225 results on '"Qinglai Feng"'
Search Results
2. Late Cretaceous Granitoids along the Northern Kuching Zone: Implications for the Paleo-Pacific Subduction in Borneo
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Chengshi Gan, Xin Qian, Yuejun Wang, Qinglai Feng, Yuzhi Zhang, and Junaidi Bin Asis
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Geology ,QE1-996.5 - Abstract
AbstractThe EW-trending Kuching zone in Borneo is a target region for exploring the southern continuation of Paleo-Pacific subduction from South China, Vietnam to SE Asia. Previous studies mainly focused on mafic igneous rocks, and poor attention has been paid to the contemporaneous granitoids in this zone. This study presented detailed zircon U-Pb geochronology and Lu-Hf isotope and whole-rock geochemistry analyses for late Cretaceous granitoids (granodiorites and granites) in the northern Kuching zone. These granitoids are dated at ~77.5-83.6 Ma with younger ages than the igneous rocks in the southern Kuching zone (~130-144 Ma). The granitoids have variable SiO2 (64.86-77.37 wt.%) and A/CNK (0.7-1.5) and are strongly enriched in LILE and depleted in HFSE with significant Ba, Nb, Sr, and Ti negative anomalies. They have variable (87Sr/86Sr)i (from 0.70656 to 0.71208), εNd(t) (from -4.4 to +0.9), and zircon εHf(t) (from -1.2 to +12.4) with high (206Pb/204Pb)i ratio of 18.78-19.74, suggesting derivation from a hybrid source involving meta-sedimentary and meta-igneous rocks. Combined with previously-published data, two episodes of Cretaceous (~77-98 Ma and ~130-144 Ma) magmatic activities are identified in the Kuching zone, showing a younging age trend from south to north. These episodes of Cretaceous igneous rocks and their spatial distribution in the Kuching zone can be totally comparable to those in South China and Vietnam. Thus, the Kuching zone was likely a part of the Paleo-Pacific subduction system during the Cretaceous, northerly linking to Vietnam and South China.
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- 2022
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3. Geochronological and geochemical constraints on the petrogenesis of late Mesoproterozoic mafic and granitic rocks in the southwestern Yangtze Block
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Guichun Liu, Jing Li, Xin Qian, Qinglai Feng, Wei Wang, Guangyan Chen, and Shaobin Hu
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Late Mesoproterozoic ,Zircon U–Pb geochronology ,Elemental and isotopic data ,Within-plate igneous rocks ,Continental rift ,Yangtze Block ,Geology ,QE1-996.5 - Abstract
Late Mesoproterozoic igneous rocks in the SW Yangtze Block are important for understanding the role of it in reconstruction of the Rodinia supercontinent. In the present study, we report new geochronological, geochemical, and Nd–Hf isotopic data for the Cuoke plagioclase amphibolites and granites in the SW Yangtze Block. Geochronological results show that the plagioclase amphibolites and granites have similar late Mesoproterozoic zircon U–Pb ages of 1168–1162 Ma, constituting a bimodal igneous assemblage. The plagioclase amphibolites have high and variable TiO2 contents (1.15–4.30 wt.%) and Mg# (34–66) values, similar to the tholeiitic series. They are characterized by enrichment in LREEs and LILEs, and have OIB-like affinities with positive Nb and Ta anomalies. The plagioclase amphibolites have positive whole-rock εNd(t) (+3.2 to +4.3) and zircon εHf(t) (+4.3 to +10.7) values, indicating that they were derived from an OIB-like asthenospheric mantle source. The granites belong to the reduced peralkaline A-type series and have negative εNd(t) value of −6.0 and εHf(t) values of −5.8 to −13.8, indicating a derivation from the partial melting of ancient mafic lower crust. In combination with the ∼1.05–1.02 Ga bimodal igneous assemblage in the SW Yangtze Block, we propose that the Cuoke 1168–1162 Ma igneous rocks were likely formed in a continental rift basin and argue against the existance of Grenvillian Orogen in the SW Yangtze Block during the late Mesoproterozoic.
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- 2021
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4. Geochemical indices and palynology comparison used for paleoproductivity and paleoredox conditions of the Huai Hin Lat Formation in part of Loei-Petchabun Fold Belt in central Thailand
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Boonnarong Arsairai, Qinglai Feng, Chongpan Chonglakmani, Akkhapun Wannakomol, and Hathaichanok Vattanasak
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toc ,hydrocarbon ,geochemistry ,kerogen ,petrography ,huai hin lat formation ,Technology ,Technology (General) ,T1-995 ,Science ,Science (General) ,Q1-390 - Abstract
Petrography and geochemistry analyzing Dat Yai section can describe paleoproductivity and past-redox condition. Paleoproductivity proxies consisted of AOM, phytoclast, TOC, excess SiO2, Ba/Al, and P/Al as high values through sections which similarly indicate high productivity. High productivity in Beds 3 and 27 showed lower peak TOC which is explained by poorer preservation. Lower productivity of Bed 18 showed a high TOC peak indicating good preservation. Paleoredox condition was evaluated using Ni/Co, U/Th, V/Cr, V/(V+Ni), Ni/V, and (Cu+Mo)/Zn. Values for V/(V+Ni) ranged from 0.67 to 0.85 exceeding the cutoff value of 0.46 for a reducing environment. The average value of V/Cr (2.07) exceeded 2.0 of anoxic. Bed 9 consisted of the highest peak of TOC that does not reflect the excellent preservation resulting from dominantly high paleoproductivity. Bed 21 exhibited lower productivity and lowest TOC which indicated a poverty-reducing effect. AOM and phytoclasts were supplied and kept in the benthic floor by extreme redox. Sediments became black shale which expelled oil and some gas.
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- 2020
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5. Proto-Tethys ophiolitic mélange in SW Yunnan: Constraints from zircon U-Pb geochronology and geochemistry
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Guichun Liu, Zaibo Sun, Jianwei Zi, M. Santosh, Tianyu Zhao, Qinglai Feng, Guangyan Chen, Xiaomei Nie, Jing Li, and Shitao Zhang
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Mayidui–Wanhe ophiolites ,Zircon U-Pb geochronology ,Geochemistry ,Proto-Tethys ,SW Yunnan ,Geology ,QE1-996.5 - Abstract
An early Paleozoic Proto-Tethys ocean in western Yunnan has long been postulated although no robust geological evidence has been identified. Here we investigated the recently-identified Mayidui and Wanhe ophiolitic mélanges in SW Yunnan, which occurs in a N–S trending belt east of the late Paleozoic Changning–Menglian suture zone. The ophiolites consist mainly of meta-basalts (amphibole schists), meta- (cumulate) gabbros and gabbroic diorites, and meta- chert-shale, representing ancient oceanic crust and pelagic and hemipelagic sediments, respectively. Six samples of gabbros and gabbroic diorites from 3 profiles (Mayidui, Kongjiao and Yinchanghe) yielded zircon U-Pb ages between 462 ± 6 Ma and 447 ± 9 Ma, constraining the formation of the Mayidui and Wanhe ophiolites to Middle Ordovician. Gabbros from the Mayidui and Kongjiao profiles share similar geochemical characteristics with affinities to tholeiitic series, and are characterized by depleted to slightly enriched LREEs relative to HREEs with (La/Sm)N = 0.69–1.87, (La/Yb)N = 0.66–4.72). These, along with their predominantly positive whole-rock εNd(t) and zircon εHf(t) values, indicate a MORB-like magma source. By contrast, the meta-mafic rocks from the Yinchanghe profile show significantly enriched LREEs ((La/Sm)N = 0.97–3.33, (La/Yb)N = 1.19–14.93), as well as positive whole-rock εNd(t) and positive to negative zircon εHf(t) values, indicating an E-MORB-type mantle source. These geochemical features are consistent with an intra-oceanic setting for the formation of the Mayidui–Wanhe ophiolites. Our data, integrated with available geological evidence, provide robust constraints on the timing and nature of the Mayidui–Wanhe ophiolitic mélange, and suggest that the ophiolites represent remnants of the Proto-Tethys Ocean, which opened through separation of the Indochina and Simao blocks from the northern margin of Gondwana before the Early Cambrian, and evolved through to the Silurian.
