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关于建立“板溪系”的建议及其基础的讨论——以黔东地区为例 总被引：1，自引：0，他引：1
作者在分析黔东新元古代早期沉积时限的基础上,结合前人关于Sturtian冰期、南华系底界、青白口系年代学的最新研究成果,指出华南新元古代裂谷盆地早期沉积(板溪群或与之相当的高涧群、芙蓉溪群、丹洲群、下江群、登山群、历口群等)时限为740～820Ma,是南华纪冰期前的非冰成沉积,是Rodinia裂解机制下的填平补齐沉积;而青白口系沉积可能是与Rodinia形成相关的板块碰撞机制下坳陷盆地沉积,南华系是与国际成冰系相对应的冰期沉积,是华南新元古代裂谷盆地的第一个盖层,因此,将板溪群、下江群等归入南华系或青白口系均不合理。由此提出了"板溪系"概念,它包括板溪群或与之相当的一套楔状地层。结合目前华南裂谷盆地开启年龄和南华纪冰期的起始年龄,板溪纪的时限暂定为850～740Ma。板溪系的提出不仅将有利于解决长期存在的南华系划分对比问题,同时也必将有利于新元古代裂谷盆地早期演化及其与Rodinia超大陆裂解、冰期形成等关系的研究和相关重大气候、环境巨变问题的探讨。 相似文献
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关于建立“板溪系”的建议及其基础的讨论——以黔东地区为例汪正江 总被引：1，自引：0，他引：1
作者在分析黔东新元古代早期沉积时限的基础上,结合前人关于Sturtian冰期、南华系底界、青白口系年代学的最新研究成果,指出华南新元古代裂谷盆地早期沉积（板溪群或与之相当的高涧群、芙蓉溪群、丹洲群、下江群、登山群、历口群等）时限为740～820Ma,是南华纪冰期前的非冰成沉积,是Rodinia裂解机制下的填平补齐沉积;而青白口系沉积可能是与Rodinia形成相关的板块碰撞机制下坳陷盆地沉积,南华系是与国际成冰系相对应的冰期沉积,是华南新元古代裂谷盆地的第一个盖层,因此,将板溪群、下江群等归入南华系或青白口系均不合理。由此提出了“板溪系”概念,它包括板溪群或与之相当的一套楔状地层。结合目前华南裂谷盆地开启年龄和南华纪冰期的起始年龄,板溪纪的时限暂定为850～740Ma。 板溪系的提出不仅将有利于解决长期存在的南华系划分对比问题,同时也必将有利于新元古代裂谷盆地早期演化及其与Rodinia超大陆裂解、冰期形成等关系的研究和相关重大气候、环境巨变问题的探讨。 相似文献
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新元古代早期(820 720 Ma),华南由扬子地块、华夏地块和江南造山带3个构造单元组成。新元古代晚期,南华纪-震旦纪(720 541 Ma)沿新元古代早期的江南造山带发育一裂谷盆地-南华裂谷,贵州东部是南华裂谷的重要组成部分。传统认为黔东地区该裂谷盆地为北北东向,越来越多的证据证明该裂谷盆地为北东东向。黔东地区南华纪裂谷盆地具有典型的地堑、地垒结构,并控制着"大塘坡式"锰矿的分布。震旦纪之后,裂谷盆地处于沉降阶段,沉降中心向南迁移到凯里-玉屏一线。震旦纪时期,扬子地块和南华裂谷存在明显的滨浅海磷矿-碳酸盐岩和深水泥质岩-硅质岩的沉积分异。扬子地块和南华裂谷控制着扬子地块震旦系陡山沱组磷矿和南华裂谷老堡组重晶石等沉积矿产的分布。富磷矿位于松桃-贵阳同沉积断裂以北的扬子地块南缘,重晶石矿发育于裂谷盆地强烈沉降区的天柱-岑巩一带。 相似文献
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华南"南华系"研究新进展--论南华系地层划分与对比 总被引：17，自引：2，他引：17
华南新元古代裂谷系由一系列地堑、地垒式次级盆地组成，裂谷系地层位于震旦系与四堡造山不整合面之间，区域上侧向延伸不连续，呈“楔状地层”展布。大量新的U-Pb同位素年龄资料表明，“楔状地层”下部(包括板溪群或与之相当的高涧群、芙蓉溪群、丹洲群、下江群、登山群、厉口群等)的底界年龄均小于或接近820Ma。因此，在华南四堡造山不整合面之上缺失了与华北青白口系相当的绝大部分地层(1000-820Ma)，这一结论与目前中国华南地层划分方案不同。由于820Ma代表了华南新元古代裂谷系沉积超覆的“起点”年龄，且这一重要沉积事件的时间又与国际地层委员会新元古界三分方案中成冰系的底界年龄接近，因此，建议将华南新元古代裂谷系沉积超覆地层与四堡造山带变质岩系之间的不整合面作为”南华系”的底界面。 相似文献
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再论华南（东）晋宁－加里东海盆地形成、演化及封闭 总被引：3，自引：0，他引：3
华南（东）晋宁－加里东海盆地形成于青白口纪，经历了晋宁期，加里东早期及加里东晚期３个演化阶段。海盆地基底为陆壳，形成于拉伸的裂谷环境，海盆地的封闭以陆内俯冲及拼贴为主，具多阶段性。海盆地基底，特别是华夏地块基底高热值属性导致了加里东海盆地有湘桂海盆地和赣闽粤海盆地２种类型，后者位于华夏基底之上，活动性明显，形成数条陆内动力热流变质带。 相似文献
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《中国地质》2021,(2)
江西省宁都某地新元古代浅变质岩风化壳中赋存离子吸附型稀土矿,文章对某矿区内原定青白口纪库里组的2件变质沉凝灰岩样品进行了碎屑锆石LA-ICP-MS U-Pb年代学研究,获得了88组和110组谐和年龄。2件样品的碎屑锆石年龄区间相似,主要分布在:810～780 Ma,峰值年龄为798 Ma(n=55);748～727 Ma,峰值年龄为737 Ma(n=127);691～667 Ma,峰值年龄为680 Ma(n=6),此外还有少量的年龄分布在2.85～1.08 Ga。认为,变质沉凝灰岩样品的沉积时代可能为南华纪,地层应归属为上施组;物源可能来自江南造山带东段(赣东北—皖南—浙西)青白口纪晚期—南华纪的火山-沉积岩;赣南区域上同时期的巨厚海相火山-碎屑沉积可能形成于华南古大陆裂解之后的裂谷盆地,赣南次级裂谷盆地的沉积时限为810～727 Ma。 相似文献
