The Tongbai-East Qinling Mountains, an important part of the Central orogenic belt, is one of the most important metallogenic belts in China and contains lots of orogenic-type and VMS-type （Volcanogenic Massive Sulfi...The Tongbai-East Qinling Mountains, an important part of the Central orogenic belt, is one of the most important metallogenic belts in China and contains lots of orogenic-type and VMS-type （Volcanogenic Massive Sulfide type） metallogenic systems. The Dahe and Shuidongling VMS-type Cu-Zn deposits, located in the Erlangping Group in Tongbai and East Qinling Mountains, respectively, show similar geological and geochemical features. The Huoshenmiao Formation in the East Qinling region and the Liushanyan Formation in the Tongbai region are spilite-keratophyre sequences occurring in the western and eastern sides of the Nanyang Basin, respectively, and are interpreted to be equivalent to each other. The orogenic-type Au-Ag deposits can be subdivided into two styles; namely, fault- or structure-controlled （e.g. Yindonggou） and stratabound （e.g. Poshan）. The Poshan and Yindongpo orogenic-type Au-Ag deposits, whose ore bodies are strictly hosted in carbonaceous strata in the Tongbai Mountains, show obvious stratabound characteristics. Their ore-fluids are enriched in K^＋ and SO^2-4 and are regarded as K^＋-SO^2-4 types. The Pb-isotope ratios of sulfides of the ores are extremely uniform and significantly different from those of the tectonostratigraphic terranes of the Qinling orogens except for the ore-hosting strata of the Waitoushan Formation. The Yindonggou and Xuyaogou orogenic Au-Ag deposits in the East Qinling Mountains, whose ore bodies are hosted in the faults cutting the hosting strata or granite body, show fault-controlled characteristics. Their ore-fluids belong to the Na^＋-Cl^- type. The Pb-isotope ratios of sulfides of ores are similar to those of the northern Qinling orogenic belt. The Waitoushan Formation, dominated by carbonaceous sericite-rich schists and only occurring in Tongbai region, should be detached from the Erlangping Group, which occurs both in the western and eastern sides of the Nanyang Basin. Future ore exploration in the Tongbai-East Qinling Mountains should focus on fault-controlled Au-Ag lodes.展开更多
Through studies of P\|T\|t paths and decompressive retrograde metamorphic textures of metamorphic rocks in the East Qinling\|Dabieshan region, the authors determined the Mesozoic crust rapid uplifting age, and then in...Through studies of P\|T\|t paths and decompressive retrograde metamorphic textures of metamorphic rocks in the East Qinling\|Dabieshan region, the authors determined the Mesozoic crust rapid uplifting age, and then inferred that in the East Qinling\|Dabieshan region lithosphere delamination occurred from T\-3 to J\-1. The Yanshanian granites produced by delamination are developed well in the East Qinling\|Dabieshan region. But due to the Gondwana plate effect, magmatism in the region caused by delamination lagged until J\-3 when the northern Tibet terrane and the Eurasian plate completely amalgamated. Additionally, due to western Pacific plate subducting underneath the Eurasian plate, in the East Qinling\|Dabieshan region the stress state was transformed from compression to extension. So in the region from J\-3 to K\-2 magmatism was most intensive, and liberalization was also relatively strong. Geophysical data reflect that in the East Qinling\|Dabieshan region the asthenosphere rose to the shallow level, the Moho is flat with no mountain root, and the crustal thickness is less than 40 km on average. These features agree with those of collisional orogenes in which delamination has occurred. Through contrasting differences in surface and interior depth between east and west Qinling we believe that delamination proceeded from east to west.展开更多
The Douling Complex occurs as a Precambrian tectonic block distributed between the North China and Yangtze plates and has a protracted evolutional history. It is composed of various metamorpnic intrusives and supracru...The Douling Complex occurs as a Precambrian tectonic block distributed between the North China and Yangtze plates and has a protracted evolutional history. It is composed of various metamorpnic intrusives and supracrustal rocks. According to the studies on geology and geochronology, it can be concluded that the complex may have been formed in the early Proterozoic, about 2000 Ma ago and experienced two phases of regional metamorphism during the Jinningian and late Caledonian-early Hercynian. It can be correlated with the Qinling Complex from the North Qinling Mountains in lithic assemblage, formation age, tectonic setting and metamorphism, and is probably a thrust nappe split from the Qinling Complex.展开更多
基金supported by the"973"project (2006CB403500),NSFC(Nos.40502012,40730421 and 40425006)the 111 Project(No.B07011).