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- 2021
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6. Evidence for a prolonged Permian–Triassic extinction interval from global marine mercury records
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Jun Shen, Jiubin Chen, Thomas J. Algeo, Shengliu Yuan, Qinglai Feng, Jianxin Yu, Lian Zhou, Brennan O’Connell, and Noah J. Planavsky
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Science - Abstract
Previously, little direct evidence has been found to link large volcanic eruption events with the end-Permian mass extinction. Here, the authors find that mercury enrichment and isotope records in marine sections across the globe can be linked to increased volcanic activity, which resulted in the protracted Permian-Triassic biocrisis
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- 2019
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7. 'Where, when and why' for the arc-trench gap from Mesozoic Paleo-Pacific subduction zone: Sabah Triassic-Cretaceous igneous records in East Borneo
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Yuejun Wang, Xin Qian, Junaidi Bin Asis, Peter A. Cawood, Sainan Wu, Yuzhi Zhang, Qinglai Feng, and Xianghong Lu
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Geology - Published
- 2023
8. A Diverse Microfossil Assemblage from the Ediacaran–Cambrian Deep-Water Chert of the Liuchapo Formation in Guizhou Province, South China
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Yan Zhang, Shan Chang, Qinglai Feng, and Shucan Zheng
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General Earth and Planetary Sciences - Published
- 2023
9. Source rock potential assessment of the Huai Hin Lat Formation, Sap Phlu Basin, Nakhon Ratchasima Province, northeastern Thailand
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Boonnarong Arsairai, Qinglai Feng, Chongpan Chonglakmani, and Sakchai Glumglomjit
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Geochemistry and Petrology - Published
- 2022
10. Early Triassic-Late Cretaceous Paleo-Pacific subduction zone along the East Asia continental margin: Fore-arc igneous records in Sabah of NE Borneo
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Yuejun Wang, Sainan Wu, Xin Qian, Junaidi Bin Asis, Yang Wang, Yuzhi Zhang, Qinglai Feng, Weitao Wang, and Peizhen Zhang
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Multidisciplinary - Published
- 2022
11. Characteristics and Sources of Organic Matter from the Early Cambrian Niutitang Formtion and Its Preservation Environment in Guizhou
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Hong Wei, Qinglai Feng, Jianxin Yu, and Shan Chang
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General Earth and Planetary Sciences - Published
- 2022
12. 滇西南原-古特提斯演化研究
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Qinglai Feng, Guichun Liu, Zhengqin Gan, Tianyu Zhao, Jianwei Zi, and Yuehua Wei
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Materials Science (miscellaneous) - Published
- 2023
13. Microfossil Assemblages and Indication of the Source and Preservation Pattern of Organic Matter from the Early Cambrian in South China
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Shucan Zheng, Qinglai Feng, Sebastiaan van de Velde, Shan Chang, Lei Zhang, and Bo Gao
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General Earth and Planetary Sciences - Published
- 2022
14. Positioning the Yangtze Block within Nuna: Constraints from Paleoproterozoic granitoids in North Vietnam
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Tianyu Zhao, Peter A. Cawood, Jian-Wei Zi, Kai Wang, Qinglai Feng, Dung My Tran, Huan Dinh Trinh, Cung My Dang, and Quyen Minh Nguyen
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Geochemistry and Petrology ,Geology - Published
- 2023
15. Integrated Radiolarian and Conodont Biostratigraphy of the Middle to Late Permian Linghao Formation in Northwestern Guangxi, South China
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Qinglai Feng, Taniel Danelian, Shan Chang, Maliha Zareen Khan, Lei Zhang, Weihong He, Qiangfen Ma, Ito Tsuyoshi, Jun Wu, Dong-xun Yuan, Marie Béatrice Forel, and Martial Caridroit
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Paleontology ,South china ,biology ,Permian ,Geology ,Biostratigraphy ,biology.organism_classification ,Conodont ,Radiolaria - Published
- 2021
16. The boundary between the Inthanon Zone (Palaeotropics) and the Gondwana-derived Sibumasu Terrane, northwest Thailand—evidence from Permo-Triassic limestones and cherts
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Hathaithip Thassanapak, Mongkol Udchachon, Qinglai Feng, and Clive Burrett
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Global and Planetary Change ,Ecology ,Permian ,Carbonate platform ,Paleontology ,Geology ,Allochthon ,Gondwana ,Continental margin ,Carboniferous ,Late Devonian extinction ,Ecology, Evolution, Behavior and Systematics ,Terrane - Abstract
The boundary between tropical Permian faunas of the Inthanon Zone and Gondwana faunas in far NW Thailand has been long debated. Both the Late Devonian and the Permian Gondwanan platform margins lie a few kilometres west of the Mae Yuam/Mae Sariang Fault (MYMS FZ). In the Permian, the margin grades eastwards into hemipelagic radiolarites along the MYMS FZ and westwards into the Thitsiphin carbonate platform of Myanmar. The area west of the MYMS FZ is the Northern part of the West Thailand Region (NWTR). Quartz-rich limestones of Roadian age in the NWTR are succeeded by deep-water platform limestones in the NWTR and shallow-water carbonates in Myanmar and contain a distinctive fusulinid fauna including Monodiexodina which does not occur in palaeotropical terranes. A 300-m section of limestone 10 km west of the MYMS FZ contains Wordian microfauna and is placed in a deep shelf to slope environment. Carboniferous to Triassic continental margin, hemipelagic, non-hydrothermal, radiolarian cherts outcrop on either side of the Mae Yuam valley and were deposited on the upwelling margins of an ocean separating the Inthanon Zone and Sibumasu Terrane. The widely accepted allochthon model proposes that the Inthanon Zone Devonian-Triassic radiolarites were pelagic and deposited on a subducting ocean that supported seamounts with Visean to Permian tropical shallow-water carbonates lasting at least 90 my. We suggest an alternative hypothesis where the radiolarites of the Inthanon Zone were continental margin as shown by their geochemistry and deposited in deeper parts of small extensional basins with limited volcanism between long-lived, isolated carbonate platforms.
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- 2021
17. The largest negative carbon isotope excursions in Neoproterozoic carbonates caused by recycled carbonatite volcanic ash
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Yongsheng Liu, Xiaobin Ou, Junhua Li, Detao He, Qinglai Feng, Jie Lin, Chunfei Chen, Stephen F. Foley, Yan’an Shen, and Wei Chen
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Multidisciplinary ,Geochemistry ,Authigenic ,010502 geochemistry & geophysics ,01 natural sciences ,Doushantuo Formation ,chemistry.chemical_compound ,Igneous rock ,chemistry ,Carbonatite ,Carbonate rock ,Carbonate ,Sedimentary rock ,Ankerite ,Geology ,0105 earth and related environmental sciences - Abstract
The late Ediacaran Shuram Excursion (SE) records the most prominent negative δ13C excursions (δ13C = −12‰) during Earth’s history. It has been hypothesized to have resulted from oxidation of dissolved organic matter, diagenetic or authigenic precipitates. However, the origin of the SE remains enigmatic; current models face challenges regarding the significant amount of atmospheric oxygen needed to balance such extensive oxidation and sustained inputs of light carbon with extremely negative C isotope compositions. Here, we show that the Doushantuo Formation at the Jiulongwan section in South China, a key stratum recording the SE event, contains mineralogical and geochemical signatures related to igneous processes. Both the occurrence of ankerite, feldspar, moissanite and euhedral quartz in the SE samples and the relatively consistent Ce anomalies of carbonate and O isotopes of quartz indicate a contribution from an igneous source. In particular, the SE samples have trace element and C isotope compositions similar to those of recycled carbonatites formed by decarbonation and melting of sedimentary carbonate rocks. These observations suggest that the deep cycle of ancient carbonate rocks, which were subjected to decarbonation during subduction, melting and eruption related to the breakup of the Rodinia supercontinent, contributed to the SE. This igneous model for the SE may provide a connection between the deep and shallow carbon cycles of the Earth.
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- 2021
18. Geochronological and geochemical constraints on the petrogenesis of late Mesoproterozoic mafic and granitic rocks in the southwestern Yangtze Block
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Wei Wang, Guichun Liu, Qinglai Feng, Jing Li, Guangyan Chen, Xin Qian, and Shaobin Hu
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Yangtze Block ,lcsh:QE1-996.5 ,Geochemistry ,Zircon U–Pb geochronology ,Elemental and isotopic data ,Crust ,engineering.material ,Peralkaline rock ,Supercontinent ,lcsh:Geology ,Within-plate igneous rocks ,Igneous rock ,Continental rift ,engineering ,Late Mesoproterozoic ,General Earth and Planetary Sciences ,Plagioclase ,Mafic ,Geology ,Zircon ,Petrogenesis - Abstract
Late Mesoproterozoic igneous rocks in the SW Yangtze Block are important for understanding the role of it in reconstruction of the Rodinia supercontinent. In the present study, we report new geochronological, geochemical, and Nd–Hf isotopic data for the Cuoke plagioclase amphibolites and granites in the SW Yangtze Block. Geochronological results show that the plagioclase amphibolites and granites have similar late Mesoproterozoic zircon U–Pb ages of 1168–1162 Ma, constituting a bimodal igneous assemblage. The plagioclase amphibolites have high and variable TiO2 contents (1.15–4.30 wt.%) and Mg# (34–66) values, similar to the tholeiitic series. They are characterized by enrichment in LREEs and LILEs, and have OIB-like affinities with positive Nb and Ta anomalies. The plagioclase amphibolites have positive whole-rock eNd(t) (+3.2 to +4.3) and zircon eHf(t) (+4.3 to +10.7) values, indicating that they were derived from an OIB-like asthenospheric mantle source. The granites belong to the reduced peralkaline A-type series and have negative eNd(t) value of −6.0 and eHf(t) values of −5.8 to −13.8, indicating a derivation from the partial melting of ancient mafic lower crust. In combination with the ∼1.05–1.02 Ga bimodal igneous assemblage in the SW Yangtze Block, we propose that the Cuoke 1168–1162 Ma igneous rocks were likely formed in a continental rift basin and argue against the existance of Grenvillian Orogen in the SW Yangtze Block during the late Mesoproterozoic.
