Acritarchs from the Lower Palaeozoic succession on the south County Wexford coast,Ireland: new age constraints for the Cullenstown Formation and the Cahore and Ribband Groups

Lower Palaeozoic sediments crop out on the southern coast of County Wexford, Ireland, comprising three distinctive lithostratigraphical units: from west to east the Cahore Group, the Blackhall Formation of the Ribband Group and the Cullenstown Formation. The three units are largely devoid of macrofossils and thus their ages have to date been uncertain and, in the case of the Cullenstown Formation, speculative. In the Cahore Group, a diverse assemblage of acritarchs composed of seventeen species has been recorded indicating a middle Early Cambrian age. This is similar to the age of the lithologically identical Bray Group to the north, in County Wicklow. In the Ribband Group, two very distinct assemblages have been noted. Both are poorly preserved, but diagnostic species have been determined giving a biostratigrapical range of early Mid‐Cambrian to Llanvirn. Palynomorphs have been recorded for the first time from the Cullenstown Formation allowing comparison with eastern Newfoundland where a similar, less diverse assemblage has been recorded. The age indicated is latest Mid‐Cambrian to early Late Cambrian. Overall, despite generally poor preservation of the organic matter, some 45 acritarch species have been distinguished, among which one new combination is proposed: Retisphaeridium postae instead of Cymatiosphaera postae. Copyright © 2004 John Wiley & Sons, Ltd.     

An Ordovician age for the Muggort's Bay Lower Palaeozoic inlier,County Waterford,Ireland—the southernmost exposure of the Irish Caledonides

The most southerly exposed Lower Palaeozoic strata in Ireland occur on the southwest coast of County Waterford along a 2.5 km long coastal section at Muggort's Bay where they are surrounded by Devonian rocks. Five formations can be distinguished which, in ascending order, are: the Ballycurreen, Carrickbrean, Rathnameenagh, Moanbrack and Killinoorin formations. The total thickness of the succession is over 1800 m. No macrofossils are present, but the lithologies are largely fine‐grained turbidites and subordinate volcanic rocks which closely resemble the Ribband Group seen elsewhere in southeast Ireland and have previously therefore been classified with it. Palynological analysis was undertaken on 25 samples collected from Muggort's Bay, of which eight were productive. Diagnostic microfossils, comprising acritarchs, chitinozoans and scolecodonts, indicate an Early to Middle Ordovician age for both the Rathnameenagh and the Moanbrack formations. These ages confirm that the strata are part of the Ribband Group which elsewhere has been biostratigraphically dated as ranging from Mid‐Cambrian to Mid‐Ordovician. Reworked mid‐Middle Cambrian acritarchs occur in the Moanbrack Formation and reworked late Middle to early Late Cambrian acritarchs in the Rathnameenagh Formation. Despite generally poor preservation of the organic matter, some 20 acritarch species have been distinguished. Among these, three species belong to the herein revised genus Retisphaeridium for which an emended diagnosis is proposed together with two new combinations, Retisphaeridium capsulatum (Jankauskas, 1976 ) Vanguestaine nov. comb. and Retisphaeridium pusillum (Moczydlowska, 1998 ) Vanguestaine nov. comb. Copyright © 2005 John Wiley & Sons, Ltd.     

浙西北地区寒武系物源分析及古地理意义:来自沉积学及碎屑锆石年代学的证据

浙西北地区寒武系沉积环境及物源分析是重建扬子板块东南缘古地理格局的关键,进而可以为华南大地构造演化提供证据.本文根据沉积相时空展布、斜层理与同沉积褶皱恢复的物源方向以及碎屑锆石LA-ICP-MSU-Pb测年,综合探讨寒武系的陆源碎屑物源方向以及物源区.浙西北地区寒武纪地层主要由碳硅质岩、硅质页岩、砾屑灰岩、砂屑灰岩、泥灰岩、泥岩等组成.沉积序列、沉积相标志研究表明,寒武系沉积构造以泄水构造、滑塌褶曲、流动构造、层间滑动、同沉积褶皱和断层等为特征,发育大量滑塌沉积及碳酸盐岩浊积岩,整体为深水盆地及斜坡环境.沉积相时空展布及古流向研究表明,水体向北西方向加深,寒武系陆源碎屑物质主要来源于南东方向,非前人通过古生物地层判断的盆地基底北西高南东低.碎屑锆石年代学研究表明,物源集中于574 Ma、747 Ma、1768 Ma以及2131 Ma,与邻区碎屑锆石年龄图谱对比分析表明,江山-绍兴断裂带及浙江中部地区为主要物源区,陆缘碎屑物质主要来自于陈蔡群、双溪坞群、河上镇群及八都群.寒武纪时期,斜坡盆地沉积基底向北西倾斜,位于盆地西北部的章里地区为沉积中心,华夏地块露出水面为剥蚀区.     

