滩间山群的重新厘定-来自柴达木盆地边缘玄武岩年代学和地球化学证据   总被引：8，自引：0，他引：8  

高晓峰  校培喜  贾群子 《地质学报》2011,85(9):1452-1463

柴达木盆地周缘滩间山群在岩石组合、玄武岩同位素年代学和地球化学特征以及在区域成矿过程中作用具有明显差异.柴北缘和柴南缘(东昆仑地区)滩间山群具有不同的岩石组合和沉积建造:柴北缘滩间山群下部为中基性海相火山岩,上部为碎屑岩-碳酸盐岩;柴南缘下部为中基性-中酸性火山岩夹碎屑岩,中部为碎屑岩夹中基性火山岩,上部为碳酸盐岩夹碎...  相似文献   

The Khao Yai Fault on the southern margin of the Khorat Plateau, and the pattern of faulting in Southeast Thailand     

Michael F. Ridd  Christopher K. Morley 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(1):143-156

A study of Google Earth images has revealed a hitherto-unrecorded gently curved lineament within the southern marginal zone of the Khorat Plateau in eastern Thailand. The lineament, confirmed by digital elevation model (DEM) images, is at least 130 km long and coincides with a dip reversal of the Mesozoic Khorat Group. It is interpreted here as a fault, named the Khao Yai Fault, and it has characteristics which make it unusual within the Khorat Plateau. The fault forms the northern boundary of a belt of several ENE-WSW trending fault splays which are thought to link with the Mae Ping Fault further south; this is interpreted as a left-stepping, sinistral strike-slip duplex about 50 km wide and 150 km long. Apatite fission track data indicate that exhumation began during the earliest Palaeogene.The Khao Yai Fault is considered in its regional context which includes the Cardamomes Mountains of Cambodia, the offshore Phuquoc-Kampot Basin, and the Khao Thalai Red-beds outlier of the Khorat Group in Southeast Thailand. The latter is interpreted as a down-faulted sliver of the Khorat Group in the Tha Mai Fault belt which is thought, in turn, to be a splay of Thailand's other major regional fault, the Three Pagodas Fault. Carboniferous, Permian and Triassic shallow-marine rocks with unusual faunas occur in a limited NNW-SSE trending zone to the west and NNW of the Tha Mai Fault and it is suggested that wrench movement on the fault played a part in the emplacement of these rocks.  相似文献   

The Lower Albian (Lower Cretaceous) Monk's Bay Sandstone Formation (formerly the Carstone) of the Isle of Wight: Its distribution, litho- and biostratigraphy     

Peter M. Hopson  Ian P. Wilkinson  Mark A. Woods  Andrew R. Farrant 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(5):816-830

The Monk's Bay Sandstone Formation (MBSF) is the new name for the Lower Albian ferruginous sandstone that was formerly known as the Carstone of the Isle of Wight. The new term was proposed to remove any confusion with the Carstone, of similar age and lithology, described from the separate Lower Cretaceous sedimentary basin of Eastern England. This paper formalises the nomenclatural change outlined in the Lower Cretaceous Framework Report, ratified by the Geological Society Stratigraphy Commission.The MBSF, representing a major mid-Albian transgressive event, is described from a series of boreholes drilled by the British Geological Survey across the Isle of Wight, and from additional coastal exposures, together with reinterpretations of sections described in earlier works.The age range of the MBSF is determined in relation to recent biostratigraphical schemes supported with new data from the previously unknown presence of foraminifera. Deposits, belonging to the Leymeriella regularis Subzone, were previously considered to be absent from the succession and represent the stratigraphical gap separating the formation from the underlying Sandrock Formation. However a first occurrence of tubular foraminifera resembling Hyperammina/‘Rhizammina cf dichotomata’ suggest that the oldest part of the formation in the northeast of the island may be of regularis Subzone age. This unconformity is correlated with the sequence boundary LG4 of Hesselbo and the presence of the Sonneratia kitchini Subzone at the base of the MBSF on the Isle of Wight suggests that this boundary should be placed at the lower of two candidate horizons within the successions of the Weald.The formation is restricted to the Isle of Wight but is coeval with similar coarse-grained sediments, e.g. the Carstone and ‘JunctionBeds’ to the north. The palaeogeography of the formation and the relationship with these similar deposits and the implications for the timing of mid-Albian structural events is briefly discussed. The identification of older Lower Greensand Group sediments beneath the MBSF in boreholes north of the Isle of Wight structure, together with new survey data indicating north-south orientated faulting affecting the early Cretaceous implies a tectonic element to the distribution the Lower Greensand Group sediments. Taken together these imply a complex interaction of tectonics and transgressive events throughout the Aptian and Albian over this structural high.  相似文献   

