昌都盆地古近系贡觉组物源及其沉积环境

为了研究昌都盆地古近系构造背景和沉积环境演化规律及其资源响应,采集12件昌都盆地贡觉组细碎屑岩样品,通过电子显微镜、XRF和等离子质谱分析（ICP-MS）以及野外沉积特征观察等方法进行系统研究。研究结果显示:盆地贡觉组以红色泥岩和砂岩为主,含纤维状石膏,发育交错层理,可见波痕构造和球状风化,揭示其气候以干旱氧化环境为主；镜下观察石英颗粒磨圆和分选性差,说明以近源沉积为主；主微量元素的岩性和构造图解显示样品主要落入长石砂岩和石英质砂屑砂岩区域以及岛弧环境；微量元素特征指示贡觉组一段和二段以半咸水—咸水的氧化环境为主,气候湿润,而第三段以咸水的强氧化环境为主,气候干热。上述特征表明贡觉组细碎屑岩主要是江达—阿中岛弧花岗岩体风化的产物,其环境演化可划分为两个阶段,第一阶段以贡觉组一段和二段的沉积环境变化为主,第二阶段以贡觉组第三段的沉积环境变化为主；进一步表明新特提斯闭合后,印度板块向欧亚板块俯冲,导致江达—阿中地区变形隆升更为强烈,类乌齐地区变形隆升相对弱,对油气资源的保存起着破坏作用。

Provenance and Sedimentary Environment of Paleogene Gongjue Formation in Qamdo Basin

To reveal the Paleogene tectonic setting, sedimentary environment evolution, and resource response of Qamdo Basin. twelve grain-fine clastic rock samples of the Gongjue Formation in the Qamdo Basin were collected and systematically studied by means of electron microscopy, XRF, plasma mass spectrometry （ICP-MS） and field observation of sedimentary characteristics. The research results show that Gongjue Formation in the basin is mainly composed of red mudstone and sandstone, containing fibrous gypsum, developing cross bedding, visible ripple structure and spherical weathering, which reveals that its climate is mainly arid and oxidative environment； Microscopic observation shows that the quartz grains are poorly rounded and sorted, indicating that the near source deposits are dominant； The lithological and structural diagrams of major and trace elements show that the samples mainly fall into feldspathic sandstone and quartzolithic sandstone areas and island arc environments； The trace element characteristics indicate that the first and second members of the Gongjue Formation are dominated by the oxidation environment of brackish water - saline water, with a humid climate, while the third member is dominated by the strong oxidation environment of saline water, with a hot and dry climate. The above characteristics indicate that the fine clastic rocks of the Gongjue Formation are mainly the products of weathering of the Jiangda Azhong island arc granite body. The environmental evolution can be divided into two environmental evolution model stages. The first stage is dominated by the changes in the sedimentary environment of the first and second members of the Gongjue Formation, and the second stage is dominated by the changes in the sedimentary environment of the third member of the Gongjue Formation； It further shows that after the closure of the New Tethys, the Indian plate subducted to the Eurasian plate, resulting in more intense deformation and uplift in the Jiangda Azhong region, and relatively weak deformation and uplift in the Leiwuqi region, which played a destructive role in the preservation of oil and gas resources.