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黔东松桃地区大塘坡组LA-ICP-MS锆石U-Pb年龄及其地质意义 总被引：4，自引：0，他引：4
南华裂谷盆地在南华纪出现地垒区与地堑区的明显沉积分异。在对黔东松桃地区将军山剖面南华系地层进行实测的基础上,与地堑区南华系地层进行了对比。发现地垒区与地堑区的沉积分异主要表现在铁丝坳组与大塘坡组的岩性与厚度变化上。在此基础之上,对将军山剖面大塘坡组底部凝灰层进行LA-ICP-MS锆石U-Pb年代学研究,得到年龄值为664.2±2.4 Ma。通过该年龄与前人在地堑区所获得的对应地层年龄进行对比,可将南华裂谷盆地地垒区Sturtian冰期结束时间限定在不晚于663~667 Ma范围内,这证明Sturtian冰期消退事件在黔东地区范围内具有等时性,整个Sturtian—Marinoan间冰期持续时间约为10 Ma。与此同时,通过与世界范围内各古板块上Sturtian冰后期沉积的最新定年结果进行对比工作,得出全球Sturtian冰期结束时间同样具有等时性的结论。 相似文献
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南岭成矿带前寒武系为金、铁、锰、磷及铅锌的赋矿层位,近年来由于高精度测年数据的应用,建立了较为清晰的年代地层格架,然而由于历史原因,前寒武系岩石地层序列在湘黔桂赣粤交界地区存在同物异名现象,不利于地质矿产图的编制,需要重新厘定完善。本文以武陵运动构造面为界,将南岭成矿带大地构造演化分为两个阶段,按中元古代至青白口纪早期、青白口纪晚期至震旦纪划分出不同地层区。早期划分出两个地层区—扬子与华夏地层区,晚期同属于华南地层区,依据处于盆地不同位置,再划分为六个地层分区。本文重点对湘黔桂交界地区的青白口系上部层位、赣湘桂地区南华系和震旦系进行了梳理,初步形成前寒武纪岩石地层序列,不再采用部分岩石地层单位,以便于编制该地区地质矿产图。 相似文献
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理塘混杂岩位于甘孜-理塘蛇绿混杂岩带中段新龙县-理塘县一带,其内部保存有完整的混杂岩系,包括蛇绿岩残片、洋岛残块、洋内弧残块、复理石建造、裂谷残片、高压变质岩等,是恢复和反演甘孜-理塘洋盆演化的理想地区。在总结前人研究的基础上,结合笔者近年来的研究成果,详细阐述了理塘混杂岩的物质组成、构造环境及形成时代,进一步约束了甘孜-理塘洋盆的时空、性质以及演化历程。LA-ICP-MS锆石U-Pb测年结果表明,甘孜-理塘混杂岩带内蛇绿岩年龄为（346±17）Ma、（286.2±5.1）Ma、（219.5±2.2）Ma、（216.1±2.3）Ma,洋岛年龄为（271±10）Ma、（245.1±1.5）Ma、（211.8±1.8）Ma,在侏罗纪瑞环山组粉砂岩夹层中测得碎屑锆石最新年龄为（196±3）Ma,结合大量的古生物化石鉴定结果,分析认为理塘混杂岩最早的年龄记录可追溯至中泥盆世,最晚可延至早白垩世,是甘孜-理塘洋盆中泥盆世-早白垩世连续演化的记录。综合以上研究成果,笔者还大致建立了甘孜-理塘洋盆晚古生代-中生代的演化过程模式。 相似文献
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桂东鹰扬关群火山岩时代和构造环境的重新厘定:对钦杭结合带西南段构造格局的制约 总被引：2，自引：0，他引：2
鹰扬关群在湘—粤—桂三省交界地区广泛发育,为一套以绿片岩相变质的细碧岩、(石英)角斑岩及相关的火山碎屑岩为主,含有细碎屑岩和碳酸盐岩组合。该群的成岩背景过去一直认为是Rodinia超大陆裂解背景下的大陆裂谷环境,时代归属为新元古代。岩石学、地球化学和锆石LA-ICP-MS U-Pb定年结果表明,鹰扬关群火山岩主要属于基性-中性火山(碎屑)岩类,在岩石化学成分上表现为明显富集大离子亲石元素(LILE,包括U、Th、Ba、K和Rb等)和轻稀土元素,而Nb、Ta、P和Ti等高场强元素和重稀土元素相对亏损,反映其具有俯冲-消减作用形成的岛弧-弧后盆地型火山岩地球化学特征;获得鹰扬关群中变角斑岩的锆石LA-ICP-MS U-Pb谐和年龄为(415.1±2.1)Ma(n=13,MSWD=1.8),表明其为加里东期海相火山喷发的产物。结合云开地块北缘存在有早古生代MORB型和岛弧型变质基性火山岩的资料表明,扬子板块和华夏板块结合带(称之为钦—杭结合带)西南段有早古生代的古洋盆,鹰扬关群岛弧-弧后盆地型火山岩可能是钦—杭结合带南西段早古生代洋陆俯冲-消减过程的地质记录,钦—杭结合带西南段加里东期的构造格局是俯冲增生造山带而不是陆内造山带。 相似文献
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桂北地区丹洲群是南华裂谷盆地南段的一套连续裂谷充填沉积,厘定各组沉积时限及区域地层关系,对理解华南新元古代裂谷作用期次具有重要意义。本文利用LA-ICP-MS锆石U-Pb同位素测年,获得丹洲群合桐组二段和拱洞组底部凝灰岩夹层形成年龄分别为801±4 Ma和781±5 Ma。研究表明,丹洲群白竹组和合桐组一段与下江群甲路组和乌叶组、板溪群沧水铺组和马底驿组、西乡群孙家河组及陆良组一段相当,沉积时限为820~800 Ma;合桐组二段与下江群番召组相当,沉积时限为800~780 Ma;拱洞组可与下江群清水江组、平略组和隆里组,板溪群五强溪组中上部和牛牯坪组,西乡群大石沟组中上部和三郎铺组,陆良组二段及澄江组、开建桥组、莲沱组、虹赤村组和上墅组的中上部直接对比,沉积时限为780~725 Ma。华南新元古代裂谷盆地系统的典型地层锆石年龄存在5组高峰,峰值年龄分别为818±2 Ma、802±1 Ma、780±4 Ma、756±4 Ma及728±5 Ma。综合华南新元古代岩浆活动特征及盆地沉积演化过程,确定华南新元古代裂谷作用可分为两期:820~800 Ma和800~725 Ma。此外,华南新元古代岩浆活动与裂谷作用之间存在明显的耦合关系,但各期岩浆活动对各裂谷盆地的影响程度存在差异。 相似文献
