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Deformation of Asian continent

亚洲大陆变形

基本信息

批准号：
09041109
负责人：
OTOFUJI Yo-ichiro
金额：
$ 2.37万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09041109/
关键词：
PALEOMAGNETISM CONTINET DEFORMATION TECTONICS 中国アジア大陸大陸変形揚子地塊白亜紀

项目摘要

Collision of India and Asia is one of the most prominent tectonic events in Cenozoic time. The Indian continent collided to Asia at about 52 Ma and continued to penetrate into the Asian continent. The northward penetration of the India gave rise to tectonic deformation in the Asian continent.The present program of investigation aims to detect tectonic defonriation on eastern part of Asian continent from paleomagnetic view points. We chose the Yunnan and Sichuan in China areas as possible areas which was subjected to deformation due to collision of Indian continent. Inner Mongolia of China and Sikhote Alim area in Russia are regarded as areas without any deformation.We carried out our paleomagnetic study in these four areas. We focused the Jurassic welded tuffs, the Jurassic red sandstones, the Upper Cretaceous red sandstones and the Paleocene wefded tuffs, because late Mesozoic formation preserves evidence of deformation later than 52 Ma when India collided. More than 750 samples were collected from these four areas. Three to ten hand samples, oriented with a magnetic compass, were distributed over a distance ranging up to 15m in a site. Localities of sites were determined by a portable navigational instrument. The present declination value at the sampling point was estimated from the calculation using the International Geomagnetic Reference Field of 1994.In the laboratory, individual specimens, 25mm in diameter and 23mm long, were prepared from samples. Natural remanent magnetizations were measured with a 2G cryogenic magnetometer. One specimen from each sample was subjected to stcpwise thermal demagnetization up to 690* 710*. Measurement data are now analyzed.

印度与亚洲的碰撞是新生代最突出的构造事件之一。印度大陆在52 Ma左右碰撞到亚洲，并继续深入亚洲大陆。印度向北渗透引起了亚洲大陆的构造变形。本次调查的目的是从古地磁角度探测亚洲大陆东部的构造变形。我们选择中国的云南和四川地区作为因印度大陆碰撞而变形的可能地区。中国内蒙古和俄罗斯锡霍特阿利姆地区被视为没有变形的地区。我们对这四个地区进行了古地磁研究。我们重点关注侏罗纪熔结凝灰岩、侏罗纪红砂岩、上白垩统红砂岩和古新世熔结凝灰岩，因为晚中生代地层保留了晚于印度碰撞时52 Ma的变形证据。从这四个地区采集了 750 多个样本。 3 到 10 个手部样本，用磁罗盘定向，分布在一个地点最远 15m 的距离内。地点的位置是通过便携式导航仪器确定的。采样点的当前磁偏角值是根据 1994 年国际地磁参考场计算得出的。在实验室中，从样品中制备了直径 25 毫米、长 23 毫米的单个样本。使用 2G 低温磁力计测量自然剩磁。每个样品中的一个样品经受高达 690* 710* 的逐级热退磁。现在分析测量数据。