the craton edge by the accretionary orogen, which allowed for the propagation of the thrust system during craton-ward progression of delamination of the cratonic lithospheric mantle. This resulted in the progressive incorporation of Archean crust into the accretionary orogen. Such a hot mode of collision provides a mechanism for the destruction of cratons by reworking of their crust into their flanking accretionary orogens and recycling of their lithospheric mantle into the asthenosphere. The hot collision mode favors the formation of specific oroclines driven by lithospheric mantle delamination.
{"title":"Archean craton assembly and Paleoproterozoic accretion-collision tectonics in the Reguibat Shield, West African Craton","authors":"Dominique Chardon , Julien Berger, Florian Martellozzo","doi":"10.1016/j.precamres.2024.107570","DOIUrl":"10.1016/j.precamres.2024.107570","url":null,"abstract":"<div><div>Interpretation of the deformation pattern of the western Reguibat Shield by integrating current geochronological knowledge allows deciphering the assembly and post-assembly tectonic history of the Awsard craton that became involved in the giant Eburnean (∼2 Ga) accretionary orogen. Final craton assembly took place along the newly recognized early Siderian (2.51–2.46 Ga) Tiris orogen. The eastern margin of the craton was then affected until 2.07–2.03 Ga by a west-verging (i.e., craton-ward) thrust system rooted in the collisional contact with the Eburnean orogen. Collision was controlled by thermal erosion and softening of the craton edge by the accretionary orogen, which allowed for the propagation of the thrust system during craton-ward progression of delamination of the cratonic lithospheric mantle. This resulted in the progressive incorporation of Archean crust into the accretionary orogen. Such a hot mode of collision provides a mechanism for the destruction of cratons by reworking of their crust into their flanking accretionary orogens and recycling of their lithospheric mantle into the asthenosphere. The hot collision mode favors the formation of specific oroclines driven by lithospheric mantle delamination.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107570"},"PeriodicalIF":3.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301926824002833/pdfft?md5=cb63018479f60a521174aede98d9d748&pid=1-s2.0-S0301926824002833-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142316219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Large granitoid batholiths contain key information about the formation and evolution of the continental crust, but their growth mechanism and compositional diversity are still not clear. The Neoproterozoic Huangling batholith, one of the largest granitoid batholith in South China, comprises several plutons and covers an area of ∼ 970 km2. The largest trondhjemitic pluton was emplaced at ca. 840 Ma, and its magmatic zircons show large variable Th/U ratios (0.22–1.81) that are strongly correlated with Ti-in-zircon temperatures, zircon U/Yb and Ce4+/Ce3+ ratios. These zircons have negative εHf (−28.3 to −14.6), variable δ18O (4.43–6.99 ‰) and δ94Zr values (−0.38 ‰ to + 0.21 ‰), as well as moderate zircon saturation temperatures (716–771 °C) and high fO2 (FMQ+1.9). The trondhjemite is therefore proposed to have been derived from the Archean amphibolitic crust and underwent fractional crystallization of zircon, magnetite, apatite and/or titanite. In comparison, one smaller granitic pluton was emplaced at 831 ± 5 Ma. The magmatic zircons have more radiogenic εHf (−11.7 to −10.4), constant δ18O (6.09–6.66 ‰) and δ94Zr values (−0.31 ‰ to + 0.06 ‰), and they have slightly higher zircon saturation temperatures (767–803 °C) and fO2 (FMQ+2.9). These geochemical features suggest that the granite was derived from a crustal source with mixed juvenile mafic materials and Archean amphibolitic rocks, and did not experience significant fractional crystallization. The Huangling granitoid batholith was formed by multiple injections of felsic melts with the compositional diversity that probably resulted from heterogeneous protoliths and complex magmatic processes in a prolonged magma evolution system.
{"title":"Large granitoid batholith formed by episodic reworking of the continental basement","authors":"Qi-Wei Li , Jun-Hong Zhao , Yun-Lai Dong , Yu-Qing Huang","doi":"10.1016/j.precamres.2024.107568","DOIUrl":"10.1016/j.precamres.2024.107568","url":null,"abstract":"<div><div>Large granitoid batholiths contain key information about the formation and evolution of the continental crust, but their growth mechanism and compositional diversity are still not clear. The Neoproterozoic Huangling batholith, one of the largest granitoid batholith in South China, comprises several plutons and covers an area of ∼ 970 km<sup>2</sup>. The largest trondhjemitic pluton was emplaced at ca. 840 Ma, and its magmatic zircons show large variable Th/U ratios (0.22–1.81) that are strongly correlated with Ti-in-zircon temperatures, zircon U/Yb and Ce<sup>4+</sup>/Ce<sup>3+</sup> ratios. These zircons have negative εHf (−28.3 to −14.6), variable δ<sup>18</sup>O (4.43–6.99 ‰) and δ<sup>94</sup>Zr values (−0.38 ‰ to + 0.21 ‰), as well as moderate zircon saturation temperatures (716–771 °C) and high <em>f</em>O<sub>2</sub> (FMQ+1.9). The trondhjemite is therefore proposed to have been derived from the Archean amphibolitic crust and underwent fractional crystallization of zircon, magnetite, apatite and/or titanite. In comparison, one smaller granitic pluton was emplaced at 831 ± 5 Ma. The magmatic zircons have more radiogenic εHf (−11.7 to −10.4), constant δ<sup>18</sup>O (6.09–6.66 ‰) and δ<sup>94</sup>Zr values (−0.31 ‰ to + 0.06 ‰), and they have slightly higher zircon saturation temperatures (767–803 °C) and <em>f</em>O<sub>2</sub> (FMQ+2.9). These geochemical features suggest that the granite was derived from a crustal source with mixed juvenile mafic materials and Archean amphibolitic rocks, and did not experience significant fractional crystallization. The Huangling granitoid batholith was formed by multiple injections of felsic melts with the compositional diversity that probably resulted from heterogeneous protoliths and complex magmatic processes in a prolonged magma evolution system.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107568"},"PeriodicalIF":3.2,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1016/j.precamres.2024.107572