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FROM BACK-ARC BASIN TO BACK-ARC FORELAND BASIN—THE SEDIMENTARY BASIN AND TECTONIC EVOLUTION OF THE LATE CALEDONIAN—EARLY HERCYNIAN STAGES IN CORRIDOR AND NORTH QILIAN MTSthenationalNaturalScienceFoundationofChina(No.4 9972 0 78) 相似文献
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Geochronology and Tectonic Evolution of the West Section of the Jiangnan Orogenic Belt 总被引：1，自引：1，他引：0
ZHANG Heng LI Tingdong XIE Ying ZHANG Chuanheng GAO Linzhi GENG Shufang CHEN Tingyu YOU Guoqing 《《地质学报》英文版》2015,89(5):1497-1515
As an important part of South China Old Land, the Jiangnan Orogenic Belt plays a significant role in explaining the assembly and the evolution of the Upper Yangtze Block and Cathaysia, as well as the structure and growth mechanism of continental lithosphere in South China.The Lengjiaxi and the Banxi groups are the base strata of the west section of the Jiangnan Orogenic Belt.Thus, the research of geochronology and tectonic evolution of the Lengjiaxi and the Banxi groups is significant.The maximum sedimentary age of the Lengjiaxi Group is ca.862 Ma, and the minimum is ca.822 Ma.The Zhangjiawan Formation, which is situated in the upper part of the Banxi Group is ca.802 Ma.The Lengjiaxi Group and equivalent strata should thus belong to the Neoproterozoic in age.The Jiangnan Orogenic Belt consisting of the Lengjiaxi and the Banxi groups as important constituents is not a Greenville Orogen Belt(1.3 Ga–1.0 Ga).The Jiangnan Orogenic Belt is a recyclic orogenic belt, and the prototype basin is a foreland basin with materials derived from the southwest and the sediments belong to the active continental sedimentation.By combining large amounts of dating data of the Lengjiaxi and the Banxi groups as well as equivalent strata, the evolutionary model of the western section of the Jiangnan Orogenic Belt is established as follows: Before 862 Ma, the South China Ocean was subducted beneath the Upper Yangtze Block, while a continental island arc was formed on the side near the Upper Yangtze Block.The South China Ocean was not closed in this period.From 862 Ma to 822 Ma, the Upper Yangtze Block was collided with Cathaysia; and sediments began to be deposited in the foreland basin between the two blocks.The Lengjiaxi Group and equivalent strata were thus formed and the materials might be derived from the recyclic orogenic belt.From 822 Ma to 802 Ma, Cathaysia