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1.
全球始新统 -渐新统界线层型剖面和层型点(GSSP)被确定在意大利安科纳 (Ancona)的马西格纳诺 (Massignano)剖面。这一工作始于 IGCP(国际地质对比计划 )第 1 74项 (1 980— 1 985 )对始新统 -渐新统界线所做的全球性协调研究 ,及项目组末次会议的出版物 (Pomerol & Premoli Silva,1 986 )。之后 ,古近纪地层分会继续努力物色合适的界线层型剖面 ,包括在世界范围内进行通讯调查 ,成立始新统-渐新统界线国际工作组 ,并与 IGCP第 1 96项项目组和地质年代学分会紧密合作。为考虑始新统 -渐新统界线 ,国际地层委员会古近纪地层分会于 1 98… 相似文献
2.
山东济阳坳陷始新统-渐新统天文地层界线年龄分析 总被引：2，自引：2，他引：0
YAO Yi-min ) XU Dao-yi ) HAN Yan-ben ) YIN Zhi-qiang ) ZHANG Hai-feng ) ) Geological Scientific Research Institute of Shengli Oilfield Company SINOPEC Dongying ) Institute of Geology China Earthquake Administration Beijing ) National Astronomical Observatories Chinese Academy of Sciences Beijing 《地层学杂志》2007,(Z2)
山东济阳坳陷沙河街组上部天文地层研究是以牛38井沙三段中亚段顶界年龄34.892Ma作为标定,分析和计算出沙二段下亚段底年龄为33.799Ma、沙段二段上亚段底为33.338Ma、沙一段底为32.940Ma和东营组底为31.829Ma。从天文地层界线年龄分析,沙三段-沙二段界线的年龄大致可对比为"国际地层表(2004)"始新统-渐新统界线年龄33.90Ma,而沙二段下亚段-上亚段界线年龄比国际始新统-渐新统界线的滞后大约600ka。在"中国区域地层表"始新统-渐新统界线年龄(32Ma)和"国际地层表"的始新统-渐新统界线年龄(33.9Ma)之差的1.9Myr,大致相当于本区计算的沙一、二段的持续时间。SP数据的小波分析表明,在沙二段-沙三上亚段界线附近,即约33.8Ma之后,约405ka周期开始变得不明显、不规则,幅度亦下降,剧烈突变发生时间在33.4Ma左右。上述界线对应偏心率周期的理论值突变的时间。因此推论始新世-渐新世转折期是偏心率多个理论周期重迭而导致的一个特殊的时期,也是本区沙二段下亚段这段地层形成不整合面的时间,大约在33.8—33.4Ma期间。 相似文献
3.
提要：南海北部及珠江口盆地渐新统-中新统界面（约23．8Ma）代表一个重大地质事件：在南海乃至东亚地区出现了一次大规模的构造运动，本文定名为“白云运动”。研究证实，白云凹陷23．8Ma以前为浅海陆架沉积，但随着南海扩张脊向南跃迁使得23．8Ma以来白云凹陷深部地幔上隆产生强烈的热沉降，陆架坡折带由23．8Ma以前位于白云凹陷南侧突变式地跳跃到凹陷的北侧；白云凹陷也由渐新世晚期的浅海陆架环境转为陆坡深水环境。沉积物地球化学的研究揭示，该构造事件也是本区沉积物源突变的主控因素，造成珠江三角洲和珠江深水扇系统在23．8Ma界面发生明显突变。32～23．8Ma的珠江流域范围可能以华南花岗岩地区为主，之后受喜马拉雅隆升的影响，珠江流域范围向西扩展，沉积物中明显存在着来自喜马拉雅东翼的物质。23．8Ma渐新统-中新统重大构造事件从根本上影响和改变了珠江流域的格局、南海北部沉积物的组成、沉积作用、海平面变化和油气成藏特点。 相似文献
4.
