Multistage deformation events have occurred in the northeastern Jiangshao Fault （Suture） Belt. The earliest two are ductile deformation events. The first is the ca. 820 Ma top-to-the-northwest ductile thrusting, whi...Multistage deformation events have occurred in the northeastern Jiangshao Fault （Suture） Belt. The earliest two are ductile deformation events. The first is the ca. 820 Ma top-to-the-northwest ductile thrusting, which directly resulted from the collision between the Cathaysia Old Land and the Chencai Arc （？） during the Late Neoproterozoic, and the Jiangnan Orogenic Belt that formed as the ocean closed between the Yangtze Plate and the jointed Cathaysia Old Land and the Chencai Arc due to continuous compression. The second is the ductile left-lateral strike-slipping that occurred in the latest Early Paleozoic. Since the Jinning period, all deformation events represent the reactivation or inversion of intraplate structures due to the collisions between the North China and Yangtze plates during the Triassic and between the Philippine Sea and Eurasian plates during the Cenozoic. In the Triassic, brittle right-lateral strike-slipping and subsequent top-to-the south thrusting occurred along the whole northeastern Jiangshao Fault Zone because of the collision between the North China and Yangtze plates. In the Late Mesozoic, regional extension took place across southeastern China. In the Cenozoic, the collision between the Philippine Sea and Eurasian plates resulted in brittle thrusts along the whole Jiangnan Old land in the Miocene. The Jiangshao Fault Belt is a weak zone in the crust with long history, and its reactivation is one of important characteristics of the deformation in South China; however, late-stage deformation events did not occur beyond the Jiangnan Old Land and most of them are parallel to the strike of the Old Land, which is similar to the Cenozoic deformation in Central Asia. In addition, the Jiangnan old Land is not a collisional boundary between the Yangtze Plate and Cathaysia Old Land in the Triassic.展开更多
The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was re...The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was regarded as a part of the 'Jiangnan old land' of Presinian till it was challenged by the present authors years ago. After we postulated that there may be some strata of Palaeozoic Era in Shangxi Group, some microfossils and then macrofossils of Palaeozoic were found in some part of it. The macrof os-sils, Lingula sp. , Conulariid and the microfossils indicate that most units of the Shangxi Group are Palaeozoic strata. Based on the discovery of these fossils and the recognition of the tectonic-setting of the different tectono-petrologic units in the Shangxi Group, three different stratigraphic sequences (island-arc volcanics, back-arc sediments and the cover of passive margin of Yangtze Continental Plate) are established and the tectonic evolution of them is postulated in the present paper. All the evidences obtained recently from the Shangxi Group indicate that there is no 'Old Land' over the discussed area, but a subduction followed by a collision zone between the island-arc and Yangtze Continental Plate; all these metamorphosed strata were originally island-arc, back-arc basin sediments during the Sinian-late Paleozoic, except the Presinian sandstone distributed in a narrow belt on the northmost margin of the metamorphic terrane.展开更多
The medusae fossil from the metamorphic rock of Mukeng Formation of Shangxi Group in the east segment of the "Jiangnan Old Land" is an important evidence to time the age of the host strata and disintegrate t...The medusae fossil from the metamorphic rock of Mukeng Formation of Shangxi Group in the east segment of the "Jiangnan Old Land" is an important evidence to time the age of the host strata and disintegrate the host metamorphic stratigraphy. The medusae fossil is different from that of Edicara and Chengjiang fauna. Morphologically, it is similar to the Aurelia occurred in pelagic sea today, and it is termed as cf. Aurelia. It is possibly the later generation of the today′s Aurelia and must be generated in the time later than that of Chengjiang fauna. The occurrence of the cf. Aurelia indicates that the age of the host metamorphic rocks are probably in the range of Cambrian to Ordovician rather than that of Middle Proterozoic as previously suggested. Therefor, the metamorphic stratigraphy in the east segment of the "Jiangnan Old Land", at least the Mukeng Formation, was not the sediments of Proterozoic as previously regarded.展开更多