关于湘西北红岩溪地区沉积-构造-成矿研究的一些认识

湘西北红岩溪地区处于湘西—鄂西多金属成矿带的中南部,属上扬子地块东南缘,主要沉积自寒武纪至志留纪地层,沿NE向红岩溪断裂在奥陶系桐梓组、红花园组灰岩中分布了大量铅锌矿点。以地层、岩石、构造特征为研究对象,突出对含矿地层、岩石、构造的刻画,查明了成矿地质背景和成矿条件,总结了成矿规律。通过分析奥陶纪—志留纪的桐梓组风暴沉积岩、红花园组生物礁灰岩、宝塔组龟裂纹构造、新滩组远源浊积岩等现象的形成机理,建立了区内奥陶纪—志留纪的沉积-构造演化模型,指示地质背景从伸展体制的被动大陆边缘演化为挤压体制的前陆盆地; 查明了区内断裂构造与铅锌成矿的关系,认为NE—NNE向断裂为铅锌的导矿构造,而NW向小断裂则为主要容矿构造; 从流体包裹体方面探讨了铅锌成矿环境,成矿热液与盆地热卤水较为相似,成矿流体原始来源为层间水和大气降水,最终建立了区内铅锌成矿模型。     

赣西北地区中元古界双桥山群沉积学特征

滩间山群是指出露于青藏高原北部柴达木盆地北缘的一套早古生代的浅变质火山岩-沉积岩地层。变质火山岩主要由玄武岩、玄武安山岩组成,夹少量变质英安岩。变质沉积岩主要由绢云片岩、含炭绢云片岩、大理岩以及砂岩、砾岩组成。前人认为这套地层的时代为晚奥陶世。野外地质研究发现,这套地层遭受多期强烈构造变形和低绿片岩相变质作用的改造。同位素年代测试显示,其中变质英安岩的单颗粒锆石U-Pb测年的上交点年龄为(953±27)Ma,下交点年龄为(486±13)Ma,结合锆石形态特征以及区域地质资料分析,认为滩间山群的时代应为早奥陶世。     

甘肃中西部龙首山一带“韩母山群”的重新厘定

关于甘肃龙首山一带“韩母山群”的划分和时代归属,前人曾有不同的认识。依据沉积建造、古生物化石、变质变形等资料,对韩母山群进行解体。将该群下部变质变形较强的烧火筒沟组(钙质砾岩、细碎屑岩夹碳酸盐岩建造)厘定为震旦系,上部变质变形较弱的草大坂组(碎屑岩、碳酸盐岩建造)厘定为寒武系,并将后者与鄂尔多斯西缘下、中寒武统对比。     

From foredeep to orogenic wedge-top: The Cretaceous Songliao retroforeland basin,China

Songliao Basin, the largest Mesozoic intracontinental nonmarine basin in eastern China, initiated during the latest Jurassic as a backarc extensional basin; rifting failed and thermal cooling controlled subsidence through the early Late Cretaceous. Integrating 2-D and 3D reflection seismic and borehole data with regional geological studies, we interpret sedimentary sequence and structural patterns of the Coniacian-Maastrichtian fill of Songliao Basin as defining a retroforeland basin system developed after 88 Ma (marked by the T11 unconformity in the basin), including (1) significant increase in the thickness of the Nenjiang Formation eastward towards orogenic highlands of the Zhangguangcai Range and the convergent continental margin; (2) a shift of detrital provenance in the basin from north to southeast; and (3) propagation of E-W shortened structures, increasing eastward in amplitude, frequency, and degree of inversion toward the orogen. During latest Cretaceous, foreland basin fill progressively deformed, as the foredeep evolved to a wedge-top tectonic setting, marked by the basin-wide T04 unconformity within the upper Nenjiang Formation at 81.6 Ma. Much of the basin was brought into the orogenic wedge and eroded by the end of the Cretaceous. Late Jurassic/Early Cretaceous backarc rifting of uncratonized basement comprised of accreted terranes likely facilitated and localized the foreland. Synrift normal faults reactivated and extensively inverted as thrust faults are prominent in the eastern 1/3 of the basin, whereas folds developed above detachments in shaley early post-rift strata dominate the western 2/3 of the basin. Songliao foreland development likely was driven by changing plate dynamics and collision along the Pacific margin after 88 Ma.     

