Provenance Study of Fe–Ti Oxide Minerals in the Quaternary Sediments in Yichang Area and Its Implication of Formation Time of the Yangtze Three Gorges, China     

XIANG Fang  DU Wen  HUANG Henxu  KANG Dongy  ZHU Hongbo  FENG Qin 《《地质学报》英文版》2018,92(4):1598-1608

The Three Gorges are considered to be critical to understand the formation of Yangtze River. Recent research results suggest that the Yangtze Three Gorges was created during the Quaternary but the exact time is debatable. Fe–Ti oxide minerals are seldom used to study sediment provenance, expecially using scanning electron microscopy(SEM), and energy dispersive spectrometer(EDS). In this study, the provenance of Quaternary sediments in Yichang area, which is located to the east of the Yangtze Three Gorges, was investigated by using SEM and EDS to research Fe–Ti oxides. The Panzhihua vanadium titanomagnetite and Emeishan basalt outcrop are located to the west of the Three Gorges. Further, the materials from them are observed in the Quaternary sediments of Yichang area. Fe–Ti oxide minerals from the Huangling granite are observed in the Yunchi and Shanxiyao Formations, which were formed before 0.75 Ma B.P., whereas Fe–Ti oxide minerals from the Huangling granite, Panzhihua vanadium titanomagnetite, and Emeishan basalt are observed in the riverbed and fifth-terrace sediments of the Yangtze River, which were formed after 0.73 Ma B.P.. Thus, we can infer that the Three Gorges formed after the deposition of the Shanxi Formation and before the fifth-terrace; i.e., 0.75–0.73 Ma B.P..  相似文献   

辽宁阜新北部至内蒙古库伦旗地区第四系冲、洪积沉积特征     

赵岩 《地质与资源》2018,27(5):417-423

辽宁阜新北部至内蒙古库伦旗地区的第四系冲、洪积地层分布广泛,但由于冲、洪积物岩性、岩相比较单调,在纵、横向上变化快,不易进行深入的研究.根据成因、孢粉以及形成时代将研究区第四系冲、洪积物划分出中更新统冲积物、上更新统冲洪积物、下全新统冲洪积物、中全新统冲积物、上全新统冲积物5个填图单位.不同时期的冲、洪积物沉积特征及沉积环境各具特色,形成了不同的地貌特征.确定冲、洪积物的沉积标志,并对其进行详细的划分,可以为研究区甚至我国整个北方地区提供第四系冲、洪积物各方面深入研究的资料.  相似文献   

The Neogene and Quaternary of England: landscape evolution,tectonics, climate change and their expression in the geological record     

Jonathan R. Lee  Ian Candy  Richard Haslam 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(3):452-481

During the Neogene and Quaternary, tectonic and climatic processes have had a profound impact upon landscape evolution in England and, perhaps as far back as 0.9 Ma, patterns of early human occupation. Until the Late Miocene, large-scale plate tectonic processes were the principal drivers of landscape evolution causing localised basin inversion and widespread exhumation. This drove, in places, the erosion of several kilometres of Mesozoic cover rocks and the development of a regional unconformity across England and the North Sea Basin. By the Pliocene, the relative influence of tectonics on landscape evolution waned as the background tectonic stress regime evolved and climatic influences became more prominent. Global-scale climate-forcing increased step-wise during the Plio-Pleistocene amplifying erosional and depositional processes that operated within the landscape. These processes caused differential unloading (uplift) and loading (subsidence) of the crust (‘denudational isostasy’) in areas undergoing net erosion (upland areas and slopes) and deposition (basins). Denudational isostasy amplified during the Mid-Pleistocene Transition (c.0.9 Ma) as landscapes become progressively synchronised to large-scale 100 ka ‘eccentricity’ climate forcing. Over the past 0.5 Ma, this has led to the establishment of a robust climate record of individual glacial/interglacial cycles enabling comparison to other regional and global records. During the Last Glacial-Interglacial Transition and early Holocene (c.16–7 ka), evidence for more abrupt (millennial/centennial) scale climatic events has been discovered. This indicates that superimposed upon the longer-term pattern of landscape evolution is a more dynamic response of the landscape to local and regional drivers.  相似文献   