柴达木盆地北缘结绿素-红山地区古新统至中新统沉积相 总被引：4，自引：2，他引：4
根据柴达木盆地北缘露头剖面、钻井剖面的地层学和岩石学研究所取得的各种定量及定性资料,采用冯增昭教授倡导的单因素分析多因素综合作图法,编制了柴达木盆地北缘结绿素—红山地区古新统—始新统、渐新统和中新统的各种单因素图和沉积相图。这是首次将定量的沉积相研究方法应用于柴达木盆地的古新统至中新统。结绿素—红山地区古新统至中新统发育2种沉积相类型,即冲积扇和辫状河。其中辫状河可划分为砾质辫状河和砂质辫状河。古新世—始新世发育冲积扇—辫状河—湖泊沉积体系,渐新世—中新世发育辫状河—湖泊沉积体系。从古新世到中新世,柴达木盆地北缘经历了由大规模冲积扇沉积到辫状河沉积的演化过程。 相似文献
5.
柴达木盆地干柴沟—咸水泉地区渐新统—中新统沉积相分布特征 总被引：2，自引：0，他引：2
柴达木盆地干柴沟—咸水泉地区渐新统—中新统地层虽具有良好的油气勘探潜力,但至今未获突破,沉积相分布特征及规律研究不够深入是其主要原因之一。本文在区域地质背景、野外地质剖面、岩芯分析化验等资料的基础上,通过系统地分析该区渐新统下干柴沟组和中新统上干柴构组岩石类型和颜色、沉积构造、古生物等相标志,识别出冲积扇、扇三角洲、湖泊和湖底扇等沉积相类型及其特征;通过编制单井、剖面和平面沉积相分布图,揭示了沉积相的纵横向分布特征及规律并建立了沉积相模式。结果表明,沿山呈带状分布的各类滩坝和河道沉积砂体是下一步深入勘探寻求突破的主要方向。 相似文献
6.
台湾始新统—中新统沉积物源与沉积环境 总被引：1，自引：1，他引：0
台湾地区出露的始新统-中新统地层属南海北侧的范畴，其物质组成及沉积环境为揭示南海新生代早期构造沉积演化提供了关键性依据。对台湾西部麓山带中部南投粗坑地区、国姓地区以及东北海岸新港-基隆地区的始新统-中新统地层进行了岩石学、矿物学、稀土元素地球化学特征以及碎屑锆石U-Pb定年分析等研究。结果显示:台湾中部和北部从始新世到中新世经历了从陆相河流-湖泊相沉积环境到滨浅海相的环境转变，其砂岩成分成熟度随时间由老变新呈现规律性变化；沉积物源分析表明研究区沉积物在始新世-早渐新世，物源以近源中生代源区为主，碎屑锆石年龄谱系出现120 Ma和230 Ma两个主要峰值，与周边及华南沿海地区中生代火山岩时代一致；进入晚渐新世以后，锆石年龄谱系出现900 Ma及1 800 Ma等古老峰值，说明古老地块物质明显增加，这可能反映了昆莺琼古河流由南海西部到东部的物质输送对台湾地区的影响作用。 相似文献
7.