基金funded by the Nonprofit Special Research Program"The formation and destruction of northeastern segment of Cathaysia-the Yangtze Plate Suture Zone and their mineralization"(No.200811015)from the Ministry of Land and Resourcethe Land Resource Survey Project of the Ministry of Land and Natural Resources,China"The convergence and breakup process of main blocks of China and their geological background for mineralization"(Nos.1212011121064,1212011121068)from the China Geological Survey
文摘Multistage deformation events have occurred in the northeastern Jiangshao Fault （Suture） Belt. The earliest two are ductile deformation events. The first is the ca. 820 Ma top-to-the-northwest ductile thrusting, which directly resulted from the collision between the Cathaysia Old Land and the Chencai Arc （？） during the Late Neoproterozoic, and the Jiangnan Orogenic Belt that formed as the ocean closed between the Yangtze Plate and the jointed Cathaysia Old Land and the Chencai Arc due to continuous compression. The second is the ductile left-lateral strike-slipping that occurred in the latest Early Paleozoic. Since the Jinning period, all deformation events represent the reactivation or inversion of intraplate structures due to the collisions between the North China and Yangtze plates during the Triassic and between the Philippine Sea and Eurasian plates during the Cenozoic. In the Triassic, brittle right-lateral strike-slipping and subsequent top-to-the south thrusting occurred along the whole northeastern Jiangshao Fault Zone because of the collision between the North China and Yangtze plates. In the Late Mesozoic, regional extension took place across southeastern China. In the Cenozoic, the collision between the Philippine Sea and Eurasian plates resulted in brittle thrusts along the whole Jiangnan Old land in the Miocene. The Jiangshao Fault Belt is a weak zone in the crust with long history, and its reactivation is one of important characteristics of the deformation in South China; however, late-stage deformation events did not occur beyond the Jiangnan Old Land and most of them are parallel to the strike of the Old Land, which is similar to the Cenozoic deformation in Central Asia. In addition, the Jiangnan old Land is not a collisional boundary between the Yangtze Plate and Cathaysia Old Land in the Triassic.
基金This work was supported by the grant from Anhui Bureau of Geology and Mineral Resources,and from the National Natural Science Foundation of China.
文摘The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was regarded as a part of the 'Jiangnan old land' of Presinian till it was challenged by the present authors years ago. After we postulated that there may be some strata of Palaeozoic Era in Shangxi Group, some microfossils and then macrofossils of Palaeozoic were found in some part of it. The macrof os-sils, Lingula sp. , Conulariid and the microfossils indicate that most units of the Shangxi Group are Palaeozoic strata. Based on the discovery of these fossils and the recognition of the tectonic-setting of the different tectono-petrologic units in the Shangxi Group, three different stratigraphic sequences (island-arc volcanics, back-arc sediments and the cover of passive margin of Yangtze Continental Plate) are established and the tectonic evolution of them is postulated in the present paper. All the evidences obtained recently from the Shangxi Group indicate that there is no 'Old Land' over the discussed area, but a subduction followed by a collision zone between the island-arc and Yangtze Continental Plate; all these metamorphosed strata were originally island-arc, back-arc basin sediments during the Sinian-late Paleozoic, except the Presinian sandstone distributed in a narrow belt on the northmost margin of the metamorphic terrane.
文摘The medusae fossil from the metamorphic rock of Mukeng Formation of Shangxi Group in the east segment of the "Jiangnan Old Land" is an important evidence to time the age of the host strata and disintegrate the host metamorphic stratigraphy. The medusae fossil is different from that of Edicara and Chengjiang fauna. Morphologically, it is similar to the Aurelia occurred in pelagic sea today, and it is termed as cf. Aurelia. It is possibly the later generation of the today′s Aurelia and must be generated in the time later than that of Chengjiang fauna. The occurrence of the cf. Aurelia indicates that the age of the host metamorphic rocks are probably in the range of Cambrian to Ordovician rather than that of Middle Proterozoic as previously suggested. Therefor, the metamorphic stratigraphy in the east segment of the "Jiangnan Old Land", at least the Mukeng Formation, was not the sediments of Proterozoic as previously regarded.
