The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relativ...The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relatively low(^(87)Sr/^(86)Sr)iratios of 0.7090-0.7169 andε_(Nd)(t)values of-9.8 to-7.8 display metaluminous,calc-alkaline dominated by I-type granite affinity and hybrid mantle-crust geochemical signatures.They may have been derived from melting of the subducted Meso-Tethyan BangongNujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting.(b)The Late Cretaceous-Paleocene granitoids with relatively high(^(87)Sr/^(86)Sr)iratios of 0.7109-0.7627,andε_(Nd)(t)values of-12.1 to-7.9 exhibit metaluminous to peraluminous,calc-alkaline dominated by S-type granite affinity and hybrid Lower-Upper crust geochemical signatures,which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block.(c)The Early Eocene granitoids have metaluminous,calc-alkaline I-type and S-type granites dual affinity,with relatively high(^(87)Sr/^(86)Sr)iratios of 0.711-0.736,ε_(Nd)(t)values of-9.4 to-4.7,showing crust-mantle mixing geochemical signatures.They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao-Myitkyian oceanic crust,and collision between the Western Burma Block and the Tengchong Block.It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.展开更多
Whole-rock major and trace element and Sr-Nd isotopic data,together with zircon LA ICP-MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their...Whole-rock major and trace element and Sr-Nd isotopic data,together with zircon LA ICP-MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their petrogenesis and tectonic implications.Zircon U-Pb data gives the emplacement ages of ca.115.3±0.9 Ma for syenites and 115.7±0.8 Ma for granites,respectively.The syenites are characterized by low SiO2 content(62.01-63.03 wt%)and notably high Na20 content(7.04-7.24 wt%)and Na20/K20 ratios(2.02-2.10),low MgO,Fe2OaT and TiO2,enrichment of LILEs(large-ion lithophile element)such as Rb,Th,U,K,and Pb)and obvious depletion HFSE(high field strength element;e.g.Nb,Ta,P,and Ti)with clearly negative Eu anomalies(dEu=0.53-0.56).They also display significant negative whole-rock eNd(t)values of-6.8 and zircon eHf(t)values(-9.11 to-0.27,but one is+5.30)and high initial S7Sr/86Sr=0.713013.Based on the data obtained in this study,we suggest that the ca.l15.3Ma syenites were possibly derived from a sodium-rich continental crustal source,and the fractionation of some ferro-magnesian mineral and plagioclase might occur during the evolution of magma.The granites have high SiO2 content(71.35-74.47 wt%),metaluminous to peraluminous,low Rb/Ba,Rb/Sr,and AI2Oa/(MgO+FeOT+TiO2)ratios and moderate(AI2Oa+MgO+FeOT+TiO2)content.They show low initial a7Sr/86Sr(0.703408 to 0.704241)and eNd(t)values(-3.8 to-3.5),plotted into the evolutionary trend between basalts and lower crust.Hence,we suggest that the granites were derived from the melting of mixing sources in the ancient continental crust involving some metabasaltic materials and predominated metasedimentary greywackes.Together with data in the literatures,we infer that the Early Cretaceous magmatism in the Tengchong block was dominated by magmas generated by the partial melting of ancient crustal material,which represent the products that associated to the closure of Bangong-Nujiang Meso-Tethys.展开更多
The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites;however, their geological background and petrogenesis have not been well constrained and elucidated. ...The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites;however, their geological background and petrogenesis have not been well constrained and elucidated. In this study, we present new zircon U-Pb dating, along with geochemical and Sr-Nd-Hf isotopic data for granites from the Tengchong–Lianghe granitoid belt(as abbreviated to Tengliang belt) and West Yingjiang batholiths from the Tengchong block. The mineralogical and geochemical features of the Tengliang granites and the West Yingjiang batholiths are ascribed to aluminous S-type granites and weak peraluminous I-type, respectively. Zircon U-Pb analyses yielded consistent ages ranging from 67.5 Ma, 68.4 Ma and 66.2 Ma from the Tengliang granitoid belt and 50.4 Ma to 60.8 Ma for three samples from the west Yingjiang batholiths. The Tengliang granites were emplaced during the Late Cretaceous(68-66 Ma) and demonstrate negative ε_(Hf)(t) values(-24 to-4) and initial ~(87)Sr/~(86)Sr ratios of 0.7101–0.7139 and significant negative ε_(Nd)(t) values from-8.91 to-13.2, indicating a Proterozoic sedimentary source or enriched components. The hornblende-bearing I-type granites from West Yingjiang are characterized by lower initial ~(87)Sr/~(86)Sr ratios of 0.7076–0.7106, compared to Tengliang granite and negative whole-rock ε_(Nd)(t) values from-4.0 to-11.9. The early Eocene west Yingjiang gneissic granites show wide ranges of ε_(Hf)(t) values from +7.4 to-8.5 and T_(2DM) of 1.30–0.65 Ga, indicating partial melting of ancient crust with contributions of depleted mantle materials. In combination with the regional background and previous studies, we propose that such a spatio-temporal distribution of the Tengchong granitoid belt might be related to the rollback or angleswitching of the Neo-Tethyan subducting slab. This study sheds new light on the evolutionary history of the Tengchong block.展开更多
