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印度-亚洲的初始碰撞问题是当今地球科学研究的热点.印度-亚洲碰撞带西段经历了从弧陆碰撞到陆陆碰撞的复杂演化过程,重建这一过程有利于更为全面地揭示和理解陆陆碰撞及造山的动力学机制.本文对西构造结附近各个地体(西拉萨-喀喇昆仑、科西斯坦-拉达克及喜马拉雅地体)白垩纪以来的古地磁数据(6个原生及35个次生分量)进行了回顾和总结,古地磁原生分量指示亚洲大陆南缘和科西斯坦岛弧在碰撞前分别位于约14°N和赤道附近,很可能代表了陆陆及弧陆初始碰撞发生的位置;统计分析表明重磁化分量对应的古纬度在分布上存在3个显著的峰值(分别为约3°S~2°N、12°N及22°N),前两个峰值与原生分量指示的古纬度重叠,暗示重磁化可能与弧陆及陆陆初始碰撞伴随的造山作用有关;现有层析成像资料业已表明印度-亚洲碰撞带之下的地幔中存在两条带状分布的新特提斯洋残留洋壳,本文进一步通过初步的动力学数值模拟,表明现今残留洋壳的位置能够大致代表洋壳断离时古缝合带的位置,而该位置又与古地磁数据所揭示的初始碰撞位置基本一致.上述结果一致地表明印度-科西斯坦-亚洲之间弧陆及陆陆初始碰撞分别发生于近赤道及北半球低纬度地区(约14°N)附近,结合最新印度板块的运动轨迹及不同的大印度模型,推测上述弧-陆及陆-陆初始碰撞时间分别不晚于约62 Ma和约48 Ma.
The initial collision problem of India-Asia is a hot spot in geoscience research today.The western section of the Indian-Asian collision zone has undergone a complicated evolution process from arc-continent collision to land-continent collision. Reconstruction is helpful to reveal and understand more comprehensively Terrestrial collision and orogenic mechanism.On the Cretaceous paleomagnetic data of six terranes (West Lhasa-Karakoram, Koskirchen-Ladakh and Himalayas) near the western tectonic knot And 35 secondary components) were reviewed and summarized. The paleomagnetic indication indicates that the southern margins of the Asian continent and the Cauchyis arcs were located at about 14 ° N and the equator near the collision respectively before the collision, which probably represent the land and the arc The statistical analysis shows that there are three significant peaks (about 3 ° S ~ 2 ° N, 12 ° N and 22 ° N, respectively) in the paleo-latitude corresponding to the components of heavy and magnetization. The first two peaks Overlapping with the paleo-latitudes indicated by the primary components suggest that the re-magnetization may be related to the orogeny accompanying the initial continental arc and land-continent collisions; the available tomographic data have shown that there are two bands in the mantle below the India-Asia collision zone Distribution of new This paper further through the initial numerical simulation of dynamics shows that the present position of the oceanic crust can roughly represent the position of the ancient suture when the oceanic crust is disconnected, which is similar to the initial The above results consistently show that the initial land-continent collision between India-Corsica-Asia occurred near the equator and in the low latitudes of the northern hemisphere (about 14 ° N), respectively. Combining the latest Indian plate motion Trajectories and different large Indian models, it is speculated that the above-mentioned initial collision time of the above arc-land and land-continental no later than about 62 Ma and about 48 Ma respectively.