滇中楚雄盆地六苴铜矿床煌斑岩地球化学、年代学及其地质意义     

吴鹏  谭茂  韩润生  江小均  王蝶  杨航 《岩石学报》2020,36(5):1409-1425

云南六苴铜矿床是楚雄盆地砂岩型铜矿床的典型代表。矿区岩浆活动不明显,近年来通过深部钻孔和竖井工程,在矿床深部揭露出煌斑岩脉。通过岩相学、电子探针、ICP-MS、锆石U-Pb定年等分析,确定六苴铜矿床的煌斑岩属云煌岩,其成岩年龄为31～33Ma,于铜矿床的改造成矿期侵位。主量元素特征显示其属于钾质钙碱性煌斑岩;微量元素表现为大离子亲石元素Sr、Th和Rb等相对富集,高场强元素Nb、Ta和Ti等亏损;稀土元素表现出轻稀土强烈富集的特点。锆石176Hf/177Hf值为0. 28230～0. 28272,比较集中的Hf同位素组成εHf(t)=-4～2。综合分析认为,六苴铜矿床的煌斑岩主要源自流体交代的富集岩石圈地幔,岩浆在快速上升过程中进一步熔融混染了少部分先存的地壳残片,为喜马拉雅期印度-欧亚板块碰撞挤压背景下,从挤压转换为拉张环境的产物。该煌斑岩与富厚铜矿体二者在空间、时间、构造-热液、产出状态、成矿流体及物质来源等方面均具有紧密联系,对铜矿体的改造富集起到重要作用,可作为预测富厚铜矿体的指示标志。煌斑岩脉内含有方铅矿、闪锌矿等金属硫化物,暗示深部具铅锌成矿潜力。  相似文献   

我国中新生代盆地砂岩型铀矿研究现状及发展方向的探讨   总被引：3，自引：0，他引：3  

陈戴生 《铀矿地质》1994,10(4):203-206

本文综述我国中新生代盆地砂岩型铀矿床的研究现状及其发展方向，探讨了砂岩型铀矿适于地浸的地质条件，并对该类型矿床的找矿靶区以及找矿方法进行了评述。  相似文献   

Sandstone weathering processes damaging prehistoric rock paintings at the Albarracin Cultural Park, NE Spain   总被引：1，自引：0，他引：1  

G. Benito  M. J. Machado  C. Sancho 《Environmental Geology》1993,22(1):71-79

The rock paintings in cliff-foot caves of the Albarracin Cultural Park are known as some of the most important evidences of the Levantine prehistoric art of Spain (8000–3000 BP). The paintings are on sandstone (Buntsandstein facies) of Triasic age, which may develop intense weathering. The analysis of the variables controlling the weathering indicate that salt and wetting-drying weathering are responsible for granular disintegration and flaking, which lead to rock painting deterioration.  相似文献   

Slope aspect, slope length and slope inclination controls of shallow soils vegetated by sclerophyllous heath—links to long-term landscape evolution     

Marshall T. Wilkinson  Geoff S. Humphreys 《Geomorphology》2006,76(3-4):347-362

On upland Triassic sandstone slopes of the western Blue Mountains, nonswamp, sclerophyllous heath (shrub-dominated vegetation) on shallow soils is commonly found downslope and adjacent to sclerophyllous forest on deeper soils. Some consider heath—and thus shallow soils—as favouring west-facing slopes, which are expected to experience drier microclimates due to insolation, strong and desiccating winds, and severe summer fires. However, our analysis of extensive areas with heath on shallow soils, based on vegetation and topographic maps, and fieldwork of uplands with various degrees of dissection, suggests that aspect is a poor predictor of shallow soils. Rather, shallow soils and heath are found on short slopes and the lower segments of longer slopes with the latter significantly steeper than forested segments.The shallow–deep soil boundary, marked by contrasting modern vegetation structures, does not signify a catchment area threshold, and correspondingly, the vegetation patterns are not in balance with distributary catchment processes, as short slopes are mantled exclusively by shallow soils. Instead, the soil depth boundary represents the propagation of base-level lowering signals, which takes place not only by the headward retreat of knickpoints but also via increased lowering of slope segments adjacent to drainage lines. This leads to steep slopes immediately adjacent to canyons, narrow gorges, and small steep valleys, that are mantled by shallow, discontinuous soils undergoing rapid erosion. These steep slopes persist in the landscape for ≥ 10 My after upland stream rejuvenation until incision of more weatherable Permian sediments, underlying the Triassic cliff-forming sandstones, triggers rapid lateral expansion of gorges. Once shallowly mantled and steeper slopes adjacent to streams are consumed by gorge widening, slopes adjacent to wide gorge clifflines reflect former upland drainage patterns rather than the redirected flow to rapidly widening gorges. Hence, modern vegetation patterns reflect a significant phase of landform development, perhaps combined with enhanced erosion during the Last Glacial Period that is compounded by a humped soil production function on bedrock.  相似文献   

512层间氧化带砂岩型铀矿床氡异常特征     

万骏 《华东地质学院学报》1998,21(3):249-253

本文以５１２矿床为例阐述层间氧化带砂岩铀矿床,矿化富集部位与铀镭平衡变化特征的关系,铀镭平衡变化特征与地面异常的关系,重点论述了层间氧化带砂岩型铀矿床的氡异常特征,评价了地面氡法寻找层间氧化带砂岩型铀矿床的作用和意义 。  相似文献   