The Early Proterozoic Nabberu Basin and associated iron formations of Western Australia

Rocks of the Early Proterozoic Nabberu Supergroup were deposited in the Nabberu Basin along the northern margin of the Archaean Yilgarn Shield in Western Australia. The Nabberu Basin consists of three tectonic-sedimentary units known as the Earaheedy, Glengarry and Padbury Sub-basins.The Earaheedy Group within the easternmost sub-basin is divided into a lower Tooloo Sub-group and an upper Miningarra Sub-group, representing succeeding sedimentary cycles totalling some 6000 m of shallow water sediments. The Tooloo Sub-group comprises thin quartzose to arkosic clastics (Yelma Formation) which rest unconformably on Archaean rocks, and are overlain by chert, shale, iron formations and minor carbonate (Frere Formation), and thinly bedded carbonate, shale and sandstone (Windidda Formation). The overlying Miningarra Sub-group includes sandstone and shale (Wandiwarra Formation), super-mature quartz sandstone and arkosic siltstone (Princess Ranges Quartzite), fine arkosic sandstone, siltstone, shale and carbonate (Wongawol Formation), limestone, shale and sandstone (Kulele Creek Limestone) and sandstone and shale (Mulgarra Sandstone). Distinctive stromatolite assemblages occur in carbonate units throughout the sequence.Iron formations of the Frere Formation are similar to those of the Lake Superior and Labrador Provinces of North America, and commonly have a distinctive pelletal (intraclastic) texture, but are locally oolitic or laminated. Benthonic microfossils found at one locality are identical to those in the Lake Superior iron formations (Walter et al., 1976).West into the Glengarry Sub-basin and Peak Hill—Robinson Ranges area the basal clastics become considerably thicker, finer-grained and more varied, and are commonly interbedded with basaltic volcanics and greywackes. The Peak Hill Beds (MacLeod, 1970), Finlayson Sandstone and Maraloou Formation (Bunting et al., 1977) may be lateral equivalents of the Yelma Formation, while the overlying Horseshoe Range Beds, Labouchere Formation and Robinson Range Formation (Barnett, 1975) are possible equivalents of the Frere Formation. The Millidie Creek Formation may be equivalent to the Wandiwarra Formation.Deformation of the Nabberu Basin has resulted in the development of the Stanley Fold Belt in the north and the Kingston Platform in the south. On the Kingston Platform the rocks dip very gently north, but deformation increases northwards. A slaty cleavage becomes more conspicuous in this direction, while folds become tighter, overturned southwards and cut by north-dipping thrusts. The fold belt trends west-northwest across the eastern portion of the basin before swinging to the southwest. Archaean basement is increasingly involved in the deformation and becomes progressively more gneissic as the Early Proterozoic rocks become more strongly schistose. Refolding of early structures is pronounced in the west. Metamorphic grade, based on mineral assemblages in basic, pelitic and carbonate rocks and iron formations, also increases north and northwest, reaching a maximum grade of granulite facies west of the Robinson Ranges. The sediments are essentially unmetamorphosed in the southeastern part of the basin.     

孙吴-嘉荫盆地晚白垩世地层物源及构造背景

为揭示孙吴-嘉荫盆地晚白垩世富饶组和太平林场组的物源特征及其构造背景,对两组样品进行了碎屑锆石LA-ICP-MS U-Pb定年和地球化学特征研究.富饶组碎屑锆石55个测点产生以下年龄峰值:65 Ma、280 Ma和496 Ma,太平林场组碎屑锆石78个测点产生以下年龄峰值:98 Ma,189 Ma,240 Ma和488 Ma,表明富饶组和太平林场组具有混合物源的特征.Al₂O₃/TiO₂平均值分别为41.42和29.31,结合主量、微量及稀土元素特征和碎屑锆石峰值年龄,确定富饶组和太平林场组物源主要为晚中生代长英质火成岩和沉积岩.地球化学和区域构造演化特征共同揭示富饶组和太平林场组物源区构造背景为活动大陆边缘,区域内晚中生代岩浆事件、佳木斯地块北部麻山群及广泛分布的古生代花岗岩为盆地晚白垩世地层提供了沉积物源.      