Understanding the tectono-magmatic evolution history of the Tengchong block is crucial for elucidating the formation of the Eastern Tethys tectonic domain.However,the correlation and evolution of the Tengchong block w...Understanding the tectono-magmatic evolution history of the Tengchong block is crucial for elucidating the formation of the Eastern Tethys tectonic domain.However,the correlation and evolution of the Tengchong block with the Sibumasu and Lhasa blocks is controversial during the Permian and Cretaceous.This study explores the information contained within magmatic rocks using big data and spatio-temporal analysis,providing quantitative constraints for the discussion of the tectonomagmatic evolution of the Tengchong block.To more accurately assess true magma activities and reduce errors caused by preservation and sampling processes,we utilized local singularity analysis to obtain the singularity index time-series.Correlation analysis of zircon ages and eHf(t)(correlation coefficient0.5)values indicates that the Tengchong block is more similar to the Sibumasu block.Results from timelagged cross-correlation analysis indicate that the Tengchong block and Sibumasu block exhibit a shorter lag in magmatic activities(3 Myr).Wavelet analysis reveals similar periods of collision-related magmatic activities(57 Myr and 43 Myr).Integrating evidence from paleontology and ophiolite belts,we propose that the Tengchong block co-evolved more closely with the Sibumasu block than with the Lhasa block,suggesting similar tectonic processes during the Early Permian to Early Cretaceous.Approximately 250–236 Ma,in the western Tengchong block,partial melting of the lower crust occurs due to crustal thickening.Around 219–213 Ma and 198–180 Ma,after the Tengchong block collided with the Eurasian continent,the subduction of the Meso-Tethys Ocean commenced.Around 130–111 Ma,the overall tectonic feature was a scissor-like closure of the Meso-Tethys Ocean from north to south.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.41972312,41672329,41272365)the National Key Research and Development Project of China(Grant No.2016YFC0600509)。
文摘The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relatively low(^(87)Sr/^(86)Sr)iratios of 0.7090-0.7169 andε_(Nd)(t)values of-9.8 to-7.8 display metaluminous,calc-alkaline dominated by I-type granite affinity and hybrid mantle-crust geochemical signatures.They may have been derived from melting of the subducted Meso-Tethyan BangongNujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting.(b)The Late Cretaceous-Paleocene granitoids with relatively high(^(87)Sr/^(86)Sr)iratios of 0.7109-0.7627,andε_(Nd)(t)values of-12.1 to-7.9 exhibit metaluminous to peraluminous,calc-alkaline dominated by S-type granite affinity and hybrid Lower-Upper crust geochemical signatures,which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block.(c)The Early Eocene granitoids have metaluminous,calc-alkaline I-type and S-type granites dual affinity,with relatively high(^(87)Sr/^(86)Sr)iratios of 0.711-0.736,ε_(Nd)(t)values of-9.4 to-4.7,showing crust-mantle mixing geochemical signatures.They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao-Myitkyian oceanic crust,and collision between the Western Burma Block and the Tengchong Block.It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.
基金supported by the National Natural Science Foundation of China(Grant Nos.41421002,41190072,41372067 and 41102037)the program for Changjiang Scholars and Innovative Research Team in University(Grant IRT1281)+2 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(201324)the MOST Special Fund from the State Key Laboratory of Continental Dynamics,Northwest UniversityProvince Key Laboratory Construction Item(08JZ62)
文摘Whole-rock major and trace element and Sr-Nd isotopic data,together with zircon LA ICP-MS in-situ U-Pb and Hf isotopic data of the syenites and granites in the Tengchong Block are reported in order to understand their petrogenesis and tectonic implications.Zircon U-Pb data gives the emplacement ages of ca.115.3±0.9 Ma for syenites and 115.7±0.8 Ma for granites,respectively.The syenites are characterized by low SiO2 content(62.01-63.03 wt%)and notably high Na20 content(7.04-7.24 wt%)and Na20/K20 ratios(2.02-2.10),low MgO,Fe2OaT and TiO2,enrichment of LILEs(large-ion lithophile element)such as Rb,Th,U,K,and Pb)and obvious depletion HFSE(high field strength element;e.g.Nb,Ta,P,and Ti)with clearly negative Eu anomalies(dEu=0.53-0.56).They also display significant negative whole-rock eNd(t)values of-6.8 and zircon eHf(t)values(-9.11 to-0.27,but one is+5.30)and high initial S7Sr/86Sr=0.713013.Based on the data obtained in this study,we suggest that the ca.l15.3Ma syenites were possibly derived from a sodium-rich continental crustal source,and the fractionation of some ferro-magnesian mineral and plagioclase might occur during the evolution of magma.The granites have high SiO2 content(71.35-74.47 wt%),metaluminous to peraluminous,low Rb/Ba,Rb/Sr,and AI2Oa/(MgO+FeOT+TiO2)ratios and moderate(AI2Oa+MgO+FeOT+TiO2)content.They show low initial a7Sr/86Sr(0.703408 to 0.704241)and eNd(t)values(-3.8 to-3.5),plotted into the evolutionary trend between basalts and lower crust.Hence,we suggest that the granites were derived from the melting of mixing sources in the ancient continental crust involving some metabasaltic materials and predominated metasedimentary greywackes.Together with data in the literatures,we infer that the Early Cretaceous magmatism in the Tengchong block was dominated by magmas generated by the partial melting of ancient crustal material,which represent the products that associated to the closure of Bangong-Nujiang Meso-Tethys.