The stratigraphical distribution of mid-Cretaceous Foraminifera near Ventnor, Isle of Wight     

Ian P. Wilkinson  Peter M. Hopson 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(5):831-841

Ventnor No. 2 Borehole, located near Ventnor, Isle of Wight, penetrated the basal part of the Chalk Group and the Selborne Group before terminating in the upper part of the Lower Greensand Group (Sandrock Formation). The borehole was examined for Foraminifera, and although they were not seen in the Sandrock Formation and Monks Bay Sandstone Formation, the remainder of the borehole yielded moderately low diversity assemblages dominated by agglutinated species. Foraminiferal zones 3-6 (H dentatus to M. fallax/M. rostratum macrofaunal zones) were identified in the Gault Formation and zones 6 (lower) to 6a (M. fallax/M. rostratum to A. briacensis macrofaunal zones) were identified in the Upper Greensand Formation. Assemblages from the overlying West Melbury Marly Chalk Formation were used to identify foraminiferal zones BGS1-BGS3 (M. mantelli and M. dixoni macrofaunal zones).  相似文献   

华北克拉通中部地区背景噪声成像   总被引：19，自引：10，他引：9       下载免费PDF全文

唐有彩  陈永顺  杨英杰  丁志峰  刘瑞丰  冯永革  李鹏  俞春泉  魏松峤  范文渊  王海洋  周仕勇  宁杰远 《地球物理学报》2011,54(8):2011-2022

利用华北地区的流动与固定地震观测台阵在2007年1月～12月期间的垂直分量记录,采用背景噪声层析成像方法获得了华北克拉通中部地区6～40 s的相速度和群速度分布图像.成像结果显示研究区地壳以及上地幔的速度结构存在很大的横向不均匀性.8～16 s的相速度以及8～20 s的群速度分布图像清晰地勾绘出华北地区盆地和隆起之间的...  相似文献   

甘肃龙首山地区韩母山群研究的新进展   总被引：1，自引：0，他引：1  

谢从瑞  校培喜  杨忠智  曹宣铎  胡云绪 《地层学杂志》2013,(1):54-57

甘肃龙首山地区的韩母山群包括下部的烧火筒沟组和上部的草大坂组。对于草大坂组的时代一直存在争议,一种观点根据其岩性主张置于寒武系,另一种观点是因其下部含冰碛砾岩主张置于震旦系。最近在金川黑沟一带的韩母山群的草大坂组中采到许多海百合茎、海绵骨针及瓶筐石化石,基本可以确定草大坂组是一个寒武纪—早奥陶世的地层单位,而非震旦纪地层。震旦纪的烧火筒沟组的冰碛砾岩沉积特征明显,区域上可与贺兰山一带的正目观组相对比。  相似文献   

南秦岭武当山群变质酸性火山岩锆石U-Pb年代学   总被引：4，自引：0，他引：4  

张永清  张健  李怀坤  陆松年 《地质学报》2013,87(7):922-930

对武当山群3个变质酸性火山岩样品的锆石U-Pb定年结果表明,武当山群变质酸性火山岩形成年龄为675.2±3.1 Ma,说明武当山群存在新元古代南华纪的地层组成.武当山群变质变形复杂,具多期岩浆活动,可能由不同时代火山岩和少量沉积岩组成,部分变质火山岩具有与耀岭河群火山岩和侵入到武当山群中的基性侵入岩相似的形成年龄,指示了武当山群变质酸性火山岩可能与基性侵入岩群和耀岭河群火山岩存在成因联系.基于现有同位素定年数据,武当山群火山岩数据具有年龄跨度大(太古宙至中生代)的显著特征,但总的趋势是新近取得的年龄数据多数比早期获得的数据要年轻.  相似文献   

