鄂尔多斯盆地渭北隆起中—新生代构造特征及多种能源矿产共存关系

魏东+马中豪+陈清石

摘要：鄂尔多斯盆地渭北隆起蕴藏着丰富的煤、油页岩、石油、铀等能源矿产，多种能源矿产共存与构造特征关系、多种能源矿产协同勘探已成为地学界研究的热点课题。在分析总结多种能源矿产时空分布规律及成因联系的基础上，以构造演化特征为主线，重点探讨了构造运动期次、沉积建造、构造单元特征、褶皱构造与多种能源矿产的关系。结果表明：渭北隆起印支期—燕山早期的成盆-差异升降运动形成了本区稳定的深湖—半深湖相含油页岩与不稳定的沼泽相含煤沉积建造组合；燕山中晚期的构造热事件促使油页岩成熟生烃、煤级升高；燕山期—喜山期的断裂、褶皱构造为油气和富铀低温油水热液运移和成藏提供了通道和富集成矿（藏）的场所；喜山期的抬升冷却和南缘断陷作用使得多种能源矿产共存富集得到了最终保存定位，且统一成矿年龄集中在74～122 Ma，稍晚于燕山中晚期的构造热事件。综合考虑地质、经济和技术因素，将彬旬凹陷成矿区划分为4个协同勘探区，并建立了合理的勘探模式。

关键词：能源矿产；共存富集；构造演化；沉积建造；构造热事件；协同勘探；渭北隆起；鄂尔多斯盆地

中图分类号：P618；TE122 文献标志码：A

Abstract： Weibei uplift in Ordos Basin is rich in coal， oil shale， oil， uranium and other energy minerals， the relationship between the coexistence of multiple energy minerals and the structural characteristics， and the co-exploration of multiple energy minerals are hot topics. On the basis of analyzing and summarizing the spatial distribution and genetic relationship of multiple energy minerals， the relationship between period of tectonic movement， sedimentary formation， characteristics of tectonic unit， fold structure and multiple energy minerals were discussed according to the characteristics of tectonic evolution. The results show that the basin formation-differential uplift in Indosinian-Early Yanshanian forms the stable deep and semi-deep lacustrine facies containing oil shale and the unstable swamp facies containing coal sedimentary formation in Weibei uplift； the tectonic thermal events in Middle-Late Yanshanian cause the oil shale hydrocarbon generation and coal quality improved； the fault and fold structure in Yanshanian-Himalayan Period provide the channel and interspace for the migration and accumulation of petroleum and hydrothermal solution containing oil water with low temperature and rich uranium； rising-cooling and the southern rift in Himalayan Period keep the coexistence and accumulation of multiple energy minerals， and the unified metallogenic ages are 74-122 Ma， which are later than the tectonic thermal events in Middle-Late Yanshanian. Finally， based on the geological， economic and technical factors， the metallogenic provinces of Binxun depression were divided into 4 co-exploration areas， and the corresponding reasonable exploration models were built.

Key words： energy mineral； coexistence and accumulation； tectonic evolution； sedimentary formation； tectonic thermal event； co-exploration； Weibei uplift； Ordos Basin

0 引 言

渭北隆起大地构造位置处于鄂尔多斯盆地西南部NE—SW向构造带上，自北向南由彬旬凹陷、北缘挠褶带、铜川断褶带组成，区内石油、油页岩、煤、砂岩型铀矿等能源矿产共存富集。长期以来，盆地构造演化与多种能源矿产共存关系的研究一直是地学界十分引人关注的课题，正在逐渐成为国家重大基础专项研究和亟待解决的科学问题[1-3]。近年来，渭北隆起虽然在油气、煤、铀、油页岩等单一矿种的成矿规律、成矿条件和富集机理等方面的研究取得了较大进展，但遗憾的是多年来各类矿产由多部门独立勘探开发和研究，对于多种能源矿产的整合研究和协同勘探开发则较为薄弱，对于多种能源矿产共存与构造演化的关系研究需要更加深入。渭北隆起彬县—铜川地区勘探历史久远，资料丰富，特别是近十年来本区油页岩、砂岩型铀矿的整装勘查和综合研究成果显著，新发现了较多的油页岩、铀、煤、石油矿产地，这一地区正在成为探索研究渭北隆起多种能源矿产共存与构造演化及其耦合成矿效应的理想基地。本文分析总结了多种能源矿产时空分布规律及成因联系，以构造演化特征为主线，重点探讨了构造演化与沉积建造、构造热事件与多种能源矿产、褶皱构造与油铀成矿（藏）的关系，进而划分了4个协同勘探区，并建立了合理的勘探模式。