楚雄盆地下侏罗统磨拉石楔沉积与含油性研究

楚雄盆地为一中生代周缘型走滑前陆盆地，通过对下侏罗统冯家河组沉积特征的详细研究与对比，作者认为早侏罗世是楚雄前陆盆地强烈坳陷与沉降的主要发展时期从早期到晚期经历了一个变深又变浅的典型前陆盆地充填过程。在前陆冲断块体的不断逆冲和加载条件下，楚雄盆地西部早侏罗世沉积物的来源主要为哀牢山造山带隆起，其沉积环境以滨，浅湖或湖泊三角洲为主。     

川西地区“西康群”研究工作中若干基本问题的思考

西康群等岩群的研究已取得初步成果,由于构造变形复杂,至今沉积地层层序等基本问题尚未解决。运用沉积地质学理论,从造山带演化观点出发,对海底扁和滨、浅海沉积等关键问题进行了讨论,提出盆地演化的初步设想,并就今后研究提出了若干意见,以促进该项研究工作的深入发展。     

盆山转换与沉积地质记录——以楚雄前陆盆地分析为例

楚雄盆地位于扬子陆块的西南边缘,为一中生代周缘型前陆盆地。根据沉积相特征、层序地层结构和古地理演化的详细研究,结合古哀牢山造山带的构造演化,笔者认为楚雄盆地经历了从古生代被动大陆边缘沉积到中生代前陆盆地沉积的演化。前陆盆地演化的阶段性明显：晚三叠世卡尼期（云南驿组沉积期）和诺利早、中期（罗家大山组沉积期）为前陆复理石沉积;诺利晚期（花果山组沉积期）－古新世（赵家店组沉积期）为前陆磨拉石沉积。磨拉石     

Oligo-Miocene extension in the Lycian orogen: evidence from the Lycian molasse basin,SW Turkey

The Lycian molasse basin of SW Turkey is a NE-SW-oriented basin that developed on an imbricated basement, comprising the allochthonous Mesozoic rocks of the Lycian nappes and Palaeocene-Eocene supra-allochthonous sediments. The imbricated basement has resulted from a complex history related to the emplacement of different tectonic units from Late Cretaceous to Late Eocene. Following imbrication, extensional collapse of the Lycian orogen resulted in extensive emergent areas, some of which coincide with present-day mountains. These were surrounded by interconnected depressions, namely, the Kale-Tavas, Çardak-Dazk?r? and Denizli subbasins.

The Lycian molasse sequence contains a relatively complete record of the tectonic history of the Lycian orogenic collapse from which it was derived. The sequence is characterised by interdependence between tectonism and sedimentation, the latter of which includes fining-and coarsening-upward sedimentary cycles with syn-depositional intrabasinal unconformities.

The Denizli subbasin consists of thick, coarse-grained wedges of alluvial fans and fine-grained fan-delta deposits formed in a shallowmarine environment. Some areas of the fan deltas were colonised by corals, red algae and foraminifera, forming patch reefs.

The first phase of extensional collapse in the region is marked by the Lycian orogenic collapse, which may have been initiated by the beginning of the Oligocene (Rupelian), following the main Menderes metamorphism. Starting in the latest Early Miocene or in the Middle Miocene, the area of the molasse basin was subject to deformation with the Lycian nappes, and to erosion as well. At that time, the Lycian nappes, with some ophiolitic assemblages, were thrust over the molasse deposits and thus, NE-SW-trending folds were formed. The molasse deposits and thrust-related deformational structures were then unconformably covered by Upper Miocene continental deposits which belong to the neotectonic period of SW Turkey. The second phase of extensional collapse is marked by granitic intrusions and the formation of Miocene detachment-related extensional basins. This phase may have been related to the exhumation of the gneissic core of the Menderes Massif, from which fragments were derived and incorporated into the upper parts of the Denizli subbasin during the Aquitanian.     

A palynostratigraphic approach to the SW Anatolian molasse basin: Kale-Tavas molasse and Denizli molasse

