青海扎陵湖和鄂陵湖盆地第四纪河湖相地层研究

通过对扎陵湖和鄂陵湖沿岸的湖积阶地中湖相沉积的野外地质调查和实测剖面,对分布于盆地内的第四纪早更新世-全新世湖相地层进行了详细的研究和划分、重新厘定了该区第四纪岩石地层单元,确立了生物地层和年代地层序列.建立了青海东南部地区第四纪早更新世-全新世湖相地层单位-黄河源群(QH),黄河源群是由第四系下更新统野生沟组(Qp~1γ)、中更新统鄂陵湖组(Qp~2e)、上更新统大野马岭组(Qp~3d)和全新统黑河乡组(Qhh)等4个组组成.为青藏高原湖泊演化、气候变化、古地理变迁研究,以及第四纪地层的划分与对比等提供了新资料.     

内蒙古东部及邻区石炭纪—二叠纪构造地层 格架与形成环境

构造带内的地层建造和区域展布主要受大地构造背景和古地理环境的双重控制。突出构造地层学方法,进行综合地层学研究,重点地层剖面实测与修订前人资料相结合,在恢复大地构造演化和沉积相分析的基础上,重新划分内蒙古东部及邻区石炭纪—二叠纪地层分区,并建立构造地层格架。2条构造线将研究区分隔成3个地层分区。西拉木伦河断裂南侧（华北地层分区）出露大陆边缘坳陷沉积和陆内裂陷槽充填,称为康保-赤峰地层小区。查干敖包-阿荣旗断裂至黑河一线北侧（兴安地层分区）属西伯利亚板块,呈现边缘坳陷沉积和裂陷槽充填的陆块南缘称东乌-龙江地层小区;而陆内坳陷沉积的北部范围称额尔古纳地层小区。2条构造线之间为板块增生带（内蒙草原地层分区）,自然分隔成锡林郭勒地层小区、科尔沁地层小区和松-辽地层小区,发育多岛洋-海槽-残余海槽的复杂环境。通过论述各岩组划分、对比和沉积相归属,构造地层格架尽可能反映当时的大地构造格局和沉积环境演变。     

南京地区新近纪地层排序及其时代

南京地区新近纪地层发育较齐全,生物化石丰富,根据哺乳动物化石最新研究成果,并通过地层对比,将其厘定为中新世早—中期洞玄观组(N1-21d)、中新世晚期的六合组(N31l)和黄岗组(N31h)以及上新统的尖山玄武岩组(N2j)。长江坳陷中砾石层相当发育,如南京附近的雨花台砾石层,安徽境内的安庆砾石层,主要由三套岩性组成,之间均呈假整合接触。第一套归属于六合组(N31l),第二套沿用雨花台组(N2y),第三套为更新统。     

华北地区晚新生代几个地层单元的讨论

阳原盆地晚新生界以其出露完好, 层序清楚, 富含古生物、古人类遗存而闻名于世。近年来, 随着研究精度的不断提高, 在地层详细划分与地层单元的使用上却不很统一, 甚至较为混乱。我们在开展《1:5万化稍营、北水泉幅区域地质调查及泥河湾层研究》和《我国北方晚更新世标准地层单元“许家窑组”再研究》等科研项目中, 对阳原盆地东部上新世红土、泥河湾层进行多重地层划分与地层单元的厘定。鉴于篇幅所限, 本文仅就阳原盆地上新世红层、许家窑组, 以及许家窑组与泥河湾层的关系等方面作一介绍。其主要成果有: 一、阳原盆地上新世红层从岩石地层、生物地层、磁性地层及古环境分析, 应属一套多成因的红层建造, 不应重复建组, 建议合并, 沿用石匣组。二、通过对许家窑遗址一带, 以火山灰层为标志的第四纪地质结构调查和剖面的测制, 化石的新发现, 证实含许家窑动物群、文化层之上的地层时代为晚更新世, 之下的岩石地层应属中更新世。这些成果为泥河湾盆地晚新生代标准地层单元的岩性特征及属性提供了新依据。     

扬子陆块东南缘南华纪地层对比

扬子陆块东南缘的南华纪地层剖面众多 ,依据我国南华系与国际上“成冰系”相对应的原则 ,选择了其中 5条具代表性的剖面进行对比研究后认为 :扬子东南陆缘的冰川事件序列为长安冰期、富禄 (莲沱 )间冰期、古城冰期、大塘坡间冰期、南沱冰期 ;鄂西一带缺失长安冰期沉积 ;长安组的底界可定为南华系的底界 ,南沱组 (或洪江组 )的顶界可定为南华系的顶界 ;上下统的分界在莲沱组 (或富禄组 )与古城组之间 ;以冰川事件为主线 ,结合同位素年龄值 ,探讨了组与组跨相区对比中存在的问题以及南华系的年限。     

