河南省华北地台区成盐条件及找盐远景     

温同想  徐松绿 《河南国土资源》1997,(4)

河南省华北地台区寒武系下统自下而上划分为辛集组含磷陆源碎屑岩，朱砂洞组蒸发岩—镁质碳酸盐岩和馒头组含陆源碎屑碳酸盐岩夹不稳定蒸发岩。早寒武世古地理环境为华北陆表海，划分为三个相区七个亚相区；有朱砂洞早期和馒头早中期两个成盐亚期，均属海相化学岩型硫酸盐岩和镁质碳酸盐岩互层的剖面结构类型；有潮上膏盐湖和潮上盐滩两种成盐环境，浅盆浅水和潮上萨勃哈两种成盐模式。经过对成盐地质条件和控矿因素综合分析，石膏成矿远景较大，石盐有局部富集成矿的可能性，钾盐有成矿的某些基本地质前提。  相似文献   

In Search of the Cretaceous-Tertiary Boundary in Heilongjiang River Area of China   总被引：1，自引：0，他引：1  

Sun G  M.Akhmetiev  Dong Z.M  A.R.Ashraf  Sun Y.W  E.Bugdaeva  D.L.Dilcher  L.Golovneva  I.Harding  K.Johnson  T.Kezina  T.Kodrul  LU J.S  V.Markevich  H.Nishida  H.Okada  Park S.O  Sun C.L  Xiong X.Z  Xing Y.L  Zhou Z.L 《世界地质(英文版)》2002,5(2)

Abstract A new geological section recognized in Baishantou of Jiayin, Heilongjiang Province, China, was studied preliminarily in searching for the K/T boundary. An early Paleocene florule characrerized by abundant Tiliaephyllum tsagajanicum leaves and its associated plants, was collected from the Baishantou Member (new member representing the lower part of the Paleocene Wuyun Formation) overlying the possible K/T boundary. A tuff bed was found from the upper part of the Furao Formation (uppermost Cretaceous) in this section. The new findings imply that the K/T boundary is probable lying in the interval between the base of the Baishantou Member and the tuff bed, based on the correlation of the present strata with the stratotype of the Tsagajan Group spanning the K/T boundary in "Belaya Gara" of the Bureya Basin, Russia. The early Paleocene florule from the Baishantou Member and the early-middle Maastrichtian dinosaurs found from the Yuliangzi Formation underlying the Furao Formation suggest that the Baishantou section is more promising for searching for the K/T boundary in this area. Further studies of the section is needed, integrating paleontological, biostratigraphic, geochemical, paleomagnetic, and sedimentary research would benefit our understanding the mass extinction event and biotic recovery in the Heilongjiang River area, China, and even all of northeast Asia during the K/T boundary interval.  相似文献   

Freshwater organic deposits and stratified sediments between Early and Late Midlandian (Devensian) till sheets,at Aghnadarragh,County Antrim,Northern Ireland     

A. Marshall McCabe  G. Russell Coope  Dorothy E. Gennard  Philip Doughty 《第四纪科学杂志》1987,2(1):11-33

The following events have been identified from a complex sequence of Midlandian (Devensian) sediments recently exposed at Aghnadarragh, County Antrim: (1) A lower till interpreted as Early Midlandian was deposited by a major lowland ice sheet which moved south-eastwards from central Ulster across the Lough Neagh depression. (2) Deglacial conditions were followed by a periglacial phase characterised by ice-wedge growth and sedimentation by gravelly debris flows. The latter contain the oldest known remains of Mammuthus primigenius in Ireland. (3) An Early Midlandian interstadial is represented by a woody detritus peat, with evidence of Betula, Pinuos and Picea woodlands and a rich beetle fauna. Wood from this horizon has been shown to be beyond the range of radiocarbon dating (>48 180 BP). (4) Interstadial conditions were succeeded by a cold, non-glacial phase dominated by in-channel gravelly flows and deposition of organic muds which contain plant and insect fossils. These horizons are older than 46 850 BP. (5) An upper, non-drumlinised till was deposited during the Late-Midlandian by a major lowland ice sheet which moved generally eastwards across the Lough Neagh Lowlands from central Ulster. This glaciation probably reached its maximum at ca 20–24 ka. (6) Drumlin formation occurred in the Lough Neagh Lowlands towards the end of the Late-Midlandian. The limiting moraines are dated to 17 ka. The lower till at Aghnadarragh is the first positive record of a major lowland ice sheet in Ireland during the early part of the last cold stage. The Early Midlandian interstadial peats have not been documented elsewhere in Ireland and correlate broadly with the Chelford Interstadial complex of the English Midlands. Related exposures elsewhere in Ulster confirm that the middle part of the last cold stage was free of major lowland ice masses but deposits of this period are absent from Aghnadarragh.  相似文献   

