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鄂尔多斯盆地西南缘中生代构造事件的裂变径迹年龄记录 总被引：2，自引：0，他引：2
运用锆石和磷灰石裂变径迹(FT)分析方法,探讨分析了鄂尔多斯盆地西南缘中生代构造事件的FT年龄分布与峰值年龄事件.结果表明:(ⅰ)早期构造事件主要发生在213～194Ma±,峰值年龄为205Ma,并以晚三叠世构造隆升及其前缘粗碎屑沉积为其地质响应.(ⅱ)中期构造事件至少包含两个幕次,一次发生在165～141Ma±,峰值年龄为150Ma;二次发生在115～113Ma±,峰值年龄为114Ma;其地质响应主要表现为晚侏罗世—早白垩世的逆冲推覆及其前缘粗碎屑沉积.(ⅲ)晚期构造事件主要表现为至少两个幕次的区域隆升作用,一次发生在100～81Ma±,峰值年龄为90Ma;二次发生在66～59Ma±,峰值年龄接近63Ma.结合成矿年代学资料分析认为,峰值年龄事件的极端环境效应和构造转换相对平稳期的适度活动,有可能是鄂尔多斯盆地多种矿产耦合成矿、共存富集的关键因素. 相似文献
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湖平面变化是影响陆相湖盆沉积与资源赋存、陆地碳收支及环境生态演化的重要因子.湖平面波动受气候作用明显,早侏罗世处在冰室、(超)温室气候动荡期,发生了全球性大洋缺氧(托阿尔期,～183Ma)和气候变冷等极端气候事件(普林斯巴赫期,～185Ma).为研究气候动荡背景下湖平面演化及地球表层水循环和调控机制,选取柴达木盆地早侏罗世湖相连续沉积记录,采用岩石粉末色度(CIE b*)序列开展米兰科维奇旋回分析,建立了基于东特提斯陆相沉积记录的早侏罗世天文年代标尺(～174.2Ma至～190.9Ma),通过沉积噪声模型重建盆地相对湖平面变化曲线,发现5～10Myr尺度湖平面变化响应于长趋势气候演化及极端气候事件; 1～2.5Myr尺度湖平面波动显著受控于天文轨道气候作用(～2.4Myr偏心率和～1.2Myr斜率周期).其中,普林斯巴赫期～1.2Myr湖平面周期波动与全球海平面呈“同相位”共变,～1.2Myr斜率周期通过控制极地地区存在的间歇性或永久性冰盖生长和消亡影响全球海平面及湖平面升降;托阿尔期～1.2Myr湖平面波动与全球海平面呈“反相位”关系,在(超)温室气候期极地地区不存在明显冰盖情况下,... 相似文献
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南海的构造与演化与资源环境等关系密切是本文研究重点。本文针对南海的东北部构造及其块体构造方向,利用所采集的区域地震剖面,通过解析地震相与构造及其演化的关系,提出以下观点:(1)构造分区特点明晰,可划分为五个不同构造单元,构造单元之间既有联系又相互独立;(2)南海沉积盆地无论表现为拉张-弱挤压-强挤压的何种构造格局,其区域构造应力场是统一的;(3)首次发现反射地震剖面上显示出两个浅俯冲点。每个块体构造层呈手风琴风箱式折曲并向东聚敛,体现沉积盆地从发育、成长、结束、消亡不同阶段在南海的表现,其块体俯冲方向以及块体包络区域性倾伏方向均与区域应力场方向一致。 相似文献
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中新世"碳位移,,事件在南海的记录 总被引：7，自引：0，他引：7
南海北部ODP1148A孔(18°50.17′N,116°33.93′E,水深3308.3m)中新世24～5Ma底栖有孔Cibicidoides
wuellerstorfi和C.kullenbergi及18～5Ma浮游有孔虫Globigerinoides sacculifer两者的δ13C曲线总体上同步波动,呈现由早-中期重值向晚期轻值的演化趋势;记录了早-中期23.1～22.2和17.3～13.6Ma两次显著的正位移和晚期10.2～9.4和6.9～6.2Ma的两次负位移,这些位移都具全球意义,为南海与全球进行同位素地层学对比提供了基础,更是研究全球碳储库及其相关的气候变化的重要资料. 相似文献
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南海北部深水区是中国重要的油气潜力区.本文在前人对其现今地温场和正演热史研究的基础上,利用磷灰石(U-Th)/He和镜质体反射率(Ro)数据对根据拉张盆地模型正演获得的热历史进行了进一步约束,并在此基础上对南海北部深水区的烃源岩热演化进行了研究.研究结果表明基于盆地构造演化模型的正演热历史可以作为烃源岩热演化计算的热史基础,而盆地内主力烃源岩热演化计算结果显示:南海北部深水区存在4个生烃中心,即珠江口盆地的白云凹陷和琼东南盆地的乐东凹陷、陵水凹陷和松南凹陷,生烃中心烃源岩有机质现今处于过成熟状态,以生气为主;受盆地基底热流显著升高的影响,32~23.3 Ma时段为南海北部深水区烃源岩快速成熟阶段,琼东南盆地烃源岩有机质现今(2.48 Ma后)还存在一期加速成熟过程,而珠江口盆地则不存在此期快速成熟过程. 相似文献
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祁连山山间盆地内的新生代沉积物是研究新生代以来祁连山构造演化的重要材料.本文以位于祁连山中部祁连盆地内的新生代沉积物为研究对象,利用磁性地层学方法结合碎屑颗粒裂变径迹定年方法获取其沉积时代框架,在此基础上,结合岩性变化与沉积环境变迁分析祁连山构造演化历史.野外实测剖面显示该盆地内的第三系可划分为下部砾岩组和上部砂岩组两大岩性单元.古地磁结果显示砾岩组的沉积时代约为10—14.3Ma.砾岩组沉积大约在14.3 Ma开始形成,指示祁连山14.3 Ma以来构造活动变强烈.磁组构结果显示砾石组顶部沉积形成时的受力方向与现今祁连盆地周缘断层分布所指示的应力方向一致,表明这些断层大约在10 Ma附近开始活动.我们的结果揭示祁连山中部山脉14.3 Ma以来尤其在10 Ma附近构造活动较强烈.这与过去低温热年代学所获得的祁连山山体的快速冷却年龄及祁连山两端大型盆地内的第三系所记录的构造事件发生的时间基本吻合.而砂岩组的古地磁结果并未通过褶皱检验,其古地磁记录发生了后期重磁化,无法获得地层的准确沉积年龄. 相似文献
