The Sukhothai Terrane in northern Thailand comprises a continental basement and a Permo-Triassic magmatic arc related to the subduction of the main Paleo-Tethys Ocean. The Donchai Group represents the oldest sedimentary sequence of the Sukhothai Terrane and consists mainly of meta-sandstone, quartzo-feldspathic schist, phyllite and silty slate. This paper presents new detrital zircon U–Pb geochronology and Lu–Hf isotope data, and geochemical results for the sedimentary rocks of the Donchai Group to elucidate the depositional age, provenance and nature of the group. The youngest detrital zircon ages (433–403 Ma) suggest that the Donchai Group was accumulated between 433 Ma and 368 Ma, revealing Silurian–Devonian arc magmatic rocks on the western margin of the Sukhothai Terrane. Sediments of the Donchai Group were sourced from both the continental basement and a Silurian–Early Devonian magmatic arc, suggesting a depositional setting on the continental slope of a back-arc basin along the western flank of the Sukhothai Terrane. The Silurian–Devonian arc belt in SW China likely extend to the Chiang Rai region, to the west of the Sukhothai Terrane, northern Thailand, revealing the northward subduction of the Proto-Tethys Ocean along the western Simao and Sukhothai margin during the middle Paleozoic. The inferred arc and back-arc configuration of the Proto-Tethys in northern Thailand is comparable with that recently established in Yunnan, SW China. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6858373
{"title":"Detrital zircon U–Pb and Hf analyses of Silurian–Devonian sediments in the Sukhothai Terrane, northern Thailand: Implications for the middle Paleozoic arc belt","authors":"Xiaomei Nie, Qinglai Feng, Jianwei Zi, Zhengqin Gan, Ian Metcalfe, Chongpan Chonglakmani, Denchok Monjai, Tianyu Zhao, Jianye Ren, Jongkonnee Khanmanee, Pradit Nulay","doi":"10.1144/jgs2023-049","DOIUrl":"https://doi.org/10.1144/jgs2023-049","url":null,"abstract":"The Sukhothai Terrane in northern Thailand comprises a continental basement and a Permo-Triassic magmatic arc related to the subduction of the main Paleo-Tethys Ocean. The Donchai Group represents the oldest sedimentary sequence of the Sukhothai Terrane and consists mainly of meta-sandstone, quartzo-feldspathic schist, phyllite and silty slate. This paper presents new detrital zircon U–Pb geochronology and Lu–Hf isotope data, and geochemical results for the sedimentary rocks of the Donchai Group to elucidate the depositional age, provenance and nature of the group. The youngest detrital zircon ages (433–403 Ma) suggest that the Donchai Group was accumulated between 433 Ma and 368 Ma, revealing Silurian–Devonian arc magmatic rocks on the western margin of the Sukhothai Terrane. Sediments of the Donchai Group were sourced from both the continental basement and a Silurian–Early Devonian magmatic arc, suggesting a depositional setting on the continental slope of a back-arc basin along the western flank of the Sukhothai Terrane. The Silurian–Devonian arc belt in SW China likely extend to the Chiang Rai region, to the west of the Sukhothai Terrane, northern Thailand, revealing the northward subduction of the Proto-Tethys Ocean along the western Simao and Sukhothai margin during the middle Paleozoic. The inferred arc and back-arc configuration of the Proto-Tethys in northern Thailand is comparable with that recently established in Yunnan, SW China. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6858373","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136294929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The collage of the Indochina Block to the Eurasian continent during the Mesozoic resulted in major changes in source-to-sink systems of East Asia, whilst the sedimentation in the Khorat-Simao Basin of the Indochina Block transited from marine to continental environments. Previous studies conducted the existence of transcontinental river systems in the East Asia mainland during the Cretaceous to early Cenozoic with few studies on pre-Cretaceous drainage systems. To determine the impact on the evolution of paleo-drainage systems triggered by tectonic movement of the Indochina Block, we performed paleomagnetic and U-Pb geochronologic analyses on the Late Triassic to Early Cretaceous sedimentary rocks in the Simao Basin. Paleomagnetic data indicate stable Jurassic