马氏珠母贝早春育苗,缩短母贝养成期试验     

陈兆和  周庆堂  何水养  王忠 《广东海洋大学学报》1989,(Z1)

在室内人工飼养马氏珠母贝亲贝,进行早春育苗。比常规生产育苗提前二个月。生长快,贝体健壮,经养殖18个月长至壳高7.1厘米,体重52克。60％以上达施术贝标准,相当于常规生产贝苗26个月的生长水平。相对地缩短了养殖周期,提高了经济效益。且设备简单,操作方便,利于推广。  相似文献   

Geochronology and geochemistry of early Paleozoic granitic and coeval mafic rocks from the Tannuola terrane (Tuva,Russia): Implications for transition from a subduction to post-collisional setting in the northern part of the Central Asian Orogenic Belt     

《Gondwana Research》2024

Early Paleozoic magmatism of the Tannuola terrane located in the northern Central Asian Orogenic Belt is important to understanding the transition from subduction to post-collision settings. In this study, we report in situ zircon U-Pb ages, whole rock geochemistry, and Sr-Nd isotopic data from the mafic and granitic rocks of the eastern Tannuola terrane to better characterize their petrogenesis and to investigate changing of the tectonic setting and geodynamic evolution. Zircon U-Pb ages reveal three magmatic episodes for about 60 Ma from ∼510 to ∼450 Ma, that can be divided into the late Cambrian (∼510–490 Ma), the Early Ordovician (∼480–470 Ma) and the Middle-Late Ordovician (∼460–450 Ma) stages. The late Cambrian episode emplaced the mafic, intermediate and granitic rocks with volcanic arc affinity. The late Cambrian mafic rocks of the Tannuola terrane may originate from melting of mantle source that contain asthenosphere and subarc enriched mantle metasomatized by melts derived from sinking oceanic slab. Geochemical and isotopic compositions indicate the late Cambrian intermediate-granitic rocks are most consistent with an origin from a mixed source including fractionation of mantle-derived magmas and crustal-derived components. The Early Ordovician episode reveal bimodal intrusions containing mafic rocks and adakite-like granitic rocks implying the transition from a thinner to a thicker lower crust. The Early Ordovician mafic rocks are formed as a result of high degree melting of mantle source including dominantly depleted mantle and subordinate mantle metasomatized by fluid components while coeval granitic rocks were derived from partial melting of the high Sr/Y mafic rocks. The latest Middle-Late Ordovician magmatic episode emplaced high-K calc-alkaline ferroan granitic rocks that were formed through the partial melting the juvenile Neoproterozoic sources.These three episodes of magmatism identified in the eastern Tannuola terrane are interpreted as reflecting the transition from subduction to post-collision settings during the early Paleozoic. The emplacement of voluminous magmatic rocks was induced by several stages of asthenospheric upwelling in various geodynamic settings. The late Cambrian episode of magmatism was triggered by the slab break-off while subsequent Early Ordovician episode followed the switch to a collisional setting with thickening of the lower crust and the intrusion of mantle-induced bimodal magmatism. During the post-collisional stage, the large-scale lithospheric delamination provides the magma generation for the Middle-Late Ordovician granitic rocks.  相似文献   

早前寒武纪地壳增生、再造作用与基底变质建造分析──以华北为例   总被引：1，自引：0，他引：1       下载免费PDF全文

张福勤 《地球物理学报》1998,41(Z1):88-98

早前寒武纪地壳演化的具体表现可以从增生作用和陆壳再造作用这两个方面进行描述按照增生表壳岩系类型可以将早前寒武纪大陆地壳划分为绿岩型和沉积型陆壳增生区;按陆壳再造作用的类型可以将早期大陆地壳划分为变质改造型和重熔分异型陆壳再造区对区域上绿岩型表壳岩系、沉积型表壳岩系;TTG岩系、钾质花岗岩系等与地壳演化进程的关系作了概括．不同类型陆壳区反映了地壳增生进程是不一样的,增生地壳受再造作用的程度以及遭受的陆壳再造作用类型也可以是不同的,而一个完整的地壳演化旋回应包含活动增生、陆壳再造与克拉通化作用,一个地壳区地壳演化往往是这些作用交替发展并形成与邻区地壳演化进程的差异．进而提出了早前寒武纪克拉通基底建造分析的思路、原则和模式  相似文献   