四川会东新田金矿矿床地质特征及找矿远景   总被引：1，自引：0，他引：1  

周邦国 《地质与勘探》2013,49(5):872-881

四川会东县新田金矿是本项目组在康滇中东部地区取得的重要找矿成果。在矿产资源调查评价时,已圈定2个铜金矿体,其中K1矿体控制长1200m,平均厚1.88m,矿石平均品位Au 2.53g/t,Cu 0.45%;K2矿体控制长400m,平均厚2.65m,矿石平均品位Au 4.56g/t,Cu 0.74%。初步估算(3341)金属量Au 5218 kg,Cu 1.27万t。本文详细介绍了新田金矿床成矿地质背景、矿床地质特征,通过对控矿因素的研究,认为新田金矿属于构造蚀变岩型金矿床,其成矿时代、矿床成因与紧邻的播卡金矿床类似,受喜山期南北向的韧性剪切带控制。结合区内化探异常成果,提出在新田矿区及外围地区,具有继续寻找同类型矿床的潜力。  相似文献   

康滇地轴北缘新台子金矿区矿床地质特征及找矿方向浅析     

杨钻云 《地质与勘探》2013,49(5):846-854

新台子金矿区在成矿区带上属于海西期构造剪切带金成矿带,该带受丹巴弧形构造、大渡河韧性剪切构造及海西期基性-超基性岩浆活动的共同影响,以分布丰富的矿产资源为特征,是扬子地块西缘重要的贵金属成矿带。文章综合分析了区内矿床地质、控矿构造、矿石矿物、蚀变组合等成矿地质条件,将区内矿床成因类型确定为浅层低温热液石英脉型和构造破碎带蚀变岩型。两种矿床类型均受到地层、构造、岩浆岩的控制,具备形成小-中型规模金矿床的有利条件:①新台子金矿区及其邻区贵金属成矿带的成矿物源主要是前震旦系康定群;②深大断裂是多源成矿物质迁移的主要通道,壳源岩浆活动为成矿物质活化提供了热源;③泥盆系危关群炭质绢云板岩、千枚岩等黑色岩系作为有机化学障,使自下而上的含矿流体内的金元素沉淀、聚集成矿。  相似文献   

柴北缘欧龙布鲁克地块寒武系-奥陶系的重新厘定   总被引：1，自引：0，他引：1  

陈青 《地质与勘探》2013,49(5):825-835

通过对柴达木盆地北缘欧龙布鲁克地区的野外地质调查和精细剖面测量,根据岩石组合、沉积构造、地层接触关系及新发现的生物化石特征,对分布于该地区的早古生代寒武纪-奥陶纪岩石地层进行了详细的划分对比和重新厘定:①欧龙布鲁克群只发育寒武系的第三统和顶部的芙蓉统,缺失底部的纽芬兰统和第二统;②多泉山组为下奥陶统,石灰沟组属于中奥陶统;③原划分的中奥陶统大头羊沟组属于构造改造的断片,不符合建组原则,应弃用;④通过柴达木盆地周缘分布的早古生界地层的区域对比,认为欧龙布鲁克地块之上出露的寒武系-奥陶系(海相碳酸盐岩沉积建造)与滩间山群、祁慢塔格群和纳赤台群(中基性火山岩建造)分别代表了不同构造背景-沉积环境的产物。本研究工作一方面为建立该地区合理和行之有效的岩石地层和年代地层系统提供依据,另一方面为柴达木盆地北缘寒武系-奥陶系地层层序-岩相古地理演化及油气资源潜力评价等研究提供详实的资料,同时也为深化塔里木东南缘陆块群的构造演化提供科学依据。  相似文献