中国南方奥陶纪构造古地理及年代与生物地层的划分与对比     

汪啸风 《地学前缘》2016,23(6):253-267

岩相、生物区系和构造组合特征的重新研究表明,在我国南方奥陶纪可以识别出三种不同类型的构造古地理区,即扬子浅海碳酸盐岩台地相区、江南和南秦岭陆棚斜坡过渡相区和华夏陆缘岛弧和边缘盆地相区。前二者应归属于扬子地块;而沉积、生物组合特征以及槽模所指示NW320°的水流方向说明,后者似应归属于华夏地块,而不是华南地块。海南岛作为一个漂移地体,奥陶系可能属于印支地块台缘陆棚相区。年代和生物地层划分和对比研究表明,我国吉林白山大阳岔小阳桥寒武系与奥陶系界线剖面发育了完整的、具有广泛对比意义的牙形石和笔石序列,建议以牙形石Cordylodus intermedius的首现取代在分类上有争议且罕见的Iapetognathus fluctivagus,作为全球寒武系奥陶系界线划分的生物标志。湖南益阳南坝泥江口剖面保存了完整特马豆克期晚期至弗洛期早期笔石序列,建议用益阳阶取代“道保湾阶”作为我国奥陶系区域年代地层单位,易于与瑞典弗洛阶金钉子剖面对比。对宜昌附近黄花场、分乡、陈家河和普溪河等以及湖南慈利茅草铺大湾组至宝塔组含牙形石碳酸盐岩地层的系统采集和研究表明,大湾组自下而上可以分为上Oepikodus communis、Oepikodus evae (s.s.)、Periodon flabellum、Microzarkodina russica、Baltoniodus triangularis、Baltoniodus navis、B.norrlandicus和Lenodus antivariabilis等8个牙形石生物带,并讨论了它们与相关笔石带的对应关系。随着牙形石Protopederodus liripipus在黄花场和普溪河剖面宝塔组底界之上2~3 m出现以及相应碳同位素偏移,说明在扬子碳酸盐岩台地上奥陶统凯迪阶下界应置于宝塔组下部,与Hamarodus? europaeus牙形石带近底部大致相当或接近。据高分辨率离子探针(SHRIMP-II)锆石U-Pb年龄测定,宜昌岩屋咀晚奥陶世五峰组底部Dicellograptus complexus笔石带之下20 cm所发现斑脱岩夹层的年龄为(448.6±4.8) Ma;而田家场Paraorthograptus pacificus笔石带顶部斑脱岩夹层的年龄为(446.5±2.1) Ma,暗示宜昌地区五峰组大约经历了5.4 Ma的沉积时间。  相似文献   

基于EMD的空间信息剖分一体化编目模型研究     

迟占福  程承旗  关丽  肖恰 《地理与地理信息科学》2009,25(6)

针对目前空间信息编目多样、缺乏全球统一编目体系的现状,借鉴地理空间信息分类框架,结合地图分幅拓展球面剖分理论,提出了基于EMD的空间信息剖分一体化编目模型.在此基础上,设计了统一剖分编目中间件,搭建了全球空间信息统一剖分编目数据的管理框架.基于EMD的空间信息剖分一体化编目模型为实现空间数据的全球化、层次化和规范化管理奠定了理论基础.  相似文献   

遥感影像剖分金字塔研究   总被引：1，自引：0，他引：1  

程承旗  张恩东  万元嵬  宋树华 《地理与地理信息科学》2010,26(1)

分析了全球剖分格网与影像金字塔的优点与不足,结合两者的优势提出了剖分影像金字塔模型及建塔策略,利用全球剖分格网面片编码的唯一性和Hilbert曲线空间连续性对影像块进行索引与组织。针对基于影像块组织的特点,提出了剖分影像金字塔局部更新的方案。实验结果表明,剖分影像金字塔不仅具有传统影像金字塔在快速浏览上的优势,并且由于其编码和索引的优势,使得在局部影像提取和更新方面效率更高,有一定的使用价值。  相似文献   

河南新乡第四纪地层划分与沉积环境分析     

郑建彬  陈建强 《现代地质》2017,31(1):81

新乡位于豫西北山地与豫东平原过渡位置,黄河冲积扇的不断发展以及第四纪早期的新构造运动对该区第四纪沉积过程产生影响。通过对新乡多个钻孔岩心进行系统性描述、年龄测试、沉积相分析以及钻孔地层间对比分析,结果显示：黄河冲积扇的发展及黄河主河道的南北向迁移,是研究区第四纪沉积过程的重要影响因素,研究区第四纪沉积相以河流相为主,横向上对比良好;多个场地的钻孔揭示研究区全新统厚度约10 m,平均年龄95 ka左右;更新统上部厚度约69 m,平均年龄129 ka左右;更新统中部厚度约55 m,平均年龄小于829 ka;更新统下部未见底。在第四纪早期,黄河冲积扇主河道在研究区西侧,尚未发育到新乡地区,对该区的影响较小,以细粒的泛滥平原沉积物为主;第四纪中期,黄河冲积扇快速向东部发展,河道迁移至研究区北东侧,沉积了明显的河流相,砂体厚度明显增加;第四纪中晚期,基本继承前期的河流相沉积,随着河道南迁,砂体含量有所下降。受到新构造运动的影响,新乡地区第四纪地层北东部出现沉积间断,并且局部地区出现差异沉降,北东侧地势高于南西侧。  相似文献   