Bioistratigraphical and sedimentological study of Upper Senonian–Lower Eocene sediments of Tripolitza Platform in central Crete (Greece)     

A. Zambetakis-Lekkas  F. Pomoni-Papaioannou  A. Alexopoulos 《Cretaceous Research》1998,19(6):715-732

The stratigraphic and palaeoenvironmental implications of a section in the Upper Senonian to Lower Eocene carbonates of the Tripolitza Platform in central Crete are discussed in this paper. The lower part (upper Campanian–lower Maastrichtian) of the succession consists of about 75 m of thickly bedded, light to dark grey limestones, dolomitic limestones and dolomites that were deposited on an inner carbonate platform. It is characterized by stratified bioclastic rudist facies (shelly limestone) associated with foraminifera and especially with species of the Rhapydioninidae family. These are overlain by 35 m of crystalline light grey dolomites that were deposited on a very restricted internal platform, characterized by intertidal-supratidal facies. The overlying 75-m-thick light grey dolomitic limestones and dolomites are characterized by the presence ofRhapydionina liburnicaStache, and in the uppermost part byNeobalkhania bignotiCherchi, Radoicic & Schroeder, dating it as Late Maastrichtian. The facies, cryptalgal laminites with fenestrae of varying dimensions, suggest relatively extensive subaerial exposure. Possible pedogenic textures are common in this sequence and especially in the uppermost part, which coincides with the K/T boundary. The presence ofPseudonummoloculina heimi(Bonet) at two levels in the Maastrichtian succession suggests transportation of Middle-Late Cenomanian sediments from emergent blocks of the platform during this period. A gap is suspected, for regional stratigraphic reasons, between this horizon and the next which containsSpirolinasp. and “Pseudochrysalidina” sp., dating it as Early-Middle Eocene.  相似文献   

华山——熊耳山地块早前寒武纪绿岩及其形成构造背景     

刘红樱  陈衍景 《地质论评》1998,44(3):233-242

华北地台南缘华山－熊耳山地块早前寒武纪绿岩带中存在有晚太古代第一期绿岩和古元古代早期第二期绿岩。它们的地质地球化学特征的研究表明：第一期绿岩为一套大洋型基性－中酸性火山岩和科马提岩类夹少量典型太古宙深海沉积建造,形成于硅镁质地壳拉开背景下的洋中脊环境,代表当时的洋壳;第二期绿岩为一套岛弧型基性－中基性火山岩夹中酸性火山岩、下部的太古宙型沉积岩和上部的后太古宙型沉积岩,形成于第一期绿岩硅铝化而成的岛  相似文献   

New Paleomagnetic Study on Early Triassic Liujiagou Formation of North China Block *     

Tian Wuhong Faculty of Earth Sciences  China University of Geosciences  Wuhan Niu Xiukai Hebei Bureau of Geology  Mineral Resources  Shijiazhuang 《中国地质大学学报(英文版)》1998,(3)

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中国东北地区二叠纪生物混生机制讨论     

彭向东  张梅生  米家榕 《国土资源》1998,(1)

生物混生现象是指不同生物古地理区系的生物出现于同一地区的同时代地层中,表明它们曾同时或略为先后地生活或埋藏在一起。中国东北地区早二叠世时期出现明显的北方冷水动物群（归属北方大区准噶尔－兴安生物省）与特提斯暖水动物群（归属特提斯大区内蒙－吉林生物省）的混生现象;晚二叠世出现安加拉植物群（Ａｎ－ｇａｒａｆｌｏｒａ）与华夏植物群（Ｃａｔｈａｙｓｉａｎｆｌｏｒａ）的混生。对于这些生物混生的机制及阻隔生物迁移扩散的障岩的详细研究,对于解决中国北方二叠纪古海盆性状和南北板块最终缝合带的位置等问题具有重大意义。  相似文献