开鲁盆地南部下三叠统红砬组地球化学特征及沉积环境分析——以奈参1井为例

GEOCHEMISTRY AND SEDIMENTARY ENVIRONMENT OF LOWER TRIASSIC HONGLA FORMATION IN SOUTHERN KAILU BASIN: A Case Study of NC1 Well

摘要: 为揭示开鲁盆地南部地区下三叠统红砬组的构造背景及沉积环境, 对奈参1井26件细碎屑岩样品进行了常量、微量以及稀土元素测试分析. 研究表明: 红砬组沉积物源具有多样性, 主要来自上地壳长英质岩石源区, 还有少量来自中、基性火成岩物源区. 物源构造背景主要为主动大陆边缘, 可能形成于靠近大陆岛弧的活动大陆边缘构造背景. 红砬组沉积环境总体上处于氧化-弱还原的陆相淡水-半咸水环境, 向上水体盐度有增大趋势, 古气候整体上为干旱炎热气候.

Abstract: The major, trace and rare earth elements of 26 fine clastic rock samples from NC1 well are tested and analyzed to reveal the tectonic setting and sedimentary environment of Lower Triassic Hongla Formation in southern Kailu Basin. The results show that the sediment sources of Hongla Formation are diverse, mainly from the felsic rock source area in the upper crust with minors from the intermediate and basic igneous rock source areas. The tectonic setting of the provenance is mainly active continental margin, which may be formed in the tectonic background of active continental margin near the continental island arc. The Hongla Formation is generally in an oxidative-weakly reductive terrestrial freshwater-brackish water sedimentary environment, with the water salinity increasing from bottom to top. The paleoclimate was arid and hot on the whole.