期刊
JOURNAL OF METAMORPHIC GEOLOGY
卷 29, 期 9, 页码 979-1002出版社
WILEY
DOI: 10.1111/j.1525-1314.2011.00952.x
关键词
accretion/collision; clockwise/anticlockwise P-T path; metamorphic patterns; Palaeozoic; Qinling-Tongbai-Dabie-Sulu orogenic belt; U-Pb dating
类别
资金
- Chinese '973' Project [2009CB825006]
- Geological Investigation Project of China Geological Survey [1212010711812]
- National Natural Science Foundation of China [40672047]
- National Science Council of Taiwan [NSC 97-2116-M-001-003, NSC 98-2116-M-001-009]
The Qinling-Tongbai-Dabie-Sulu orogenic belt comprises a Palaeozoic accretion-dominated system in the north and a Mesozoic collision-dominated system in the south. A combined petrological and geochronological study of the medium-to-high grade metamorphic rocks from the diverse Palaeozoic tectonic units in the Tongbai orogen was undertaken to help elucidate the origins of Triassic ultrahigh-pressure metamorphism and collision dynamics between the Sino-Korean and Yangtze cratons. Peak metamorphic conditions are 570-610 degrees C and 9.3-11.2 kbar for the lower unit of the Kuanping Group, 630-650 degrees C and 6.6-8.9 kbar for the upper unit of the Kuanping Group, 550-600 degrees C and 6.3-7.7 kbar for the Erlangping Group, 770-830 degrees C and 6.9-8.5 kbar for the Qinling Group and 660-720 degrees C and 9.1-11.5 kbar for the Guishan complex. Reaction textures and garnet compositions indicate clockwise P-T paths for the amphibolite facies rocks of the Kuanping Group and Guishan complex, and an anticlockwise P-T path for the granulite facies rocks of the Qinling Group. Sensitive high-resolution ion microprobe U-Pb zircon dating on metamorphic rocks and deformed granite/pegmatites revealed two major Palaeozoic tectonometamorphic events. (i) During the Silurian-Devonian (c. 440-400 Ma), the Qinling continental arc and Erlangping intra-oceanic arc collided with the Sino-Korean craton. The emplacement of the Huanggang diorite complex resulted in an inverted thermal gradient in the underlying Kuanping Group and subsequent thermal relaxation during the exhumation. Meanwhile, the oceanic subduction beneath the Qinling continental arc produced magmatic underplating and intrusion, leading to granulite facies metamorphism followed by a near-isobaric cooling path. (ii) During the Carboniferous (c. 340-310 Ma), the northward subduction of the Palaeo-Tethyan ocean generated a medium P/T Guishan complex in the hangingwall and a high P/T Xiongdian eclogite belt in the footwall. The Guishan complex and Xiongdian eclogite belt are therefore considered to be paired metamorphic belts. Subsequent separation of the paired belts is inferred to be related to the juxtaposition of the Carboniferous eclogites with the Triassic HP metamorphic complex during continental subduction and exhumation.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据