continued pushing to the Upper Yangtze Block, experienced the Jinning-Sibao Movement(Wuling Movement); as result, the folded basement of the Jiangnan Orogenic Belt was formed.After 802 Ma, Cathaysia and the Upper Yangtze Block were separated from each other, the Nanhua rift basin was formed and began to receive the sediments of the Banxi Group and equivalent strata.These large amounts of dating data and research results also indicate that before the collision of the Upper Yangtze Block with Cathaysia, materials of the continental crust became less and less from the southwest to the east in the Jiangnan Orogeneic Belt; only island arc and neomagmatic arc were developed in the eastern section.Ocean-continent subduction or continent-continent subduction took place in the western and southern sections, while intra-oceanic subduction occurred in the eastern section.Comprehensive analyses on U-Pb ages and Hf model ages of zircons, the main provenance of the Lengjiaxi Group is Cathaysia. 相似文献
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Process of Rifting and Collision along Plate Margins of the Qinling Orogenic Belt and Its Geodynamics 总被引：3，自引：0，他引：3
LIU Shaofeng Earth Science Resource Faculty China University of Geosciences Beijing and ZHANG Guowei Northwest University Xi''an Liu Xinzhu 《《地质学报》英文版》1999,73(3):275-288
The Qinling erogenic belt underwent complicated processes of rifting and collision, as shown by the coexistence of (1) ocean extension and plate margin rifting and (2) subduction of the frontal oceanic crust and extension of the rear plate margin. These resulted in a basin-mountain framework characterized by the coexistence of plates separated by the ocean basin and continental blocks demarcated by the rifting sea trough in the marginal region and the coexistence of subduction orogeny and ocean extension. Generally speaking, the plate marginal area between the North China plate and Yangtze plate continually rifted from north to south and the rifted micro-plates continually accreted northwards. This especial orogenic process was probably controlled by two events of deep mantle geody-namic adjustment and mantle plume activities, which occurred in the Shangdan suture belt and Mianlue suture belt from north to south respectively. 相似文献
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Interaction of an antecedent fluvial system with early normal fault growth: Implications for syn‐rift stratigraphy,western Corinth rift (Greece) 
