胶莱盆地东北缘中生界粗碎屑岩段的沉积层序及含金性   总被引：8，自引：2，他引：6  

周江羽  李思田 《沉积学报》1998,16(1):140-145

胶莱盆地属于晚中生代断陷盆地,东北缘广泛出露中生界的粗碎屑岩系。在对其进行详细的野外宏观描述、室内微观鉴定及样品含金量测试的基础上,研究了粗碎屑岩段的沉积物组成、沉积类型和微观特征,建立了该岩段在不同地区的垂向沉积层序及典型展序组合类型。不同的水动力条件是造成砾岩层内部结构复杂性变化的主要原因。通过与国内外有关资料的对比分析,指出研究区粗碎屑岩段形成于干旱、近源快速堆积的陆上冲积扇环境,且探讨了其含金性。  相似文献   

大兴安岭南段多金属矿成矿作用和找矿潜力   总被引：4，自引：0，他引：4  

曾庆栋  刘建明  褚少雄  郭云鹏  高帅  郭理想  翟媛媛 《吉林大学学报(地球科学版)》2016,46(4):1100-1123

大兴安岭南段多金属成矿带位于中亚造山带东部贺根山断裂与西拉沐伦河断裂之间,处于古亚洲洋构造与古太平洋构造的叠加部位。具有双层结构特征(基底以二叠纪地层为主,盖层为侏罗纪早白垩世地层),发育了多期的构造、岩浆活动,以及众多的多金属矿床。区内矿床以多成矿元素共生、伴生为特点,按成矿作用特征划分为4个成矿系统(斑岩、矽卡岩、热液脉状、碱性花岗岩成矿系统)。斑岩成矿系统包括斑岩钼多金属、锡多金属2个亚成矿系统,矽卡岩成矿系统包括矽卡岩型铁锡、铅锌银2个亚成矿系统,热液脉状成矿系统包括银多金属、铜多金属、锡多金属3个亚成矿系统,碱性花岗岩成矿系统为稀有稀土成矿系统。大兴安岭南段多金属矿床形成于2个主要时期:晚二叠—世三叠纪、晚侏罗世—早白垩世。两期成矿作用均与花岗质岩浆活动密切相关,成矿物质来源既包括深部岩浆带来的物质,也包括区内地层,具有多来源特点。晚二叠—世三叠纪多金属矿床形成于古亚洲洋构造体系,晚侏罗世—早白垩世多金属矿床形成于古太平洋构造体系。优越的成矿地质条件及良好的地球物理与地球化学异常表明大兴安岭南段仍具有巨大的找矿潜力。  相似文献   

三论蒙阴地区金刚石原生矿的形成时代          下载免费PDF全文

杨斌  孙秀珠  罗文强  马祥县  唐璐璐 《山东国土资源》2016,32(9)

该文以地质基本事实为依据,以地质构造发展史为主线,结合华北地台奥陶纪后演化史,以及石炭纪以后古金刚石砂矿储集层为佐证,再加金伯利岩切穿辉绿岩和煌斑岩脉的实证,都显示出蒙阴地区金刚石原生矿形成时代不在奥陶纪而在中生代。  相似文献   

A new species of Vetanthocoridae (Heteroptera: Cimicomorpha) from the Lower Cretaceous of China     

《Cretaceous Research》2016

A new species, Crassicerus limpiduspterus sp. n., is characterized, described and assigned to the tribe Crassicerini of the fossil family Vetanthocoridae. All of the specimens were collected from the Lower Cretaceous Yixian Formation at Chaomidian Village, Liaoning Province. The Crassicerini are interpreted to have thrived in live plant habitats, including flowers, shrubs and trees, based on their antennal type.  相似文献   

Sequence and scale of changes in the terrestrial biota during the Cretaceous (based on materials from fossil resins)     

《Cretaceous Research》2016

Сomparative analysis of arthropod assemblages found in Cretaceous fossil resins is provided. Arthropod-bearing Cretaceous resin sites are reviewed, and a list of arthropod records (identified to the family level) published up to 2015 is provided. Also, new records of mites, and new arthropod records from the Siberian resins are given. An efficient method for extracting amber from loose sediments in situations of limited infrastructure but easy access to water is described as well.The sequence of arthropod assemblages in Cretaceous resins according to their evolutionary aspect does not match their geological sequence. This can be only partly explained by taphonomic constraints and inadequacy of the material: there is a deeper difference between somewhat contemporary assemblages than was characteristic of Permian assemblages studied in a similar way in previous studies. Our results confirm the earlier hypothesis that the Palaeozoic–Mesozoic biotic crisis was not so much a mass extinction as a biotic reorganisation that opened the way to diversification. These results might indicate a peculiar feature of the immediate effects of such reorganisations, namely that Mesozoic–Cenozoic communities became differentiated in their compositions much deeper than Palaeozoic ones (i.e., that their constituent groups acquired the ability to evolve much deeper changes while adapting to the ecological specifics of their environments). A transformation of organisms and/or their communities took place, comparable in scope to the rise of skeletal fauna in the Cambrian. The difference between these two transformations is that the later one resulted not from a particular adaptation (the skeleton) but from the ability to specialize more deeply than was possible in the Palaeozoic.  相似文献   

An unusual new lineage of sawflies (Hymenoptera) in Upper Cretaceous amber from northern Myanmar     