同构造沉积分析反演逆冲构造变形过程--燕山东段凌源南部中生代逆冲构造变形过程研究

介绍了同构造沉积分析的基本概念、研究思路、主要研究方法及其在区域构造变形过程研究中的重要作用。基于对辽西凌源南部区域构造变形、晚侏罗世土城子组同构造沉积粗碎屑沉积物成分变化规律的研究 ,获得如下主要认识 :( 1)同构造沉积始于髫髻山组火山活动之后 ;沉积物成分变化及古水动力特征表明 ,同构造沉积物源区主体位于盆地西侧褶皱隆起区 ,而不是来自南东方向的大型逆冲断层上盘的前渊沉积 ;而且显示了正常层序的物源区倾斜岩层的剥蚀和揭顶过程 ;当时的剥蚀作用已达中元古界蓟县系雾迷山组上部。 ( 2 )分布于郭家店盆地和邓杖子盆地之间的中元古界长城系地层“残片” ,与其东侧北票组间为向SEE逆冲的断层接触 ,而西侧与土城子组 (原邓杖子组 )之间为不整合接触 ;在老虎沟东南长城系地层“残片”不复存在的区域 ,土城子组不整合于北票组之上。该“残片”很可能是髫髻山组火山活动之前指向SEE的逆冲构造变形形成的飞来峰构造的残余部分。( 3 )凌源南部中生代逆冲构造变形可以区分为 :早侏罗世北票组之前 (印支期 )由北向南的逆冲作用、北票组之后髫髻山组之前向SEE的冲断推覆、髫髻山组之后的逆冲褶皱变形与同构造沉积作用以及九佛堂组之后局部的逆冲作用。指向SEE的主要逆冲作用以及伴生褶皱变形     

Kinematics of syn-tectonic unconformities and implications for the tectonic evolution of the Hala'alat Mountains at the northwestern margin of the Junggar Basin,Central Asian Orogenic Belt

The Hala’alat Mountains are located at the transition between the West Junggar and the Junggar Basin.In this area,rocks are Carboniferous,with younger strata above them that have been identified through well data and high-resolution 3D seismic profiles.Among these strata,seven unconformities are observed and distributed at the bases of:the Permian Jiamuhe Formation,the Permian Fengcheng Formation,the Triassic Baikouquan Formation,the Jurassic Badaowan Formation,the Jurassic Xishanyao Formation,the Cretaceous Tugulu Group and the Paleogene.On the basis of balanced sections,these unconformities are determined to have been formed by erosion of uplifts or rotated fault blocks primarily during the Mesozoic and Cenozoic.In conjunction with the currently understood tectonic background of the surrounding areas,the following conclusions are proposed:the unconformities at the bases of the Permian Jiamuhe and Fengcheng formations are most likely related to the subduction and closure of the Junggar Ocean during the late Carboniferous-early Permian;the unconformities at the bases of the Triassic Baikouquan and Jurassic Badaowan formations are closely related to the late Permian-Triassic Durbut sinistral slip fault;the unconformities at the bases of the middle Jurassic Xishanyao Formation and Cretaceous Tugulu Group may be related to reactivation of the Durbut dextral slip fault in the late Jurassic-early Cretaceous,and the unconformity that gives rise to the widely observed absence of the upper Cretaceous in the northern Junggar Basin may be closely related to large scale uplift.All of these geological phenomena indicate that the West Junggar was not calm in the Mesozoic and Cenozoic and that it experienced at least four periods of tectonic movement.     

