新疆古地理研究专辑摘要

太古宙以来,新疆陆块经历了离散→聚合→裂解→拼合的复杂过程,地壳运动和构造格局直接控制了古地理环境的变迁。新元古代塔里木陆块和准噶尔地块之间,有南天山洋相隔。古元古代兴地运动,使塔里木基底基本固结,中－新元古代均为稳定型盖层沉积。中、新元古代其间有3次构造运动使本区经历了3次大的海进和海退,陆地增加而海域缩小,沉积环境渐趋稳定。长城纪1 650～1 350 Ma以稳定碎屑岩沉积为主,蓟县纪1 350～1 050 Ma以稳定的滨浅海碳酸盐岩沉积为主,青白口纪1 050～800 Ma则以不纯的灰岩及细碎屑岩沉积为主。准噶尔…     

滇东南丘北地区晚二叠世吴家坪早期岩相古地理特征

滇东南丘北地区上二叠统吴家坪阶主要为一套含铝土矿的碎屑岩系。根据区内实测剖面的沉积特征以及区域地质资料分析,认为研究区吴家坪早期为低能淤泥质海岸到局限浅海的沉积环境。在对54条剖面的岩性、厚度、沉积特征等资料定性、定量分析的基础上,采用单因素分析、多因素综合作图法编制了丘北地区吴家坪早期的岩相古地理图,分析了其沉积相分布和演化特征。吴家坪早期,丘北地区总体表现为潮坪-局限浅海的沉积环境,铝土矿主要发育在吴家坪阶下部的第一个三级层序中。通过对区内已知矿点与古地理关系的研究,认为铝土矿成矿的最有利沉积环境是潮下带-浅海上部。     

山东淄博地区上寒武统沉积地球化学特征及其层序地层学意义

根据微量元素和稳定同位素的特征可以推断古盐度、古水温和古水深 ,恢复古沉积环境 ,并判断海平面的相对变化。对淄博地区上寒武统微量元素Sr、Ba、V、Ni和氧 碳同位素的研究结果表明其属于稳定的浅海环境 ,微量元素和氧 碳同位素的变化趋势与海平面的波动有一定的对应关系 ,而且从地球化学方面为层序地层的划分提供了依据。研究结果也表明 ,由于沉积地球化学特征的复杂性 ,不能简单地用一种因素来分析。     

从地球生物学角度讨论华南中二叠世海相烃源岩缺氧沉积环境成因模式

探讨陆棚环境缺氧沉积的成因, 对查明海相优质烃源岩时空分布、恢复地史时期古环境演化具有重要意义.华南地区中二叠世栖霞组有机质丰富, 出现多方面缺氧沉积特征, 同时多门类底栖生物繁盛, 其成因一直令人困惑.简要介绍了陆棚浅海缺氧环境的生物特征及古氧相划分, 分析了栖霞组一个由纹层状灰岩和块状灰岩组成的典型的沉积序列的古氧相特征.块状灰岩的生物特征和地球化学特征均指示常氧沉积环境; 而纹层状灰岩的生物特征偏向常氧相, 沉积地球化学特征偏向厌氧相, 体现了陆棚缺氧沉积环境水体溶氧量不稳定的特点.栖霞组沉积特征表明, 栖霞组缺氧沉积环境的频繁出现与较高的生物产率有关.结合区域古地理和古特提斯古海洋背景, 认为华南地区中二叠世缺氧环境的成因与当时陆海分布格局和古海洋表面洋流系统有关.      