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野外地质调查、室内显微构造及石英EBSD组构分析等综合研究表明,排山楼金矿区发育了三期韧性剪切活动,并先后形成了东西向、北东向延伸的韧性剪切带.前者主要表现为右行压扭活动,后者切割了前者,先后经历了左行压扭、左行走滑-伸展等多期构造活动.东西向韧性剪切带中发育大量多晶石英条带与云母的显微构造分层现象,形成于较深的地壳层次及中高温的环境下,石英结晶学优选(CPO)表明石英以柱面a、柱面c滑移为主,该剪切带可能形成于印支期,是蒙古带与华北太古宇克拉通沿索伦-林西缝合带拼合作用在排山楼地区的一种构造表现.北东向韧性剪切带早期的韧性剪切活动可能发生于~160 Ma,是燕山运动早期活动的结果,该期韧性剪切形成于中低温环境及中浅层地壳层次,显微构造以多晶石英集合体和石英的亚颗粒旋转为代表,石英以菱面a滑移为主.晚期的韧性剪切以韧性变形为主,叠加了后期脆性变形,主要表现为低温变形的左行走滑-拆离伸展,发育石英低温颗粒边界迁移、膨凸重结晶和方解石机械双晶,形成于地壳较浅层次,可能与130~120 Ma期间华北克拉通岩石圈大规模减薄与破坏作用有关,该期韧性剪切与拆离伸展运动可能直接导致了排山楼金矿的形成. 相似文献
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西昆仑造山带构造-岩浆演化史 总被引：31，自引：2，他引：29
通过对西昆仑造山带 80年代以来陆续发表的 1 70余个岩浆岩、变质岩、构造岩、矿石同位素年龄数据进行统计与分析 ,同时结合野外实地考察及必要的同位素年龄补充测试 ,以及研究区的沉积、岩浆、变质作用和构造运动等特点 ,将西昆仑造山带的构造 岩浆演化划分为 5个阶段 :Ar3 Pt12 构造 岩浆活动阶段 (Ⅰ ) ;Pt22 构造 岩浆演化稳定阶段 (Ⅱ ) ;Pt13 P2 构造 岩浆活动阶段 (Ⅲ ) ;T1 T2 构造 岩浆演化稳定阶段(Ⅳ ) ;T3 Q构造 岩浆活动阶段 (V) .对每个阶段及其次级阶段 (期 )的岩浆活动形式及总程序、构造环境等特征进行了讨论 相似文献
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A compilation of available marine deposition data from offshore S-SE China reveals evidence of rifting and breakup of the South China Sea (SCS) during the Paleogene. Marine deposition started earlier in the Paleocene in the East China Sea (ECS)-Taiwan region before expanding southwestward into the SCS region in the middle Eocene. Our data indicate the existence of an elongated Paleogene China Sea in these areas stretching along the northeasterly structural belts, probably as part of the marginal western paleo-Pacific. The southwestward shift of marine influence in the middle Eocene was responding to a period of intensive rifting and subsidence in the SCS region, while the sea in the ECS-Taiwan region started to shrink and shoal after the late Eocene, likely associated with local breakup and initial spreading in the Taiwan-Taixinan Basin area. The accumulation of hemipelagic sediments at ODP 1148 and IODP U1435 from near the continent-ocean boundary and at many other shelf-slope sites was in response to a large-scale breakup 34 to 33 Ma ago, subsequently leading to the birth of the SCS in the Oligocene. 相似文献
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Monazite age spectra in the Late Cenozoic strata of the Changjiang delta and its implication on the Changjiang run-through time 总被引：6，自引：0，他引：6
Yokoyama Kazumi 《中国科学D辑(英文版)》2005,48(10)
Uplift of the Tibetan Plateau, inversion of eastern and western geomorphology, eastward flowing of large rivers, and run-through of the Changjiang River exert great influence on sedimentation and environ-mental variations in the East China Sea. Provenance discrimination of Tibetan-Plateau-originated sediments in the river-mouth areas and marginal seas is key to figure out these issues.In the past, most studies of the run-through time of the Changjiang and the Yellow rivers focused on geomo… 相似文献
