岩石矿物学杂志2026，Vol.45Issue(3)：584-602,19.DOI:10.20086/j.cnki.yskw.2026.5092
鄂尔多斯盆地北部中侏罗统直罗组岩石地球化学特征及其地质意义
Lithogeochemical characteristics of the Middle Jurassic Zhiluo Formation in the northern Ordos Basin and its geological significance
摘要
Abstract
The Hangjinqi area in Inner Mongolia is one of the significant uranium-bearing regions in the northern Ordos Basin,with favorable geological conditions and promising exploration prospects for mineralization.This paper conducts sedimentological,petrological and geochemical analyses on the core samples of the Middle Jurassic Zhiluo Formation from the borehole X7-6 in the Hangjinqi area,systematically studying the conditions conducive to urani-um enrichment and mineralization.The research results show the lower section of the Zhiluo Formation comprises braided river deposits,mainly composed of the thick-bedded gray sandstone and thin mudstone interbedded with thin coal seams,rich in carbonaceous debris and pyrites,while the upper section is characterized by meandering river and deltaic sedimentation,dominated by purple-red siltstone and mudstone.The geochemical characteristics exhibit a"right-inclined"pattern with enrichment of light rare earth elements and depletion of heavy rare earth ele-ments.The chemical index of alteration(CIA)values rangs from 54 to 77,indicating moderate chemical weathering of the Zhiluo Formation during deposition.The paleoenvironmental and paleoclimatic discrimination indicators Sr/Cu,U/Th,V/Cr,Ni/Co,V/(V+Ni),and Sr/Ba values suggest that the paleowater system during the deposition of the Zhiluo Formation was an oxygen-rich freshwater environment,and the paleoclimate underwent a transition from alternating dry and wet conditions to arid and semi-arid conditions.The tectonic setting of source areas of the Zhiluo Formation are continental arcs,and the provenances are primarily composed of the upper crustal felsic rock.The sedimentary environments,tectonic setting,paleoclimate and provenance characteristics can provide favorable geological conditions for uranium enrichment and mineralization in the Zhiluo Formation of the Hangjinqi area.关键词
鄂尔多斯盆地/直罗组/沉积环境/地球化学/成矿条件Key words
Ordos Basin/Zhiluo Formation/sedimentary environment/geochemistry/mineralization conditions分类
天文与地球科学引用本文复制引用
李宗谚,王涛,彭楠,李素萍,贾建亮,李文强,姚清继..鄂尔多斯盆地北部中侏罗统直罗组岩石地球化学特征及其地质意义[J].岩石矿物学杂志,2026,45(3):584-602,19.基金项目
国家重点研发计划(2023YFC2906701) （2023YFC2906701）
地球深部探测与矿产资源勘查国家科技重大专项(2025ZD1006801) National Key Research and Development Program(2023YFC2906701) （2025ZD1006801）
Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(2025ZD1006801) （2025ZD1006801）