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- 2021
19. A refined Archean-Paleoproterozoic magmatic framework of the Cuoke Complex, SW China, and its implications for early Precambrian evolution of the Yangtze Block
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Zhao Yang, Jian-Wei Zi, Peter A. Cawood, Tianyu Zhao, Guichun Liu, Jing Li, Hu Zhang, Yuehua Wei, and Qinglai Feng
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Geochemistry and Petrology ,Geology - Published
- 2023
20. Mercury fluxes record regional volcanism in the South China craton prior to the end-Permian mass extinction
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Jun Shen, Shucheng Xie, Jiubin Chen, Yi-Gang Xu, Qinglai Feng, Guozhen Xu, Yong Lei, Jianxin Yu, Thomas J. Algeo, and Noah J. Planavsky
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geography ,South china ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Geochemistry ,chemistry.chemical_element ,Geology ,Volcanism ,010502 geochemistry & geophysics ,01 natural sciences ,Mercury (element) ,Craton ,chemistry ,Permian–Triassic extinction event ,0105 earth and related environmental sciences - Abstract
Enhanced regional subduction-related volcanism in the South China craton concurrent with Siberian Traps large igneous province magmatism was a likely contributor to major biotic and environmental stresses associated with the Permian-Triassic boundary (ca. 252 Ma) mass extinction. However, the timing, intensity, and duration of this regional volcanic activity remain uncertain. We analyzed mercury (Hg) concentrations in three widely separated marine sections in the South China craton (Shangsi, Ganxi, and Chaohu) as well as Hg isotopic compositions in one section (Shangsi) from the Upper Permian (Changhsingian) through the lowermost Triassic (Induan) in order to track volcanic inputs. Four mercury enrichment (ME) intervals, dating to the lowermost Changhsingian (ME1), mid–Clarkina changxingensis zone (ME2), upper C. changxingensis to lower C. yini zones (ME3), and latest Permian mass extinction (LPME) interval (ME4), were recognized on the basis of elevated Hg/total organic carbon ratios. These records provide evidence of strong volcanism in the Tethyan region starting ∼2 m.y. before the LPME, whereas only the ME4 event is recorded in extra-Tethyan sections. Mercury isotopes support the inference that pre-LPME Hg peaks were related to regional subduction-related volcanism, and that Hg emissions at the LPME were the result of Siberian Traps large igneous province intrusions into organic-rich sediments. This study demonstrates the feasibility of distinguishing flood-basalt from subduction-related volcanic inputs on the basis of marine sedimentary Hg records.
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- 2020
21. Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan
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Miao Sang, Wenjiao Xiao, Qinglai Feng, and Brian F. Windley
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Geochemistry ,Geology ,Accretionary complex - Published
- 2020
22. Geochronological and Geochemical Constraints on the Petrogenesis of Early Paleoproterozoic (2.40-2.32 Ga) Nb-Enriched Mafic Rocks in Southwestern Yangtze Block and Its Tectonic Implications
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Jian-Wei Zi, Guichun Liu, Jing Li, Shaobin Hu, Qinglai Feng, Xin Qian, Guangyan Chen, and Tianyu Zhao
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020209 energy ,Geochemistry ,Partial melting ,02 engineering and technology ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Tectonics ,0202 electrical engineering, electronic engineering, information engineering ,General Earth and Planetary Sciences ,Mafic ,Biogeosciences ,Geology ,0105 earth and related environmental sciences ,Zircon ,Petrogenesis ,Lower degree - Abstract
Recent geological survey has identified the Early Paleoproterozoic meta-mafic intrusions in the southwestern Yangtze Block. We present geochronological, whole-rock geochemical and Nd isotopic data for these meta-mafic rocks to better address the tectonic evolution of the Yangtze Block during the Early Paleoproterozoic Period. Geochronological data show that the meta-mafic rocks have zircon ages of 2 395-2 316 Ma. They have high TiO2 contents of 1.40 wt.%3.66 wt.% and Nb concentrations of 13.7 ppm45.5 ppm, thus aregrouped as Nb-enriched mafic rocks. These mafic rocks are characterized by tholeiitic compositions with enrichment of LREEs and LILEs, and can be divided into two groups. Group 1 samples display E-MORB-like geochemical characteristics. Group 2 samples have positive eNd(t) values of 4.0–5.0. Geochemical data indicate that all meta-mafic rocks were likely derived from a depleted asthenospheric mantle. REE modeling indicates lower degree of partial melting for Group 2 samples (3%–10%) relative to Group 1 samples (15%–20%). Taking into account contemporaneous post-collisional granitoids in southwestern Yangtze Block, we propose that these meta-mafic rocks were formed in a post-collisional extension setting. These meta-mafic rocks can be compared with those in Africa, South America and Europe, and might be linked with the Arrowsmith orogenic belt. KEY WORDS: zircon dating, geochemistry, Early Paleoproterozoic, Nb-enriched rocks, Yangtze Block.
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- 2020
23. New Insight into Factors Controlling Organic Matter Distribution in Lower Cambrian Source Rocks: A Study from the Qiongzhusi Formation in South China
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Nicolas Tribovillard, Shucan Zheng, Bo Gao, Qinglai Feng, Thomas Servais, and Yan Zhang
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Total organic carbon ,Palynology ,chemistry.chemical_classification ,020209 energy ,Earth science ,02 engineering and technology ,Biogenic silica ,010502 geochemistry & geophysics ,01 natural sciences ,Carbon cycle ,Source rock ,chemistry ,0202 electrical engineering, electronic engineering, information engineering ,General Earth and Planetary Sciences ,Sedimentary organic matter ,Sedimentary rock ,Organic matter ,Geology ,0105 earth and related environmental sciences - Abstract
Sedimentary organic matter (OM) is a major reservoir of organic carbon in the global carbon cycle. Despite many studies, there still exist many debates on the mechanism of OM accumulation and preservation in marine sediments. We present a new field study of a Lower Cambrian shallow marine shelf sequence in the northern edge of the Yangtze Plate, China. Our results show that palynological OM and biogenic silica (Bio-Si) could be used alongside more conventional redox and paleo-productivity proxies to study the distribution of OM in marine sediments. The qualitative and quantitative study of palynological OM provides more detailed information on the nature of sedimentary organic carbon, which can be helpful in the assessment of primary productivity and OM preservation. In addition, the presence of Bio-Si stimulates the physical preservation of OM. Further analysis indicates that an increase in Bio-Si can promote OM preservation. This case-study provides insight into the intertwined factors controlling OM accumulation in the Early Cambrian.
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- 2020
24. Mercury isotope evidence for a non-volcanic origin of Hg spikes at the Ordovician-Silurian boundary, South China
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Jun Shen, Thomas J. Algeo, and Qinglai Feng
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Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) - Published
- 2022
25. Mercury evidence of intense volcanic effects on land during the Permian-Triassic transition
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Shucheng Xie, Jun Shen, Qinglai Feng, Wenchao Shu, Xiao Shi, Noah J. Planavsky, Jianxin Yu, Jiubin Chen, Thomas J. Algeo, and Guozhen Xu
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geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Permian ,Geochemistry ,chemistry.chemical_element ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Mercury (element) ,Volcano ,chemistry ,0105 earth and related environmental sciences - Abstract
The Siberian Traps large igneous province (STLIP) was the likely trigger for the ca. 252 Ma latest Permian mass extinction (LPME), but direct evidence for global volcanic effects on land remains rare. Here, we used mercury (Hg) enrichments, a proxy for ancient volcanic activity, to assess volcanic inputs to two terrestrial Permian-Triassic boundary (PTB) sections that were separated by thousands of kilometers and represent different latitudinal zones—the peri-equatorial Lubei section (South China craton) and the high-latitude (40–60°N) Dalongkou section (Junggar terrane). Both sections exhibit strong Hg enrichment within a discrete (≤40 m) stratigraphic window representing the LPME. At Lubei, this interval is also characterized by negative mass-independent fractionation (MIF) of odd Hg isotopes, consistent with massive volcanogenic and/or terrestrial Hg inputs. These findings are significant in documenting Hg spikes and negative MIF excursions near the PTB in terrestrial sections for the first time, providing evidence of the global influence of the STLIP, as well as in demonstrating at high stratigraphic resolution its synchronicity with the PTB negative carbon-isotope excursion (CIE), supporting a common global cause for these anomalies.
- Published
- 2019
26. Early Cambrian radiolarians and sponge spicules from the Niujiaohe Formation in South China
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Qinglai Feng and Ke Zhang
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010506 paleontology ,Series (stratigraphy) ,South china ,Stratigraphy ,Lower ordovician ,Paleontology ,010502 geochemistry & geophysics ,01 natural sciences ,Sponge spicule ,Stage (stratigraphy) ,Cambrian Series 2 ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences - Abstract
Most of the reported Cambrian radiolarians are from middle Cambrian (Miaolingian Series, Wuliuan Stage) and onward, the radiolarians from lower Cambrian (Terreneuvian and Cambrian Series 2), on the other hand, are poorly documented, thus their morphological characteristics have not been well understood. In this study, we extracted spherical radiolarians and sponge spicules from the chert of the Cambrian Series 2 Niujiaohe Formation in southern Jiangxi Province, China. The well-preserved radiolarian fossils, identified as Paraantygopora porosa, consist of perforate plate shells pierced by dense pores with elevated rims, and display similarities to those from Lower Ordovician. Seven forms of sponge spicules are recognized, including monaxons, diaxons, tetractines, hexactines, triaxon tetractines, triaxon pentactines and irregular tetraxon tetractines, which are similar to those from the Qiongzhusian Stage in South China. Our results, combined with previously reported early Cambrian radiolarians from South China, indicate that the early Cambrian radiolarians developed advanced spherical skeletons.