冰川底部富铁溶液氧化沉淀:塔里木北缘新元古界库鲁克赛铁矿床的成因   总被引：1，自引：1，他引：0  

高丙飞  吴昌志  李伟强  杨涛  叶辉  雷如雄  刘倩 《矿床地质》2018,37(1):1-26

新元古代沉积变质铁矿床是继大氧化事件(GOE)后,沉积间断10亿年(~1800 Ma至~750 Ma)之后,再次大规模出现的一种沉积铁建造类型。这类铁建造与新元古代冰碛岩密切伴生,是新元古代雪球地球事件的重要证据。文章选择与新元古代雪球地球事件有关的沉积变质赤铁矿床—库鲁克赛铁矿进行研究,通过锆石U-Pb定年和区域地层对比工作限定其形成时代为新元古代青白口纪末期—南华纪早期。锆石年龄谱值对比和岩相学研究表明,铁矿床中的碎屑物质主要来自于青白口系下部独断山组石英砂岩地层。主、微量元素研究表明,库鲁克赛铁矿形成于相对富氧或者从贫氧向富氧变化的环境,其成矿元素应主要与陆源物质风化有关,可能有少量成矿元素来自于低温海底热液或海水。笔者认为,库鲁克赛铁矿的形成与成冰纪冰水沉积作用有关,来自冰下水体、从冰下通道中流出的富铁缺氧水溶液与富氧的表层海水混合时,成矿元素快速氧化沉淀,胶结冰水中的近源砾石,进而形成了此种富铁砾岩型铁矿。  相似文献   

New results concerning the pedo- and chronostratigraphy of the loess–palaeosol sequence Attenfeld (Bavaria,Germany) derived from a multi-methodological approach     

Lydia Krauss  Nicole Klasen  Philipp Schulte  Frank Lehmkuhl 《第四纪科学杂志》2021,36(8):1382-1396

Loess–palaeosol sequences (LPS) represent important records of palaeoenvironmental dynamics throughout the Quaternary. During the Pleistocene's dry and cold phases, the Danube's riverbed was one of the major sources for loess sediments that built up LPS in southern Germany and southeastern Europe. Surprisingly, studies addressing Bavarian LPS along the Danube River often lack actuality. The Attenfeld site was one of them and is often cited as a typical LPS. Nevertheless, the site's previous interpretations are based on a few empirical data and field observations. Considering the site's closeness to the sediment's source area, the Alps, and the region's importance in Middle and Upper Palaeolithic migrational movements, those former renditions needed an evaluation. Therefore, we applied a multi-proxy approach (including analyses of grain-size distribution, element composition, and sediment colour attributes) combined with optically stimulated luminescence. Based on our findings, we conclude that the Attenfeld site's former interpretations might be too generalised. We identified units that were not mentioned by previous studies (e.g. Early Glacial dark greyish horizon). Field observations, sediment characteristics, and age estimates indicate sediment deposition of the dated units partly before MIS 4, which contrasts with previous interpretations. The results further demonstrate how sensitive LPS are to environmental settings and dynamics.  相似文献   

The Callander (Auchenlaich) moraine: A new site report for the Western Highland Boundary block of the Quaternary of Scotland Geological Conservation Review (GCR)     

John Lowe  Vanessa Brazier 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(1):24-33

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Deformation patterns of upper Quaternary strata and their relation to active tectonics,Po Basin,Italy     

Alessandro Amorosi  Luigi Bruno  Bruno Campo  Bianca Costagli  Wan Hong  Vincenzo Picotti  Stefano Claudio Vaiani 《Sedimentology》2021,68(1):402-424

Despite increased application of subsurface datasets below the limits of seismic resolution, reconstructing near‐surface deformation of shallow key stratigraphic markers beneath modern alluvial and coastal plains through sediment core analysis has received little attention. Highly resolved stratigraphy of Upper Pleistocene to Holocene (Marine Isotope Stage 5e to Marine Isotope Stage 1) alluvial, deltaic and coastal depositional systems across the southern Po Plain, down to 150 m depth, provides an unambiguous documentation on the deformation of previously flat‐lying strata that goes back in time beyond the limits of morphological, historical and palaeoseismic records. Five prominent key horizons, accurately selected on the basis of their sedimentological characteristics and typified for their fossil content, were used as highly effective stratigraphic markers (M1 to M5) that can be tracked for tens of kilometres across the basin. A facies‐controlled approach tied to a robust chronology (102 radiocarbon dates) reveals considerable deformation of laterally extensive nearshore (M1), continental (M2 and M3) and lagoon (M4 and M5) marker beds originally deposited in a horizontal position (M1, M4 and M5). The areas where antiformal geometries are best observed are remarkably coincident with the axes of buried ramp anticlines, across which new seismic images reveal substantially warped stratal geometries of Lower Pleistocene strata. The striking spatial coincidence of fold crests with the epicentres of historic and instrumental seismicity suggests that deformation of marker beds M1 to M5 might reflect, in part at least, syntectonically generated relief and, thus, active tectonism. Precise identification and lateral tracing of chronologically constrained stratigraphic markers in the ¹⁴C time window through combined sedimentological and palaeoecological data may delineate late Quaternary subsurface stratigraphic architecture at an unprecedented level of detail, outlining cryptic stratal geometries at the sub‐seismic scale. This approach is highly reproducible in tectonically active Quaternary depositional systems and can help to assess patterns of active deformation in the subsurface of modern alluvial and coastal plains worldwide.  相似文献   

