Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the bou...Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.展开更多
Geochronological studies on the crust-derived Tianmenshan pluton were undertaken by SHRIMP zircon U-Pb dating and Ar-Ar dating of biotite,muscovite and K-feldspar,giving a petrogenetic age of 167 Ma.Owing to the closu...Geochronological studies on the crust-derived Tianmenshan pluton were undertaken by SHRIMP zircon U-Pb dating and Ar-Ar dating of biotite,muscovite and K-feldspar,giving a petrogenetic age of 167 Ma.Owing to the closure systems in different minerals,the cooling history of the pluton can be determined with an age-temperature diagram.The late hydrothermal event has been recognized,which is related probably with mineralization.In terms of the comparative geochronological and petrologic records,it is concluded that there are some constrains on tectonic evolution and that the formation of the Tianmenshan pluton proceeded in a transition period from Indosinian post-orogeny extension to strong compressive tectonics.And the timing of the hydrothermal event matches the compressive climax of the Yanshanian orogeny.The temporal gap between granite emplacement and wolframite mineralization could last 10-20 Ma owing to the low cooling rate of the pluton.展开更多
基金financially supported by China National Natural Science Foundation(Grant No.40172078).
文摘Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.
文摘Geochronological studies on the crust-derived Tianmenshan pluton were undertaken by SHRIMP zircon U-Pb dating and Ar-Ar dating of biotite,muscovite and K-feldspar,giving a petrogenetic age of 167 Ma.Owing to the closure systems in different minerals,the cooling history of the pluton can be determined with an age-temperature diagram.The late hydrothermal event has been recognized,which is related probably with mineralization.In terms of the comparative geochronological and petrologic records,it is concluded that there are some constrains on tectonic evolution and that the formation of the Tianmenshan pluton proceeded in a transition period from Indosinian post-orogeny extension to strong compressive tectonics.And the timing of the hydrothermal event matches the compressive climax of the Yanshanian orogeny.The temporal gap between granite emplacement and wolframite mineralization could last 10-20 Ma owing to the low cooling rate of the pluton.