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- 2019
27. Origin of chert in Lower Silurian Longmaxi Formation: Implications for tectonic evolution of Yangtze Block, South China
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Mou Li, Zihui Lei, Ankun Zhao, Qinglai Feng, Qian Yu, Lintao Du, Jian Wang, and Shahin E. Dashtgard
- Subjects
010506 paleontology ,Terrigenous sediment ,Outcrop ,Geochemistry ,Paleontology ,010502 geochemistry & geophysics ,Oceanography ,Block (meteorology) ,01 natural sciences ,Hydrothermal circulation ,Katian ,Tectonics ,Clastic rock ,Ordovician ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
Upper Ordovician (Katian) to Lower Silurian (Rhuddanian) strata in the Middle–Upper Yangtze Block, South China contain extensive chert beds, although the origin of microcrystalline silica in these cherts is largely unknown. In this study, the mineralogy and structure of chert as well as major, trace, and rare earth elements are used to determine the origin of microcrystalline silica in 29 chert samples from Longmaxi Formation (Rhuddanian) in Baizitian outcrop, west of Kangdian Uplift (KU). Results show that 21 of the 29 chert samples have a biogenic origin, 2 indicate a hydrothermal origin, and 6 show a mixed origin. Cherts from Baizitian outcrop are compared to contemporaneous cherts deposited east of KU. Cherts both east and west of KU are mainly biogenic in origin, which is attributed to high productivity in the paleo-seaway. Hydrothermal microcrystalline silica is relatively uncommon in the Longmaxi Formation across the Middle-Upper Yangtze Block, and only occurs in Baizitian outcrop. Terrigenous influx contributed to chert accumulation both east and west of KU; however, cherts east of KU received much more clastic material than those in Baizitian outcrop. A comparison of chert composition and geochemistry to geological reconstructions of the Middle-Upper Yangtze Block reveal that accumulation of hydrothermal chert is closely linked to tectonic evolution. During the Early Silurian, the Middle-Upper Yangtze Block was in a compressional tectonic regime with limited heat supply, and hence, low hydrothermal circulation; this is manifested in the paucity of hydrothermal microcrystalline silica in cherts east of KU. In contrast, hydrothermal microcrystalline silica in cherts west of KU is interpreted to have formed in an extensional tectonic regime with sufficient heat supply. This research demonstrates that chert source is, in part, tectonic controlled, and chert geochemistry can be used in reconstructing paleoenvironments.
- Published
- 2019
28. Mercury enrichments provide evidence of Early Triassic volcanism following the end-Permian mass extinction
- Author
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Jun Shen, Jiubin Chen, Harry Rowe, Qinglai Feng, Lian Zhou, Haijun Song, Jianxin Yu, Thomas J. Algeo, Huyue Song, and Noah J. Planavsky
- Subjects
geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Siberian Traps ,Large igneous province ,Early Triassic ,Volcanism ,010502 geochemistry & geophysics ,01 natural sciences ,Sedimentary depositional environment ,Paleontology ,Volcano ,General Earth and Planetary Sciences ,Ecosystem ,Permian–Triassic extinction event ,Geology ,0105 earth and related environmental sciences - Abstract
Oceanic environments and biotas were in a state of near-continuous perturbation during the Early Triassic, the ~5-million-year interval following the latest Permian mass extinction (LPME), but the underlying cause(s) remain uncertain. The role of episodic volcanic or intrusive magmatic activity in triggering global-scale perturbations during this interval is suspected but has not been strongly evidenced to date. Here, we investigate the record of volcanism through the Early Triassic (with a focus on the Smithian-Spathian Boundary, or SSB) using mercury (Hg) concentrations in marine sediments as a proxy. This study examines five marine sections from three paleo-oceans (Paleo-Tethys, Neo-Tethys, and Panthalassa) representing a range of depositional settings from shallow platform to deep slope. Our results suggest that volcanic and magmatic activity of the Siberian Traps Large Igneous Province (STLIP) was most intense during the first ~1.3 million years following the LPME, and that termination of its most active stage was responsible for a sharp cooling event at the SSB. Variations in the intensity of STLIP activity are thus likely to account for the large (>8‰) fluctuations of δ13Ccarb and related changes in oceanic redox and environmental conditions that characterized the Griesbachian to Smithian substages of the Early Triassic in marine sections globally. We hypothesize that a strong reduction or cessation of STLIP activity at the SSB set the stage for the recovery of marine biodiversity and ecosystems in the Spathian and later.
- Published
- 2019
29. Cambrian intra–oceanic arc trondhjemite and tonalite in the Tam Ky–Phuoc Son Suture Zone, central Vietnam: Implications for the early Paleozoic assembly of the Indochina Block
- Author
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Hung Quoc Nguyen, Tianyu Zhao, Jian-Wei Zi, Quyen Minh Nguyen, Hai Thanh Tran, Dung My Tran, Thanh Xuan Ngo, and Qinglai Feng
- Subjects
010504 meteorology & atmospheric sciences ,Subduction ,Paleozoic ,Geochemistry ,Geology ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Gondwana ,engineering ,Suture (geology) ,Shear zone ,0105 earth and related environmental sciences ,Hornblende ,Zircon ,Terrane - Abstract
The Truong Son and Kon Tum terranes in northeastern Indochina are thought to, respectively, form part of the Indian and Australian margins of Gondwana and separated one another by the Tam Ky–Phuoc Son Ocean during the early Paleozoic. In this paper, we present results of a comprehensive geochronological and geochemical study on a trondhjemite–tonalite suite identified in the Tam Ky–Phuoc Son Suture Zone. LA–ICP–MS zircon U–Pb dating yielded weighted mean 206Pb/238U ages of 518.5 ± 7.1 Ma and 502.1 ± 6.0 Ma for the trondhjemite and tonalite, respectively. These are the oldest magmatic zircons recorded in this area so far. Both rocks consist primarily of plagioclase (oligoclase), quartz, with minor, variable amounts of hornblende and biotite. They have high SiO2, Na2O and Y, but low Al2O3, K2O, Sr and Rb contents, and are characterized by depletion in LREEs with flat HREE patterns. These features are similar to those of typical oceanic plagiogranites. Our new evidences from field geology, geochemistry, and zircon Hf isotopic data, along with previously published data from the Tam Ky–Phuoc Son Suture Zone, suggest that the plagiogranites were originated from extensive fractionation of hydrous basaltic magmas. Furthermore, they were generated in an intra-oceanic arc system above a northward subduction zone within the Tam Ky–Phuoc Son Ocean. The final closure of this ocean took place before the late Silurian, marked by collision of the Truong Son Terrane with the Kon Tum Terrane along the Tam Ky–Phuoc Son Suture Zone to form the Indochina Block. After elimination of the southeastward offset along the Red River shear zone and the clockwise rotation of Indochina relative to South China since the Tertiary, the eastern part of the Tam Ky–Phuoc Son Suture aligns well with the Kuungan Suture on Hainan Island, together they have likely recorded the final assembly of Gondwana in this region.
- Published
- 2019
30. Early Paleoproterozoic magmatism in the Yangtze Block: Evidence from zircon U-Pb ages, Sr-Nd-Hf isotopes and geochemistry of ca. 2.3 Ga and 2.1 Ga granitic rocks in the Phan Si Pan Complex, north Vietnam
- Author
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Tianyu Zhao, Quyen Minh Nguyen, Qinglai Feng, Jian-Wei Zi, Dung My Tran, Kai Wang, Peter A. Cawood, and University of St Andrews. School of Earth & Environmental Sciences
- Subjects
Yangtze Block ,010504 meteorology & atmospheric sciences ,NDAS ,Geochemistry ,010502 geochemistry & geophysics ,01 natural sciences ,Supercontinent ,Early Paleoproterozoic ,Petrography ,Geochemistry and Petrology ,Zircon U-Pb-Hf isotopes ,0105 earth and related environmental sciences ,geography ,GE ,geography.geographical_feature_category ,Partial melting ,Quartz monzonite ,Geology ,Craton ,Nuna supercontinent ,Magmatism ,Laurentia ,GE Environmental Sciences ,Zircon - Abstract
This study was financially supported by projects from the China Natural Science Foundation (41672222) and State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan (MSFGPMR201802). PAC acknowledges support from Australian Research Council grant FL160100168. This study was also supported by the Ministry of Natural Resources and Environment of Viet Nam, Project BĐKH.29/16-20 to Dung My Tran. Our understanding of the early evolution of the Yangtze Block is limited by the sparsely dispersed nature of pre-Neoproterozoic exposures. New, integrated petrographic, zircon U-Pb age and Hf-Nd isotope analyses, and whole-rock geochemical data for early Paleoproterozoic granites in the Phan Si Pan Complex provides new insights into the evolution of the Yangtze Block as well as its role in the Pre-Nuna supercontinent. LA-ICP-MS zircon U-Pb dating of magmatic zircons from quartz monzonite and gneissic granite yielded 207Pb/206Pb ages of 2306 ± 12 Ma and 2096 ± 15 Ma, respectively. Zircons from the quartz monzonite have εHf(t) values ranging from -4.1 to -2.1, corresponding to TDM2 model ages of 3002–2890 Ma, whereas zircons in the gneissic granite have εHf(t) values between -0.95 and +1.72 and corresponding TDM2 model ages of 2660–2516 Ma, which are consistent with their whole-rock Nd isotope values. Geochemically, the quartz monzonites are I-type granites. Combined with their relatively high Sr/Y ratios and low Y concentrations, as well as fractionated REE patterns with relatively high LREE but low HREE concentrations, they were probably generated by partial melting of the thickened middle-lower crust under elevated temperature. Geochemical and isotopic signatures suggest that the ca. 2.1 Ga gneissic granites are high-K calc-alkaline, ferroan A-type granites formed by partial melting of juvenile crustal source at high temperature and low pressure with little involvement of ancient crustal material. The Phan Si Pan complex has a distinct early Paleoproterozoic crustal evolution history compared with the other crustal provinces of the Yangtze Block, suggesting independent histories that were not unified until the late Paleoproterozoic during the assembly of Nuna. Moreover, the magmatism and tectonic evolution of the north Vietnam region is broadly similar to that of the Arrowsmith Orogen of the Rae craton in Laurentia suggesting a potential spatial linkage. The geologic record of the Yangtze Block does not support an early Paleoproterozoic shutdown of plate tectonics. Postprint
- Published
- 2019
31. Mercury in marine Ordovician/Silurian boundary sections of South China is sulfide-hosted and non-volcanic in origin
- Author
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Jianxin Yu, Jinling Liu, Thomas J. Algeo, Jiubin Chen, Jun Shen, Qinglai Feng, and Noah J. Planavsky
- Subjects
Extinction event ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Large igneous province ,Geochemistry ,Sediment ,chemistry.chemical_element ,Volcanism ,010502 geochemistry & geophysics ,01 natural sciences ,Mercury (element) ,Geophysics ,Volcano ,chemistry ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Ordovician ,Laurentia ,Geology ,0105 earth and related environmental sciences - Abstract
Mercury (Hg) enrichment in stratigraphic successions is now widely used as a proxy for volcanic inputs, often for the purpose of documenting a relationship between large igneous province (LIP) magmatism and ecosystem perturbations. Earlier studies of Hg in Ordovician/Silurian boundary (OSB) sections in South China and Laurentia identified transient spikes in Hg/TOC ratios, on the basis of which a link between volcanism and the Late Ordovician mass extinction (LOME) was claimed. However, Hg enrichments must be tested based on normalization to their main host phase, and Hg/TOC is a suitable proxy only if Hg is mainly complexed by organic matter in the sediment. Here, we demonstrate that Hg in three OSB sections in South China (Qiliao, Yanzhi, and Jiaoye) is overwhelmingly associated with pyrite, as shown by r(Hg–TS) > 0.9 (versus r(Hg–TOC) Δ 199 Hg) values (+0.11 ± 0.03‰) that are inconsistent with volcanic inputs. We therefore infer that previous reports of Hg enrichments in OSB sections were due to the presence of Hg-rich sulfides, and that Hg data from both the present and earlier studies provide no evidence of any volcanic influences on the LOME. The results of the present study highlight the need for caution in applying the Hg proxy for volcanic inputs and the importance of evaluating the main host phase of Hg in paleo-marine sediments.