Cryptic diversity of marine gastropod Monodonta labio (Trochidae): did the early Pleistocene glacial isolation and sea surface temperature gradient jointly drive diversification of sister species and/or subspecies in the Northwestern Pacific?          下载免费PDF全文

Dan Zhao  Qi Li  Lingfeng Kong  Hong Yu 《Marine Ecology》2017,38(4)

Formation of glacial refugia during the Pleistocene climatic oscillations has been put forward to elucidate the diversification of marine organisms in the north‐western Pacific. The marine gastropod Monodonta labio is one of the most common species in the Northwestern Pacific and possibly possesses cryptic diversity. Here, we investigate the phylogeographic pattern of this species to test the potential mechanisms driving its diversification in the Northwestern Pacific. Genetic information for two mitochondrial genes (Cytochrome oxidase subunit I and 16S rDNA) and one nuclear gene (internal transcribed spacer 1) was acquired to detect genetic structuring and to reconstruct the gastropod's phylogenetic history. Our results revealed that M. labio is comprised of five main clades, and divergence time estimates place their cladogenesis as corresponding to the initiation (c. 2.5 mya) and intensification (c. 0.9 mya) of large‐scale Northern Hemisphere ice sheets. The early and middle Pleistocene divergence times are consistent with the emergence times of the Dongshan land bridge, which would seperate the ancient East China Sea and the ancient South China Sea forming two potential refugia. In addition, the deep trough in the Qiongzhou Strait would possibly act as another potential refugium with the uplift of the Qiongzhou Strait at mid‐Pleistocene. This study suggests that the current genetic architecture of M. labio is probably correlated with glacial isolation and sea surface temperature gradient. We also put forward the possibility that these factors were probably an important driver for the diversification of sister species or subspecies of other taxa in the Northwestern Pacific.  相似文献   

应用电子探针研究蒙其古尔铀矿床含矿砂岩岩石学特征及铀矿物分布规律   总被引：3，自引：1，他引：2  

黄广文  潘家永  张占峰  黄广楠  张涛  廖志权  杜后发 《岩矿测试》2017,36(2):196-207

国内外铁矿石价格对标基准多采用离岸价或到岸价,而非盈亏平衡运营成本,难以揭示我国铁矿石所面对的真实市场承压价格。为了厘清国际一线生产商的铁矿石盈亏平衡运营成本价格,本文对世界上最重要的条带状铁建造（BIF）矿产地——西澳哈默斯利盆地高品位赤铁矿矿床的矿化特征及代表性铁矿石产品展开系统研究,同时引入巴西铁四角地区的铁英岩型赤铁矿矿石作为对照,分析全球典型高品位赤铁矿矿石经济指标。结合前人研究成果,将西澳哈默斯利盆地与BIF相关的高品位赤铁矿的富集矿化类型划分为假象赤铁矿-针铁矿、微板状赤铁矿与河道沉积型赤铁矿,巴西铁四角主要为铁英岩型赤铁矿。上述各矿化类型对应的铁矿石产品的铁元素含量均高于56%;在杂质元素含量上,假象赤铁矿-针铁矿的磷含量高,微板状赤铁矿的磷、硫含量较高,河道沉积型赤铁矿的磷、硫含量较低,铁英岩型赤铁矿含锰。经定量估算,西澳力拓、必和必拓、FMG和巴西淡水河谷的铁矿石盈亏平衡运营成本价格分别为34.66、36.76、47.35、38.07美元/干吨,可为中国海外权益铁矿项目开发提供运营成本的参考。  相似文献   

华北峡谷珍品--河北野三坡"百里峡构造-冲蚀嶂谷"的成因   总被引：4，自引：0，他引：4  

宋志敏聂泽同  赵崇贺梁定益 《地质通报》2005,24(6):582-587

野三坡国家地质公园位于紫荆关大断裂北端,河北涞水县境内。百里峡构造一冲蚀嶂谷由3条分裂嶂谷组成,总长达52．5h,发育在紫荆关大断裂东侧的中元古界雾迷山组燧石条带白云岩中。中一新生代4期宏大而直立的构造节理,特别是喜马拉雅期南北向追踪张节理,是嶂谷形成的先决条件;更新世阶段地壳迅速的抬升、外力的物理风化作用,特别是晚更新世间歇性山区洪水的冲蚀,是形成嶂谷的直接原因。百里峡构造一冲蚀嶂谷是喀斯特地貌中一种特殊的类型。  相似文献   

Sequence subdivision and development characteristics of low-accommodation non-marine basins: a case study of the Yanchang Formation in the Ordos Basin     

