The senonian succession in israel—Lithostratigraphy,biostratigraphy and sea level changes     

A. Flexer  A. Honigstein 《Cretaceous Research》1984,5(4):303-312

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Lithostratigraphy and biostratigraphy of the lewes and seaford chalks: A link across the Anglo-Paris basin at the Turonian-Senonian boundary     

B. Pomerol  H. W. Bailey  C. Monciardini  R. N. Mortimore 《Cretaceous Research》1987,8(4)

The positioning of the Turonian/Senonian boundary has been highly discussed since the introduction of the Senonian stage by d'Orbigny. In England the Early Senonian is conventionally represented by white chalks at the base of the Micraster cortestudinarium zone which to some has meant the top surface on the Top Rock or Navigation Hardgrounds. New macro- and microfaunal data on the Sussex White Chalk of Southern England, while providing a suitable framework for the comparison between the microfaunal zonation of the Paris basin chalks and macro- and microfaunal zonations commonly used in England, emphasize the positioning of the Turonian/Senonian boundary in the Anglo-Paris basin. This boundary falls within the interval Chalk Rock/Top Rock and is outlined by distinct changes in Micraster lineage (appearance of M. normanniae) and in benthic foraminiferal associations.  相似文献   

四川宣汉盘龙洞上二叠统长兴组沉积相与岩石地层精细划分   总被引：5，自引：0，他引：5  

吴亚生  姜红霞  刘丽静  赵锐 《地质学报》2015,89(2):412-424

盘龙洞剖面长兴组与普光气田同属于川东北的碳酸盐台地边缘相礁滩相层序,其岩石地层和沉积相研究结果对于认识普光气田、龙岗气田的储层发育和分布规律具有很好的参考作用。根据对薄片的仔细观察分析以及对相关地层的认识,对剖面长兴组的结晶白云岩地层进行了原岩恢复。根据古生物面貌及岩石组构特征,将盘龙洞剖面长兴组自下而上划分四段:下生屑岩段、礁灰岩段、上生屑岩段、微生物岩段。下生屑岩段包括了下部含小型有孔虫的深水陆棚相泥晶灰岩、以及上部含腕足类和棘皮类的浅水陆棚相生屑泥粒岩。礁灰岩段厚达108m,由海绵骨架岩和障积岩组成。上生屑岩段厚约45.3m,已经白云石化为细晶白云岩,导致前人往往误划分为蒸发台地相。仔细观察后仍然可以进行原岩恢复,主要由生屑泥粒岩、粒泥岩组成,含棘皮类、有孔虫、粗枝藻、等组成的群落。微生物岩段厚约8.7m,不仅地层以不规则薄层状为特征,而且含有特征的微生物群落。与普光6井、湖北利川见天坝长兴组剖面对比后发现,它们有相似的沉积层序:下部的深水相灰岩、中部的生物礁岩、上部的开阔台地相或相似环境的生屑灰岩。这应代表台缘礁滩相带的典型层序,可作为认识台缘礁滩相储层的基础。前人研究未能识别长兴组顶部的微生物岩段。这直接导致了二叠系—三叠系界线的无法正确确定。本文提出可以把微生物岩段作为一个岩石地层单位对待,可以作为确定二叠系—三叠系界线的标志层,把界线放在微生物岩段的中部。  相似文献   

Upper Neoproterozoic–Lower Cambrian sedimentary successions in the Central Iberian Zone (Spain): sequence stratigraphy, petrology and chemostratigraphy. Implications for other European zones     

M. I. Valladares  P. Barba  J. M. Ugidos  J. R. Colmenero  I. Armenteros 《International Journal of Earth Sciences》2000,89(1):2-20

2 O₃, TiO₂, Zr, and Nb abundances in shales from all the units, strongly suggest a gradual compositional change within this sedimentary succession. Together with the petrological data, the chemical results do not reveal any obvious coeval volcanic contribution to the sediments. On the basis of the chemical data, a comparison is made with other European zones containing detrital sediments composed of reworked crustal components. Received: 4 January 1999 / Accepted: 1 December 1999  相似文献   

苏南地区前第四纪岩石地层主要特征及几点认识   总被引：1，自引：1，他引：0  

许鸿基 《江苏地质》1999,23(2):71-79

依据“苏南及沿江地区１∶５万区调片区总结”的成果,概述了苏南地区前第四纪岩石地层的划分、岩性、分布、古地理沉积环境及其演化等主要特征,并就埤城岩群的原岩恢复,大王山组、黄尖组的时代归属,西区中—上新世地层划分等问题进行了讨论,提出了一些新认识。  相似文献   

造山带地层研究中几个问题的讨论          下载免费PDF全文

李日俊 《地质科学》1999,34(4):518-522

造山带地层的复杂性造成造山带地层研究的困难。史密斯地层和非史密斯地层并存,特别是非史密斯地层学尚不完善,因而造山带地层研究中往往会出现一些概念和认识上的混乱:混杂岩是不是地层?属不属于地层学研究的范围?根据某些新的发现对以往建立的一些岩石地单位的“解体”和“重新命名”是否合适?有时甚至会对一个地层单位的真正涵义发生误解。本文根据国际地层指南和中国地层指南所给出的地层划分、命名的原则、方法,试就这些问题进行探讨。  相似文献   