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Ulrich Knittel 《Island Arc》2011,20(1):138-146
The discovery of a low‐grade meta‐rhyolite with an age of 83 ± 1 Ma documents a so‐far unknown episode of magmatism in northern Mindoro Island, which is located at the northeastern edge of the Palawan Continental Terrane. This terrane is thought to have rifted from Southeast China in the Oligocene as a result of the opening of the South China Sea. Rhyolite volcanism was widespread in southeastern China in the Cretaceous; hence this discovery provides the first direct link between the geological evolution of the Palawan Continental Terrane and Southeast China in Cretaceous time. In addition, it provides further evidence that the northeastern part of Mindoro is indeed part of the Palawan Continental Terrane and not part of the Philippine Mobile Belt to the east, a previously contentious issue. 相似文献
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Provenance of a prominent sediment drift on the northern slope of the South China Sea 总被引：1，自引：0，他引：1
The sedimentation rate of the sediment drift in the southeast of Dongsha Islands is as high as 49 cm/ka in the last 1.05 Ma. Although the sedimentation rate changes with time, the contents of rare elements of the sediments remain almost the same, indicating that the source area of the sediments has been constant with time. On the triangular diagrams of La-Th-Sc and Th-Sc-Zr/10, the samples from the southeast of Dongsha Islands fall within the continental island arc field, overlapping the samples from Taiwan, while the samples from the Pearl River, those from the west of the Philippines that contain volcanic material, are separated from them. This indicates that the sediments from the southeast of Dongsha Islands have a close relationship to those from Taiwan in terms of provenance. In fact, the sediments on the northern slope of the South China Sea were derived from northeast direction, as well as from Taiwan, most probably transported from Taiwan through Penghu channel into the South China Sea. The terrigenous part of the deep-sea sediments in the north of the South China Sea was provided by different sources. 相似文献
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国家重点基础研究发展计划(973)项目(2007CB411700)首次在南海南部大陆边缘及西南次海盆开展长排列大震源多道地震、海底地震仪(OBS)折射/反射地震等的综合地球物理探测,结合地质构造、地球化学、动力模拟等的综合研究,形成如下重要认识:南海海盆新生代发生了早、晚两期海底扩张.早期扩张发生于33.5～25 Ma... 相似文献
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以28口钻井、3条主干地震剖面最新解释成果资料为依据的构造沉降史恢复结果表明：琼东南盆地新生代存在三期快速沉降过程和一期缓慢沉降过程：第一期为始新世,第二期为渐新世—早中新世,第三期存在时空差异：在盆地西部乐东凹陷为晚中新世以来,在盆地中东部陵水凹陷和松南-宝岛凹陷为上新世以来;缓慢沉降过程亦存在时空差异,盆地西部中中新世沉降缓慢,盆地中东部中—晚中新世沉降缓慢.第一期快速沉降过程受东亚陆缘扩张和红河断裂左旋走滑共同影响,第二期快速沉降受南海海底扩张和红河断裂左旋走滑联合作用,第三期快速沉降主要受红河断裂右旋走滑控制,缓慢沉降过程与南海海底扩张停止以及红河断裂构造活动处于宁静阶段相耦合. 相似文献