Pleistocene stratigraphy in the southern Lower Mississippi Valley

Scientific inquiry into Pleistocene stratigraphy of the Lower Mississippi Valley (LMV) dates to early writings of European naturalists in the late 19th century. By the early 20th century, landscape evolution concepts, stratigraphic models, and regional syntheses had developed for most areas. The 1944 monograph of H.N. Fisk marks the advent of a predictive stratigraphic and landscape evolution model that links form and process to a predominantly glacioeustatic mechanism. The Fiskian model gained widespread acceptance, and decades passed before significant alternate models began to emerge. Revised stratigraphic and geomorphic concepts are presently developing from newly acquired environmental and engineering data. Present scenarios classify Pleistocene outcrop areas into erosional and constructional landscapes, and veneers of eolian, colluvial, fluvial, coastal, and marine origin can drape both types of surfaces.

The southern LMV and adjacent Gulf Coastal Plain (GCP) experienced significant landscape change during the Pleistocene. Late Tertiary (Pliocene?) to Early Pleistocene deposition of the Upland Complex was by streams with a high sand and gravel load relative to its mud load. The regional drainage network and fluvial system behavior was probably significantly different from the modern. Braided stream alluvial fan complexes received sediment from highland source areas adjacent to the LMV and the glaciated mid-continent. It is plausible that part of Upland Complex deposition predates initial glacial advances.

From Early to Middle Pleistocene, an erosional landscape formed during a dissection period that chiefly postdates soil formation on stable landscape positions of the Upland Complex. Slope evolution truncated a regionally extensive geosol in multiple phases, and parts of the erosion surface complex are graded to the oldest preserved constructional alluvial plains in present valleys. Toe and foot slope positions of the erosion surface complex and its correlative alluvial plains are presently delineated as the Intermediate Complex. Constructional landscapes formed at this time are sparsely preserved; Fisk's Montgomery Terrace in the Lower Red River Valley (LRRV) is the best preserved example. Influences on the development of erosion surfaces in the LMV are not well understood; however interactions of relative sea level fall, climate change, and epirogenic crustal movement are plausible factors.

From the latter part of Middle Pleistocene to the Holocene, there was widespread evolution of modern constructional landscapes. Constructional alluviation preserved lithofacies of mixed load, laterally accreting, meandering streams that developed over large areas of the southern LMV to form parts of the Prairie Complex. Lateral planation in valleys and stable rates of upland sediment generation were dominant processes during Prairie Complex deposition.

Pleistocene stratigraphic examples considered important by Fisk are still considered relevant to modern stratigraphic investigators. Presently, Pleistocene units of the southern LMV, the adjacent LRRV, and central GCP can be correlated only by relative stratigraphic relationships. Refined chronostratigraphic and paleoenvironmental models for these areas would help improve the understanding of the geomorphic influences on Quaternary landscape evolution in the region.     

Aminostratigraphic results from Cape Lookout, N.C., and their relation to the preserved Quaternary marine record of SE North Carolina

Aminostratigraphic data were obtained for Mulinia lateralis samples from closely spaced drillholes on the Cape Lookout, North Carolina barrier islands. Two major aminozones are recognized in the subsurface section based upon D-alloisoleucine/L-isoleucine (A/I) values. These major aminozones can each be subdivided into two additional aminozones based upon direct comparisons with Mulinia A/I data from other North Carolina localities. Correlation of the Cape Lookout Mulinia aminostratigraphy with U-series calibrated A/I data in N.C. indicates that the sampled units represent deposition during the middle to late Pleistocene. The four Cape Lookout aminozones may be assigned to late and early stage 5 (or possibly stages 5 and 7), a portion of the interval during stages 17–19, and at least one interglacial in stages 25–31 of the oxygen isotope record based on correlation to calibrated sites and kinetic model extrapolation.

The aminostratigraphic data obtained from the Cape Lookout barrier islands and nearby areas indicate that there are significant differences in the extent of preservation of the Pleistocene sedimentary record to the southwest of Cape Lookout compared with that to the north-northeast. All four of the recognized Cape Lookout aminozones are present in the subsurface section to the north-northeast of Cape Lookout. In contrast, the two late Pleistocene aminozones are almost completely absent in the subsurface of the barrier islands, and in Onslow Bay, to the southwest of Cape Lookout. These aminostratigraphic interpretations are consistent with the incomplete stratigraphic record recognized by previous investigators for the Cape Lookout-Onslow Bay area. The calibrated kinetic model age estimates for the Cape Lookout aminostratigraphic data now permit quantification of these stratigraphic gaps. The detailed aminostratigraphic results from Cape Lookout also have significant consequences for regional aminostratigraphic correlations on the Atlantic Coastal Plain, and provide valuable information with which to test contrasting models proposed for regional correlation within the context of the preserved stratigraphic record.     