豫西栾川地区栾川群的层序、沉积环境及其构造古地理意义

运用构造分析与地层研究相结合的方法,修订了豫西栾川地区栾川群的地层层序,进而研究了栾川群的沉积环境及构造古地理特征。研究结果表明,栾川群主要为浅海一潮坪相的碳酸盐及碎屑泥质沉积,其中碎屑岩的成分和结构成熟度均较高,具有被动大陆边缘稳定型沉积特点。下栾川群沉积时期环境比较稳定,上栾川群反映沉积环境的动荡多变,可能为被动大陆边缘向主动大陆边缘转化的先期特征．     

河南箕山地区中元古界五佛山群沉积环境及岩相古地理特征

河南箕山地区中元古界五佛山群是太古界、下元古界褶皱变质基底之上的第一盖层，由于基底构造的差异性，造成五佛山群马鞍山组、峡外组在海侵过程中处于不同的沉积环境，但总的看来，箕山地区中部为基底隆起区，东部为沉陷区，西部为一向西倾斜的缓坡区。在五佛山群马鞍山组沉积的早期，区内以河流相沉积为主；在马鞍山组沉积的中、晚期，东、西部均处于滨浅海环境，为滨浅海相碎屑岩沉积，中部隆起区呈多岛状，出现潮坪沉积环境，为潮坪相碎屑沉积。在五佛山群峡外组沉积期，古地理分异格局消失，箕山地区全部转化为潮坪环境。     

东北佳木斯-内蒙古地区中二叠世岩相古地理研究

严格按照等时性对比原则,选取岩相古地理图的制图单元.以野外实测剖面为基础,做精细沉积微相研究,在东北地区地层露头剖面识别出海相(浅海亚相、半深海亚相)、三角洲相(三角洲前缘:水下分流河道、河口坝,前三角洲)沉积.在露头点测量基础上,以点带线、以线带面,分析古沉积环境.在野外剖面沉积微相精细划分基础上,结合区域地质资料,...     

华北盆地西部太原组遗迹化石组合对古水深变化的响应

通过对豫西—晋中南地区上石炭统—下二叠统太原组碳酸盐岩中遗迹化石的组成、产状及分布特征的研究,结合部分生物潜穴中Sr含量、Sr/Ba值、1000×(Sr/Ca)值和δ13C值,得到不同地区太原组沉积期古水深的变化曲线,建立了3种不同水深的遗迹组合:(1) Nereites-Chondrites遗迹组合,产生于氧化还原界面附近水体相对较深的浅海下部环境;(2) Zoophycos-Teichichnus遗迹组合,形成于浪基面至氧化还原界面之间的浅海中部沉积环境;(3) Zoophycos-Thalassinoides遗迹组合,出现在平均海平面至浪基面之间的浅海上部或较为闭塞的海湾潟湖沉积环境。依据这3种遗迹组合在各剖面上的变化特征和古水深,认为在豫西—晋中南地区太原组沉积期发生过2次较大规模的海侵。这一成果为精细研究华北西部地区太原期沉积环境演变规律及对比地层提供了生物遗迹学方面的依据。     

我国南方的两种现代滨海沉积类型

“滨海相”是古代沉积层中广泛分布的一种沉积相,因此,详细讨论这种现代沉积的沉积环境和沉积物的差别,对于研究古代沉积的岩相和古地理将具有启示作用。我国的海岸线很长,滨海沉积的种类也是多种多样的,作者研究了我国南方的两种现     

黔南桂西早三叠世大陆斜坡碳酸盐重力流沉积

黔南桂西地区(东经105°-107°,北纬24°20′-26°40′)地跨扬子准地台和加里东褶皱带两个一级大地构造单元。早三叠世时该区由西北向东南,从浅海沉积环境变为深海沉积环境。沿贵州福泉、惠水、紫云、贞丰、安龙以及广西隆林、西林一带长约400公里、宽25-70公里的“S”形狭长地区是分隔浅海、深海沉积环境的古大陆斜坡。该区的沉积相带划分如图1。各相带的主要沉积特征见表1。斜坡相带沉积物主要为低密度浊流和远洋悬浮沉积的暗色薄板状泥晶灰岩,具重力滑移构造(图版Ⅰ,6)。     