- Published
- 2019
32. Evidence for a prolonged Permian–Triassic extinction interval from global marine mercury records
- Author
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Noah J. Planavsky, Jiubin Chen, Thomas J. Algeo, Jianxin Yu, Qinglai Feng, Shengliu Yuan, Jun Shen, Lian Zhou, and Brennan O'Connell
- Subjects
0301 basic medicine ,Geologic Sediments ,Large igneous province ,Oceans and Seas ,Science ,General Physics and Astronomy ,02 engineering and technology ,Diachronous ,Volcanic Eruptions ,Extinction, Biological ,General Biochemistry, Genetics and Molecular Biology ,Article ,03 medical and health sciences ,Paleontology ,Phanerozoic ,lcsh:Science ,Permian–Triassic extinction event ,Extinction event ,geography ,Multidisciplinary ,Vulcanian eruption ,geography.geographical_feature_category ,Siberian Traps ,General Chemistry ,Mercury ,social sciences ,021001 nanoscience & nanotechnology ,humanities ,Mercury Isotopes ,030104 developmental biology ,Volcano ,lcsh:Q ,0210 nano-technology ,Geology - Abstract
The latest Permian mass extinction, the most devastating biocrisis of the Phanerozoic, has been widely attributed to eruptions of the Siberian Traps Large Igneous Province, although evidence of a direct link has been scant to date. Here, we measure mercury (Hg), assumed to reflect shifts in volcanic activity, across the Permian-Triassic boundary in ten marine sections across the Northern Hemisphere. Hg concentration peaks close to the Permian-Triassic boundary suggest coupling of biotic extinction and increased volcanic activity. Additionally, Hg isotopic data for a subset of these sections provide evidence for largely atmospheric rather than terrestrial Hg sources, further linking Hg enrichment to increased volcanic activity. Hg peaks in shallow-water sections were nearly synchronous with the end-Permian extinction horizon, while those in deep-water sections occurred tens of thousands of years before the main extinction, possibly supporting a globally diachronous biotic turnover and protracted mass extinction event., Previously, little direct evidence has been found to link large volcanic eruption events with the end-Permian mass extinction. Here, the authors find that mercury enrichment and isotope records in marine sections across the globe can be linked to increased volcanic activity, which resulted in the protracted Permian-Triassic biocrisis
- Published
- 2019
33. Radiolarian fauna from the Chiungchussuan Shuijingtuo Formation (Cambrian Series 2) in Western Hubei Province, South China
- Author
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Wenchao Cao, Lei Zhang, Qinglai Feng, Songzhu Gu, Yan Ye, and Qiangfen Ma
- Subjects
South china ,010504 meteorology & atmospheric sciences ,biology ,Fauna ,Spumellaria ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Paleontology ,Taxon ,Ordovician ,General Earth and Planetary Sciences ,Taxonomy (biology) ,Cambrian Series 2 ,Radiolaria ,Geology ,0105 earth and related environmental sciences - Abstract
Little is known regarding characteristics and evolution of radiolarian fossils in the early Cambrian due to its rarity and poor preservation. Here we report a new radiolarian fauna from the Cambrian Shuijingtuo Formation corresponding to the Chiungchussuan Stage (Cambrian Series 2) in western Hubei, China. It contains over 300 radiolarian tests and these fossils belong to 4 morphotypes, including Paraantygopora porosa gen.et sp. nov., Braunosphaera sinensis gen.et sp. nov., Tetrasphaera ? sp. and incertae spherical radiolarians. In taxonomy, Spumellaria predominates in the fauna and comprises 92% of the total. In shell structure, about 73% of all specimens are similar to the early Ordovician radiolarian fossils, with the shell walls characterized by perforated plate structures. The spherical radiolarians with latticed shells constitute another feature of the early Cambrian radiolarian fauna. The radiolarian fauna reported here contains many fossil specimens and covers different taxonomical taxa. These specimens usually consist of distinctive concentric multi-layers with complex structure. These characteristics indicate that Radiolaria had already thrived during the Cambrian Chiungchussuan Stage (Series 2, Stage 3), which may have occurred synchronously with the explosion and prosperity of macrobiota recorded in the strata deposited in shallower water condition.
- Published
- 2019
34. Tracing the provenance of volcanic ash in Permian–Triassic boundary strata, South China: Constraints from inherited and syn-depositional magmatic zircons
- Author
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Qinglai Feng, Tianyu Zhao, Guozhen Xu, Thomas J. Algeo, and Jian-Wei Zi
- Subjects
geography ,Provenance ,geography.geographical_feature_category ,Permian ,Siberian Traps ,Large igneous province ,Geochemistry ,Paleontology ,Oceanography ,Craton ,Carboniferous ,Ecology, Evolution, Behavior and Systematics ,Geology ,Earth-Surface Processes ,Volcanic ash ,Zircon - Abstract
The Permian-Triassic boundary (PTB) mass extinction, the most severe biocrisis in Earth's history, is thought to have been triggered by catastrophic volcanic activity. PTB sections in South China contain numerous volcanic ash beds, the source of which is inferred to have been either the Siberian Traps Large Igneous Province (STLIP) or intraregional subduction-zone arc volcanism. In this study, the provenance of these ash beds is determined through a comprehensive analysis based on the geochronological and geochemical signatures of zircons from four PTB sections (Dongpan, Xinmin, Ganxi and Shangsi). Inherited zircons yielded U–Pb ages of 250–3521 Ma with major age clusters in the Permian, Carboniferous to Silurian, early Cambrian to Neoproterozoic, early Neoproterozoic to late Mesoproterozoic, and early Paleoproterozoic. The age spectrum of these zircons is similar to those of detrital zircons from sedimentary and magmatic rocks of the South China and Indochina cratons but different from those of the Siberian Craton, providing evidence for an intraregional source of the volcanic material. The trace-element, eHf(t), and δ18O signatures of syn-depositional magmatic zircons are consistent with an arc-related/orogenic setting. PTB sections in South China can be assigned to sectors based on the number and cumulative thickness of ash beds and the length of zircon crystals. Sector I (South) includes the Dongpan and Xinmin sections, which have cumulative ash-bed thicknesses of 0.86–1.14 m and average zircon lengths of 151–217 μm. Sector II (North) includes the Ganxi, Shangsi and Daxiakou sections, which have cumulative ash-bed thicknesses of 0.17–0.33 m and average zircon lengths of 82–104 μm. Sector III (Northeast) includes the Niushan and Meishan sections, which have cumulative ash-bed thicknesses of 0.1–0.14 m and average zircon lengths of 71–73 μm. Systematic trends toward fewer and thinner ash beds and as well as smaller zircon sizes from Sector I to Sector III indicate a paleo-northward or -northeastward direction of ash transport. Collectively, our findings provide evidence that the source of volcanic ash in South China PTB sections was intraregional subduction-zone arc volcanism along the convergent margin between the South China and Indochina cratons.
- Published
- 2019
35. Study of Rock Mechanic Property and Mineralogy Relationship of the Huai Hin Lat Formation, Sap Phlu Basin, Northeastern Thailand: Implications for Understanding of Shale Gas Reservoir Rock
- Author
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Nawarak Ruenmai, Qinglai Feng, Boonnarong Arsairai, and Chongpan Chonglakmani
- Subjects
010504 meteorology & atmospheric sciences ,Mineralogy ,Young's modulus ,010502 geochemistry & geophysics ,01 natural sciences ,Petroleum reservoir ,Poisson's ratio ,Natural gas field ,symbols.namesake ,Compressive strength ,Brittleness ,symbols ,Porosity ,Quartz ,Geology ,0105 earth and related environmental sciences - Abstract
Thailand is lacked of gas that more information of probable (P2) and possible (P3) reserve data including shale gas can be acceptable to prove (P1) reserve data for new gas field. This research had implicated for understanding of unconventional reservoir rock by rock mechanical, micro-CT, and geochemistry analysis of the Huai Hin Lat Formation. The rock mechanical analysis is composed of average young’s modulus, Poisson’s ratio, and compressive strength of 1933.79 MPa, 0.1472, and 52.56 MPa. The average porosity of 6.89% consists of 5.41% and 1.48% of closed and open porosities. The average mineralogical results consist mainly of 57.60% and 42.40% of brittle and ductile minerals indicating more elasticity except Bed 6. The Bed 6 is significantly higher quartz (15%) and brittle minerals (64%) indicating to easier fracture are, therefore, lower compressive strength (25.93 MPa), young’s modulus (1729.10 MPa) and Poisson’s ratio (0.0705). The Beds 3B is slightly higher clay containing slightly higher closed porosity (5.46%) but the Bed 14 is slightly higher brittle mineral indicating to slightly higher open porosity.