松嫩平原东部中、晚更新世地层界限：光释光年龄及元素变化

松辽平原东部受第四纪差异性构造活动影响,形成特殊的更新世沉积地层。由于第四纪划分方案和地域差异,松辽平原东部中、晚更新世界限仍处于不确定状态。通过黑龙江省方正剖面的研究、中更新统顶部(149.6±10.4) ka光释光年龄和主要氧化物、微量元素、稀土元素分析以及区域剖面对比,认为将松辽盆地东缘中、晚更新世的界限年龄置于140 ka更适合地层实际情况。中更新世地层以河湖相、河流相和洪积相沉积物为主,完整的晚更新世地层应该包括下部的沼泽漫滩相黏土、亚黏土和上部亚砂土、黄土沉积。黑龙江省荒山剖面哈尔滨组下部可能由于相变而缺少沼泽漫滩相的沉积物。方正剖面与榆树东岗组剖面地层可以对比。中、晚更新世沉积环境发生了明显变化,主要氧化物、微量元素和稀土元素含量在中、晚更新世的地层界限处都发生了明显的突变。     

海南岛北部第四纪早中更新世多文组的建立

在1：25万琼海县幅区域地质调查中，对海南岛北部地区出露的一套早、中更新世形成的基性火山岩进行了详细研究，新创建多文组，并进一步划分为上、下段，分别代表早更新世晚期一中更新世早期、中更新世中晚期形成的基性火山熔岩、火山碎屑岩。其层位比道堂组、石山组低，且岩性组合存在差异。对该组的分布范围、岩性、岩相、形成时代、地球化学特征进行了总结，并讨论了其形成的构造环境。     

哈密坡子泉地区石炭系研究的新认识

通过野外工作 ,在前人所划的坡子泉地区石炭系白山组内新发现三个角度不整合 ,而将白山组解体成四个组。结合古生物化石和同位素年龄资料 ,将狼泉组和坡子泉组划归下石炭统 ,黑石山组和马庄山组划归上石炭统。在此基础上 ,研究了新划四个组的沉积环境 ,总结了坡子泉地区石炭纪地壳演化简史 ,建立了地层组合模式     

甘肃的第四系

在全面系统分析、整理第四纪地层资料基础上，以岩石地层为基础，以古地磁、１４Ｃ、热释光测年资料为依据，以化石资料为参考，对更新统及全新统进行了岩石地层、磁性地层单位的对比和划分；重新厘定了一些地层单位的名称和含义；统一了各地层区的地层系统；建立并进一步完善了甘肃第四纪地层层序。确定了兰州、陇西及陇东地区黄土的开始沉积时间。对甘肃第四系的动物群及新构造运动的特征进行了论述。     

江苏侏罗系—白垩系火山岩地层对比及划分探讨

排除火山岩系的复杂性产生的对区域地质调查和地层划分造成的干扰,综合生物化石、同位素年龄及地球化学特征等数据提出了江苏地区侏罗系—白垩系火山岩系地层的层序划分,建议将燕山运动以来侏罗系—白垩系火山喷发岩系的三大旋回所形成的各火山岩和火山碎屑岩组,包括龙王山组、云合山组、大王山组、姑山组、娘娘山组名称取消,并将其作为不同时期的火山喷发岩系夹层分别归入西横山组、浦口组、赤山组,同时将苏北地区的象山群也归入西横山组,将白垩系底界放在西横山组与苏南所见的象山组之间。     

华北晚前寒武纪（中、新元古代）岩石地层单位及多重划分对比

晚前寒武纪地层是华北早前寒武纪褶皱变质基底之上的第一套沉积盖层。主要发育和分布于华北晚前寒武纪的一些裂谷系－裂陷槽中，但各地沉积开始时间不一，后期遭受剥蚀程度不一。长期以来在地层划分、岩石地层命名、使用及年代属性上认识不统一，在一些地区认识分岐很大。笔者在岩石地层单位、地质特征认识的基础上，进行了全区（群、组）统一对比，明确了可作为华北晚前寒武纪沉积序列的代表性岩石地层单位及岩石组合特征；并介绍晚前寒武纪叠层石组合、微古植物特征性分子和已发现的宏观藻类和后生动物，论述了层型所在地区年代地层划分及层型以外各地层分区岩石地层单位年代属性的确定依据。     