文摘The Tongbai-East Qinling Mountains, an important part of the Central orogenic belt, is one of the most important metallogenic belts in China and contains lots of orogenic-type and VMS-type （Volcanogenic Massive Sulfide type） metallogenic systems. The Dahe and Shuidongling VMS-type Cu-Zn deposits, located in the Erlangping Group in Tongbai and East Qinling Mountains, respectively, show similar geological and geochemical features. The Huoshenmiao Formation in the East Qinling region and the Liushanyan Formation in the Tongbai region are spilite-keratophyre sequences occurring in the western and eastern sides of the Nanyang Basin, respectively, and are interpreted to be equivalent to each other. The orogenic-type Au-Ag deposits can be subdivided into two styles; namely, fault- or structure-controlled （e.g. Yindonggou） and stratabound （e.g. Poshan）. The Poshan and Yindongpo orogenic-type Au-Ag deposits, whose ore bodies are strictly hosted in carbonaceous strata in the Tongbai Mountains, show obvious stratabound characteristics. Their ore-fluids are enriched in K^＋ and SO^2-4 and are regarded as K^＋-SO^2-4 types. The Pb-isotope ratios of sulfides of the ores are extremely uniform and significantly different from those of the tectonostratigraphic terranes of the Qinling orogens except for the ore-hosting strata of the Waitoushan Formation. The Yindonggou and Xuyaogou orogenic Au-Ag deposits in the East Qinling Mountains, whose ore bodies are hosted in the faults cutting the hosting strata or granite body, show fault-controlled characteristics. Their ore-fluids belong to the Na^＋-Cl^- type. The Pb-isotope ratios of sulfides of ores are similar to those of the northern Qinling orogenic belt. The Waitoushan Formation, dominated by carbonaceous sericite-rich schists and only occurring in Tongbai region, should be detached from the Erlangping Group, which occurs both in the western and eastern sides of the Nanyang Basin. Future ore exploration in the Tongbai-East Qinling Mountains should focus on fault-controlled Au-Ag lodes.
文摘Through studies of P\|T\|t paths and decompressive retrograde metamorphic textures of metamorphic rocks in the East Qinling\|Dabieshan region, the authors determined the Mesozoic crust rapid uplifting age, and then inferred that in the East Qinling\|Dabieshan region lithosphere delamination occurred from T\-3 to J\-1. The Yanshanian granites produced by delamination are developed well in the East Qinling\|Dabieshan region. But due to the Gondwana plate effect, magmatism in the region caused by delamination lagged until J\-3 when the northern Tibet terrane and the Eurasian plate completely amalgamated. Additionally, due to western Pacific plate subducting underneath the Eurasian plate, in the East Qinling\|Dabieshan region the stress state was transformed from compression to extension. So in the region from J\-3 to K\-2 magmatism was most intensive, and liberalization was also relatively strong. Geophysical data reflect that in the East Qinling\|Dabieshan region the asthenosphere rose to the shallow level, the Moho is flat with no mountain root, and the crustal thickness is less than 40 km on average. These features agree with those of collisional orogenes in which delamination has occurred. Through contrasting differences in surface and interior depth between east and west Qinling we believe that delamination proceeded from east to west.
基金Project supported by the National Natural Science Foundation of China.
文摘The Douling Complex occurs as a Precambrian tectonic block distributed between the North China and Yangtze plates and has a protracted evolutional history. It is composed of various metamorpnic intrusives and supracrustal rocks. According to the studies on geology and geochronology, it can be concluded that the complex may have been formed in the early Proterozoic, about 2000 Ma ago and experienced two phases of regional metamorphism during the Jinningian and late Caledonian-early Hercynian. It can be correlated with the Qinling Complex from the North Qinling Mountains in lithic assemblage, formation age, tectonic setting and metamorphism, and is probably a thrust nappe split from the Qinling Complex.
