Constraining the Nature and Formation Age of the Shyok Suture Zone in Ladakh, NE India

喜马拉雅山脉的壮观高度和长度激励了世界各地的几代人。 山脉是在大约4000万至5000万年前印度大陆和欧亚大陆碰撞期间形成的。 在这次碰撞发生之前，一个名为Neotethys的海洋将两个大陆分开，它消失的时间仍然是一个悬而未决的问题。该项目将通过对印度北方科希斯坦-拉达克地区的年龄测定和古地磁测量，更好地确定两个大陆碰撞的时间。 更好地限制新特提斯洋碰撞和消失的时间不仅对我们了解喜马拉雅山脉至关重要，而且对解决其他大问题也至关重要，例如构造板块在重大碰撞事件中如何重组以及构造力对全球气候的影响。该项目的主要目标是更好地限制Shyok缝合带的性质和年龄，并测试科希斯坦-拉达克-欧亚大陆碰撞的替代模型。如果Shyok缝合线比Indus缝合线年轻，那么Shyok-Tsangpo缝合带，而不是Indus-Tsangpo缝合带，记录了印度和亚洲的最后碰撞，并且两个俯冲系统存在于Neotethys海洋中，直到大约50 Ma。 我们将结合野外地质填图、岩石学/地球化学、锆石U-Pb年代学和古地磁测量进行详细的研究。这项工作将限制目前未知的年龄和物源的多个沉积序列中的缝合带，以及提供新的信息的地球化学特征和年龄的深成岩在缝合带和邻近的岩石。此外，拟议的古地磁工作将确定印度-欧亚大陆碰撞的关键时刻科希斯坦-拉达克弧和欧亚大陆边缘的未知古纬度，从而使我们能够评估不同的碰撞情景。与该项目相关的工作构成了对喜马拉雅山脉关键但不受约束的缝合带的全面和多方面的记录，并提供了利用最近增加的印度拉达克关键暴露的机会。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The spectacular height and length of the Himalayan Mountain Belt has inspired generations of people across the world. The mountain chain was formed during the collision of the Indian and Eurasian continents approximately 40-50 million years ago. Before this collision occurred, an ocean called the Neotethys separated the two continents and the timing of its disappearance remains an open question. This project will better constrain the timing of the collision between the two continents by age dating and paleomagnetic measurements in the Kohistan-Ladakh region of northern India. A better constraint on the timing of the collision and disappearance of the Neotethys ocean is essential not only for our understanding of the Himalayas, but also for addressing other big questions such as the how tectonic plates reorganize during major collisional events and the influence of tectonic forces on global climate.The principal goals of this project are to better constrain the nature and age of the Shyok suture zone, and to test alternative models for the Kohistan-Ladakh-Eurasia collision. If the Shyok suture is younger than the Indus suture, then the Shyok-Tsangpo suture zone, not the Indus-Tsangpo suture zone, records the final collision of India and Asia, and two subduction systems were present in the Neotethys ocean until approximately 50 Ma. We will conduct a detailed study combining field geologic mapping, petrology/geochemistry, U-Pb zircon geochronology, and paleomagnetic measurements. This work will constrain the currently unknown age and provenance of multiple sedimentary sequences in the suture zone as well as provide new information on the geochemical characteristics and ages of plutonic rocks within the suture and in neighboring terranes. Additionally, the proposed paleomagnetic work will determine the unknown paleolatitudes of both the Kohistan-Ladakh arc and Eurasian margins during the crucial time of the India-Eurasia collision and thus allow us to evaluate the different collision scenarios. The work related to this project constitutes a comprehensive and multifaceted documentation of a pivotal yet unconstrained suture zone in the Himalaya and offers the opportunity to capitalize on the recently increased access to crucial exposures in Ladakh, India.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.