Geologic framework for the coal-bearing rocks of the Central Appalachian Basin

Coal production has been an important economic factor in the Central Appalachian Basin. However, regional stratigraphic and structural relationships of the coal-bearing rocks of the basin have been poorly understood due to numerous separate nomenclatural schemes employed by various states. In order to estimate coal resources and understand mechanisms controlling the distribution of coal within the basin, a reliable geologic framework is necessary. Seven detailed cross sections across the Central Appalachian Basin were constructed in order to examine the stratigraphic and structural framework of the coal-bearing rocks in the basin. The cross sections were based on more than 1000 oil and gas well logs, measured sections, and borehole information from Kentucky, Ohio, Tennessee, Virginia and West Virginia.The cross sections revealed three main points discussed here: southeast thickening of the Pennsylvanian strata, uncomfortable northwestward onlapping relationship of Lower Pennsylvanian strata over underlying Lower Pennsylvanian and Mississippian strata and regional continuity of beds. The cross sections, geologic mapping, coal-resource studies, extensive new highway exposures and the occurrence of tonstein beds indicate that many coal beds and marine strata are laterally extensive, albeit locally variable across the basin. Certain quartzose sandstone bodies are also extensive over large areas of the basin.Existing stratigraphic nomenclature schemes obscured the geologic framework of the basin, so a new unified nomenclature scheme was devised to better describe stratigraphic features of the basin. The new stratigraphic nomenclature, now only formalized for Kentucky, was based on key stratigraphic units that proved to be extensive across the basin. Lower and Middle Pennsylvanian rocks are now recognized as the Breathitt Group (the Breathitt Formation was elevated to group rank). The Breathitt Group was subdivided into eight coal-bearing formations by relatively thick marine strata, and, in the lower part of the Breathitt Group, by quartzose sandstone formations. The new coal-bearing units are formally ranked as formations and, in ascending order, are the Pocahontas, Bottom Creek, Alvy Creek, Grundy, Pikeville, Hyden, Four Corners and Princess Formations. The quartzose sandstone units are also formally ranked as formations and are, in ascending order, the Warren Point, Sewanee, Bee Rock and Corbin Sandstones. The sandstone formations were previously recognized units in some states, but have been extended (formally in Kentucky) across the basin. The key stratigraphic marine units are formally ranked as members, and are, in ascending order, the Betsie Shale Member, the Kendrick Shale Member, Magoffin Member and Stoney Fork Member.     

鄂尔多斯盆地奥陶系层序地层格架

通过大量露头、钻井与地震层序地层学综合分析,建立了全盆地奥陶系层序地层格架。研究提出了“碳酸盐岩层序地层划分与对比五要素”分析方法。应用该分析方法在奥陶系识别出3个二级层序界面、6个三级层序界面,将奥陶系划分为2个二级层序和8个三级层序。盆地不同构造环境形成不同的层序地层格架:在盆地西部窄大陆边缘北部奥陶系发育层序 Osq3-层序Osq7五套地层,持续时间从早奥陶世弗洛阶到晚奥陶世桑比阶末,南部发育层序Osq1-层序Osq7七套地层,持续时间从早奥陶世特马道克阶到晚奥陶世桑比阶末,总体上西部地层西厚东薄,南北向条带状展布,向伊盟隆起-庆阳古隆起上超覆尖灭;在盆地南部宽大陆边缘奥陶系发育盆地所发现的8个层序,持续时间从早奥陶世弗洛阶到晚奥陶世凯特阶早期,地层南厚北薄,向庆阳古隆起上超覆尖灭;在盆地中东部台内洼陷奥陶系仅发育层序Osq3-层序Osq5 TST,以盆地东部洼陷东侧最厚向伊盟隆起-庆阳古隆起上超覆尖灭;盆地北部伊盟古隆起、西南部庆阳古隆起主体一直处于隆起剥蚀状态,二者的鞍部仅发育Osq4 TST层序,表明盆地西部的祁连海槽与盆地东部的华北海在中奥陶世晚期有过短暂连通。     