永定河中下游MIS7以来地层沉积演化及新石器时代以来气候变化          下载免费PDF全文

赵勇  杨誉博  李瑞杰  杨吉龙  王强  李亚林  王纯君  魏波  方同明  王志辉 《中国地质》2021,48(4):1188-1199

利用廊坊东A27钻孔岩心资料,样品微体生物、孢粉特征综合分析,结合AMS14C测年,对永定河中下游地区MIS7以来的地层进行分析,建立了MIS7以来的沉积地层格架,并对其进行了年代厘定,讨论了该地区大约MIS7阶段以来氧同位素分期气候下的地层及环境效应。结果表明,永定河中下游地区晚第四纪可划分为U1～U8共8个沉积单元,分别对应于MIS1～MIS7以及MIS8晚期的沉积地层,与海洋氧同位素分期有很好的对应关系。U1单元为MIS1形成的湖沼—河谷—泛滥平原沉积,U2单元为MIS2形成硬质黏土(第1硬土层)—下切河谷—湖沼沉积,U3单元为MIS3形成的湖沼—河谷—泛滥平原沉积,U4单元为MIS4形成的河间地块沉积(第2硬土层,暴露失水沉积),U5单元为MIS5形成的湖沼夹分支河道沉积,U6单元为MIS6形成的下切河谷夹短暂湖沼沉积,U7单元为MIS7形成的以湖沼为主沉积,U8单元为MIS8晚期形成的泛滥平原沉积,重塑了MIS7以来沉积环境模式,建立了本区晚第四纪精细年代地层框架。笔者认为永定河中下游在新石器时期以河湖共存为主,在其晚期为湖沼发育达到顶峰,出现泥炭层,直至商周时期后在气候变化影响下湖沼消退转变为泛滥平原面貌,为区域古地理环境及生态修复提供重要参考依据。  相似文献   

五大连池第四纪火山岩层序划分及其构造与生态意义     

曾普胜  丘顺帆  李睿哲  刘斯文  王十安  赵九江 《地球学报》2021,42(6):785-802

大量前人成果和1:5万区调钻孔资料证实,五大连池第四纪火山地层属于水平岩层.因此,该地区第四纪火山地层的划分,是在地表岩石层序与钻孔岩石层序充分划分与对比的基础上进行的.从沉积角度看,五大连池火山地层属于松嫩盆地连续沉积过程中的第四纪短暂幕式火山喷发所形成的水平岩层.本文结合K-Ar同位素测年新资料,将该区第四纪岩石地层重新划分为11个组级地层单位.其中的火山岩石地层可以自下而上划分为:下更新统焦得布玄武岩(1.214—1.113 Ma);中更新统尾山玄武岩(0.62—0.285 Ma);中更新统笔架山玄武岩(0.24—0.132 Ma)和全新统老黑山玄武岩(距今290～288 a),对夹于其间的正常沉积地层也进行了相应的划分.对层状火山岩层序的层位划分和空间分布研究对于理解五大连池火山群的构造背景和生态环境具有特别重要的意义,五大连池火山群处于中国大陆内部的大同—大兴安岭火山岩带的最北东端,是地幔流体向北东方向流动的最前缘;这类富钾的碱性玄武岩的火山喷发活动对东北富饶的黑土地的形成具有重要贡献,火山岩在嫩江平原上塑造的台地和火山锥地形地貌对生态多样性和优质地下水的生态要素具有重要影响.  相似文献   

BP人工神经网络法在大同市日极大风速预报中的应用     

刘洁莉  刘冬辉  韩登云  徐鑫 《内蒙古气象》2019,(2):34-38

文章利用2010年1月1日—2013年12月31日逐日NCEP再分析资料(1°×1°)和大同地区地面常规观测资料,采用BP人工神经网络法建立大同市分站点、分季节日极大风速人工神经网络预报模型并且在对T639数值预报产品和EC细网格数值预报产品释用基础上建立了台站日极大风速的客观预报系统,对2015年9月1日—2016年7月31日进行了24h预报,试用结果显示,各季模式平均绝对误差在3.2~5.7m·s^-1之间,因此,该系统可以为预报员快速做出日极大风速的预报提供客观参考依据。  相似文献