【作者】 于文斌；

【导师】 冯本智； 董清水； 简晓飞；

【作者基本信息】 吉林大学 ， 矿物学、岩石学、矿床学， 2009， 博士

【摘要】 松辽盆地南部不仅是重要的油气成藏区,也是砂岩型铀矿富集成矿区。本文在综合研究钻井、地震及其它地质资料的基础上,运用砂岩型铀成矿理论及层序地层、沉积体系分析方法,结合实验分析测试数据成果,对砂岩型铀矿富集形成的构造环境、沉积相、砂体特征、后生改造条件及铀矿化特征、控矿因素进行了研究。根据白垩系层序地层研究,认为松辽盆地南部有利成矿砂体为上白垩统泉头组一段和姚家组低水位体系域形成的辫状河砂体。沉积体系、沉积相及其有利相带分析表明,松辽盆地南部泉头组有利于铀成矿的辫状河砂体主要分布于章古台—协尔苏、通辽—保康及杨大城子地区。铀成矿规律研究表明,辫状河相是砂岩型铀矿找矿的主要沉积相类型。松辽盆地南部铀矿化主要受盆内反转背斜带和盆缘掀斜两种构造环境控制,其中掀斜作用形成的斜坡带控制着区域层间氧化带;盆内反转隆升形成的构造剥蚀天窗控制着局部氧化带,铀成矿作用与局部氧化带关系密切,受局部氧化带发育规模及程度控制。松辽盆地南部砂岩型铀矿床矿体形态有别于经典层间氧化带型卷状铀矿体,其矿体形态呈板状产出。“局部氧化带控制板状铀矿体”的新发现,丰富了氧化带型砂岩铀成矿理论。并首次提出了构造剥蚀天窗控制局部氧化带、断裂制约蚀变带、天窗两翼辫状河砂体富集成矿的新认识,建立了“深部含油气细碎屑岩沉积建造-浅部辫状河粗碎屑岩沉积建造-断裂-构造剥蚀天窗”四位一体的局部层间氧化带型砂岩铀矿成矿模式。通过已发现铀矿床成矿条件深入剖析,确定了目的层选择依据、预测准则及评价机制,预测出钱家店—保康、双辽—协尔苏和杨大城子三个有利铀成矿远景区,并利用所建成矿模式在铀矿勘查中获得重要突破。更多还原

【Abstract】 The south of Songliao basin is not only a very important oil and gas accumulating area, but also a metallogenic area of sandstone type uranium.Based on comprehensive research on basic geology,well drilling,logging,seismic and aeromagnetic materials ,takeing the metallogenic theory of modern sandstone type uranium as the guide, using the methods of sequence stratigraphy and sedimentary system analysis with a combination of samples analyzing and testing in the laboratory, a systematic studies on Mesozoic tectonic activities, sequence stratigraphic frame work, the distribution of depositional system and facies, environment of sandstone type uranium deposit,sandbody conditions,features of epigenic ransformation,metallogenic conditions of uranium deposit,mineralization features and mineralization controlling factors have been done in this paper.According to the three sequence interfaces ( T3 ,T11 and T03) which were formed during the three episodes(episodeⅠ,Ⅱ,Ⅲ)of late Yanshan movement,combined with the identification of sequence boundary,the sequence stratigraphic framework of southern Songliao Basin has been established. Upper Cretaceous can be divided into three super sequences(namely, thermal subsidence depression ,depression expansion ,and inverse atrophy) , ten third-order sequences and a series of system tracts . According to the integrity,layering ,connectivity and permeability of preserved sandbodies ,it is suggested that LST in Yaojia Formation and the 1st member of Quantou Formation are favourable metallogenic strata in the south of the basin . The braided river sand bodies are favourable for uranium metallization.According to the analysis of sedimentary system ,sedimentary facies and favourable facies for uranium mineralization, it is demonstrated that the provenance of late Cretaceous is mainly from the long axis of basin , minorly from short axis of basin, and with the features of intermittence.It is mentioned that Baokang water system developed along the long axis provenance of basin consists of Tongliao and Shuangliao water system,the two water systems merged into lake and formed large-scale delta system at Baokang—Changling area. Meanwhile, during the run off process , braided river channels deposit developed along Yuliangbao—Kulun—Tongliao—Baxing area,and deposited a large sacle of braided river sand bodies in which uranium mineralization has been found, which indicates that braided river facies is the major sedimentary facies for sandstone type uranium exploration in southern Songliao basin.The research on uranium mineralization features of BX deposit suggest that: 1)uranium pre-enriching of primary gray layer is the basis of sandstone type uranium mineralization .2)gray sandstone layers which were formed by epigenetic reducing alteration of red sandbodies whose reducing fluid came from deep fluid intrusing upward and diffusing along through-faults are the precondition of sandstone type uranium mineralization. 3) the formation of local oxidation zone is the key to sandstone type uranium mineralization .According to the analysis of tectonic evolution in Mesozoic, it is demonstrated that uranium mineralization in southern Songliao basin is connected with the tectonic inversion of the end stage of Formation. A new understanding that two tectonic positions control two kinds of oxidation zones, and form two kinds of uranium mineralization has been put forward . The slope zone formed by tilting at southeastern margin of Songliao basin controlled the regonial interlayered oxidation zone and formed roll or roll-like uranium ore bodies. But the uranium mineralization scales are small because of the fierce uplifting in southeastern margin of the basin and incompletely preserved oxidation zones. Structure fenster formed by inverse uplifting and denudation controlled the local oxidation zones and formed tabular uranium ore bodies.Based on comprehensive research, a new understanding that“four-layer structures”prospecting marks of Yaojia Formation in southern Songliao basin is established, i.e., from the bottom to the up is the top of lower member of Yaojia Formation is red mudstone,upper oxidized sand bodies ,gray uranium–bearing layers ,lower oxidized sand bodies from top to bottom vertically.Research on metallogenic regularity of sandbodies uranium deposit in southern Songliao basin indicate that: 1)the shapes of uranium body is different from that of traditional typical interlayered oxidation sandstone type uranium deposit. The shapes of ore body are tabular, but not roll. 2)uranium metallogenesis is controlled by the scale and degree of local interlayered oxidation zones.Based above ,a renovating idea that“local oxidation zone controls tabular uranium body””local interlayered oxidation type uranium deposit”has been put forward, which enriched the theory of interlayered oxidation type uranium metallogenic. A new understanding that“structure denudation fenster controls local oxidation zone, fault restricts alteration zone, and uranium mineralization enriches in braid river sand-bodies in two wings of tectonic fenster”has been first put forward .The quaternity metallogenic model of“oil-gas bearing fine clastic rock depositional construction in deep, depositional construction of braid river coarse clastic rock in low,fault, and structure denudation fenster”has been established in this paper by comprehensive studying on metallogenic environment in southern Songliao basin, and characteristics of uranium mineralization ,mineralization–controlling factors and metallogenic rules of important areas.Three uranium prospecting target areas ,Qian Jiadian-baokang area,Shuangliao-Xie Ersu area ,Yang Dachengzi Area are forecasted according to the selection of the target layers , forecasting criteria of target area and metallogenic model of uranium deposite. thirdmore, key breakthrough has been made in uranium deposit exploitation.更多还原