腕足类化石壳体同位素地球化学在恢复古环境中的应用

地球历史时期的生物硬壳或骨骼记录着丰富的地球过去环境特征的信息,对这些化石成分进行同位素地球化学研究是发掘其中信息、探索地球历史环境变化的有效途径之一。过去四十年来化石同位素地球化学在恢复古海洋环境、气候、盐度以及研究碳、氧同位素长期变化等方面的应用越来越受到人们的重视。腕足类化石壳体是古生代海洋环境恢复的主要手段之一。但这一方法也还存在一定的问题,这些问题集中在腕足壳体是否与其生存的海水存在同位素的平衡、是否存在由于生物生命过程中的新陈代谢作用造成的稳定同位素分馏的同位素生命效应(VitalEffects)、是否保存其原始的同位素信息等方面。详细回顾了腕足类化石壳体同位素——这种在恢复古环境研究中广泛应用方法的发展历史、研究现状、存在的问题,以及不同的学者对这些存在的问题所做的工作和他们对这些问题的不同观点。同时也介绍了这一方法的一些研究新进展。     

南京汤山驼子洞洞穴堆积及其意义

通过对南京汤山驼子洞洞穴堆积观察描述和样品分析测试,结合前人研究成果和汤山地区地质地貌演化的历史,讨论了驼子洞堆积的时代、堆积过程和方式,并对其蕴含的构造、地貌、气候和生物进化等古环境信息进行了合理的挖掘。初步研究表明驼子洞堆积可能是跨早更新世与中更新世早期的地层,其上部含哺乳动物化石的堆积可能反映了偏暖的气候环境。     

First report of turtle tracks from the Lower Cretaceous of Korea

A partial trackway of a turtle from the Jinju Formation (Sindong Group) is the first report of Mesozoic turtle tracks from Korea and the first report of traces of an aquatic tetrapod from Korea. Six tracks show a partial trackway configuration inferred to represent a partially buoyant trackmaker, possibly engaged in “bottom walking” behavior. Although turtle tracks often co-occur with crocodylian tracks in Cretaceous coastal plain facies in other regions, especially North America, to date there are no such co-occurrences in east Asia. This suggests that in Asia paleoenvironments suitable for turtles were quite widespread, but paleoenvironments were not suitable for crocodylians.     

Paleolithic archeology and the paleogeographical study of loess-paleosol sequences in Eastern Europe

The paper is concerned with problems of the study of Paleolithic sites in the loess regions of the Russian Plain. It is of great significance to correlate prehistorical settlement with Upper Pleistocene cycles of loess and soil formation — not solely in the reconstruction of paleoenvironments. From the cultural layers at various sites paleontological finds and objects were collected for radiocarbon dating. A complex analysis of archeological objects embedded in the loess-paleosol sequence helps us date Upper Pleistocene loess formation cycles. The data acquired from the investigation of the lithological properties of loess and their modification through time and their dependence on relief characteristics permitted a correlation between the various paleoenvironments and the dust accumulation cycles, which played a decisive role in the selection of the most habitable sites.     

辽河群沉积期古环境分析

根据辽河群地质特征，岩石化学，稳定同位素特征分析认为：浪子山组沉积期方环境为浅海潮坪相；里尔峪组沉积期为强氧化泻湖相；高家峪组沉积期为强还原环境的泻湖相；大石桥组沉积环境为低能、还原环境的滨海碳酸盐台地相；盖县组沉积期为开阔正常浅海潮坪相。辽河群从发生发展到结束古环境演化规律是：构造上由优地槽向冒地槽演变；气候上由炎热转变为温湿；古地理环境从有障壁的局限海变为无障壁的开阔海，从咸化海向正常海，从泻湖相向潮坪相转化。物质补给由火山为主转为陆源碎屑为主。     

Chad Basin: Paleoenvironments of the Sahara since the Late Miocene

Since the mid 1990s, the Mission paléoanthropologique francotchadienne (MPFT) conducts yearly paleontological field investigations of the Miocene-Pliocene of the Chad Basin. This article synthesizes some of the results of the MPFT, with focus on the Chad Basin development during the Neogene. We propose an overview of the depositional paleoenvironments of this part of Africa at different scales of time and space, based on a multidisciplinary approach (sedimentary geology, geomorphology, geophysic, numerical simulations and geochronology). The Miocene-Pliocene paleoenvironments are examined through the sedimentary archives of the early hominids levels and the Holocene Lake Mega-Chad episode illustrates the last major paleoenvironmental change in this area. The sedimentary record of the Chad Basin since the Late Miocene can be schematized as the result of recurrent interactions from lake to desert environments.     

