塔里木盆地顺托果勒低隆起顺北4号走滑断裂带成岩流体类型及活动特征

Types and features of diagenetic fluids in Shunbei No. 4 strike-slip fault zone in Shuntuoguole Low Uplift, Tarim Basin

宋刚 李海英 叶宁 韩俊 肖重阳 鲁子野 李映涛

SONG Gang LI Haiying YE Ning HAN Jun XIAO Chongyang LU Ziye LI Yingtao

中国石油化工集团有限公司, 北京 100728 中国石化 西北油田分公司 勘探开发研究院, 乌鲁木齐 830011 西南石油大学 地球科学与技术学院, 成都 610050 中国石化 石油勘探开发研究院, 北京 102206

China Petroleum and Chemical Corporation (SINOPEC), Beijing 100728, China Research Institute of Exploration and Production, SINOPEC Northwest Oilfield Branch Company, Urumqi, Xinjiang 830011, China School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 102206, China

塔里木盆地顺托果勒低隆起顺北4号走滑断裂带是该地区重点勘探目标，中奥陶统碳酸盐岩是主要的含油气层系。断裂活动及伴随断裂活动的断裂流体活动控制了研究区内储层的分布，因此，研究断裂流体的活动特征对勘探工作至关重要。针对研究区顺北4号断裂带内中奥陶统碳酸盐岩裂缝中的方解石进行了岩石学、原位锶同位素、原位稀土元素和U-Pb测年研究。方解石的锶同位素比值为0.708 498~0.709 177，方解石稀土元素表现出明显的Ce负异常、Eu正异常和高Y/Ho比值。方解石U-Pb测年获得的年龄分别为(433±17) Ma和(449±15) Ma。方解石的原位锶同位素和稀土元素特征说明流体充分继承了碳酸盐岩围岩的特征且经历了高温；U-Pb年龄则说明顺北4号断裂带方解石记录的更可能是与阿尔金造山带挤压造山相关的加里东中期Ⅲ幕运动的断裂流体活动。

The Shunbei No. 4 strike-slip fault zone is an important exploration target in the Shuntuoguole Low Uplift of Tarim Basin, and the Middle Ordovician carbonate is a major hydrocarbon-bearing stratum. Fault structures and accompanied fluids play a key role for the distribution of carbonate reservoirs, and it is therefore important to study the fluids accompanied with fault evolution. Petrography, in situ Sr isotopic compositions, in situ rare earth elements (REE) and U-Pb dating were carried out to reveal the fluids from which the calcites in fractures precipitated. The calcites in fractures show 87Sr/86Sr ratios of 0.708 498-0.709 177, and the REE patterns of the calcites are characterized by negative Ce anomaly, positive Eu anomaly and high Y/Ho ratios. The calcite samples show U-Pb isochron age of (433±17) Ma and (449±15) Ma, respectively. The 87Sr/86Sr ratios and REE patterns of the calcites suggest that parent fluids experienced elevated temperature environment and buffered by carbonate host rocks. The U-Pb isochron age implies that the calcites may record the fault-related fluids during the Ⅲ stage of the Middle Caledonian Movement, which might be associated with the Altyn orogeny.

https://doi.org/10.11781/sysydz202204603