Collaborative Research: Investigation of Syncollisional Extension and Basin Development in the High Himalaya

合作研究：喜马拉雅高山同步碰撞伸展和盆地发育调查

• 批准号: 0438115
• 负责人: Peter DeCelles
• 金额: $ 29.07万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0438115&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigation; Syncollisional; Extension

A team of scientists from the University of Arizona and the University of Houston are investigating the nature of the transition from contraction to extension in the Zada basin area of the Himalayan uplift. The Zada basin is the largest late Tertiary basin in the Himalaya and is broadly constrained to be Late Miocene to Pleistocene in age. The basin fill and its underlying basement are spectacularly exposed owing to incision by the Sutlej River, a major southward-flowing trans-Himalayan drainage. The basin currently lies at approximately 3500 m elevation in the hinterland of the Himalayan thrust belt and developed on top of a regionally extensive Early to Middle Miocene thrust system. The thrust system flanks a second major basin, the Kailas basin, which is considered to have developed during mid-Tertiary time, but remains poorly dated. Together, the Zada and Kailas basins archive the collapse of this region from high to relatively low elevation and the transition from erosional denudation to thick sediment accumulation in only a few million years. The multidisciplinary study is using structural analysis, thermobarometry, argon-argon thermochronology, basin analysis, and oxygen isotope paleoaltimetry to place constraints on: (1) geometry, kinematics, and magnitude of slip of the Qusum detachment, South Tibetan Detachment, and Great Counter thrusts; (2) provenance and subsidence history of the Kailas thrust basin and Zada basin; (3) paleoelevation history of the Zada basin; (4) pressure-temperature-time paths recorded in the rocks exhumed by the major faults; and (5) the depth to which the major structures operated. Results are being used to determine the: (1) timing of onset of high-elevation extension in this part of the Himalaya; (2) mode of kinematic accommodation of extension in and around the Zada basin; (3) rates of arc-perpendicular and arc-parallel extension; (4) elevation at which extension began, and the evolution of paleoelevation and paleoenviornments of deposition in the Zada basin in response to ongoing extension; and (5) date at which the paleodrainage pattern in Zada basin become integrated into the headwaters of the modern Sutlej River. By answering these questions, three theories to explain the transition from arc-normal contraction and to arc-parallel extension in major orogenic belts are being tested: (1) extension occurs in regions of overthickened crust; (2) extension is due to outward expansion of the arc-shaped thrust front; or (3) extension is caused by extrusion of the middle crust. The project involves undergraduate and graduate students in the research, collaboration with Chinese scientists, and education and outreach efforts in both the United States and China.

来自亚利桑那大学和休斯顿大学的一组科学家正在研究喜马拉雅隆起扎达盆地地区从收缩到伸展的转变的性质。扎达盆地是喜马拉雅地区最大的晚第三纪盆地，其时代大致为晚中新世至更新世。由于苏特利河的切割，盆地填充物及其下面的地下室惊人地裸露出来，萨特利河是一条主要的向南流动的跨喜马拉雅水系。该盆地目前位于喜马拉雅冲断带腹地，海拔约3500m，发育在一个区域性广泛的早中新世逆冲系统之上。冲断系统位于第二个主要盆地凯拉斯盆地的两侧，该盆地被认为是在中第三纪时期发育的，但年代仍然很差。Zada和Kailas盆地共同记录了该地区从高海拔到相对低海拔的崩溃，以及从侵蚀剥蚀到厚重沉积物堆积的过渡，仅用了几百万年。这项多学科的研究正在利用构造分析、温压测量、Ar-Ar热年代学、盆地分析和氧同位素古海拔测量来限制：(1)库苏姆拆离、藏南拆离和大逆冲断层的几何学、运动学和滑动强度；(2)凯拉斯冲断盆地和扎达盆地的起源和沉降史；(3)扎达盆地的古隆起史；(4)主要断裂出土的岩石中记录的压力-温度-时间路径；以及(5)主要构造活动的深度。结果将用于确定：(1)喜马拉雅这一部分高海拔伸展的开始时间；(2)扎达盆地及其周围伸展的运动调节方式；(3)弧形垂直和弧形平行伸展速率；(4)扎达盆地开始伸展的海拔高度，以及对正在进行的伸展做出响应的古海拔和古沉积环境的演变；(5)扎达盆地的古排水模式融入现代苏特勒吉河源头的日期。通过回答这些问题，检验了解释主造山带从弧正收缩向弧平伸展转变的三种理论：(1)伸展发生在超厚地壳区域；(2)伸展是由于弧形逆冲前缘向外扩张；(3)伸展是由中地壳挤压引起的。该项目吸引了本科生和研究生参与研究，与中国科学家合作，以及在美国和中国的教育和推广工作。