四川盆地：周缘活动主控下形成的叠合盆地

四川盆地位于扬子板块西缘和青藏高原东缘,地震勘探资料等揭示盆地前寒武纪基底保存完整的古俯冲带和地堑-地垒结构,说明盆地基底后期构造活动非常稳定;显生宙以来经历晚震旦世-石炭纪、二叠纪-中三叠世两幕克拉通边缘强拉张-强挤压,而克拉通内弱拉张-弱挤压的构造演化过程,体现出盆地内部稳定性结构沉积演化特征。克拉通内弱拉张初期以海相碳酸盐岩大面积稳定沉积（即震旦系灯影组和二叠系栖霞-茅口组）和随后的风化壳岩溶作用（即桐湾期、东吴期等不整合面）为特征,弱拉张期以拉张槽（如：绵阳-长宁拉张槽和开江-梁平拉张槽等）的形成为典型特征;弱挤压则以古隆起（如：加里东期乐山-龙女寺古隆起、印支期泸州古隆起等）的发育为典型特征。四川盆地晚三叠世后的前陆盆地演化阶段受控于其周缘造山带逆冲推覆构造活动,是现今地貌和构造盆地的主要建造期,形成了四川盆地周缘突变（线型）和渐变（弥散型）两种盆山结构。盆地西边界（龙门山）和北边界（米仓山-大巴山）即是线型突变边界,也是扬子地块（板块）的边界,边界几何形状和扬子板块刚性特征对盆山系统结构-构造特征等有较大的控制作用;四川盆地的东边界（齐岳山-大娄山）和西南边界（大凉山）即是渐变弥散型边界,同时也是板（陆）块内部的边界,它们受控于邻区（盆外）的构造变形和盆内沉积盖层中滑脱层的分布特征。受控于盆地（克拉通）周缘活动,四川盆地垂向上前寒武纪基底与盖层、盖层内早期和晚期构造具解耦特征。基底与盖层构造的解耦有利于盆地内部前寒武纪基底结构构造的保存和盖层内大型隆-坳结构的形成演化;盖层内早期和晚期构造的解耦有利于早期构造免遭后期破环,对深层油气藏的保存意义重大。总之,四川盆地可能是具独特形成过程和特征的叠合盆地新类型,其突出特征表现为周缘活动、内部稳定及早期和晚期构造解耦。     

Earthquake-induced Soft-sediment Deformation Structures in the Dengfeng Area, Henan Province, China: Constraints on Qinling Tectonic Evolution during the Early Cambrian

Soft-sediment deformation structures are abundant in the Cambrian Zhushadong and Mantou formations of the Dengfeng area, Henan Province, China. Soft-sediment deformation structures of the Zhushadong Formation consist of fluidized deformation, synsedimentary faults, seismo-folds and plastic deformation; the Mantou Formation is dominated by small-scale horst faults, intruded dikes, fluidized veins, and seismo-cracks. These structures are demonstrated to be earthquake-related by analysis of trigger mechanisms, and may indicate the activity of the Qinling tectonic belt during the early Cambrian. Furthermore, the assemblages of soft-sediment deformation structures altered with time: large-scale, intense deformation in the Zhushadong Formation alters to small-scale, weak deformation in the Mantou Formation. This striking feature may have been caused by changes in hypocentral depth from deep-focus to shallow-focus earthquakes, indicating that the Qinling tectonic belt developed from the subduction of the Shangdan Ocean to the extension of the Erlangping back-arc basin. This study suggests that soft-sediment deformation structures can be used to reveal the activity of a tectonic belt, and, more importantly, changes in deformation assemblages can track the evolution of a tectonic belt.     

皖南兰田残留向斜不是构造窗

兰田地区翔实的１：５万区调填图工作,收集了丰富的前震旦系实测地层剖面资料、震旦系休宁组底界角度不整合资料及后期构造变动的证据,证实了皖南属晋宁期造山带,并存在元古宙地层的完整层序,而震旦系－寒武系则为原地沉积在前震旦系基底之上的盖层。加里东期区域伸展体制条件下兰田地区产生滑覆断层体系,震旦系－寒武系盖层残留在前震旦系基底之上形成向斜构造。中生代的构造作用对兰田地区构造轮廓产生了不可忽视的改造,但未     

冀北金台子盆地早白垩世酸性火山岩地球化学、锆石年代学及其地质意义

华北克拉通在中生代以来遭受了显著破坏。前人的研究对克拉通破坏的机制和峰期取得了较大共识, 但是关于克拉通破坏的启动时间一直存在争议。本文通过对冀北金台子中生代盆地构造特征及其填充的火山岩地球化学和年代学进行分析, 为华北克拉通破坏启动时间提供新的约束。研究表明, 金台子盆地为一伸展断陷盆地。盆地呈北东-南西向展布, 东侧被正断层控制, 西侧为地层超覆边界。盆地内自下而上发育后城组、白旗组、啕北营组、九佛堂组火山-沉积组合。后城组是一套稳定的河流相红色砂砾岩沉积地层;白旗组和啕北营组主体为巨厚层流纹岩、流纹质凝灰熔岩, 局部夹安山岩和火山碎屑岩;九佛堂组是一套以砾岩、砂砾岩等为主体的碎屑岩。地球化学分析表明金台子盆地中发育的酸性火山岩源于地壳重熔。锆石U-Pb年代学研究显示, 金台子盆地内流纹岩自约145 Ma开始广泛喷发并形成巨厚层的酸性火山岩地层, 表明此时在华北北缘地区的岩石圈减薄和破坏可能就已非常剧烈, 据此华北克拉通在其北缘的破坏至少应早于145 Ma。     