山东东营凹陷渐新统东营组的天文地层研究 总被引：4，自引：2，他引：2
XU Dao-yi ) YAO Yi-min ) ZHANG Hai-feng ) HAN Yan-ben ) YIN Zhi-qiang ) HE Qing-fang ) BIAN Xue-mei ) ) Institute of Geology China Earthquake Administration Beijing ) Geological Scientific Research Institute of Shengli Oilfield Company SINOPEC Dongying ) National Astronomical Observatories Chinese Academy of Sciences Beijing 《地层学杂志》2007,(Z2)
选定东营凹陷牛38、郝科1和利1等3口井东营组进行天文地层研究。以牛38井沙河街组一段顶界31.8Ma作为东营组底界年龄,得到3口井各段的年龄平均值为:东二段底28.406Ma,东一段底25.385Ma和顶界24.467Ma。东营组底界(31.829Ma)大致相当于"中国区域地层表"提出的32Ma的渐新统底年龄,但是与"国际地层表"提出的渐新世鲁培尔阶底界(33.9Ma)相差1.9Myr。东三段底界、顶界的平均年龄分别为31.829Ma、28.406Ma大致可与中国的乌兰布拉格阶或国际的鲁培尔阶中上部相当;东二段底界至东一段顶界的平均年龄大致相当于塔本布鲁克阶或夏特阶。根据东营组岩石地层与天文地层研究认为,在三角洲沉积过程中,东营组各段界线是穿时的,如东三与东二段界线的年龄相差可达1.4Myr。根据偏心率理论曲线和小波分析,夏特阶底界(28.4Ma)附近的变化可能与偏心率100ka左右理论周期的特殊变化有关。 相似文献
8.
我国中新生代陆相沉积，特别是咸化湖泊沉积中普遍发现属于“海源陆生”的沟鞭藻化石，由于其良好的生油特性，被认为是我国白垩纪—第三纪陆相油气资源的重要来源。柴达木盆地第三系始新统下干柴沟组是该地区最主要的烃源岩，生油岩及原油中富含公认的沟鞭藻生物标志物4 甲基甾烷和甲藻甾烷，但迄今该地区尚未发现可靠的沟鞭藻化石。本次研究在柴达木盆地北缘昆2井下干柴沟组发现了类型单调但化石丰富的以Subtilisphaera为主的沟鞭藻化石组合，为肯定柴达木盆地第三系原油沟鞭藻的贡献提供了直接化石证据。研究表明，沟鞭藻发育的第三系中始新统可能是本地区最有利的生油层，形成于湿热气候所控制的陆相咸水湖泊。 相似文献
9.
南海北部沉积物成分在渐新世末(23.8Ma)发生剧烈改变,出现地球化学成分上的突变,并在深海沉积中发生沉积间断及滑塌堆积。这些沉积事件在时间上与南海扩张轴由东西方向转为北东—南西方向发生跳跃的时间十分吻合,是渐新世以来南海构造演化史上最为重大的构造事件。经过这次构造事件,白云凹陷由渐新世晚期的浅水陆架环境转为中新世以后的深水陆坡环境,南海北部地区沉积物源由渐新世近源为主转变为中新世远源为主的供给特点;并使南海北部地区自中新世以来总体呈现海侵的特征。这次沉积环境与物源突变事件对南海北部地区油气藏的形成影响深远。 相似文献
10.
深海钻探揭示的古新统—始新统界线上许多全球性变化引起了地质学家的普遍关注。这些变化包括：岩性上从海绿石石英砂岩变化到粘土岩、粘土矿物组合从伊利石／蒙脱石为主变化为高岭石为主、大陆植物群的绝灭和迁移、钙质超微化石物种更新速度加快、底栖有孔虫绝灭和分异度降低、碳氧同位素强烈负异常、大陆哺乳动物演化发生变化、大气环流强度减弱、海洋环流模式改变、海平面上升、海底热液活动呈１～２个数量级加强。通过对古新世—始新世的地层沉积学、古生物学、古气候学和古海洋学研究，确认古新统—始新统地层界线是全球构造事件的结果，表现为全球板块边界重组、扩张中心和转换断层模式改变、海底热液活动呈１～２个数量级加强。 相似文献
11.