Ion Francovschi , Leonid Shumlyanskyy , Volodymyr Grytsenko , Adam Hoffmann , Simon A. Wilde , Andrey Bekker
The Neoproterozoic is marked by two long-lasting global Snowball Earth glaciations—the Sturtian (ca. 715–660 Ma) and the Marinoan (ca. 639–635 Ma)—as well as the shorter-lived, potentially regional Gaskiers glaciation at ca. 580–579 Ma. The subsequent Ediacaran and early Cambrian periods are generally interpreted to be characterized by a warm climate without low-latitude, sea-level glaciations. However, a number of locally, and, sometimes regionally developed sedimentary units worldwide have been interpreted to record sea-level glaciations during this time interval. Some of these units crop-out poorly, were affected by deformation and metamorphism, lack definitive sedimentologic textures and structures, and are poorly dated. Their sedimentological characteristics, as well as age constraints, are thus often insufficient to determine whether they have a glacial origin and if their ages fit into well-defined time intervals marked by cold climate indicators. Detrital zircon geochronology may help distinguish between the heterogeneous and extensive provenances that are indicative of glaciation, and more homogenous, and local provenances that are more typical of alluvial settings. In this paper, we use trends in detrital zircon age distribution patterns from the lowermost late Ediacaran sedimentary succession of the Moldova-Podillya basin in Baltica to constrain the provenance of the Volyn Group sediments. Here, the origin of diamictites within the Hrushka Formation has long been a topic of debate, centered on either a glacial or alluvial origin. Detrital zircons from two sandstone samples and one conglomerate sample from the Bakhtyn Beds of the Hrushka Formation, and two sandstone samples from the Lomoziv Beds of the unconformably overlying Mohyliv Formation were dated using U-Pb zircon LA-ICP-MS techniques. Their age patterns are compared with published data for the overlying Cosăuți (Yampil) and Bernashivka beds as well as new dates for the immediately underlying Paleoproterozoic granites to test for a proposed glacial origin for the Bakhtyn Beds. The areal distribution of the Volyn Group sediments, inferred from drill-core data, is used to constrain the evolution of the sedimentary basin. The detrital zircon results indicate that terrigenous material in the Moldova-Podillya sedimentary basin was sourced from the Precambrian basement during deposition of the Bakhtyn to Cosăuți beds. This is consistent with an alluvial rather than a glacial origin. We infer that detrital zircon geochronology provides a largely untapped potential for testing a glacial origin for units that are otherwise poorly genetically characterized and dated.
{"title":"U–Pb geochronology and Hf isotope systematics of detrital zircon from the basal part of the late Ediacaran sedimentary succession of the Moldova-Podillya basin (SW Baltica): Implications for glacial vs. alluvial origin","authors":"Ion Francovschi , Leonid Shumlyanskyy , Volodymyr Grytsenko , Adam Hoffmann , Simon A. Wilde , Andrey Bekker","doi":"10.1016/j.precamres.2024.107572","DOIUrl":"10.1016/j.precamres.2024.107572","url":null,"abstract":"<div><p>The Neoproterozoic is marked by two long-lasting global Snowball Earth glaciations—the Sturtian (ca. 715–660 Ma) and the Marinoan (ca. 639–635 Ma)—as well as the shorter-lived, potentially regional Gaskiers glaciation at ca. 580–579 Ma. The subsequent Ediacaran and early Cambrian periods are generally interpreted to be characterized by a warm climate without low-latitude, sea-level glaciations. However, a number of locally, and, sometimes regionally developed sedimentary units worldwide have been interpreted to record sea-level glaciations during this time interval. Some of these units crop-out poorly, were affected by deformation and metamorphism, lack definitive sedimentologic textures and structures, and are poorly dated. Their sedimentological characteristics, as well as age constraints, are thus often insufficient to determine whether they have a glacial origin and if their ages fit into well-defined time intervals marked by cold climate indicators. Detrital zircon geochronology may help distinguish between the heterogeneous and extensive provenances that are indicative of glaciation, and more homogenous, and local provenances that are more typical of alluvial settings. In this paper, we use trends in detrital zircon age distribution patterns from the lowermost late Ediacaran sedimentary succession of the Moldova-Podillya basin in Baltica to constrain the provenance of the Volyn Group sediments. Here, the origin of diamictites within the Hrushka Formation has long been a topic of debate, centered on either a glacial or alluvial origin. Detrital zircons from two sandstone samples and one conglomerate sample from the Bakhtyn Beds of the Hrushka Formation, and two sandstone samples from the Lomoziv Beds of the unconformably overlying Mohyliv Formation were dated using U-Pb zircon LA-ICP-MS techniques. Their age patterns are compared with published data for the overlying Cosăuți (Yampil) and Bernashivka beds as well as new dates for the immediately underlying Paleoproterozoic granites to test for a proposed glacial origin for the Bakhtyn Beds. The areal distribution of the Volyn Group sediments, inferred from drill-core data, is used to constrain the evolution of the sedimentary basin. The detrital zircon results indicate that terrigenous material in the Moldova-Podillya sedimentary basin was sourced from the Precambrian basement during deposition of the Bakhtyn to Cosăuți beds. This is consistent with an alluvial rather than a glacial origin. We infer that detrital zircon geochronology provides a largely untapped potential for testing a glacial origin for units that are otherwise poorly genetically characterized and dated.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"413 ","pages":"Article 107572"},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142271944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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