| 新疆大陆基底分区模式和主要地质事件的划分 |
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| 引用本文： | 胡霭琴,张国新,陈义兵,张前锋.新疆大陆基底分区模式和主要地质事件的划分[J].新疆地质,2001,19(1):12-19. |
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| 作者姓名： | 胡霭琴 张国新 陈义兵 张前锋 |
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| 作者单位： | 中国科学院广州地球化学研究所, |
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| 基金项目： | 国家305项目（969150705A）和国家自然科学基金重点项目（9633250）联合资助 |
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| 摘 要： | 在同位素年代学和地球化学研究的基础上，概括了1982～2000年间的同位素年代学和地球化学研究成果，特别是1987～2000年"305"项目的研究成果。展现了近年来对新疆大陆前寒武纪基底同位素年代学研究的新成果塔里木北缘灰色片麻岩锆石U-Pb年龄为2600Ma，西昆仑基底石榴黑云母片麻岩中的锆石U-Pb一致年龄则为
（2048±20）Ma，阿尔金灰色片麻岩锆石U-Pb上交点年龄为（1820±277）Ma，测定了东天山星星峡群片麻岩的锆石U-Pb上交点年龄为（1404±18）Ma，与1986年的结果一致（1400±42）Ma，获得西天山温泉群、那拉提群和木扎尔特群混合岩化片麻岩中锆石U-Pb年龄分别为（821±11）～（798±8）Ma，（882±83）Ma和（707±7）Ma；基于Sm-Nd模式年龄统计结果，将新疆大陆基底分为5个区域，即塔里木大陆太古宙－古元古代（3.2～2.2）Ga基底区，昆仑-阿尔金造山带古元古代基底区（2.0～1.8）Ga，天山古中元古代基底区（2.1～1.7）Ga，准噶尔为年轻地壳基底区（1.4～0.7）Ga和阿尔泰古元古代、中新元古代复合基底区（≤2.6～2.4Ga,1.5～0.9Ga）；基于多年研究的积累，并综合了国内外一些可以应用的同位素年代学研究结果，提出以塔里木太古宙大陆地核向南、北逐步增生的新疆大陆地壳基底演化模式；确定了新疆大陆地壳构造演化中15次主要地质事件的时限为（3000～3200）Ma；2800Ma；2600～2500Ma；2200Ma；2000～1700Ma；1400Ma；1000Ma;；800Ma；700～>500Ma；520～480Ma；450Ma；360～300Ma；300～250Ma；210～135Ma；65～5Ma。这些同位素年代学和Nd同位素示踪研究结果无疑将成为进一步探讨新疆大陆地壳构造演化的一些重要依据。
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| 关 键 词： | 新疆 同位素年代学 地质事件 演化 大陆地壳 地球化学 |
| 文章编号： | 1000-8845(2001)01-012-08 |
| 修稿时间： | 2000年12月6日 |
A MODEL OF DIVISION OF THE
CONTINENTAL CRUS BASEMENT AND THE TIME SCALES OF THE MAJOR GEOLOGICAL EVENTS IN THE
XINJIANG -BASED ON STUDIES OF ISOTOPIC GEOCHRONOLOGY AND GEOCHEMISTRY |
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| HU Ai-qin,ZHANG Guo-xin,CHEN Yi-bing,ZHANG Qian-feng.A MODEL OF DIVISION OF THE
CONTINENTAL CRUS BASEMENT AND THE TIME SCALES OF THE MAJOR GEOLOGICAL EVENTS IN THE
XINJIANG -BASED ON STUDIES OF ISOTOPIC GEOCHRONOLOGY AND GEOCHEMISTRY[J].Xinjiang Geology,2001,19(1):12-19. |
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| Authors: | HU Ai-qin ZHANG Guo-xin CHEN Yi-bing ZHANG Qian-feng |
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| Abstract: | All results of radiometric isotopic dating, geochemical and Ndisotopic characterization for basement rocks and granitoids in the major tectonic terranes gained by the author from 1982 to 2000，especially, during 1987-2000 are summarized in this paper. The U-Pb ages of zircons for basement rocks of Xinjiang obtained recently are outlined, that are: age of 2600Ma for gneiss of the North Tarim, (2 048±20) Ma for garnet-biotite gneiss in the West Kunlun Orogen, (1820 ± 277) Ma for gneiss in Altun Orogen，(1 404 ± 18) Ma again measured for granitic gneiss of the Xingxingxia Group in the East Tianshan, which is as same as the result gained by author in 1986(1400 ± 42) Ma，(821 ± 11) Ma and (798 ± 8) Ma，(882 ± 83) Ma, and (707 ± 7) Ma for granitic gneisses of the Wenquan Group, the Nalati Group and the Muzha'erte Group in the West Tianshan, respectively；Baed on Nd model ages (TDM) used single- or two-stage model calculation and a model of the divisions of continental crustal basement of Xinjiang have been advanced. The five terranes are supposed in the Xinjiang: Tarim Terrane consists of Archean bimodal suite (TTG gneisses and amphibolites) and Proterozoic granitic gneisses. They have model age ranging from 3.2 to 2.2 Ga; Tianshan Terrane has distinguished basement rocks from Tarim. The Nd model ages of Tianshan basement fall in the range from 1.7 to 2.1 Ga and Kunlun-Altun Terrane, as same as Tianshan, the basement rocks also have TDM ages of 2.0-1.8 Ga; The basement rocks of Altai Terrane have TDM in two apparently discrete groups at 0.9-1.5 Ga and 2.4-2.6 Ga,; However, Jungger Terrane has very young basement rocks with TDM ages of 0.7-1.4 Ga. Presence of a minor Precambrian crustal component is possible, but no data of zircon U-Pb have shown Precambrian ages for Junggar basement anywhere. Using all data obtained by the author and together with published available data in the Xinjiang, a model of continental growth of Xinjiang from Tarim as a Archean continental nucleus to both sides of south and north was suggested. The time scales for 15 major events in geological evolutional history in the Xinjiang were limited, which are as follows：3 000~3 200 Ma；2 800 Ma；2 600~2 500 Ma；2 200 Ma；2 000~1 700 Ma； 1 400 Ma； 1 000 Ma； 800 Ma；700~>500 Ma；520~480 Ma；450 Ma；360~300 Ma；300~250 Ma；210~135 Ma； 65~5 Ma. All results of dating and Nd isotopic characteristics for rocks in Xinjiang would be as an important evidence to understand continental crustal evolution in Xinjiang. |
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| Keywords: | Xinjiang Isotopic geochronology Major geological events and evolution |
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