tectonic environments between the Indochina and Songpan Ganzi-South China blocks, following their Late Triassic collision. Based on detrital zircon U-Pb dating, the Late Triassic age spectra consist of mainly Phanerozoic components, while the Jurassic to Cretaceous age spectra displayed more Precambrian age peaks. The contribution of potential provenance to the Simao Basin changed during the Early Cretaceous, suggesting several sedimentary provenance transitions. Also, we believe that large continental-scale drainage systems sourced from the Songpan-Ganzi Block flowing through North Qiangtang, Sichuan, Simao, and Khorat basins since after the Late Jurassic. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change Supplementary material: https://doi.org/10.6084/m9.figshare.c.6862918
{"title":"Mesozoic evolution of large-scale drainage systems in the Indochina Block: evidence from paleomagnetic and U-Pb geochronological constraints","authors":"Zhenyang Lai, Qian Zhao, Yonggang Yan, Danxin Li, Bingxu Liu, Kang Liu, Baochun Huang, Peizhen Zhang","doi":"10.1144/jgs2023-084","DOIUrl":"https://doi.org/10.1144/jgs2023-084","url":null,"abstract":"The collage of the Indochina Block to the Eurasian continent during the Mesozoic resulted in major changes in source-to-sink systems of East Asia, whilst the sedimentation in the Khorat-Simao Basin of the Indochina Block transited from marine to continental environments. Previous studies conducted the existence of transcontinental river systems in the East Asia mainland during the Cretaceous to early Cenozoic with few studies on pre-Cretaceous drainage systems. To determine the impact on the evolution of paleo-drainage systems triggered by tectonic movement of the Indochina Block, we performed paleomagnetic and U-Pb geochronologic analyses on the Late Triassic to Early Cretaceous sedimentary rocks in the Simao Basin. Paleomagnetic data indicate stable Jurassic tectonic environments between the Indochina and Songpan Ganzi-South China blocks, following their Late Triassic collision. Based on detrital zircon U-Pb dating, the Late Triassic age spectra consist of mainly Phanerozoic components, while the Jurassic to Cretaceous age spectra displayed more Precambrian age peaks. The contribution of potential provenance to the Simao Basin changed during the Early Cretaceous, suggesting several sedimentary provenance transitions. Also, we believe that large continental-scale drainage systems sourced from the Songpan-Ganzi Block flowing through North Qiangtang, Sichuan, Simao, and Khorat basins since after the Late Jurassic. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change Supplementary material: https://doi.org/10.6084/m9.figshare.c.6862918","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134975059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Increasing mineralogical and textural evidence from podiform chromitites in ophiolites show their ultra–high pressure origin (>150 km), challenging the conventional models for their formation under low pressure conditions (< 60 km) in the upper mantle. However, this challenge remains controversial due to the lack of in-situ mineralogical evidence. Here, we report new data and observations from the Skenderbeu massif in Mirdita ophiolite, Albania. Transmission electron microscopy (TEM) analysis reveal for the first time that these chromitites (Cr#= 41.8-43.2) have numerous exsolution lamellae of diopsidic clinopyroxene and orthoenstatite. TEM analysis also show that these lamellae have a crystallographic topotaxy relationship with the host chromite, i.e., (020) Cpx ∥︀ (22(—)0) Chr , (2(—)00) Cpx ∥︀ (111) Chr , and (010) Opx ∥︀ (22(—)0) Chr , (200) Opx ∥︀ (22(—)0) Chr , indicating an exsolution origin. The abundant presence of pyroxene exsolution lamellae in center of the host chromites implies the incorporation of Si 4+ and Ca 2+ cations in the precursor chromite, a CaFe 2 O 4 -structured high-pressure polymorph, which was stable >12.5 GPa (i.e., 380 km deep). These in-situ, nano-scale observations, and geological occurrence, together with previously discovered ophiolitic diamonds in the Mirdita ophiolite, suggest a much deeper origin for ophiolitic chromitites than conventional interpretations, and provide a valuable opportunity to understand the composition of the deep mantle. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists
{"title":"Two-pyroxene, intergrowth exsolution textures in ophiolitic chromites: implications for the deep mantle origin of the Mirdita Ophiolite, Albania","authors":"Weiwei Wu, Jingsui Yang, Yildirim Dilek, Souvik Das, Dongyang Lian, Pengjie Cai, Yun Wang, Yu Yang, Yuanyun Wen","doi":"10.1144/jgs2023-128","DOIUrl":"https://doi.org/10.1144/jgs2023-128","url":null,"abstract":"Increasing mineralogical and textural evidence from podiform chromitites in ophiolites show their ultra–high pressure origin (>150 km), challenging the conventional models for their formation under low pressure conditions (< 60 km) in the upper mantle. However, this challenge remains controversial due to the lack of in-situ mineralogical evidence. Here, we report new data and observations from the Skenderbeu massif in Mirdita ophiolite, Albania. Transmission electron microscopy (TEM) analysis reveal for the first time that these chromitites (Cr#= 41.8-43.2) have numerous exsolution lamellae of diopsidic clinopyroxene and orthoenstatite. TEM analysis also show that these lamellae have a crystallographic topotaxy relationship with the host chromite, i.e., (020) Cpx ∥︀ (22(—)0) Chr , (2(—)00) Cpx ∥︀ (111) Chr , and (010) Opx ∥︀ (22(—)0) Chr , (200) Opx ∥︀ (22(—)0) Chr , indicating an exsolution origin. The abundant presence of pyroxene exsolution lamellae in center of the host chromites implies the incorporation of Si 4+ and Ca 2+ cations in the precursor chromite, a CaFe 2 O 4 -structured high-pressure polymorph, which was stable >12.5 GPa (i.e., 380 km deep). These in-situ, nano-scale observations, and geological occurrence, together with previously discovered ophiolitic diamonds in the Mirdita ophiolite, suggest a much deeper origin for ophiolitic chromitites than conventional interpretations, and provide a valuable opportunity to understand the composition of the deep mantle. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"203 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135592407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jialun Huang, Xiubin Lin, Kaixuan An, Yang Qu, Li Li, Lin Jiang, Zhuxin Chen, Hanlin Chen, Xiaogan Cheng, Lining Wang, Cai Chen, Liang Zhang, Wei Liu, Xianzhang Yang, Yong Li, Yuqing Zhang, Nan Su
The Tian Shan is one of the world's largest intracontinental orogens and provides an excellent example for deciphering the intracontinental responses to the tectonics of plate boundaries. Despite its significance, the timing and driving mechanism of the Cenozoic mountain building of the Tian Shan in the context of the India-Eurasia collision remain controversial. In this study, Cenozoic stratigraphy of the Tiereke section along the western Kuqa Depression of the northern Tarim Basin on the south foreland of Eastern Tian Shan (east of 80°E) has been investigated. The results indicated that the Cenozoic deposition of the Tiereke region sequentially experienced a transgression from the Kumugeliemu Group to the Suweiyi Formation and a regression from the Suweiyi to the Kuqa Formations. Based on the contact relationships and conglomerate textures, three stages of high-energy alluvial deposition have been identified in the lower Kumugeliemu Group, upper Jidike, and Kangcun-Kuqa Formations, respectively. These sedimentary events were interpreted to represent phases of Eastern Tian Shan mountain building at ca. 54 Ma, ca. 27 Ma and since ca. 9.7 Ma according to previous magnetostratigraphic results, which were possibly related to the initial India-Eurasia collision, the collision between the India and Tarim lithospheric mantles, and the basinward propagation of deformation, respectively. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change
{"title":"Cenozoic sedimentary evolution of the Tiereke section on the northern Tarim Basin: implications for the intracontinental mountain building of the Eastern Tian Shan","authors":"Jialun Huang, Xiubin Lin, Kaixuan An, Yang Qu, Li Li, Lin Jiang, Zhuxin Chen, Hanlin Chen, Xiaogan Cheng, Lining Wang, Cai Chen, Liang Zhang, Wei Liu, Xianzhang Yang, Yong Li, Yuqing Zhang, Nan Su","doi":"10.1144/jgs2023-114","DOIUrl":"https://doi.org/10.1144/jgs2023-114","url":null,"abstract":"The Tian Shan is one of the world's largest intracontinental orogens and provides an excellent example for deciphering the intracontinental responses to the tectonics of plate