浙江白垩纪火山岩的地层划分及钕同位素特征

浙江晚中生代火山岩系的划分和对比一直存在不同认识。根据近年来获得的新资料,结合前人的研究成果,对有关浙江白垩纪火山岩的地层划分和对比提出浙江白垩纪火山岩Nd同位素组成主要变化规律为:不同大地构造单元(浙西扬子地块和浙东华夏地块)的火山岩Nd同位素组成差异较大,显示出古老变质基底岩石对火山岩Nd同位素组成的制约;建德群下部劳村组和黄尖组以及磨石山群下部的大爽组、高坞组、西山头组火山岩εNd值变化不大,而与上部的寿昌组以及九里坪组火山岩εNd值有明显的不同,表明两个旋回火山岩物质来源有一定差异;火山岩的εNd值随时代变新有增大的趋势。Nd同位素示踪信息也就有可能作为火山地层划分和对比的重要依据之一。     

包头地区晚更新世—全新世地层划分对比及环境变迁

对包头平原第四纪堆积物的年代地层、生物地层、岩石地层和磁性地层的研究表明,该区晚更新世—全新世地层可与我国华北晚更新世—全新世典型地层剖面——萨拉乌苏河滴哨沟湾剖面对比,并可进一步划分出萨拉乌苏组、城川组、大沟湾组和滴哨沟湾组。这一研究不仅重新厘定了包头平原这一时段地层的层序,完成大区域地层对比,同时也为研究包头地区乃至呼包盆地晚更新世—全新世古气候和古地理环境变迁提供了基础资料。     

台湾省地层多重划分对比研究

台湾省地层多重划分对比研究福建省地矿局台湾省地层研究组（福建省地质矿产局，福州，３５０００３）地层学是地层领域中的基础学科。随着现代地层学和沉积学的发展，地质学家普遍认识到沉积地层叠复是在复杂的侧向堆积过程中形成的，且岩石地层单位具有普遍的穿时性。因...     

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.     

Similarity of palaeocurrent: A tool for stratigraphic correlation

Conventional stratigraphic correlations are based on similarity of lithology, order of superposition, marker bed, unconformity, grade of metamorphism, fossil content and geochronology of the rock units. The Gondwana strata have been correlated referring to the above mentioned criteria. In the present work, the Talchir and Karharbari formations of two adjacent Gondwana basins separated by over 200 Km were examined with respect to their palaeocurrent directions. The study suggests that the palaeocurrent populations of different formations in both the basins are statistically dissimilar, this is because, both are stratigraphically distinct in order of superposition and thus are not correlatable. On the other hand, the palaeocurrent populations of the same formation in both the basins are statistically similar and stratigraphically correlatable. It is suggested that the similarity of palaeocurrent can be regarded as a criterion for stratigraphic correlation at least in local and regional scale.     

中新世以来吕梁山及邻区构造——沉积演化

裂变径迹研究显示中新世早期(23±3Ma)现今吕梁山及周缘地区发生了一次整体性快速隆升。中新世晚期(约8Ma前),吕梁山前、鄂尔多斯盆地及东部宁武—沁水盆地结束了长期剥蚀历史,开始广泛接受新生代沉积。沉积物的垂向叠置关系及横向展布特征显示:8.35～6.7Ma为吕梁山快速差异隆升期,在山前(东西两侧)堆积了冲积扇相芦子沟组砾岩层,暗示了吕梁山已经地貌上成山;与此同时地势相对平坦且摆脱地表水流影响的鄂尔多斯盆地广泛堆积了风尘堆积—红黏土(保德组)。中新世晚期—早更新世早期(6.7～1.8Ma),吕梁山西部山前及鄂尔多斯地区整体缓慢隆升,堆积了新近纪保德组上部、静乐组红黏土及早更新世午城组黄土—古土壤序列。受西部六盘山快速抬升作用影响,鄂尔多斯西部抬升速率略高于东部,于早更新世中期(1.8～1.4Ma)形成现今西高东低的地势格局和南北向晋陕谷地,进而黄河及其支流顺流而下。中更新世以来,鄂尔多斯地区沉积与抬升并重,最终形成现今黄土高原。吕梁山以东的沁水盆地中新世演化史与西部相似,上新世起盆地开始断陷,汾河地堑开始形成。断陷一直持续到早更新世,自下而上依次沉积了下土河组、小白组、大沟组、木瓜组湖相地层,盆地边缘则持续抬升堆积了静乐组和午城组风成堆积。中更新世以来,断陷结束,盆地整体抬升。