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《China Geology》2022,5(4):637-648
Based on the 16 scenes GF-1 satellite multi-spectral remote sensing images, through the adoption of data processing methods including orthorectification, geometric rectification, data fusion and image mosaic, integrated with field surveys, the remote sensing interpretation signs for the inland wetland types have been built, and the remote sensing survey of inland wetlands in Yadong region has been initiated, with six types of inland wetlands recognized in Yadong region, namely permanent rivers, seasonal rivers, lakes, salt lakes, alpine meadows, and inundated land. The spatial distribution characteristics and the spreading rules of these wetlands have also been revealed. Based on full understanding of the overall characteristics of the inland wetlands in the Yadong region, using the three phases of TM images acquired in 1989, 2003 and 2008 as well as the PMS2 data gathered by GF-1 in 2014, and the wide-range data (WFV3) gathered by GF-1 in 2020. As to the typical salt lakes, a long- time salt lakes transition study was carried out. The results show that the typical salt lakes in Yadong have been shrinking in the past three decades. The average annual shrinkage of Duoqing Co (Co means lake in Tibetan) was stronger than that of Gala Co, which are respective 87.30 hectares (usually short as ha; 1 ha equals to 0.01 km2) /a and 24.20 ha/a; the shrinkage degree of Gala Co was higher than that of Duoqing Co, shrank by 59.27% and 35.73% respectively. Based on the remote sensing survey results and an integrated analysis of the predecessors’ researchers, the reason for the shrinkage of the salt lakes is more inclined to geological factors. Geological process is manifested by a series of extensional faults at the bottom of the lake basin generated from tectonic activities, providing fluid infiltration channels, and inducing the eventual leakage of lake water to the lower strata. The result provides an important instance for understanding the evolution characteristics of wetlands and salt lakes in specific environment of the Tibetan Plateau.©2022 China Geology Editorial Office. 相似文献
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喜马拉雅造山带亚东地区多期构造热事件——锆石和独居石U-Th-Pb年代学证据 总被引：1，自引：0，他引：1
喜马拉雅造山带是研究板块构造的天然实验室,位于造山带核心部位的大喜马拉雅岩系是揭示碰撞造山过程和造山带演化的关键。本文主要对亚东地区大喜马拉雅岩系中的花岗质片麻岩进行了岩相学、锆石和独居石UTh-Pb年代学以及全岩主微量地球化学研究。野外和显微结构特征观察表明,花岗质片麻岩的矿物组合为斜长石+钾长石+石英+黑云母+石榴石,岩石发生了部分熔融,经历了高角闪岩相至麻粒岩相的变质作用。年代学和全岩地球化学研究表明,花岗质片麻岩的原岩包括新元古代(～800 Ma)的花岗闪长岩和志留纪(～440 Ma)的花岗岩,二者均在中新世(～16 Ma)发生了变质作用。新元古代花岗闪长岩具有负的εHf(t)值(-16. 4～-12. 2),地壳Hf模式年龄为3. 11～2. 79 Ga,说明其起源于古老下地壳物质的部分熔融。新元古代花岗闪长岩和志留纪花岗岩具有相似的弧花岗质岩石地球化学特征,即具有高场强元素Nb、Ta、P和Ti的负异常。本次研究表明大喜马拉雅岩系经历了多期构造热事件,其不仅记录了新生代的碰撞造山作用,还记录了与新元古代与罗迪尼亚超大陆演化相关的岩浆热事件以及古生代冈瓦纳大陆拼合后的周缘安第斯型造山作用。 相似文献
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断裂带中的方解石脉作为流体的直接记录,保存了丰富的断层活动信息。亚东裂谷是藏南地区南北向裂谷系中一条具有区域规模的大型裂谷,自北向南分别为热隆、涅如堆以及帕里次级裂谷。本文在涅如堆地堑南、北部和帕里地堑北部裂谷断层选取三个采样点,对沿断层发育的方解石脉进行研究,揭示了脉体与地震活动的关系、流体来源以及古地震发生时间。显微结构观察显示,方解石脉主要具有块状和拉长块状结构,分别代表了同震快速沉淀以及震后的同构造期沉淀。涅如堆地堑北部方解石脉具有Eu元素正异常以及高87Sr/86Sr比值的热液特征,异常轻的碳氧同位素值显示出地幔流体和大气水贡献。涅如堆地堑南部和帕里地堑北部方解石脉具有Ce和Eu负异常以及Y正异常的低温特征,与区域内灰岩相近的δ13C和87Sr/86Sr值反映了围岩来源,偏负的δ18O表明同样存在大气水贡献。方解石的地球化学特征反映了裂谷断层切割深度大,在断层活动期间能够沟通不同深度域的流体。断层亚东裂谷涅如堆段方解石脉铀系测年结果为距今679±129ka,帕里段北部结果为距今544±26ka、444±15ka和408±13ka,由于以上样品均具有同震或同构造期的内部结构特征,因此测年结果代表了地震活动时间。结合涅如堆段发育的断层三角面高差,计算出裂谷断层中更新世以来的E-W向伸展速率为0.17~0.24mm/yr,小于晚更新世以来0.8±0.3mm/yr的伸展速率,以及GPS观测的伸展速率6mm/yr。即中更新世以来,亚东裂谷涅如堆段断层活动速率逐渐增大。该地区断裂带中广泛发育的方解石脉能够为基岩区的断层活动和古地震研究提供宝贵的资料。 相似文献
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藏南拆离系和亚东裂谷是藏南地区重要的伸展构造,与青藏高原的隆升和生长密切相关,其新生代以来的构造热-年代学研究,对探讨高原的生长过程和大陆变形动力学具有重要意义。本文对西藏南部亚东地区的冲巴雍错花岗岩进行了U-Pb定年和低温热年代学分析,结果表明,岩体自22Ma侵位后经历了5个不同的冷却阶段：18~15.6Ma期间岩体的冷却速率为125℃/Myr;15.6~11Ma期间,平均冷却速率约94℃/Myr;11~7Ma期间,平均冷却速率约24℃/Myr;7~3Ma平均冷却速率约5℃/Myr;3Ma以后平均冷却速率约为14℃/Myr。因岩体位于藏南拆离系内,又被亚东断层切过,认为藏南拆离系的活动时限为22~11Ma,亚东正断层的起始活动时间为11Ma,且热历史模拟结果显示岩体在~3Ma发生了快速冷却,可能指示了亚东裂谷的一次强烈活动。 相似文献