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Early Paleozoic subduction of the Paleo-Asian Ocean: Geochronological and geochemical evidence from the Dashizhai basalts, Inner Mongolia

文献类型：期刊论文

作者Guo Feng1; Fan WeiMing1; Li ChaoWen1; Miao LaiCheng2; Zhao Liang1
刊名SCIENCE IN CHINA SERIES D-EARTH SCIENCES
出版日期2009-07-01
卷号52期号:7页码:940-951
关键词subduction Paleo-Asian Ocean Dashizhai basalts early Paleozoic Inner Mongolia
ISSN号1006-9313
DOI10.1007/s11430-009-0083-2
文献子类Article
英文摘要Zircon U-Pb results of basalt from the Dashizhai Town in Inner Mongolia, NE China, shows that the basaltic lava was erupted at 439 +/- 3 Ma, much older than the "Permian basalts" as previously thought. These rocks show arc-type trace element patterns (i.e., Nb-Ta depletion and light REE and large ion lithophile element enrichment) and unradiogenic Sr and highly radiogenic Nd and Hf isotope compositions. They can be subdivided into two petrogenetic groups: Group 1 basalts have relatively high TiO(2), MgO and compatible elements and low Sr and Th, characterized by mid-oceanic ridge basalt (MORB)-type Sr-Nd-Hf isotope compositions ((87)Sr/(86)Sr(i)=0.7028-0.7032, epsilon(Nd)(t)=+9.8-+11.2, epsilon(Hf)(t)=+16.1-+18.4). Group 2 has lower TiO(2), MgO and compatible elements and higher Sr and Th, and relatively evolved Sr-Nd-Hf isotope compositions ((87)Sr/(86)Sr(i)=0.7037-0.7038, epsilon(Nd)(t)=+5.7-+7.3, epsilon(Hf)(t)=+12.6-+13.0). Both groups were interpreted as melts derived from a metasomatized mantle wedge formed during the subduction of Paleo-Asian Ocean. The mantle source for Group 1 was probably a highly isotopically depleted oceanic mantle modified by predominant slab fluids; whereas subducted sediments had an important contribution to the melting source for Group 2. The petrogenesis of the Dashizhai basalts provides clear evidence for early Paleozoic subduction of the Paleo-Asian Ocean, and the highly radiogenic Nd and Hf compositions in these rocks suggest that these lavas and their possible intrusive counterparts were one of the important components for Phanerozoic crustal growth. Our and previous studies on the "Dashizhai Formation" volcanic rocks yield an unrealistic eruption range of 440-270 Ma for different rock types, we thus advise to disassemble the previously defined "Dashizhai Formation" into multiple lithologic units and to reinterpret the spatial and temporal distributions of different volcano-sedimentary associations.
WOS关键词DA-HINGGAN MOUNTAINS ; A-TYPE GRANITES ; OROGENIC BELT ; VOLCANIC-ROCKS ; CRUSTAL GROWTH ; TECTONIC IMPLICATIONS ; CONTINENTAL GROWTH ; NORTHEASTERN CHINA ; ISOTOPIC EVIDENCE ; MANTLE SOURCE
WOS研究方向Geology
语种英语
WOS记录号WOS:000267687400005
出版者SCIENCE PRESS
资助机构National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504) ; National Basic Research Program of China(2006CB403504)
源URL[http://ir.iggcas.ac.cn/handle/132A11/70507]  
专题中国科学院地质与地球物理研究所
通讯作者Guo Feng
作者单位1.Chinese Acad Sci, Key Lab Marginal Sea Geol, Guangzhou Inst Geochem, Guangzhou 510640, Guangdong, Peoples R China
2.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China
推荐引用方式
GB/T 7714		 Guo Feng,Fan WeiMing,Li ChaoWen,et al. Early Paleozoic subduction of the Paleo-Asian Ocean: Geochronological and geochemical evidence from the Dashizhai basalts, Inner Mongolia[J]. SCIENCE IN CHINA SERIES D-EARTH SCIENCES,2009,52(7):940-951.
APA Guo Feng,Fan WeiMing,Li ChaoWen,Miao LaiCheng,&Zhao Liang.(2009).Early Paleozoic subduction of the Paleo-Asian Ocean: Geochronological and geochemical evidence from the Dashizhai basalts, Inner Mongolia.SCIENCE IN CHINA SERIES D-EARTH SCIENCES,52(7),940-951.
MLA Guo Feng,et al."Early Paleozoic subduction of the Paleo-Asian Ocean: Geochronological and geochemical evidence from the Dashizhai basalts, Inner Mongolia".SCIENCE IN CHINA SERIES D-EARTH SCIENCES 52.7(2009):940-951.

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来源：地质与地球物理研究所

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