基金the financial support provided by the open fund from the Key Laboratory of Deep-Earth Dynamics of the Ministry of Natural Resources, Institute of Geology, as well as Chinese Academy of Geological Sciences (Grant No. J1901-16)the State Key Laboratory for Mineral Deposits Research, Nanjing University (Grant No. 2020-LAMD-K04)+1 种基金the National Natural Science Foundation of China (Grant No. 41403029)The support provided by the China Scholarship Council (CSC) during a visit to the University of Arizona (201709110012)。
文摘The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites;however, their geological background and petrogenesis have not been well constrained and elucidated. In this study, we present new zircon U-Pb dating, along with geochemical and Sr-Nd-Hf isotopic data for granites from the Tengchong–Lianghe granitoid belt(as abbreviated to Tengliang belt) and West Yingjiang batholiths from the Tengchong block. The mineralogical and geochemical features of the Tengliang granites and the West Yingjiang batholiths are ascribed to aluminous S-type granites and weak peraluminous I-type, respectively. Zircon U-Pb analyses yielded consistent ages ranging from 67.5 Ma, 68.4 Ma and 66.2 Ma from the Tengliang granitoid belt and 50.4 Ma to 60.8 Ma for three samples from the west Yingjiang batholiths. The Tengliang granites were emplaced during the Late Cretaceous(68-66 Ma) and demonstrate negative ε_(Hf)(t) values(-24 to-4) and initial ~(87)Sr/~(86)Sr ratios of 0.7101–0.7139 and significant negative ε_(Nd)(t) values from-8.91 to-13.2, indicating a Proterozoic sedimentary source or enriched components. The hornblende-bearing I-type granites from West Yingjiang are characterized by lower initial ~(87)Sr/~(86)Sr ratios of 0.7076–0.7106, compared to Tengliang granite and negative whole-rock ε_(Nd)(t) values from-4.0 to-11.9. The early Eocene west Yingjiang gneissic granites show wide ranges of ε_(Hf)(t) values from +7.4 to-8.5 and T_(2DM) of 1.30–0.65 Ga, indicating partial melting of ancient crust with contributions of depleted mantle materials. In combination with the regional background and previous studies, we propose that such a spatio-temporal distribution of the Tengchong granitoid belt might be related to the rollback or angleswitching of the Neo-Tethyan subducting slab. This study sheds new light on the evolutionary history of the Tengchong block.
文摘Understanding the tectono-magmatic evolution history of the Tengchong block is crucial for elucidating the formation of the Eastern Tethys tectonic domain.However,the correlation and evolution of the Tengchong block with the Sibumasu and Lhasa blocks is controversial during the Permian and Cretaceous.This study explores the information contained within magmatic rocks using big data and spatio-temporal analysis,providing quantitative constraints for the discussion of the tectonomagmatic evolution of the Tengchong block.To more accurately assess true magma activities and reduce errors caused by preservation and sampling processes,we utilized local singularity analysis to obtain the singularity index time-series.Correlation analysis of zircon ages and eHf(t)(correlation coefficient0.5)values indicates that the Tengchong block is more similar to the Sibumasu block.Results from timelagged cross-correlation analysis indicate that the Tengchong block and Sibumasu block exhibit a shorter lag in magmatic activities(3 Myr).Wavelet analysis reveals similar periods of collision-related magmatic activities(57 Myr and 43 Myr).Integrating evidence from paleontology and ophiolite belts,we propose that the Tengchong block co-evolved more closely with the Sibumasu block than with the Lhasa block,suggesting similar tectonic processes during the Early Permian to Early Cretaceous.Approximately 250–236 Ma,in the western Tengchong block,partial melting of the lower crust occurs due to crustal thickening.Around 219–213 Ma and 198–180 Ma,after the Tengchong block collided with the Eurasian continent,the subduction of the Meso-Tethys Ocean commenced.Around 130–111 Ma,the overall tectonic feature was a scissor-like closure of the Meso-Tethys Ocean from north to south.