Composition and Formation Conditions of Lower Eocene Shallow-Marine Carbonates in Southern Armenia

Lithology and Mineral Resources - Nummulite facies are known to be a good indicator of Eocene shallow-water paleoenvironments. Nummulitic limestones are widespread in the Lower Eocene of...     

The role of principles and methods in loess-paleosol investigations

In the process of loessification, the development of loess fabric, the role of zonal, regional and partly of local environmental factors is regarded decisive. In the loess sequences various genetic types of loess pockets and paleosols occur and reflect different climatic and paleogeographical conditions.As a consequence, even within a single profile the colour, grain size and mineral composition, CaCO₃ content, degree of weathering and fabric of loess may vary. Zonal, regional or even local variations in such loess properties may equally derive from syngenetic or postgenetic processes. For similar reasons, spatially and temporally different forms, types and subtypes of paleosol also developed.This way, loess and soil formation resulted in various spatial types in the same glacial, interstadial or interglacial phase in the various geographical zones and regions. Although there exist major loess regions where the interglacial soils (eg brown forest soils) are markedly distinct from interstadial steppe soils or from other types of humic soils, continental loess areas can also be observed where the paleosols developed under interglacial and interstadial conditions (eg steppe or forest steppe soils) cannot be referred into different genetic types. In such cases the changes in paleoenvironments are difficult and uncertain to reconstruct.The interregional correlation of paleosols is occasionally hindered by the various terminologies applied to denote them. In addition, there are uncertainties concerning the dating and identification of paleoenvironments of polygenetic soils and of soil complexes consisting of paleosol units: how many soil formation phases they represent and how long erosional gaps can be reckoned with between these phases.     

亚洲人类的起源及其演化途径的初步研究

自１９４９ 年新中国建立以后,在中国各地相继发现中新世早期以来的远古人类化石,使之有可能逐渐阐明亚洲人类的演化过程,笔者根据各化石的特征考察它们的系统,根据各时期的古环境及古气候情况推断它们的演化途径,把在欧洲出现的古类人猿 Ａｌｓａｔｉｃｏｐｉｔｈｅｃｕｓ 当成发现种,非洲系人类在非洲及欧洲或亚洲中部完成了演化。同时,把在缅甸出现的古类人猿 Ａｍｐｈｉｐｉｔｈｅｃｕｓ 或 Ｐｏｎｄａｕｎｇｉａ 当成发源种,亚洲系人类在亚洲东南部完成了演化。在此期间,在非洲及欧洲或亚洲中部的巴基斯坦出现的西瓦古猿及腊玛     

Neoproterozoic chemostratigraphy

Chemostratigraphy has diverse applications to investigating the rock record, such as reconstructing paleoenvironments, determining the tectonic setting of sedimentary basins, indirect dating, and establishing regional or global correlations. Chemostratigraphy is thus an integral component of many investigations of the ancient sedimentary record. In this contribution, we review the principle inorganic geochemical methods that have been applied to the Neoproterozoic sedimentary record. Analysis of the traditional stable and radiogenic isotope systems, such as δ¹³C, δ¹⁸O, δ³⁴S, and ⁸⁷Sr/⁸⁶Sr, is routine, particularly in successions rich in carbonate. These mainstay applications have yielded invaluable data and information bearing on the chronology and evolution of this eventful era in Earth history. Alongside the growing database of traditional data, a series of novel geochemical techniques have given rise to important new models and constraints on Neoproterozoic biogeochemical change. In particular, a range of proxies for water column redox, mainly obtained from black shales, have shed light on the pace and tempo of Neoproterozoic oxygenation and its link to the appearance of early animal evolution. Increased integration of diverse geochemical, sedimentological, and paleontological datasets, and the gradual radiometric calibration of the stratigraphic record promise to bring the details of the evolution of the Neoproterozoic Earth system into ever greater focus.