米仓山南缘寒武纪岩石地层及层序地层   总被引：5，自引：0，他引：5  

赵兵  杜思清  徐新煌 《矿物岩石》1997,(Z1)

本文对米仓山南缘寒武纪地层进行了详细的剖面描述和岩石地层划分，自下而上划分为筇竹寺组、仙女洞组、阎王碥组、石龙洞组和陡坡寺组。孔明洞组采用石龙洞组一名，同时对筇竹寺组、阎王碥组及陡坡寺组进行细分，并讨论了各组段的空间变化规律。首次将该区寒武纪地层划分为四个层序、一个超层序，并分析了各层序的组成和时限。认为该区寒武纪地层具明显的东西向变化规律。  相似文献   

Tectonic and lithological constraints on the evolution of the Karoo graben of northern Malawi (East Africa)     

U. Ring 《International Journal of Earth Sciences》1995,84(3):607-625

The results of a lithostratigraphic, tectonic and kinematic study of the Karoo deposits of northern Malawi are reported. The objective of the lithostratigraphic study is to correlate the deposits of the Karoo basins of northern Malawi with the well-known deposits of southern Tanzania, thus establishing a stratigraphic framework through which the timing of faulting can be constrained. The kinematic analysis of faulting constrains the opening direction for the Karoo graben in this area and provides basic data to discuss the Karoo graben development within the regional tectonic framework of south-eastern Africa. The studied adults are defined by moderately to steeply dipping cataclastic zones with a width of up to 15 m and are characterized by an array of slickensided fault surfaces with different orientations and slip directions. In this study, small faults (offset < 10 m) and meso-scale faults (offset > 10 m, but generally not exceeding 30–40 m) have been distinguished. Methods used to analyse the kinematic data include the ‘pressure tension’ (PT) method, which estimates the principal axes for the bulk brittle strain, and the internal rotation axis (IRA) method, which estimates the axis of bulk internal rotation and the overall sense of slip at the faults. A mass balance calculation reveals a volume increase of up to 16% during cataclastic deformation in the fault zones. The PT method shows an approximately east trending extension direction for faults that occur only in the latest Carboniferous (?) and Early Permian strata, whereas the fault kinematics from faults that cut middle Permian to Early Triassic rocks is characterized by a ESE to SE trending extension direction. The small faults yield essentially the same kinematic results as the meso-scale faults. In a transport-parallel cross-sectional view, the principal extension axes are at an acute angle of approximately 60° to the major fault planes. Given the moderate fault density, the relatively high angle between the orientation of the principal extension axis and the fault planes suggest only a moderate amount of horizontal extension across the Karoo graben of northern Malawi. Riedel structures in the fault zones formed within two conjugate sets of localized shear zones; slip on one set was top to the W/NW and, on the other, top to the E/SE. The two conjugate sets of Riedel structures have an acute angle about the regional shortening axes, implying that no pronounced rotation of the strain axes occurred. The internal rotation axes for the Riedel structures reveal a largely bimodal distribution and inferred weakly monoclinic to orthorhombic symmetry. Therefore the overall deformation during Karoo rifting in northern Malawi is interpreted to be close to a coaxial deformation with a limited amount of horizontal extension.[/p]  相似文献   

Quantification of Holocene lake-level changes in Finnish Lapland using a cladocera – lake depth transfer model     

Atte?KorholaEmail author  Matti?Tikkanen  Jan?Weckstr?m 《Journal of Paleolimnology》2005,34(2):175-190

During recent years, numerous studies dealing with Holocene lake level fluctuations have been conducted in Finnish Lapland. However, no quantification of lake level variations exists to date. Here, we applied a recently developed modern cladocera – lake depth transfer model to subfossil cladocerans analysed from three small and shallow (< 6 m) kettle-hole lakes in northwestern Finnish Lapland to provide estimates of the amplitudes of long-term lake-level changes in the region. The quantitative inferences were compared to pollen, charcoal and geochemical records from one of the study sites. The lake levels were inferred to be high during the early Holocene; they faced marked reduction up to 4–6 m in the mid-Holocene (≈7000–4000 cal yr BP), and rose again during the latter part of the Holocene. There is some indication of lowered lake levels around 1500 cal yr BP, but interpretation of such small-scale changes is hazardous due to large prediction errors in the initial cladoceran model. The overall pattern of the Holocene lake level variation generally followed the regional changes in climate humidity as reconstructed in previous studies by means of other sedimentary proxy indicators, such as pollen and oxygen isotopic compositions. We postulate that changes in winter precipitation may have had a greater influence on lake-levels than variations in summer precipitation or evaporation.  相似文献   

老挝万象地区含盐系地层   总被引：4，自引：0，他引：4  

冯明刚  吴军  韩润生  朱延浙  严城民 《云南地质》2005,24(4):407-413

老挝万象地区的含盐地层称为塔贡组(E1tg)。该组可划分为三个岩性段,每个岩性段均由下部膏盐层、上部陆源碎屑岩组成,均属湖泊沉积。该套地层的介形虫属Sinocypris—Cypris(Cristocypris)—Parailyocypris组合、轮藻属Peckichara—Obtusochara组合,属古新统。岩石地层、生物地层及年代地层上,该组与我国滇西地区的勐野井组(Em)较为相似。  相似文献