柴达木盆地为青藏高原东北缘的一个内陆沉积盆地,发育了巨厚的中-新生代沉积地层,这些地层记录了盆地及周缘山地的构造、环境演变历史。本文通过对柴达木盆地西北部红沟子地区晚新生代天然剖面沉积物岩石磁学的研究,表明在约9.8 Ma磁化率值突然增大,同时沉积物中磁铁矿的含量也明显增加。结合剖面沉积物岩相、岩性及沉积速率等分析,依据沉积物磁学性质与环境变化和构造运动之间的关系,我们认为该地区晚新生代物源变化,可能是造成岩石磁学特征在大约9.8 Ma变化的主要原因,同时可能还暗示了青藏高原东北缘一次强烈的构造隆升事件,阿尔金山作为柴达木盆地的物源之一,也响应了此次构造运动,隆升到了一定高度使剥蚀速度增加,这一过程被柴西地区的红沟子构造所记录。 相似文献
12.
柴达木盆地厚达万米的新生代沉积物记录了青藏高原东北部隆升和古气候变化信息.本文基于盆地北缘大红沟剖面高分辨率的磁极性年代标尺,对该剖面古—新近纪河湖相沉积物进行了颜色测量,首次获得了柴达木盆地长时间尺度（52~7 Ma）的色度参数变化序列.在此基础上,综合沉积相与区域构造和古气候记录,探讨了影响河湖相沉积物颜色参数的因素及柴达木盆地古—新近纪的气候演变.结果表明,大红沟剖面沉积物颜色的变化与全球温度变化趋势基本一致,说明温度是影响颜色参数,特别是红度（a*）的主要因素;沉积相变化,尤其是水面上、下的氧化—还原环境变化对颜色参数也有重要影响.根据色度参数在时间标尺上的变化,将柴达木盆地的气候变化划分为8个阶段:（a）52.0~44.2 Ma湿热,（b）44.2~33.7 Ma在干湿波动中逐渐变干,（c）33.7~27.1 Ma进一步变干,（d）27.1~19.7 Ma逐渐变湿,（e）19.7~17.0 Ma较干旱,（f）17.0~13.3 Ma气候湿润,（g）13.3~9.5 Ma快速变干,（h）9.5~7.0 Ma进一步变干旱.影响柴达木盆地古—新近纪气候变化的主要因素包括全球温度、副特提斯海、青藏高原构造隆升和东亚夏季风. 相似文献
13.
柴达木盆地西部新生代砂岩碎屑组分变化记录的沉积转型事件 总被引：5，自引：1，他引：4
应用砂岩碎屑成分分析法对柴达木盆地西部干柴沟地区新生代地层进行了系统的物源分析。砂岩组分镜下鉴定和含量统计分析结果表明,研究区内砂岩类型以长石砂岩和岩屑长石砂岩为主,岩屑类型以沉积岩岩屑为主。镜下识别出一些标志性的矿物和岩屑,它们的出现及其含量在剖面垂向上的变化,指示柴达木盆地西部干柴沟地区上干柴沟组与下油砂山组界线附近的沉积物源发生了明显变化,说明柴达木盆地西部地区在渐新世与中新世之交约20Ma时发生了一次重大的沉积转型事件。这次沉积事件在青藏高原北部其他地区也可以找到一系列踪迹和响应,是探索青藏高原北缘构造隆升历史的一个重要界线。 相似文献
14.
