藏南床得剖面古地磁结果对印度-亚洲碰撞方式的约束

发布时间：2018-03-04 13:50

  本文选题：藏南　切入点：床得剖面　出处：《科学通报》2017年04期 　论文类型：期刊论文

【摘要】：特提斯喜马拉雅位于大印度最北端,其构造演化是理解印度-亚洲大陆碰撞过程的关键之一.为了更好地限定特提斯喜马拉雅中生代以来的古地理位置及其漂移历史,本文对藏南江孜床得剖面侏罗系下热组、维美组和白垩系床得组开展了古地磁研究.古地磁样品取自39个采样点,其中下热组5个,岩性为青灰色安山岩;维美组25个,岩性为粉砂岩和砂岩;床得组9个,岩性为灰岩.对118个古地磁柱状样品进行的逐步热退磁和交变退磁结果显示,下热组和维美组样品未能分离出稳定的特征剩磁;床得组样品分离出了稳定的特征剩磁(Ch RM),且具有正反极性,并通过了倒转检验.结合沉积学和岩石磁学结果,床得组样品的特征剩磁很可能为原生剩磁,其年龄为86.3~74.0 Ma.床得组样品特征剩磁的平均方向为Ds=152.0°,Is=?52.9°,?=18.0,?95=5.9°.该数据表明,特提斯喜马拉雅江孜地区在晚白垩世(80.1±6.2 Ma)所处的古纬度为南纬33.1°±5.6°,与印度板块北缘同时代所处的古纬度一致(参考点28.0°N,88.5°E),说明二者至少在晚白垩世之前从运动学意义上仍然是一个块体,缺乏大洋分隔的证据.这为理解印度-亚洲大陆碰撞方式提供了新的古地磁约束.
[Abstract]:The Tethys Himalayas are located at the northernmost tip of Greater India, and their tectonic evolution is one of the keys to understanding the process of the Indo-Asian continent collision. In order to better define the paleogeographic location and drift history of the Tethys Himalayas since the Mesozoic, In this paper, paleomagnetic studies have been carried out on the lower Jurassic heat formation, the Weimei formation and the Cretaceous bed formation in Jiangzi bed section of southern Tibet. The paleomagnetic samples were collected from 39 sampling sites, of which 5 were from the lower heat formation, and 25 from the Weimei formation, with the lithology of bluish-gray andesite and the Weimei formation. The lithology is siltstone and sandstone, the bed formation is 9 and the lithology is limestone. The results of gradual thermal demagnetization and alternating demagnetization of 118 paleomagnetic columnar samples show that the samples of lower heat formation and Weimei formation can not separate stable characteristic remanence. The stable characteristic remanent magnetic remanence (CHRMN) was separated from the bed group, and it had positive and negative polarity, and passed the inversion test. Combined with the results of sedimentology and rock magnetism, the remanent magnetism of the bed group was likely to be primary remanent magnetism. The average direction of remanent magnetism of the bed samples is Ds=152.0 掳Isa? 52.9 掳? 18. 0? 955.9 掳. The data show that, The paleolatitude of the Tethys Himalayan Jiangzi area in the late Cretaceous (80.1 卤6.2 MaA) is 33.1 掳卤5.6 掳south latitude, which is the same as that of the northern margin of the Indian plate (reference point 28.0 掳Nwe 88.5 掳E ~ (-1)), which indicates that the paleolatitudes of the two regions were kinematic at least before the late Cretaceous. It's still a block, The lack of evidence of ocean separation provides a new paleomagnetic constraint for understanding the Indian-Asian continental collision pattern.
【作者单位】： 南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室;
【基金】：国家自然科学基金(41274071,41525007) 国家重点基础研究发展计划(2012CB822001)资助
【分类号】：P318.44;P542

【参考文献】

中国期刊全文数据库 前5条

1 陈曦;王成善;胡修棉;黄永建;魏玉帅;王平康;;西藏南部江孜盆地上侏罗统至古近系沉积岩石学特征与盆地演化[J];岩石学报;2008年03期

2 Jansa Luba;;Upper Cretaceous oceanic red beds in southern Tibet:Lithofacies,environments and colour origin[J];Science in China(Series D:Earth Sciences);2006年08期

3 朱弟成,潘桂棠,莫宣学,廖忠礼,江新胜,王立全;藏南特提斯喜马拉雅带中段二叠纪——白垩纪的火山活动(Ⅰ):分布特点及其意义[J];地质通报;2004年07期

4 李祥辉,王成善,万晓樵,陶然;藏南江孜县床得剖面侏罗-白垩纪地层层序及地层划分[J];地层学杂志;1999年04期

5 吴浩若;西藏南部江孜地区晚白垩世晚期及早第三纪(?)地层[J];地层学杂志;1987年02期

【共引文献】

中国期刊全文数据库 前10条

1 胡修棉;李娟;安慰;王建刚;;藏南白垩纪—古近纪岩石地层厘定与构造地层划分[J];地学前缘;2017年01期

2 潘桂棠;陆松年;肖庆辉;张克信;尹福光;郝国杰;骆满生;任飞;袁四化;;中国大地构造阶段划分和演化[J];地学前缘;2016年06期

3 董磊;李光明;李应栩;代作文;;藏南马扎拉地区玄武岩地球化学特征、成因及其地质意义[J];沉积与特提斯地质;2016年03期

4 董磊;李光明;李应栩;代作文;梁维;;藏南马扎拉矿区英安岩年代学与地球化学特征及其地质意义[J];地质通报;2016年08期

5 葛玉魁;王成善;戴紧根;李亚林;;西藏仲巴县特提斯喜马拉雅早白垩世日朗组玄武岩地球化学特征及其构造意义[J];现代地质;2016年01期

6 刘飞;杨经绥;连东洋;赵慧;张岚;张利;黄健;;西藏雅鲁藏布江缝合带西段南北亚带蛇绿岩的成因探讨[J];岩石学报;2015年12期

7 牛晓路;李国彪;韩子晨;O獾，

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