- Published
- 2019
36. Deep-water fossil assemblages from the Ediacaran-Cambrian transition of western Hunan, South China and their biostratigraphic and evolutionary implications
- Author
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Yuhao Yi, Fayao Chen, Thomas J. Algeo, and Qinglai Feng
- Subjects
Paleontology ,Oceanography ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Published
- 2022
37. Closure of the East Paleotethyan Ocean and amalgamation of the Eastern Cimmerian and Southeast Asia continental fragments
- Author
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Peizhen Zhang, Huichuan Liu, Peter A. Cawood, Huiying He, Yanhua Zhang, Yuejun Wang, Qinglai Feng, Xin Qian, and Guochun Zhao
- Subjects
010504 meteorology & atmospheric sciences ,Subduction ,Metamorphic rock ,Metamorphism ,Structural basin ,010502 geochemistry & geophysics ,01 natural sciences ,Paleontology ,Igneous rock ,Tectonics ,General Earth and Planetary Sciences ,Sedimentary rock ,14. Life underwater ,Suture (geology) ,Geology ,0105 earth and related environmental sciences - Abstract
The Phanerozoic record of Southeast Asia preserves the history of opening and subsequent consumption of the Paleotethyan Ocean and the assembly of continental fragments into Asia as part of the broader-scale reconstruction of Pangea. However, uncertainty remains as to which of the many suture zones in Southeast Asia represents the relict of the main ocean, when final ocean closure occurred, and the assembly history of the Eastern Cimmerian and Southeast Asia continental fragments. Our overview of the geological features of the suture zones, the bounding continental fragments and their magmatic, metamorphic and sedimentary records resolves many of these key issues. The sedimentary, biogeographical, structural, lithological, geochemical and geochronological data from the Changning-Menglian, Inthanon and Bentong-Raub suture zones argue for their linkage with the Longmu Co-Shuanghu suture zone in Central Tibet, and together constitute the main East Paleotethyan Ocean relict. The eastward subduction of the ocean resulted in the development of a series of magmatic arc-back-arc basin and continental fragments in Southeast Asia, including, from west to east, the Lincang-Sukhothai-East Malaya arc, the Jinghong-Nan-Sa Kaeo back-arc basin, the Simao/west Indochina fragment, the Luang Prabang-Loei back-arc basin, the south Indochina fragment, the Wusu and Truong Son back-arc basins, the north Indochina fragment, the Jinshajiang-Ailaoshan-Song Ma branch/back-arc basin and the South China Block. Assembly of these fragments resulted in Indosinian high temperature and high pressure metamorphism and related tectonothermal event. Available data indicate a switch from subduction of the main East Paleotethyan Ocean to the collision of the Sibumasu with Simao/Indochina blocks at ~ 237 Ma, with subsequent syn- and post-collisional events at ~ 237–230 Ma and ~ 230–200 Ma, respectively, along the Changning-Menglian, Inthanon and Bentong-Raub suture zones. The timing of initial-, syn- and post-collision events along the Jinshajiang-Ailaoshan-Song Ma suture zone with its record of back-arc basin closure is at ~ 247 Ma, ~ 247–237 Ma and ~ 237–200 Ma, generally ~ 10 Ma older than that along the Changning-Menglian, Inthanon and Bentong-Raub suture zones. Our synthesis of all available data enables establishment of a comprehensive geodynamic model for the East Paleotethyan evolution. This model links the spatial-temporal pattern across Southeast Asia into a series of tectonic events including ocean/back-arc basin opening, subduction/closure, subsequent assemblage and orogenic collapse, along with associated igneous, metamorphic and sedimentary activities.
- Published
- 2018
38. Tracking Prototethyan assembly felsic magmatic suites in southern Yunnan (SW China): evidence for an Early Ordovician–Early Silurian arc–back-arc system
- Author
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Qinglai Feng, Guangyan Chen, Guichun Liu, M. Santosh, Zaibo Sun, Xin Qian, Tianyu Zhao, Jian-Wei Zi, and Shen Ma
- Subjects
Felsic ,010504 meteorology & atmospheric sciences ,Subduction ,Paleozoic ,Geochemistry ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Igneous rock ,Gondwana ,Ordovician ,Mafic ,0105 earth and related environmental sciences ,Zircon - Abstract
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 eNd(t) values of −1.9 to −3.5 and eHf(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 eNd(t) value of −6.2 and eHf(t) values of −5.0 to −0.4. The alkali granites belong to the high-K calc-alkaline series and yield eNd(t) values of −10.1 to −10.7 and eHf(t) values of −7.9 to −2.3. The gneissic granites were derived from an ‘ancient9 lower mafic crust, whereas the alkali granites were derived from a meta-sedimentary source. These granitoids were formed during the subduction of the Prototethyan Ocean beneath the Simao Block and can be compared with similar igneous rocks from the Truong Son and Tam Ky-Phuoc Son zones in southern Laos. Our study, along with Early Paleozoic igneous suites from southern Laos, central Vietnam and the Malay Peninsula, suggests an arc–back-arc system along the northern margin of Gondwana. Supplementary material: Tables of zircon U–Pb and in-situ Hf and geochemical data are available at https://doi.org/10.6084/m9.figshare.c.5322386
- Published
- 2021
39. Silicon isotopes reveal a decline in oceanic dissolved silicon driven by biosilicification: a prerequisite for the Cambrian Explosion?
- Author
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Qinglai Feng, Patrick J. Frings, Yan Ye, and Friedhelm von Blanckenburg
- Subjects
chemistry.chemical_classification ,010504 meteorology & atmospheric sciences ,Silicon ,Saturation (genetic) ,Earth science ,Trace element ,Geochemistry ,chemistry.chemical_element ,010502 geochemistry & geophysics ,01 natural sciences ,Geophysics ,chemistry ,Space and Planetary Science ,Geochemistry and Petrology ,Phanerozoic ,Earth and Planetary Sciences (miscellaneous) ,Cambrian explosion ,Seawater ,Organic matter ,Precipitation ,Isotopes of silicon ,Geology ,0105 earth and related environmental sciences - Abstract
The Early Phanerozoic witnessed one of the most important events in Earth history - the Cambrian Explosion. There is also a consensus that at roughly the same time oceanic dissolved silicon (DSi) concentrations decreased from close to saturation to somewhere below saturation. Yet the timing and magnitude of the putative DSi decrease, and any relationship with biological innovations, remain poorly known. Here, we study the widespread chert formed during the Ediacaran-Cambrian transition (ca. 551-522 Ma) on the Yangtze Block, South China. Major and trace element geochemistry suggest the silicon for the chert is predominantly sourced from seawater, and most likely precipitated via adsorption on organic matter and uptake by silica-secreting organisms. New and compiled silicon isotope data from seven sections spanning the E-C boundary show an increase in divergence of δ 30 Si values at ca. 533 Ma. Using mass-balance arguments, we interpret this as evidence that the radiation of siliceous sponges and radiolarians contributed to a substantial (ca. 80%) decrease in oceanic DSi concentrations, which is corroborated by fossil records and simple box-models. Reduced oceanic DSi may reduce the effort needed to maintain intracellular Si concentrations below the level at which harmful Si precipitation in organismal cytoplasm occurs. This energy can be reallocated to other metabolic pathways of new functional types, potentially the establishment of suspension-feeding communities that triggered Phanerozoic-type mixground ecology. Therefore, the early appearance of silicifiers (∼540-530 Ma) may have made conditions more favorable for the main stage (∼520 Ma) of Cambrian Explosion in functional and ecological diversification.
- Published
- 2021
40. Diverse cuticular remains in Cambrian (Series 2) SSF assemblages from China and the pioneer metazoan colonization of offshore environments
- Author
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Mats Eriksson, Maliha Zareen Khan, Lei Zhang, Jean Vannier, Qinglai Feng, Marie Béatrice Forel, Sébastien Clausen, Can Chen, Michael Steiner, Shan Chang, School of Earth Sciences, China University of Geosciences, Wuhan, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Évolution, Écologie et Paléontologie (Evo-Eco-Paleo) - UMR 8198 (Evo-Eco-Paléo (EEP)), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Évolution, Écologie et Paléontologie (Evo-Eco-Paleo) - UMR 8198 (Evo-Eco-Paléo)
- Subjects
010506 paleontology ,Series (stratigraphy) ,Range (biology) ,Fauna ,Paleontology ,Lagerstätte ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Waves and shallow water ,Assemblage (archaeology) ,Submarine pipeline ,14. Life underwater ,Cambrian Series 2 ,[SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
International audience; Our understanding of the early Cambrian bioradiation is largely driven by the contrasting information obtained from small skeletal fossils (SSF) and various types of exceptionally preserved fossils from different parts of the world. In this study, a new 'Orsten'-type fossil Lagerstätte is reported from the Cambrian Series 2 upper Shuijingtuo Formation in the eastern Three Gorges area, South China. The Shuijingtuo Formation yielded a range of microscopic fragments of metazoan cuticles as well as fragments of possible epithelial tissue. Seventeen different types of micro-ornamentation patterns are recognized on the surface of these cuticular fragments. Based on comparisons with fossil organisms recorded from coeval strata elsewhere, as well as extant relatives, possible affinities with arthropods, palaeoscolecids, acrotretid brachiopods and mollusks are discussed. This 'Orsten'-type fossil assemblage was deposited in offshore environments, and the lack of evidence for long-distance transportation indicates that a highly diverse fauna was present in, or very close to, the relatively deep shelf settings in the Three Gorges area during the early Cambrian (Series 2, Stage 3). The invasion of metazoans into deeper, offshore environments could have closely followed, or even been coeval, with their radiation in relatively shallow water settings. Thus, albeit highly fragmented, such cuticular fossils can aid in providing a more complete picture of the Cambrian bioradiation.