新疆准噶尔盆地北西部层间氧化带砂岩型铀矿形成条件分析   总被引：3，自引：3，他引：3  

林双幸 《铀矿地质》1997,13(2):《铀矿地质》-1997年13卷2期,13(2)-97-97,13(2)页-《铀矿地质》-1997年13卷2期,13(2)-97-97,13(2)页

本文从盆地结构、沉积盖层构造特征、盆地沉积的岩相条件及岩石地球化学地特征、区域水文地质条件以及沉积盖层中的后生改造作用等方面，分析准噶尔盆地北西部层间氧化带砂岩型铀矿形成的地质条件。  相似文献   

碎屑岩的物质成分、物质来源与大地构造关系──以宣龙内陆海长城期常州沟─串岭沟组碎屑岩为例     

聂逢君 《华东地质学院学报》1996,(4)

应用ＷＲＤｉｃｋｉｎｓｏｎ等人对砂岩与物源分析结果，对我国华北地台第一沉积盖层的宣龙内陆海长城系的常州沟组和串岭组的砂岩和石英岩状砂岩进行投点，结果表明，形成砂岩和石英岩状砂岩的主要物源，是内陆海南北两侧的大陆块蚀源区的克拉通源区。通过阴极发光分析，进一步揭示了克拉通古陆火成岩的物源略多于变质岩。重矿物鉴定结果，确定了火成岩主要为花岗岩和花岗闪长岩；变质岩为合石榴石斜长片麻岩和角闪片麻岩等。克拉通岩石经过长期风化，碎屑经过远距离搬运和充分地离解和分解之后，在宣龙内陆海沉积了常州沟、串岭沟组的砂岩和石英岩状砂岩。  相似文献   

伊犁盆地含煤系地层沉积相特征及其与层间氧化带砂岩型铀矿成矿关系   总被引：16，自引：1，他引：16  

李胜祥  陈戴生 《铀矿地质》1996,12(3):129-134

本文从研究伊犁盆地不同地段含煤系地层岩性变化特征入手，提出冲积扇快速入湖的扇三角洲沉积相模式，并讨论了４个沉积亚相，即冲积扇、扇前辫状河、滨湖三角洲、湖沼相的沉积相特征及其空间展布规律，研究了含煤系沉积相与层间氧化带砂岩型铀矿的成矿关系，指出了滨湖三角洲相砂体是寻找层间氧化带砂岩型铀矿的主要部位。  相似文献   

Silurian to mid-Devonian basin development of the Melbourne Zone, Lachlan Fold Belt, southeastern Australia   总被引：1，自引：0，他引：1  

C. McA. Powell  P. W. Baillie  A. H. M. VandenBerg   《Tectonophysics》2003,375(1-4):9

The Melbourne Zone comprises Early Ordovician to Early Devonian marine turbidites, which pass conformably upward into a mid-Devonian fluviatile succession. There are four pulses of Silurian to mid-Devonian deep-marine sandstone-dominated sedimentation: Early Silurian (late Llandovery), Late Silurian (Ludlow), earliest Devonian (Lochkovian) and late Early Devonian (Emsian). Two dispersal patterns have been defined using more than 1100 palaeocurrent measurements, mainly from sole marks and cross-laminations in graded beds, together with sandstone compositions. The older pattern, of Silurian to earliest Devonian age, contains the lowest three sandstone pulses. Palaeocurrents and provenance define a wedge of southwesterly derived sediment, of largely cratonic provenance, thinning eastward. This older dispersal pattern is part of an Early Ordovician to earliest Devonian east-facing passive continental margin succession. Palaeocurrents and provenance in the Emsian sandstone pulse comprise three patterns: (1) west- to southwesterly directed palaeocurrents associated with fine- to coarse-grained, locally conglomeratic, lithic sandstones containing a high proportion of volcanic detritus; (2) east- to northeasterly directed palaeocurrents associated with fine- to medium-grained quartz-lithic sandstones; (3) north- to northwesterly and south- to southeasterly directed palaeocurrents associated with fine- to medium-grained sandstones of variable lithic composition. The palaeocurrent and provenance pattern defines a NNW-elongate basin with a tectonically active eastern margin, and is similar to the coeval Mathinna basin of northeastern Tasmania. Both basins are part of the same system of wrench basins, which developed along the western side of the Wagga–Omeo Metamorphic Belt during the earliest Devonian to Middle Devonian. The change in tectonic setting in the earliest Devonian appears to have occurred during an interval of significant dextral translation of the eastern Lachlan Fold Belt towards the SSE along the Governor and associated fault zones.  相似文献   

西北738铀矿床碳酸盐产出特征及成因机制探讨   总被引：4，自引：0，他引：4  

乔海明  贾恒 《华东地质学院学报》2002,25(2):128-131

含矿含 水层中的碳酸盐对砂岩型铀矿床的地浸开采影响;较大，根据岩矿鉴定结果及化学分析资料，结合野外岩、矿心编录，对738矿岩型铀矿床含矿含水层中的碳酸盐产出特征及成因机制进行了研究。认为含矿含水层中的致密钙质胶结层是成岩阶段的产物；碳酸盐的溶解迁移和沉淀析出是氧化－还原作用引起酸碱平衡破坏的结果。分析了不同存在形式的碳酸盐对地浸工艺的影响。  相似文献