boundaries. Despite its significance, the timing and driving mechanism of the Cenozoic mountain building of the Tian Shan in the context of the India-Eurasia collision remain controversial. In this study, Cenozoic stratigraphy of the Tiereke section along the western Kuqa Depression of the northern Tarim Basin on the south foreland of Eastern Tian Shan (east of 80°E) has been investigated. The results indicated that the Cenozoic deposition of the Tiereke region sequentially experienced a transgression from the Kumugeliemu Group to the Suweiyi Formation and a regression from the Suweiyi to the Kuqa Formations. Based on the contact relationships and conglomerate textures, three stages of high-energy alluvial deposition have been identified in the lower Kumugeliemu Group, upper Jidike, and Kangcun-Kuqa Formations, respectively. These sedimentary events were interpreted to represent phases of Eastern Tian Shan mountain building at ca. 54 Ma, ca. 27 Ma and since ca. 9.7 Ma according to previous magnetostratigraphic results, which were possibly related to the initial India-Eurasia collision, the collision between the India and Tarim lithospheric mantles, and the basinward propagation of deformation, respectively. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"219 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135548078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jean-Bernard Caron, Mark Webster, Derek E.G. Briggs, Giovanni Pari, Guy Santucci, M. Gabriela Mángano, Alejandro Izquierdo-López, Michael Streng, Robert R. Gaines
Discovered over a century ago, the lower Cambrian (Series 2, Stage 4) Cranbrook Lagerstätte of southeastern British Columbia's Eager Formation is one of the oldest Burgess Shale-type deposits in North America. This Konservat-Lagerstätte is rich in olenelloid trilobites, but also yields a very low-diversity soft-bodied fossil assemblage including Tuzoia and Anomalocaris , and a low-diversity ichnofauna. Its scientific study, however, remains limited. A 2015 field-based investigation by the Royal Ontario Museum has revealed new information about the site's biota, depositional environment, and taphonomic conditions. Not only is the Cranbrook Lagerstätte significant for early Cambrian biostratigraphy and comparisons with other Burgess Shale-type deposits, it also reveals some of the little-known diversity of life along a distal outer shelf environment during the Cambrian period. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6850810
{"title":"The lower Cambrian Cranbrook Lagerstätte of British Columbia","authors":"Jean-Bernard Caron, Mark Webster, Derek E.G. Briggs, Giovanni Pari, Guy Santucci, M. Gabriela Mángano, Alejandro Izquierdo-López, Michael Streng, Robert R. Gaines","doi":"10.1144/jgs2023-106","DOIUrl":"https://doi.org/10.1144/jgs2023-106","url":null,"abstract":"Discovered over a century ago, the lower Cambrian (Series 2, Stage 4) Cranbrook Lagerstätte of southeastern British Columbia's Eager Formation is one of the oldest Burgess Shale-type deposits in North America. This Konservat-Lagerstätte is rich in olenelloid trilobites, but also yields a very low-diversity soft-bodied fossil assemblage including Tuzoia and Anomalocaris , and a low-diversity ichnofauna. Its scientific study, however, remains limited. A 2015 field-based investigation by the Royal Ontario Museum has revealed new information about the site's biota, depositional environment, and taphonomic conditions. Not only is the Cranbrook Lagerstätte significant for early Cambrian biostratigraphy and comparisons with other Burgess Shale-type deposits, it also reveals some of the little-known diversity of life along a distal outer shelf environment during the Cambrian period. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6850810","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135387223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jose Nano, David W. Haig, Edwin Ornai Fraga, Moises Soares, Isaias Santos Barros, Eujay McCartain, Peter Baillie