Abstract

The study, explains stratigraphy of the Oligo-Miocene molasse around the Denizli province (SW Anatolia), based on the palynology which is also supported by the detailed mapping and correlation of the measured sections from the coal-bearing sequences of the molasse deposits. For this purpose, two huge depressions named as the Kale-Tavas molasse and Denizli molasse basins were examined. The Kale-Tavas molasse deposits has a basal unconformity with the underlying pre-Oligocene basement and begins with the Chattian Karadere and Mortuma formations which are covered unconformably by the Aquitanian Yenidere formation. An angular unconformity between the Chattian and the Burdigalian is only observed in the middle part of the basin, around Kale, In the Tavas section, the Aquitanian and the Burdigalian are absent. The Denizli molasse is characterized by Chattian-Aquitanian sequence consisting of distinctive sedimentary facies, alluvial fan and deltaic-shallow marine deposits with carbonate patch reefs. Palynostratigraphic studies, which have given the Chattian age, have been carried out from the coal lenses of alluvial fan and delta plain deposits. In addition to the palynological determinations, coral and foraminiferal content of the carbonate patch reefs which rest conformably on the coal-bearing sequences have yielded the Chattian- Aquitanian age. Two different palynomorph associations have been determined from the molasse deposits. The first palynomorph association which is established in the samples from the Sa?dere and Mortuma formations, corresponds to the Chattian age, whilst the second is of the Aquitanian age. The Late Oligocene-Early Miocene which is claimed as the time of N-S-extensional tectonics in western Turkey, is related to the depositional time of the molasse sequences in the study area. Thus, the molasse is older than the basal deposits of the Gediz and Büyük Menderes grabens. © 2001 Éditions scientifiques et médicales Elsevier SAS     

西昆仑山前晚新生代磨拉石时代及意义

西昆仑山前柯克亚剖面晚新生代沉积记录了昆仑山乃至整个青藏高原的隆升过程.古地磁研究结果显示,西昆仑山前磨拉石形成于中新世晚期-上新世早中期,反映西昆仑山-青藏高原在中新世晚期有一次快速的隆升过程.孢粉记录结合区域地质资料分析表明,柯克亚剖面上部厚层砾岩的形成时代应为上新世早中期,而整个磨拉石开始沉积的时代应更早,为中新世晚期.沉积记录和气候变化显示了青藏高原在中新世晚期发生了显著的构造隆升事件.      

五台山早元古代碰撞造山带初步认识

五台山地区分布着复杂的变质杂岩。过去人们把这些变质岩作为地层分成群组段。龙泉关剪切构造岩的发现突破了这种传统观念。野外工作中发现所谓五台群主要包含了三个蛇绿混杂带;阜平群和恒山群的主要成分是灰片麻岩,它们构成两个太古代陆块的基底。五台地区的花岗岩类由代表弧环境的双花岗岩带的I型和S型花岗岩组成,它们与变质的钙碱性火山岩代表了古代的岩浆弧。滹沱群的豆村和东冶亚群以及过去划入阜平群和五台群的某些变沉积岩是阜平陆块被动大陆边缘的沉积。滹沱群的郭家寨亚群则是前陆盆地的磨拉石沉积。因此可以认为,这是一个由恒山仰冲陆块、北台-车厂弧和阜平俯冲陆块构成的碰撞造山带,碰撞时间大致是距今2050Ma。闭合的弧前大洋和弧后盆地形成了三条蛇绿混杂带。     

“磨拉石建造”和“不整合”在地层对比中的意义——以扬子地块及其北缘晚前寒武纪地层为例

扬子地块及其北缘晚前寒武纪地层划分对比争议较大,主要是对“地层不整合”和“磨拉石建造”存在认识上的分歧,笔者据现代构造理论,对地壳变形和沉积建造的控制作用认为,地层不整合可以发育在被动大陆边缘形成初始阶段的裂谷期和裂谷期后,又可产生于造山作用过程;磨拉石建造应按构造动力学背景划分为拉张型、挤压型和剪切型三类;它们分别代表了威尔逊旋回不同阶段的产物。     

新疆西准噶尔布龙果尔组的建造类型、时代及有关问题研究的新进展

本文对布龙果尔组的建造类型及地质时代进行了论证,认为其应属磨拉石建造叠加坍塌建造的复合型建造,并将其地质时代从晚奥陶世厘正为早志留世早期。此外,首次提出早古生代西准噶尔北部地区有一次造山运动,这次运动北疆邻区称为“艾比湖运动”,其发生的确切时间应为晚奥陶世末期。最后,根据布龙果尔组中出现蛇绿岩套的近源砾石。推断洪古勒楞蛇绿岩的形成年代早于早志留世。可能是奥陶纪。     

闽西南"丁屋岭砾岩"地质特征及时代探讨

福建长汀蔡坑地区原划震旦纪丁屋岭组下段的“丁屋岭砾岩”以复成分砾岩、岩屑石英砂岩为主要岩性的、形成于山间盆地的红色杂陆屑建造为加里东期的磨拉石建造，岩性组合、岩相、变质程度及其形成的地质背景都比较特殊。对它的详细研究对福建省乃至华南地区的基础地质研究具有重要意义。