中巴经济走廊带末次冰期以来的冰进序列及其年代学研究

Glaciers are highly sensitive to climate change and have been responsible for shaping some of the most spectacular landscapes in high and cold regions throughout the world. These landforms are direct imprints of past glacial fluctuations and represent important archives of past climatic and environmental information. Studies of glacial landforms can define the timing, extent, properties, and types of ancient glaciers, and can improve our understanding of temporal and spatial shifts of past glaciers. This can help us understand paleoenvironments and potential impacts of future climate change. .Developing an accurate and reliable chronological framework for glacial events and glacial landform evolution has traditionally been one of the most challenging problems in Quaternary research. Newer dating techniques, including cosmogenic radionuclides (CRN), optically stimulated luminescence (OSL) and electron spin resonance (ESR) have been developed and refined over the past three decades and are now being used to provide reliable quantitative constraints on the ages of glacial sediments and landforms. Research on Quaternary glaciations has thus entered a new stage in which the emphasis is on accurate dating, with quantitative techniques augmenting conventional mapping and relative age dating. This is producing significant advances in our understanding of Quaternary glaciations, and is yielding scientific data that can be compared reliably with international chronological records. .The China–Pakistan Economic Corridor runs through the eastern Pamir, Karakoram, and the western segment of the Himalayas and Hindu Kush. This region is one of the most tectonically active and highly glaciated mountain systems on Earth. During glacial-interglacial cycles in the Quaternary, glaciers in this region have experienced extensive advance and retreat, producing spectacular erosional, depositional, and glaciofluvial landforms from multiple glaciations that are well preserved in valleys and on piedmonts. Distinct and integrated sets of landforms from the last glacial cycle are the focus of our study of late Quaternary glaciations along this corridor. We will use CRN, supplemented by OSL and ESR dating techniques, to determine the timing of the glacial landforms in the Gaizi and Tashkurgan River valleys in China, and the Hunza catchment in Pakistan. This project will provide a reliable chronological framework for late Quaternary glacial events along the China–Pakistan Economic Corridor, and will test the hypothesis that there was a large glacial advance during middle marine oxygen isotope stage (mid-MIS) 3 that was similar in extent to the advance during the global Last Glacial Maximum (gLGM). In addition, we will be able to assess the properties and types of ancient glaciers, and will use ArcGIS software and computer modeling to analyze glacial landform evolution in key areas along the corridor..Building on the achievements of traditional mapping, the addition of accurate dating will fill an important gap in knowledge in the China–Pakistan Economic Corridor and provide essential information for palaeoclimatic modeling and palaeoenvironmental reconstructions, as well as new data for late Quaternary glaciation research and glacial landform evolution in High Asia. In addition, the results of our study can be of value in selecting appropriate construction lines or sites for important engineering projects, and in hazard analyses that reduce the potential for damage to key infrastructure.

高寒地区形态独特的冰川地形是古冰川时空演化最直接的证据，包含有重要的古气候环境变化信息。中巴经济走廊带横贯东帕米尔高原、喀喇昆仑山、喜马拉雅山西段与兴都库什山等山系和高原的交汇区，该廊带地质构造活跃且为地球中低纬度冰川最发育、分布最密集的区域。在第四纪冰期间冰期旋回中，多次规模较大的冰川进退留下了多套形态清晰的冰川地形，其中末次冰期以来的冰川地形保存的最为完整，是研究走廊带晚更新世以来冰川变化与环境演化的理想素材。我们将应用CRN，辅以OSL与ESR等测年技术对走廊带中的盖孜河、塔什库尔干河与洪扎河流域末次冰期以来的冰川地形进行综合定年，确定其时序、规模与性质；检测走廊带MIS 5d、5b与3中期冰进事件的有无；重建全新世的冰川波动史。本研究可为走廊带末次冰期以来的气候模拟与环境重建提供可靠的古冰川信息，还可为走廊带中点线状工程的建设选址、安全运营、以及防灾减灾等提供科学依据与数据支持。

高寒地区冰川侵蚀与沉积地形是古冰川时空演化最直接的证据，对他们进行研究可获得古冰川的规模、期次、类型与性质等重要信息。课题执行期间，我们运用地貌地层学原理辅以分辨率高的遥感影像/地形图等，对中巴经济走廊带中的木吉河流域（盖孜河一支流）与巴基斯坦境内的洪扎河流域的冰川地貌进行了考察，根据冰川沉积的接触关系，风化胶结状况与土壤植被等发育状况，初步确定它们的相对年代序列。采集了可以直接测定冰川沉积年龄的宇宙成因核素（CRN）年代学样品68个，洪扎河流域17个样品的测试结果显示，在巴托拉冰川、帕苏冰川与古尔金冰川外围，保存有小冰期、新冰期与晚冰期的冰川沉积地形，结合此前已有的CRN与OSL年代学资料，初步获得洪扎河流域末次冰期以来较为完整的冰川演化序列。已送至美国Purdue大学的其他样品将陆续得到测试结果。届时可以获得中巴经济走廊带末次冰期以来的冰川时空变化与地貌演化信息。本研究为中巴经济走廊带的第四纪冰川研究增添新的内容，特别是小冰期、新冰期与晚冰期确切的定年结果。同时也为本区末次冰期以来的气候模拟与环境重建提供基本可靠的古冰川信息，而且还可为走廊带点、线状工程的建设选址、安全运营、以及防灾减灾等提供科学依据与数据支持。