The northeastern Tibetan Plateau is located at the convergence of the Asian winter and summer monsoons and westerlies; thus, this area has witnessed historic climate changes.The Xunhua basin is an intermontane basin on the northeastern margin of the Tibetan Plateau.The basin contains more than 2000 m of Cenozoic fluvial–lacustrine sediments, recording a long history of climate and environmental changes.We collected the mid-Miocene sediments from the Xunhua basin and used palynological methods to discuss the relationship between aridification in the interior of Asia, global cooling, and uplift of the Tibetan Plateau.Based on the palynological analysis of the Xigou section, Xunhua basin, the palynological diagram is subdivided into three pollen zones and past vegetation and climate are reconstructed.Zone I, Ephedripites–Nitraridites–Chenopodipollis–Quercoidites(14.0–12.5 Ma), represents mixed shrub–steppe vegetation with a dry and cold climate.In zone II, Pinaceae–Betulaepollenites–Ephedripites–Chenopodipollis–Graminidites(12.5–8.0 Ma), the vegetation and climate conditions improved, even though the vegetation was still dominated by shrub–steppe taxa.Zone III, Ephedripites–Nitrariadites–Chenopodipollis(8.0–5.0 Ma), represents desert steppe vegetation with drier and colder climate.The palynological records suggest that shrub–steppe dominated the whole Xigou section and the content gradually increased, implying a protracted aridification process, although there was an obvious climate improvement during 12.5–8.0 Ma.The aridification in the Xunhua basin and surrounding mountains during 14.0–12.5 Ma was probably related to global cooling induced by the rapid expansion of the East Antarctic ice-sheets and the relatively higher evaporation rate.During the 12.5–8.0 Ma period, although topographic changes(uplift of Jishi Shan) decreased precipitation and strengthened aridification in the Xunhua basin on leeward slopes, the improved vegetation and climate conditions were probably controlled by the decrease in evaporation rates as a result of continuous cooling.From 8.0 to 5.0 Ma, the rapid development of the desert steppe can be attributed to global cooling and uplift of the Tibetan Plateau. 相似文献
15.
Magnetostratigraphy and Anisotropy of Magnetic Susceptibility of the Lulehe Formation in the Northeastern Qaidam Basin 总被引：1，自引：0，他引：1
The timing of onset of deposition of the Lulehe Formation is a significant factor in understanding the genesis of the Qaidam basin and the evolution of the Tibetan Plateau. Here, we describe a detailed magnetostratigraphic and magnetic fabric study of the middle and lower parts of the Lulehe Formation. A total of 234 samples were collected from 117 sites throughout a thickness of almost 460 m of fluvial and lacustrine deposits at the Xitieshan section in the northeastern Qaidam basin. Out of these sites, 94 sites yielded well-defined characteristic remanent magnetization components by stepwise thermal demagnetization and were used to establish the magnetostratigraphy of the studied section. Based on correlation with the geomagnetic polarity timescale, the studied section spans the period from 53.8 Ma to 50.7 Ma. Our results show a three-fold decrease in sedimentation rates as well as marked change in facies from braided river to delta and shore–shallow lake around 52.6 Ma, which suggests tectonic uplift of the northeastern Qaidam basin margin ridge was rapid at the onset of formation of the Qaidam basin and subsequently weakened after 52.6 Ma. The anisotropy of magnetic susceptibility results indicate that tectonic compression stress had reached the northeastern Tibetan Plateau by the early stages of Indo–Eurasian plate collision and that the direction of stress in the study area was NE–SW. Furthermore, a weakening of tectonic compression stress around 52.6 Ma is consistent with sedimentary records. The age of initial deposition of the Qaidam basin (around 53.8 Ma) was almost synchronous with that of the Qiangtang, Hoh Xil, Xining, and Lanzhou basins, which implies that stress was transferred rapidly through the Tibetan Plateau during or immediately after the onset of Indo–Eurasian collision. 相似文献
16.
为探究青藏高原的气候环境演化, 对青藏高原不同部位的盆地沉积物的粘土矿物特征进行深入系统的研究.结果表明, 古新世阶段—始新世阶段时期, 青藏高原古气候以行星风系居主导地位, 青藏高原北部以温暖和季节性干旱为特征.柴达木地区在~36 Ma的降温事件则明显早于全球降温事件(~34 Ma)近2 Ma.在渐新世(34~23 Ma)期间, 古气候以干旱炎热为特征, 但气温相对要低于始新世.在中新世—上新世(23.0~2.6 Ma)期间, 青藏高原北缘的柴达木、循化盆地均在~21.5 Ma发生气候变冷事件, 而8~7 Ma的气候变化事件遍及整个青藏高原.在藏南的吉隆盆地、青藏高原西北部的叶城盆地, ~1.8 Ma之前的盆地沉积物中仍然有相当高含量的蒙脱石, 说明这些地区在~1.8 Ma之前, 虽然总体上气候变冷、变干, 但仍然处于一种相对湿润的气候环境. 相似文献
17.