塔里木盆地塔中低凸起古构造演化与变形特征

通过区域地质和构造地震精细研究,提出了塔里木南缘早古生代板块构造控制塔南—塔中从伸展到挤压盆地演化：寒武纪—早奥陶世板缘拉张控制了塔中北斜坡断陷构造;中奥陶世北昆仑洋盆关闭后塔中前缘隆起;晚奥陶世—晚泥盆世塔中前陆冲断与走滑构造变形。晚奥陶世塔南前陆冲断构造由东南向西北方向传播,形成塘北—塔中南—塔中5号断裂带等弧形断裂体系和塔中低凸起中西段与Ⅰ号断裂带小角度斜交的走滑断裂体系。冲断构造位移的传播受控于两个滑脱层：其一是沿寒武系内部膏盐岩的滑脱,形成弧形冲断构造,终止于塔中南缘断裂带;另一个是沿中地壳韧性变形带的滑脱,形成塔中1号断裂带东端的弧形构造带。塔中1号断裂带东段的构造变形方式主要为向北传播水平位移的断层传播褶皱和向南反向冲断的楔形构造。塔中低凸起的中西段右行走滑构造导致了向东收敛的扫帚状走滑断裂体系的形成,剖面发育花状构造。塔中低凸起的古构造演化与变形特征、构造变形样式、构造变形成因和断裂体系,是克拉通盆地内部叠合盆地深层的主要构造地质特征。     

柴达木盆地大柴旦地区盆地中新生代演化机制电性特征分析

柴达木盆地位于青海省西北部,是在昆仑山、阿尔金山和祁连山控制形成的山间断陷盆地,由于盆地中生代沉积了大范围的侏罗系地层,因此盆地内含有丰富的油气资源,众多学者对柴达木盆地的构造演化做了大量的研究,受限于盆地的山盆耦合模式,地形、地质条件复杂,山前地带大多是地震的空白区,仅在局部获得了地震勘探资料,但资料品质较差。由于缺乏详细资料,关于该区域构造演化的研究没能深入开展,盆地内部构造演化的研究主要在构造背景和构造格架上,对于构造的细节没有得到解析。本文通过音频大地电磁法探测大柴旦地区盆地地质特征,基于三维非线性共轭梯度(3D NLCG)反演算法,获得研究区三维电性模型,结合区域地质、地球物理资料研究盆地构造演化,结果表明：三维电性模型揭示了柴北缘地区盆地中生代以拉张为主形成一系列断陷盆地,新生代以喜山构造活动为主产生一系列挤压为主的冲断构造,造成早侏罗系-晚白垩系地层的局部缺失等地质活动的盆地演化动力学电性特征。     

四川盆地东部海相下组合油气勘探领域与有利勘探方向

四川盆地是一个大型叠合含油气盆地,经历了多期伸展-聚敛旋回,资源潜力巨大。近年来,盆地中部下组合天然气勘探在震旦系灯影组和下寒武统龙王庙组获得重大突破,但盆地东部尚未获得实质性进展,有利勘探方向尚待明确。以构造-沉积演化分析为基础,将盆地东部及邻区海相下组合划分为伸展分异台地(震旦纪至早寒武世沧浪铺期)、稳定统一台地(早寒武世龙王庙期至中奥陶世宝塔期)和挤压前陆坳陷(晚奥陶世至志留纪)三个演化阶段;根据油气成藏要素和运聚特征,划分出寒武系盐下碳酸盐岩、寒武系盐上碳酸盐岩和志留系致密碎屑岩等三个油气勘探领域,不同勘探领域制约油气成藏和富集的关键因素差异较大;指出了川东南震旦系灯影组四段台缘带、川东寒武系洗象池群碳酸盐岩浅滩和志留系小河坝组大型三角洲砂体等,为盆地东部海相下组合的有利勘探方向,同时明确了重点突破地区。