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WANG Rujian FANG Dianyong SHAO Lei CHEN Muhong XlA Peifen Ql Jingyu 《中国科学D辑(英文版)》2001,44(10):912-918
The abundance of radiolarian, diatom and sponge spicule and H4SiO4 in pore-waters increase abruptly at the boundary between Early and Late Oligocene (about 30-27.5 Ma) at Site 1148 of the
northern South China Sea (SCS), indicating high biogenic silica accumulation during this time. At the same time (about 30-28
Ma), high biogenic silica deposition occurred in the central equatorial Pacific. Comparison of the biogenic silica accumulation
at Site 1148 of the SCS with that at Site 929 of the Atlantic verifies that the biogenic silica accumulation between the low
latitude Pacific and Atlantic oceans expresses the evident relationship of compensation during the Oligocene. Biogenic silica
accumulation decreased in the Atlantic, whereas it increased in the Pacific at the boundary between the Early and Late Oligocene.
It resulted from the formation and presence of North Atlantic deep water (NADW) in the Atlantic basin, indicating an intensive
basin-basin fractionation. XRD analysis and SEM observation of the samples from Site 1148 demonstrate that most of radiolarian,
diatom and sponge spicule have suffered from dissolution and reprecipitation, suggested by the opal-A→opal-CT transformation.
As a result of the transformation, porosity increased, but dry and bulk densities decreased, reflecting the consequence of
diagenesis on the physical property of sediment. 相似文献
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ZHAO Quanhong WANG PinXian CHENG Xinrong Wang Jiliang Huang Baoqi XU Jian ZHOU Zhen JIAN Zhimin 《中国科学D辑(英文版)》2001,44(10):943-951
High-resolution δ13C records are presented for the Miocene benthic foraminifersCibicidoides wuellerstorfi andC. kullenbergi (24-5 Ma) and the planktonic foraminiferGlobigerinoides sacculifer (18-5 Ma) from ODP Site 1148A (18° 50.17’N, 116° 33.93’E, water depth 3308.3 m), northern South China Sea. The general pattern of parallel benthic and planktonic δ13C shows a decrease trend of δ13C values from the early-middle Miocene to the middle-late Miocene. Two distinct δ13C positive excursions at 23.1-22.2 and 17.3-13.6 Ma, and two negative excursions at 10.2-9.4 and 6.9-6.2 Ma have been recognized. All these events are cosmopolitan, providing the good data for the stratigraphic correlation of the South China Sea with the global oceans as well as for studying the changes of the global carbon reservoir and its corresponding climate. 相似文献