- Published
- 2020
41. Author response for 'Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan'
- Author
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Wenjiao Xiao, Miao Sang, Qinglai Feng, and Brian F. Windley
- Subjects
Geochemistry ,Geology ,Accretionary complex - Published
- 2020
42. Influence of palaeo-redox and diagenetic conditions on the spatial distribution of Cambrian biotas: A case study from the upper Shuijingtuo Formation (Cambrian Series 2, Stage 3), Three Gorges area of South China
- Author
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Lei Zhang, Cui Luo, Shan Chang, Qinglai Feng, Sébastien Clausen, Michael Steiner, Marie-Béatrice Forel, Maliha Zareen Khan, Kai Liu, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences [Wuhan] (CUG), Thomas J. Watson Research Center, IBM Corporation, Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Sciences pour l'environnement (SPE), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Laboratoire de paléontologie et paleogéographie du paleozoique (LPPP), and Université de Lille, Sciences et Technologies-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
010506 paleontology ,Outcrop ,Paleontology ,Biota ,Structural basin ,010502 geochemistry & geophysics ,Oceanography ,Spatial distribution ,01 natural sciences ,Diagenesis ,Water column ,13. Climate action ,Benthic zone ,14. Life underwater ,Cambrian Series 2 ,[SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology ,Ecology, Evolution, Behavior and Systematics ,Geology ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
From the wake of the Marinoan glaciations to the early Cambrian, the global ocean experienced progressive but likely nonuniform and nonlinear oxygenation to levels that, although still low with respect to the modern ocean, and might be therefrom triggered the ecological expansion of animals. In this study, integrated palaeontological and geochemical analyses were conducted on the upper Shuijingtuo Formation (Cambrian Series 2, Stage 3) which outcrops western Yichang City, Hubei Province, South China, in order to assess the influence of oxygen on Cambrian ecosystem diversification in the local environment. To better understand the oxygen fluctuations in the water column over the Yangtze Block and their correlation with the spatial distributions of marine biota during the early Cambrian, three sections representing different environmental settings are investigated: from the carbonate epicontinental platform (Changkan section) to the intra-platform basin (Luojiacun and Qiaojiaping sections). The semi-quantitative analysis shows that the assemblages from the epicontinental platform are dominated by eodiscoid trilobites and brachiopods. Assemblages from the intra-platform basin differ in being dominated by articulated sponges and possible cnidarians, while brachiopods and trilobites are rare. Diagenetic effects on these observed patterns are assessed by SEM-coupled EDS analysis: they indicate that although such effects cannot be definitely discarded, the observed faunal distribution and relative abundance most probably reflect variations in environmental settings. The geochemical analysis (Mo-EF vs. U-EF) furthermore provides evidence of an oxygen gradient from the edge of the platform down to the intra-platform basin. Variations in palaeo-redox conditions between the different studied settings can be observed, which undoubtedly influenced the observed differentiation of benthic communities. Frequent anoxic events in the intra-platform basin were fatal for benthic communities, but dysoxic environments could have favored the persistence and even prosperity of metazoans such as sponges and possible cnidarians that can endure lower dissolved oxygen in the water column than other groups.
- Published
- 2020
43. A study on the geochemical characteristics of Upper Permian continental marginal arc volcanic rocks in the northern segment of South Lancangjiang Belt
- Author
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Shangyue, Shen, Qinglai, Feng, Qirong, Wei, Zhibin, Zhang, and Hu, Zhang
- Published
- 2006
- Full Text
- View/download PDF
44. New probable cnidarian fossils from the lower Cambrian of the Three Gorges area, South China, and their ecological implications
- Author
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Min Shi, Sébastien Clausen, Yan Zhang, Shan Chang, David J. Bottjer, Michael Steiner, Qinglai Feng, and Lei Zhang
- Subjects
010506 paleontology ,biology ,Ecology ,Fauna ,Byronia ,Cambrorhytium ,Paleontology ,010502 geochemistry & geophysics ,Oceanography ,biology.organism_classification ,01 natural sciences ,Sphenothallus ,Taxon ,Mackenzia ,Stage (stratigraphy) ,Benthic zone ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
Lower Cambrian assemblages of phosphatic and chitinous tubular fossils of probable cnidarian affinities were recovered from the Yanjiahe, Shuijingtuo and Shipai formations in the Three Gorges area, South China. Terreneuvian Cambrorhytium cf. C. major co-occur with an unnamed taxon in the Yanjiahe Formation. They can be compared with specimens from the Ediacaran Miaohe Fauna in the Three Gorges area. The most abundant and diversified cnidarian assemblages, including Cambrorhytium gracilis n. sp., Cambrorhytium cf. major, Cambrorhytium minor, Sphenothallus songlinensis, Sphenothallus taijiangensis?, Sphenothallus kozaki, ?Sphenothallus sp., ?Byronia sp., and ?Mackenzia sp. are reported from the overlying, Cambrian Stage 3–4, Shuijingtuo and Shipai formations. These new fossils show previously unknown evidence for cnidarian affinities, such as an attachment disk, clonal clusters and probable budding structures. These diversified assemblages of probable cnidarian fossils further fill major gaps in the Cambrian record of stem metazoans and document associated early evolutionary patterns. In addition, our discovery suggests that along with sponges, these tubular fossils represent another important component of benthic ecosystems that colonized often dysoxic, deep-settings during the Cambrian explosion. The observed increases of average body-size and biomineralization among these probable cnidarians are tentatively linked to oxygenation of deep oceanic settings and appearance of predatory pressure during the Ediacaran–Cambrian transition, respectively.
- Published
- 2018
45. Upper Darriwilian (Middle Ordovician) Radiolarians and Ostracods from the Hulo Formation, Zhejiang Provicnce, South China
- Author
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Jonathan C. Aitchison, Aihua Yuan, Qinglai Feng, and Yuhao Yi
- Subjects
010506 paleontology ,biology ,Carbonate platform ,Range (biology) ,Fauna ,Macrofossil ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Paleontology ,Genus ,Ostracod ,Ordovician ,General Earth and Planetary Sciences ,Sedimentary rock ,Geology ,0105 earth and related environmental sciences - Abstract
Considerable research has been done on the Ordovician marine fossils from South China, including macrofossils such as brachiopods, graptolites, bivalves, trilobites, some microfossils like conodonts and acritarches. However, radiolarians and ostracods that are also important constituents of the Ordovician marine ecosystem have been paid little attention in this region. In this study, ten radiolarians species belonging to four genera and sixteen ostracods species grouped into nine genera were found from the Hulo Formation at the Hengdu Section of the Jiangshan District, western Zhejiang Province, South China. The fossil-bearing strata belong to the graptolite Pterograptus elegans Zone which indicates the Late Darriwilian Age. This radiolarian fauna is the first record of the Middle Ordovician radiolarian body fossils and also the earliest Ordovician radiolarian fauna reported from South China. The occurrence of Beothuka in this fauna extends the stratigraphic range of the genus to the Upper Darriwilian. Reviews of previous literatures suggest that the diversity of Beothuka was greater during the Early Ordovician, and then declined gradually from the Early Ordovician to the Middle Ordovician before its extinction. The co-occurring ostracod fauna belongs to a shallow-water ecotype. This is contrary to the host lithofacies of the ostracod fauna which represent a deep-water environment. Therefore, these ostacods may have been transported from the shallow-water environment, most likely from the Yangtze carbonate platform. If this conjecture is the truth, then the Jiangshan District was near the shallow-water carbonate platform and received its sediments during the Darriwilian. It is still essential to do more work in the future to better understand the ecology of the Ordovician ostracod fanuas and their role in the sedimentary system of South China.
- Published
- 2018
46. New Siliceous Microfossils from the Terreneuvian Yanjiahe Formation, South China: The Possible Earliest Radiolarian Fossil Record
- Author
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Qinglai Feng, Shan Chang, and Lei Zhang
- Subjects
010506 paleontology ,Paleontology ,Fossil Record ,South china ,Paleozoic ,Genus ,General Earth and Planetary Sciences ,010502 geochemistry & geophysics ,Biogeosciences ,01 natural sciences ,Geology ,0105 earth and related environmental sciences ,Spherical shape - Abstract
Radiolarians form an important part of the planktonic realm in the ocean of Early Paleozoic, but their origin and evolutionary processes has long been enigmatic. The ancestral representatives of radiolarians have been considered to belong to the order Archaeospicularia, whose unquestionable fossil records were dated back to the Middle Cambrian. Here we report ?Blastulospongia and unnamed spherical radiolarians in the Terreneuvian from the Yanjiahe Formation in Hubei Province, South China. Blastulospongia is an enigmatic siliceous microfossil genus, with affinities proposed amongst the radiolarian, sphinctozoan-grade sponges and uncertain protists. As for the newly discovered unnamed radiolarians, morphologically they possess latticed shell, spherical shape and are all small in size. Our discoveries support the idea that spherical radiolarians is an ancient representative, whose origin and diversification was probably much earlier than generally accepted. The hypothesis that the oldest radiolarians belong to the order Archaeospicularia needs to be re-examined.