Timor lies at the centre of a rapidly evolving orogenic belt. Matebian Range, one of its largest mountains, was previously mapped as Lower Miocene neritic Cablac Limestone and regarded as allochthonous (viz. Banda Terrane). New analyses have demonstrated a disjunct stratigraphy, extending from the Lower Jurassic to lowest Miocene and encompassing neritic to abyssal strata. Positioning each stratigraphic unit (six new) on a time vs. bathymetry plot and identifying clast types in conglomerates and turbidites allows reconstruction of changes in provenance to depo-centres through time. Terrane progression from the northern margin of Gondwana to the southern Sundaland margin (Asia) and then back to the northwest margin of the Australian continent is indicated involving progressive amalgamation and rifting and substantial episodes of uplift, particularly during the Middle Eocene and the Late Oligocene. The youngest unit (Late Oligocene–earliest Miocene) was deposited adjacent a rapidly rising hinterland (southern Sundaland) very different from that on the coeval Australian margin. The study provides a model for the tectonostratigraphic reconstruction of limestone-dominated mountains in young orogenic belts and demonstrates the importance of using sedimentary clasts in mass-flow deposits to interpret ages and depositional environments of reworked material and to stitch together tectonostratigraphic pathways through time. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6852387
{"title":"Debris-slides, olistoliths and turbidites: keys to understanding the tectonostratigraphic affinities of a terrane block in a young orogenic belt, Timor-Leste","authors":"Jose Nano, David W. Haig, Edwin Ornai Fraga, Moises Soares, Isaias Santos Barros, Eujay McCartain, Peter Baillie","doi":"10.1144/jgs2023-079","DOIUrl":"https://doi.org/10.1144/jgs2023-079","url":null,"abstract":"Timor lies at the centre of a rapidly evolving orogenic belt. Matebian Range, one of its largest mountains, was previously mapped as Lower Miocene neritic Cablac Limestone and regarded as allochthonous (viz. Banda Terrane). New analyses have demonstrated a disjunct stratigraphy, extending from the Lower Jurassic to lowest Miocene and encompassing neritic to abyssal strata. Positioning each stratigraphic unit (six new) on a time vs. bathymetry plot and identifying clast types in conglomerates and turbidites allows reconstruction of changes in provenance to depo-centres through time. Terrane progression from the northern margin of Gondwana to the southern Sundaland margin (Asia) and then back to the northwest margin of the Australian continent is indicated involving progressive amalgamation and rifting and substantial episodes of uplift, particularly during the Middle Eocene and the Late Oligocene. The youngest unit (Late Oligocene–earliest Miocene) was deposited adjacent a rapidly rising hinterland (southern Sundaland) very different from that on the coeval Australian margin. The study provides a model for the tectonostratigraphic reconstruction of limestone-dominated mountains in young orogenic belts and demonstrates the importance of using sedimentary clasts in mass-flow deposits to interpret ages and depositional environments of reworked material and to stitch together tectonostratigraphic pathways through time. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6852387","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135387362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanisms of the upward and outwards growth of the Tibetan Plateau are crucial for understanding the geodynamic significance of Cenozoic continental collisions. Northeastern Tibet has been suggested as one of the youngest deforming and uplifting margins surrounding the plateau. The existence of fluvial knickpoints and low-relief topographic surfaces along the Yellow River and its tributaries indicate the transience of the landscape in response to active tectonic uplift. Therefore, the uplift history of the North Eastern Tibetan Plateau (NETP) can be potentially inverted from the disequilibrium channel profiles of the Yellow River and its tributaries. The West Qinling Fault (WQF) is part of the geomorphological and topographic boundaries of the NETP. Its uplift history helps explore the deformation history of the Tibetan Plateau. In this study, the focus was on the Daxia River (one of the Yellow River tributary) in order to identify the distribution of peneplain surfaces and knickpoints, and present a linear inversion on the fluvial longitudinal profiles for the relative uplift history of the West Qinling. We obtained a relative uplift history with two pulses of change in the uplift rates at ∼5 Ma and ∼2 Ma. Rates of relative uplift maintained low values during the Late Miocene, then slowly increased from 0.1 mm/a to 0.2 mm/a since ∼5 Ma and suddenly jumped to 0.3 mm/a at ∼2 Ma, consistent with recent findings on the deformation records in the NE Tibetan Plateau. We suggest that 1) the Late Miocene-Pliocene landscape evolution was driven by both tectonics and climate change and 2) inversion of the transient longitudinal channel profiles, if applied, may provide broader insights into the upward and outwards growth patterns of the NE Tibetan Plateau. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change