《Cretaceous Research》2016

A peculiar new lineage of sawflies (‘Symphyta’) is described and figured from a female beautifully preserved in Upper Cretaceous (Cenomanian) amber from northern Myanmar. Syspastoxyela rhaphidia Engel and Huang, gen. et sp. nov., shares many plesiomorphic features with the primitive Xyelidae, 2Xyelotomidae, and 2Xyelydidae such as enlarged and thickened first flagellomere succeeded by a series of thinner and shorter flagellomeres, absence of a transverse mesoscutal sulcus, multiple preapical spurs, and two protibial spurs among other traits. However, the new lineage has an apomorphically contracted forewing venation, lacks a subcostal vein, has a single marginal cell, and lacks crossvein 1r-rs, and thus it is segregated into a new family, Syspastoxyelidae Engel and Huang, fam. nov. The phylogenetic affinities of the new family are discussed and a position near Pamphilioidea or Pamphilioidea + Unicalcarida is advocated.  相似文献   

First record of the family Scolebythidae (Hymenoptera) in mid-Cretaceous amber from Myanmar     

《Cretaceous Research》2016

Two new genera and species belonging to the family Scolebythidae are described from mid-Cretaceous amber of Myanmar, Cursoribythus silvestris and Siccibythus musculosus. These taxa are introduced into the current phylogenetic tree of the family, in order to analyze their relationships and observe their impacts on our understanding of the family. The implication of the findings (this is the first record of the family in the Cretaceous amber deposits of Myanmar) are discussed.  相似文献   

华北克拉通东南部蚌埠隆起晚中生代花岗岩类岩体内变形记录与构造意义   总被引：5，自引：0，他引：5  

宋利宏  朱光  赵田  林少泽 《地质论评》2016,62(2):400-418

华北克拉通东南部蚌埠隆起上出露了一系列晚中生代花岗岩类岩体,记录了丰富的变形过程。本次与前人锆石定年结果表明,该区经历过两期岩浆活动,分别是中—晚侏罗世(167～148 Ma)和早白垩世(130～112Ma)。区内晚侏罗世蚂蚁山岩体记录了切过该岩体的一条北北东向左行韧性变形带,是北北西—南南东向挤压的产物。该走滑变形带在走滑隆升中又被脆性平移断层所叠加。走滑活动时间可以限定在148～130 Ma之间。研究区在130～112 Ma期间转变为强烈的伸展活动,区域拉张方向为北西西—南东东向,并伴随着岩浆活动与区域隆升。在此伸展过程中,中—晚侏罗世荆山—涂山岩体与早白垩世淮光岩体记录了深部韧性伸展拆离变形带抬升至浅部被脆性正断层所叠加的变形过程,而其它岩体内均记录了地壳浅部的脆性正断层活动。这些岩体的变形记录,指示华北克拉通东部晚中生代由挤压向伸展构造体制转变发生在148～130 Ma期间,提供了在早白垩世克拉通峰期破坏中目前非盆地区构造过程的实例。  相似文献   

长江中下游地区晚中生代岩浆岩氧逸度特征及意义          下载免费PDF全文

姚洪忠  闫峻  刘晓强  刘建敏  李全忠 《地质科学》2016,(4):1163-1180

长江中下游地区是我国东部重要的多金属成矿区,区内中生代岩浆活动强烈,可分为4个阶段。本文选择代表性岩石,开展了锆石原位微量元素测试,结合全岩数据,应用拟合法、插值法进行锆石氧逸度估算。结果表明：相比插值法,拟合法获得的锆石氧逸度数据结果更加准确集中,分布趋势更加明显,尤其修改的M估计估算方法可有效削弱拟合法估算过程中遇到的轻重稀土元素异常分馏等不利影响。最终确定,基于全岩和锆石微量元素数据的最小二乘法估算结果更加符合实际。长江中下游地区晚中生代4个阶段岩浆岩的氧逸度普遍较高,其中第1和第4阶段岩浆岩氧逸度相似,为高氧逸度岩浆岩,第2与第3阶段岩浆岩的氧逸度较低,表现出晚中生代早期到晚期,岩浆氧逸度从高降低、再升高的变化趋势。各阶段岩浆岩的氧逸度高低与岩浆起源和成矿属性有着良好的对应关系。  相似文献   

浙西余杭、临安和富阳交界区中生代侵入岩年代学、地球化学特征及其地质意义   总被引：1，自引：0，他引：1  

唐增才  陈忠大  胡文杰  董学发  吴小勇  袁强 《地质学报》2016,90(3):451-467

浙西余杭、临安和富阳交界区中生代岩浆侵入活动频繁,发育有闲林、千家花岗闪长岩,拔山、长乐桥二长花岗(斑)岩,鹤山坞和朱村花岗岩,与成矿作用关系密切。SHRIMP锆石U-Pb定年结果表明,中生代岩浆侵入活动分为晚侏罗世(152~147 Ma)、早白垩世早期(139~137 Ma)和早白垩世晚期(104~103 Ma)3个期次,分别对应于花岗闪长岩、二长花岗(斑)岩、花岗岩的成岩时段,即由早期至晚期,岩性具花岗闪长岩→二长花岗(斑)岩→花岗岩的演变规律,与岩石HREE和LREE/HREE分异程度逐渐减弱的地球化学特征一致。余临富交界区中生代中酸性侵入岩具有低TFeO/MgO(1.72~5.28)特征,且P_2O_5与SiO_2呈明显负相关关系,属"Ⅰ"型花岗岩,为地壳深熔和壳幔混合作用的产物。研究表明,晚侏罗世花岗闪长岩形成于太平洋板块俯冲的挤压环境,早白垩世早期二长花岗(斑)岩形成于后碰撞挤压背景向伸展背景的转换阶段,而晚期花岗岩则形成于持续伸展扩张的构造环境。余临富交界区成岩时代与区域晚侏罗世(164~145 Ma)、早白垩世早期(139~135 Ma)和早白垩世晚期(109Ma左右)的3期成矿时代具有较好的一致性,显示了良好的找矿前景。  相似文献