S. Fu  Y.-Z. Li  Y.-R. Guo  X.-M. Xu  J.-J. Liu 《Australian Journal of Earth Sciences》2018,65(6):823-850

The third-order sequences of the Yanchang Formation in the Ordos Basin were determined by a comprehensive analysis of surface outcrops, core, logging and seismic data. Natural gamma curves were studied by the band-pass method. The hidden stratigraphic sequence and six lithological cycles were extracted. By examining sequence boundaries and lithological cycles, we identified six third-order (including SQ1, SQ2, SQ3, SQ4, SQ5 and SQ6) and three second-order sequences in the Yanchang Formation. The sequence stratigraphy of the Ordos Basin was found to have the following special development characteristics: (1) the third-order sequence growths were totally stable, and the thickness of the Ordos Basin was relatively stable; (2) thick sand bodies did not form in lowstand systems because of underdeveloped slope breaks; (3) the third-order sequences had diverse features at different sedimentary periods; (4) the distribution of the depositional systems had various characteristics in different tectonic belts, and the entire sequence had the filling characteristics of multiprovenances and multicycles. The low-accommodation Ordos Basin in the Upper Triassic was limited by slow subsidence, gentle basement paleorelief, stable tectonic settings and sufficient sediment supply. The characteristics of the basin included stable developed sequences, limited preserved lowstand systems tracts, multiple depocentres and subsiding centres, development of many delta systems in the north and south of the basin controlled by the gradient of the basement paleorelief, and laterally stretching sediments. Results further indicated that the controlling factors of the third-order stratigraphic sequences of Yanchang Formation in the low-accommodation lacustrine Ordos Basin included sediment supply (provenance), climate and lake-level fluctuation. Overall, our case study indicated that the development characteristics and controlling factors of sequence stratigraphy in a low-accommodation lake basin provided a comprehensive method of establishing the sequence stratigraphic framework of a low-accommodation non-marine basin. Our results also predicted that the SQ3, SQ4 and SQ5 of the Qiaochuan and Zhidan areas favoured oil and gas prospecting of the Yanchang Formation.  相似文献   

辽东半岛南部中新元古界地层的重新厘定     

牛绍武  辛后田 《华北地质》2012,(1):1-15

近年来,燕山地区原青白口系下马岭组的年代学研究取得了突破性进展(其年龄为1368±12 Ma,1370±11 Ma,1366±9 Ma);在研究区金州大和尚山侵入于“桥头组”辉绿岩也获得新元古代锆石U-Pb年龄(904±15 Ma~1125±38 Ma).这些年代数据使我们认为对于辽南地区前人所划“震旦系”地层的划分与对比应进行重新考虑.本文以岩石地层和旋回地层为实际材料,生物地层和事件地层以及年代地层为手段,从长岭子组能否作为标志层入手,对辽南地区中-新元古界进行了系统研究,否定了长岭子组在地层对比中的标志层意义,首次提出葛屯组才是金县地区与复县地区进行地层对比的标志,并将复县地区的五行山群置于金县群之上,从而将辽南地区“震旦系”由老到新重新厘定为中元古界旅大群、革镇堡群和金县群与新元古界永宁群、细河群和五行山群.以碎屑岩为主要特征的岩石组合与海底火山喷发事件,将辽东半岛南部旅大群与蓟县剖面长城系进行了对比;以碳酸盐岩为主要特征并含丰富的叠层石Paraconophyton-Conophyton-Baicalia-Chihsienia等组合的革镇堡群与蓟县剖面蓟县系对比;富含叠层石Linella-Gymnosolen-Katavia-Cuijiatunia-Xingmincunella组合的金县群可与下马岭组对比,从而将金县群首次置于中元古界上部.含宏观藻类化石Chuaria-Tawuia-Longfengshania组合和蠕形类化石Pararenicola-Paleolina组合的永宁群-细河群-五行山群与加拿大新元古界小达尔群-含铜白云岩对比,永宁群-五行山群的时代应为新元古代早期.据此,笔者全面调整了徐淮胶辽吉中-新元古界的地层划分与对比,为在我国建立中-新元古界系一级的地层单元打下良好的基础,具有重要的地层学和年代学意义.同时,由于对该区中-新元古界重新进行了划分与对比,确认了大连上升是中元古界与新元古界的分界面,并大体相当于北美格林威尔运动在华北地块上的响应,为探讨燕山地区与徐淮胶辽吉中-新元古代的沉积特征,海水进退归程,构造运动以及重建Rodinia超大陆提供了地层资料,具有重要的古地理学和古构造学理论意义  相似文献   

几内亚共和国Firawaya一带铁矿床地质特征及找矿标志     

赵超  马俊 《吉林地质》2014,(3):56-59

几内亚拥有丰富的矿产资源,目前宁巴山铁矿和西芒杜铁矿均为世界级铁矿,位于几内亚东南部,品位均达到66%~68%。本文通过对矿区地质特征的研究,确立磁铁矿的找矿标志,对指导本区域BIF型铁矿的地质找矿具有实际意义。  相似文献