{"title":"Inversion of Late Miocene uplift history from the transient Daxia River landscape, NE Tibetan Plateau","authors":"Yihui Zhang, Huiping Zhang, Zifa Ma, Yizhou Wang, Xudong Zhao","doi":"10.1144/jgs2023-030","DOIUrl":"https://doi.org/10.1144/jgs2023-030","url":null,"abstract":"The mechanisms of the upward and outwards growth of the Tibetan Plateau are crucial for understanding the geodynamic significance of Cenozoic continental collisions. Northeastern Tibet has been suggested as one of the youngest deforming and uplifting margins surrounding the plateau. The existence of fluvial knickpoints and low-relief topographic surfaces along the Yellow River and its tributaries indicate the transience of the landscape in response to active tectonic uplift. Therefore, the uplift history of the North Eastern Tibetan Plateau (NETP) can be potentially inverted from the disequilibrium channel profiles of the Yellow River and its tributaries. The West Qinling Fault (WQF) is part of the geomorphological and topographic boundaries of the NETP. Its uplift history helps explore the deformation history of the Tibetan Plateau. In this study, the focus was on the Daxia River (one of the Yellow River tributary) in order to identify the distribution of peneplain surfaces and knickpoints, and present a linear inversion on the fluvial longitudinal profiles for the relative uplift history of the West Qinling. We obtained a relative uplift history with two pulses of change in the uplift rates at ∼5 Ma and ∼2 Ma. Rates of relative uplift maintained low values during the Late Miocene, then slowly increased from 0.1 mm/a to 0.2 mm/a since ∼5 Ma and suddenly jumped to 0.3 mm/a at ∼2 Ma, consistent with recent findings on the deformation records in the NE Tibetan Plateau. We suggest that 1) the Late Miocene-Pliocene landscape evolution was driven by both tectonics and climate change and 2) inversion of the transient longitudinal channel profiles, if applied, may provide broader insights into the upward and outwards growth patterns of the NE Tibetan Plateau. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135536642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dongping Shi, Hongbing Tan, Yu Zhang, Peixin Cong, Yucheng Cao
The Yarlungzngbo River (YR) is the largest river system draining the northern slopes of the Himalayan ranges on the southern Tibetan Plateau and is critical to the water supply of the people downstream. In this paper the chemical composition of the YR and its major tributaries (Nianchu River and Lhasa River) are studied. Water samples (n=165) were collected and analyzed for major ions and trace elements. Multivariable analysis shows that geology and climate are the major explanatory variables for the spatio-temporal variation in water chemistry in this river system. Water chemistry is mainly controlled by carbonate weathering, with Ca 2+ and HCO 3 - being the dominant ions. Furthermore, hot spring discharge rich in Na + , Cl - , SO 4 2- and Li is another potential ion source affecting river water chemistry, resulting in higher solute concentrations in the source region and upstream, TDS reached 176.9 mg/L. Levels of most trace elements were generally found to be low. However, elevated As (16.6 μg/L) and Sb concentration (2.08 μg/L) in the headwaters and additions from untreated wastewater were evident, which exceeded the national standard of China (GB) and the World Health Organization (WHO) drinking water guide, posing a risk to human livelihood in the local and surrounding areas. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6850720