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下载免费PDF全文 Continental ‘overfilled’ conditions during rift initiation are conventionally explained as due to low creation of accommodation compared with sediment supply. Alternatively, sediment supply can be relatively high from the onset of rifting due to an antecedent drainage system. The alluvial Lower Group of the western Plio–Pleistocene Corinth rift is used to investigate the interaction of fluvial sedimentation with early rifting. This rift was obliquely superimposed on the Hellenide mountain belt from which it inherited a significant palaeorelief. Detailed sedimentary logging and mapping of the well‐exposed syn‐rift succession document the facies distributions, palaeocurrents and stratigraphic architecture. Magnetostratigraphy and biostratigraphy are used to date and correlate the alluvial succession across and between fault blocks. From 3·2 to 1·8 Ma, a transverse low sinuosity braided river system flowed north/north‐east to east across east–west‐striking active fault blocks (4 to 7 km in width). Deposits evolved downstream from coarse alluvial conglomerates to fine‐grained lacustrine deposits over 15 to 30 km. The length scale of facies belts is much greater than, and thus not directly controlled by, the width of the fault blocks. At its termination, the distributive river system built small, stacked deltas into a shallow lake margin. The presence of a major antecedent drainage system is supported by: (i) a single major sediment entry point; (ii) persistence of a main channel belt axis; (iii) downstream fining at the scale of the rift basin. The zones of maximum subsidence on individual faults are aligned with the persistent fluvial axis, suggesting that sediment supply influenced normal fault growth. Instead of low accommodation rate during the early rift phase, this study proposes that facies progradation can be controlled by continuous and high sediment supply from antecedent rivers. 相似文献
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对班公湖-怒江西段舍马拉沟蛇绿岩中层状辉长岩的Sm-Nd、K-Ar同位素测定结果表明,Sm-Nd内部等时线年龄为(191 22)Ma,K-Ar年龄为(140 4．07)Ma和(152．30 3．60)Ma,结合地质资料分析,认为前者代表了洋盆张开年龄为早侏罗世,后者代表受到洋壳俯冲影响的时问;根据中段、东段蛇绿岩带已有的资料,讨论了班公湖-怒江蛇绿岩带的洋盆张开时代、俯冲时间及闭合时代,认为班公湖-怒江洋盆可能在早侏罗世自东向西同时张开,中侏罗世开始极性向南的俯冲,洋盆最终在早侏罗世末封闭。 相似文献
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湖南板溪期地层层序分析及格架探讨 总被引：2，自引：0，他引：2
该文对省内扬子大陆东南缘青白口纪板溪期地层进行层序地层分析，建立起该时期的地层格架，并据此探讨了板溪期地层的穿时性；推定了常德太阳山、石门杨家坪等地板溪期的沉积时限；论证了板溪群与峡山莲沱组的关系。 相似文献
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自中生代末期以来,东北地区形成了以松辽地堑为主体,联合下辽河裂谷、伊通-依兰裂谷、抚顺-密山裂谷以及邻近断陷盆地的大陆裂谷系,并向南北两端延伸,在亚洲东部构成一条大的裂谷带。这个大陆裂谷系的形成和发展是由中央向两侧展开的,与板块俯冲、弧后扩张密切相关。 相似文献