- Published
- 2018
47. Uppermost Permian trace fossils along a shelf to slope transect in South China and their implications for oceanic redox evolution and extinction pattern
- Author
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Luis A. Buatois, Qinglai Feng, Li-Jun Zhang, M. Gabriela Mángano, Yiming Gong, Mao Luo, Yong-An Qi, and Xin Zhang
- Subjects
Extinction event ,010506 paleontology ,Global and Planetary Change ,Planolites ,biology ,Permian ,Trace fossil ,010502 geochemistry & geophysics ,Oceanography ,biology.organism_classification ,01 natural sciences ,Fodinichnia ,Paleontology ,13. Climate action ,Thalassinoides ,Zoophycos ,14. Life underwater ,Geology ,Permian–Triassic extinction event ,0105 earth and related environmental sciences - Abstract
Trace fossils are important evidence of benthic activity and proxies of bottom and interstitial water oxygen content, making them a promising tool to understand the oceanic redox evolution and extinction patterns during the end-Permian mass extinction (EPME). Detailed bed-by-bed ichnologic studies were performed at a high-resolution scale from two uppermost Permian sections (Shangsi and Dongpan) in South China, documenting the presence of Chondrites targionii, Chondrites isp., Nereites isp., Planolites isp. A, Planolites isp. B, Palaeophycus isp., Phycosiphon incertum, Thalassinoides isp., and Zoophycos isp. The uppermost Permian strata at the Shangsi section mainly comprise siliceous limestone interbedded with illite-montmorillonite claystone and shale, recording a deep shelf setting. The uppermost Permian strata at the Dongpan section consist of mixed chert, mudstone and claystone, formed in a slope environment. Bioturbation index in uppermost Permian strata is mostly 1–2, but with thin intervals reaching 3–4. Fluctuating bioturbation intensities, ichnofaunal composition (Thalassinoides, Planolites, Zoophycos) and ethologies, as well as the ratio of highly reactive iron to total iron (FeHr/FeT) and the proportion of the highly reactive iron pool in the form of pyrite (Fepy/FeHR) suggest that bottom and interstitial oxygen levels were not permanently anoxic/euxinic, but were interrupted by brief periods of aerobic conditions during the latest Permian. Three bioturbation phases in the EPME are identified. Phase I is characterized by the absence of typical pascichnia ichnotaxa (e.g. Nereites isp.) and relatively large fodinichnia burrow (e.g., Planolites isp. B; Zoophycos isp.). Phase II mainly consists of smaller Planolites isp. A, Thalassinoides isp. and Chondrites isp., recording a transition from softground to firmground. Only occasional smaller Planolites isp. A occur in Phase III without any associated vertical burrows. Ichnodiversity and bioturbation index from Phase I to Phase III show a step by step decline, corresponding to the two-stage extinction patterns. Long-term environmental stress (e.g., oceanic anoxia, volcanic winter, global warming, ocean acidification, hypercapnia) may have played major role in the collapse of the infaunal ecospace and only facies-crossing, highly tolerant, opportunistic organisms may have persisted in otherwise vacant ecological niches in the aftermath of the extinction.
- Published
- 2018
48. The Upper Ordovician Microfossil Assemblages from the Pagoda Formation in Zigui, Hubei Province
- Author
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Aihua Yuan, Ke Zhang, and Qinglai Feng
- Subjects
010506 paleontology ,biology ,Biota ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Pagoda ,Katian ,Sedimentary depositional environment ,Paleontology ,Ostracod ,Ordovician ,General Earth and Planetary Sciences ,Assemblage (archaeology) ,Conodont ,Geology ,0105 earth and related environmental sciences - Abstract
The Pagoda Formation is a lithologically and biologically distinctive unit among the Upper Ordovician. The strata are characterized by a nodular limestone, which yields fossil assemblages of high diversity. Conodonts of 14 genera 20 species (6 undetermined species) and ostracods of 14 genera 26 species (16 undetermined species) are identified. In addition, spherical radiolarians and minute-walled foraminifers were first reported from this formation in South China. The conodont assemblage is attributed to the Hamarous europaeus Zone, which indicates the Early Katian Age. The conodont HDS biofacies, along with thin-shelled ostracods, spherical radiolarians and foraminifers, suggest relatively deep and quiet water depositional environment. Accordingly, these fossil materials not only enrich the diversity of the Pagoda biota, but also provide evidence for discussions of depositional environments and stratigraphic correlations for the Pagoda Formation.
- Published
- 2018
49. Alatoconchids: Giant Permian bivalves from South China
- Author
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Jiaxin Yan, Paul B. Wignall, Qinglai Feng, Wuqiang Xue, Qi Meng, Fayao Chen, and Jinxiong Luo
- Subjects
010506 paleontology ,geography ,geography.geographical_feature_category ,biology ,Permian ,Carbonate platform ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Wackestone ,chemistry.chemical_compound ,Paleontology ,Waves and shallow water ,chemistry ,Algae ,General Earth and Planetary Sciences ,Carbonate ,Coquina ,Reef ,Geology ,0105 earth and related environmental sciences - Abstract
Alatoconchidae, a unique bivalve family from the Permian, are characterized by a giant body size (up to 100 cm long), and unusual shell form with wing-like flanges and coarse prismatic outer layer of the shell wall. Palaeogeographically, they are restricted to low-latitude Tethyan and Panthalassan regions. However, the clams have not been previously been reported from South China even though this is one of the main, eastern Palaeotethyan terranes. Here we show that these giant clams were in fact widely distributed in South China, but they have been previously misidentified as phylloid algae. The present study verifies their occurrence in the region using reconstruction of shell forms from a series of transverse sections, as well as their characteristic shell microstructure. The alatoconchids occur commonly as coquina beds. Over thirty occurrences, ranging from the early Kungurian to probably the latest Capitanian in time, have been found. Based on detailed lithological and microfacies observation at more than ten fossil localities, most alatoconchid-bearing horizons (ABH) are autochthonous deposits, confined to medium- to thick-bedded limestones (often wackestone) of shallow water carbonate platforms. Two occurrences from an intra-platform basin are allochthonous deposits shed from the nearby carbonate platform by gravity flows, and featured by completely disintegrated fragments. Autochthonous and condensed accumulation of the fossil materials with great lateral persistence imply a gregarious habit of the clam, although slightly reworking might be involved. Its absence from high energy conditions, as well as the completeness of shell preservation, suggests it was not a reef dweller. To obtain gigantism in the tropical oligotrophic environment, alatoconchids may have harboured photosymbionts like present-day tridacnids, facilitated by its transparent shell texture, although this notion is challenged by Asato et al. (2017). Their association with calcareous algae and corals in the ABH indicates that the optimum belt of the clams is likely within the euphotic zone, but below that of calcareous green algae judging from the lithological succession and skeletal grain association.
- Published
- 2018
50. The link between metazoan diversity and paleo-oxygenation in the early Cambrian: An integrated palaeontological and geochemical record from the eastern Three Gorges Region of South China
- Author
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Taniel Danelian, Qinglai Feng, Nicolas Tribovillard, Shan Chang, Michael Steiner, Sébastien Clausen, Lei Zhang, and Maliha Zareen Khan
- Subjects
010504 meteorology & atmospheric sciences ,Biodiversity ,Paleontology ,Biota ,Context (language use) ,Ecological succession ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Anoxic waters ,Sponge spicule ,Water column ,Benthic zone ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
The link between environmental perturbations, especially oceanic redox conditions, and evolution during the “Cambrian Biodiversification” event is still highly controversial, although this issue has attracted considerable attention for decades. We here report on the fossil record of the early Cambrian biota discovered in the uppermost Yanjiahe and Shuijingtuo formations that crop out in the Luojiacun and Qiaojiaping sections, eastern Three Gorges area, South China. The uppermost member of the Yanjiahe Formation contains abundant benthic algae. Based on the fossil record, four distinct intervals were recognized in the Shuijingtuo Formation: i) few sessile suspension feeders, such as sponges, were recovered from Interval I; ii) Interval II is dominated by bivalved arthropods living in the water column; in this interval are also found a few sponges and eodiscoid trilobites, iii) no fossils other than few sponge spicules were recovered from Interval III; iv) diverse benthic communities composed of sponges, cnidarians, brachiopods, as well as bradoriids dominate Interval IV. Comprehensive research on framboidal pyrite morphology, whole rock geochemistry, as well as in-situ LA-ICP-MS analyses were carried out on samples from the Luojiacun section in order to assess paleo-redox conditions. The results show that the overall evolution of the paleo-redox conditions was characterized by a double episode of sharp anoxic events (AE) observed at the base of intervals I and III, followed by a gradual oxygenation event (OE). Evidence of oxygenation fluctuations were detected, especially within Interval IV. A case study is presented herein, which brings together early Cambrian changes in metazoan diversity and changes in environmental conditions. It is suggested that periodical oxygenation of the water column increased the biological diversity in the restricted basins of the eastern Three Gorges. Thus, four intervals of habitat succession can be tentatively reconstructed in the studied area for the Cambrian Age 2–Age 3 interval indicating a transition from uninhabited sediments to well-populated habitats. Finally, both the temporal and spatial characteristics of the Cambrian AEs/OEs and the fossil record in South China are compared and links between them are discussed in the context of their specific paleo-geographical setting.
- Published
- 2018
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