{"title":"Water quality of the southern Tibetan Plateau: hydrogeochemistry assessment of the Yarlungzangbo River","authors":"Dongping Shi, Hongbing Tan, Yu Zhang, Peixin Cong, Yucheng Cao","doi":"10.1144/jgs2023-040","DOIUrl":"https://doi.org/10.1144/jgs2023-040","url":null,"abstract":"The Yarlungzngbo River (YR) is the largest river system draining the northern slopes of the Himalayan ranges on the southern Tibetan Plateau and is critical to the water supply of the people downstream. In this paper the chemical composition of the YR and its major tributaries (Nianchu River and Lhasa River) are studied. Water samples (n=165) were collected and analyzed for major ions and trace elements. Multivariable analysis shows that geology and climate are the major explanatory variables for the spatio-temporal variation in water chemistry in this river system. Water chemistry is mainly controlled by carbonate weathering, with Ca\u0000 2+\u0000 and HCO\u0000 3\u0000 -\u0000 being the dominant ions. Furthermore, hot spring discharge rich in Na\u0000 +\u0000 , Cl\u0000 -\u0000 , SO\u0000 4\u0000 2-\u0000 and Li is another potential ion source affecting river water chemistry, resulting in higher solute concentrations in the source region and upstream, TDS reached 176.9 mg/L. Levels of most trace elements were generally found to be low. However, elevated As (16.6 μg/L) and Sb concentration (2.08 μg/L) in the headwaters and additions from untreated wastewater were evident, which exceeded the national standard of China (GB) and the World Health Organization (WHO) drinking water guide, posing a risk to human livelihood in the local and surrounding areas.\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.6850720","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135538435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Asian monsoon affects the natural environmental climate pattern in China, and its origin and evolution have been a debated issue in paleoclimatology. Results from recent studies indicate the Asian monsoon reached the subtropical zone at least ∼ 41 Ma and expanded to the central Tibetan Plateau during the Late Oligocene, but more geological evidence is still required to confirm its spatial and temporal evolution. The well-developed Late Oligocene paleosol in the Lunpola Basin, central TP, is ideal material for addressing the issue. In this paper, observations of various climatic indicators suggest these paleosols were forest cinnamon soils, shown by the compound Bt and Bk horizons, abundant clay coating and carbonate nodules, and diagnostic clay chemical composition in Bt horizons. High CIA values, Rb/Sr ratios, and high contents of illite/smectite mixed layer minerals show paleosols experienced intense weathering and leaching pedogenesis. Furthermore, the mean annual temperature and mean annual precipitation during the paleosol developmental period were 10.4∼14.8 ℃ and 615∼1128 mm, respectively, as estimated by the empirical formulas, which are comparable to the parameters of cinnamon soils in monsoon climate. This study provides important independent evidence of paleosol for the study of the evolution of the Asian monsoon. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change Supplementary material: https://doi.org/10.6084/m9.figshare.c.6850703
{"title":"Late Oligocene monsoonal climate in the Lunpola Basin, central Tibetan Plateau: evidence from paleosol records","authors":"Zengguang Guo, Fuli Wu, Xiaomin Fang, Chengcheng Ye, Yibo Yang, Jinbo Zan, Ziqiang Mao, Maohua Shen","doi":"10.1144/jgs2023-045","DOIUrl":"https://doi.org/10.1144/jgs2023-045","url":null,"abstract":"The Asian monsoon affects the natural environmental climate pattern in China, and its origin and evolution have been a debated issue in paleoclimatology. Results from recent studies indicate the Asian monsoon reached the subtropical zone at least ∼ 41 Ma and expanded to the central Tibetan Plateau during the Late Oligocene, but more geological evidence is still required to confirm its spatial and temporal evolution. The well-developed Late Oligocene paleosol in the Lunpola Basin, central TP, is ideal material for addressing the issue. In this paper, observations of various climatic indicators suggest these paleosols were forest cinnamon soils, shown by the compound Bt and Bk horizons, abundant clay coating and carbonate nodules, and diagnostic clay chemical composition in Bt horizons. High CIA values, Rb/Sr ratios, and high contents of illite/smectite mixed layer minerals show paleosols experienced intense weathering and leaching pedogenesis. Furthermore, the mean annual temperature and mean annual precipitation during the paleosol developmental period were 10.4∼14.8 ℃ and 615∼1128 mm, respectively, as estimated by the empirical formulas, which are comparable to the parameters of cinnamon soils in monsoon climate. This study provides important independent evidence of paleosol for the study of the evolution of the Asian monsoon. