Paleomagnetism of the Xigaze ophiolite and flysch (Yarlung Zangbo suture zone, southern Tibet): latitude and direction of spreading
Paleomagnetism of the Xigaze ophiolite and flysch (Yarlung Zangbo suture zone, southern Tibet): latitude and direction of spreading
复制标题
日喀则蛇绿岩和复理石（藏南雅鲁藏布江缝合带）的古地磁：纬度和扩散方向
DOI：
10.1016/0012-821x(84)90022-0
复制
发表时间：
1984
影响因子：
5.3
通讯作者：
Lisheng Xing
中科院分区：
文献类型：
--
作者：
J. Pozzi;M. Westphal;J. Girardeau;J. Besse;Yaoxiu Zhou;X. Chen;Lisheng Xing
出露于雅鲁藏布江缝合带的日喀则蛇绿岩(29.2°N，89.5°E)代表了北至拉萨地块与南至印度板块之间形成于白垩纪中期的大洋岩石圈残留物。为了确定形成蛇绿岩的扩张中心的古方位和纬度，对火山岩中的3个地点和构成蛇绿岩序列上部的(或夹层)放射石进行了古地磁研究，并在北部地层上覆盖火山岩的日喀则群复理石中的7个地点进行了古地磁研究。在每个地点，仔细定位的手块都有太阳罗盘和磁罗盘的样本。古地磁数据结合蛇绿岩侵入岩的构造数据，可以部分重建日喀则蛇绿岩形成时的南欧亚大陆。日喀则蛇绿岩及其上覆沉积的古纬度为10-20°N，蛇绿岩和盆地都经历了85±20°的逆时针旋转。对应的山脊接近拉萨地块南缘，方位为N175±25°。
The Xigaze ophiolite (29.2°N, 89.5°E), which outcrops in the Yarlung Zangbo suture zone, represents the remnants of an oceanic lithosphere formed in middle Cretaceous times between the Lhasa block to the north and the Indian plate to the south. In an attempt to define the paleo-orientation and latitude of the spreading center at which it has been created, a paleomagnetic study has been done on three sites in volcanics and overlying (or interbedded) radiolarites forming the upper part of the ophiolite sequence and also on seven sites in the Xigaze Group flysch which stratigraphically overlies the volcanics to the north. In each site, hand-blocks carefully oriented both with sun and magnetic compass have been sampled. The paleomagnetism data, combined with structural data on the ophiolite dolerite intrusives, allow a partial reconstruction of South Eurasia at the time of formation of the Xigaze ophiolite. The paleolatitude of accretion and deposition of the Xigaze ophiolite and overlying sediments is found to be 10–20°N. Both ophiolite and basin have encountered a 85 ± 20° anti-clockwise rotation. The corresponding ridge was close to the southern margin of the Lhasa block and was oriented N175 ± 25°.