青藏高原东北缘是高原由西南向东北方向扩展的前缘位置，其新生代构造变形对揭示青藏高原隆升、扩展的过程与动力学机制具有重要的意义。柴达木盆地是青藏高原东北缘最大的新生代沉积盆地，发育巨厚的新生代地层，这些地层所记录的古地磁极旋转信息是定量约束柴达木盆地新生代以来构造变形发生的时间、方式与幅度的载体。本文以柴达木盆地北缘新生代地层出露良好、具有精确地层年代控制的路乐河剖面为研究对象，开展了古地磁极旋转研究，统计分析路乐河剖面24. 6~5. 2 Ma之间1477个可靠古地磁样品的特征剩磁方向(ChRM)，发现柴达木盆地北缘路乐河地区在24. 6~16. 4 Ma发生小幅度(不显著)的逆时针旋转，旋转角度约为8. 4°±6. 1°；16. 4~13. 9 Ma路乐河地区发生显著的顺时针旋转，旋转角度可达36. 1°±6. 0°；13. 9~5. 2 Ma 该地区未发生明显的构造旋转；5. 2 Ma以后路乐河地区逆时针旋转了~6°。结合柴达木盆地北缘区域构造变形的分析，我们提出柴达木盆地北缘路乐河地区在16. 4~13. 9 Ma 之间发生强烈的顺时针旋转构造变形(~36°)可能代表了盆地北缘中中新世遭受强烈的地壳差异缩短变形，从而成为高原最新形成的部分。 相似文献
18.
The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian (493.1±4.9 Ma), the Silurian (422.9±8.0 Ma-420.4±4.6 Ma) and the Late Permian-Middle Triassic (257.8±4.0 Ma-228.8±1.5 Ma), respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma (main), 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic (P-T) granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism (293.6-270 Ma) occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basement thrust system developed in the eastern Qaidam Basin, the nearly N-S-trending shortening and deformation in the basement of the basin tended to intensify from west to east, which went contrary to the distribution trend of N-S-trending shortening and deformation in the Cenozoic cover of the basin, reflecting that there was a transformation of shortening and thickening of Cenozoic crust between the eastern and western parts of the Qaidam Basin, i.e., the crustal shortening of eastern Qaidam was dominated by the basement deformation (triggered at the middle and lower crust), whereas that of western Qaidam was mainly by folding and thrusting of the sedimentary cover (the upper crust). 相似文献
19.
SONG Bowen ZHANG Kexin CHEN Ruiming WANG Chaowen LUO Mansheng ZHANG Jianyu JIANG Shangsong 《《地质学报》英文版》2013,87(2):528-539
The thick, Eocene to Pliocene, sedimentary sequence in Qaidam Basin at the northern margin of the Tibetan Plateau records the surface uplift history of the northeastern Tibetan plateau. In this study, we present detailed geochemistry, heavy mineral, and clay mineralogy data of the well preserved sedimentary record in the Dahongou section in the northeast of the Qaidam Basin. The results suggest that the sedimentary sequence recorded a 30 Ma young uplift/unroofing event in the northern edge of the Qaidam Basin, which is characterized by high ZTR index value and chlorite content, and low CIW`. The results are consistent with previous sedimentological studies of the Qaidam Basin, which indicated rapid increase of the accumulation rates around 30 Ma. Based on past thermochronological data from the mountains around the Qaidam Basin and the accumulation rates of the Cenozoic basins in the northeastern Tibetan Plateau, we infer a regional uplift and denudation event along the northeastern Tibetan Plateau during early Oligocene (～30 Ma), indicating that the Tibetan Plateau had expanded north-eastward of the study area at that time. 相似文献