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change Supplementary material: https://doi.org/10.6084/m9.figshare.c.6850703","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135538247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Band-e-Zeyarat ophiolite (BEZO) sedimentary cover in the Makran Accretionary Prism (SE Iran) records a complex tectono-sedimentary evolution, extending from its formation at a mid-ocean ridge setting to deformation in an accretionary prism. Stratigraphic and biostratigraphic data indicate the occurrence of a Valanginian transition zone sequence separating the volcanic sequence and pelagic sedimentary cover. The latter consists of lower Hauterivian cherty limestone passing upwards to upper Hauterivian – Barremian marl and limestone. The pelagic sedimentary cover continues with post-Barremian – Cenomanian (?) marls. Arenites are interlayered in the sedimentary cover; they are composed of rock fragments derived from volcanic arc and continental margin settings. The BEZO sedimentary cover is intruded by dykes and sills showing enriched mid-ocean ridge (MOR) basalt chemical affinity. Structural analysis indicates a polyphase deformation history that involved faulting and folding. Our multidisciplinary results indicate that the BEZO formed in a MOR setting and that it was subsequently overprinted by off-axis and within-plate magmatism as it spread away from this MOR. The Band-e-Zeyarat oceanic crust was incorporated into the Makran prism in the latest Late Cretaceous – Paleocene, and was further deformed via strike-slip faulting along the dextral Minab-Sabzevaran fault during the Miocene - Pliocene. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists Supplementary material: https://doi.org/10.6084/m9.figshare.c.6843835
{"title":"The journey of the Band-e-Zeyarat ophiolite (Makran Accretionary Wedge, SE Iran) from the mid-ocean ridge to the accretionary complex: New insights from its sedimentary cover and associated basaltic dykes and sills","authors":"Edoardo Barbero, Luca Pandolfi, Morteza Delavari, Asghar Dolati, Emilio Saccani, Rita Catanzariti, Michele Marroni","doi":"10.1144/jgs2023-043","DOIUrl":"https://doi.org/10.1144/jgs2023-043","url":null,"abstract":"The Band-e-Zeyarat ophiolite (BEZO) sedimentary cover in the Makran Accretionary Prism (SE Iran) records a complex tectono-sedimentary evolution, extending from its formation at a mid-ocean ridge setting to deformation in an accretionary prism. Stratigraphic and biostratigraphic data indicate the occurrence of a Valanginian transition zone sequence separating the volcanic sequence and pelagic sedimentary cover. The latter consists of lower Hauterivian cherty limestone passing upwards to upper Hauterivian – Barremian marl and limestone. The pelagic sedimentary cover continues with post-Barremian – Cenomanian (?) marls. Arenites are interlayered in the sedimentary cover; they are composed of rock fragments derived from volcanic arc and continental margin settings. The BEZO sedimentary cover is intruded by dykes and sills showing enriched mid-ocean ridge (MOR) basalt chemical affinity. Structural analysis indicates a polyphase deformation history that involved faulting and folding. Our multidisciplinary results indicate that the BEZO formed in a MOR setting and that it was subsequently overprinted by off-axis and within-plate magmatism as it spread away from this MOR. The Band-e-Zeyarat oceanic crust was incorporated into the Makran prism in the latest Late Cretaceous – Paleocene, and was further deformed via strike-slip faulting along the dextral Minab-Sabzevaran fault during the Miocene - Pliocene. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists Supplementary material: https://doi.org/10.6084/m9.figshare.c.6843835","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135539127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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