新疆境内塔拉斯-费尔干纳断裂早侏罗世走滑的古地震证据

在野外考察过程中,于新疆乌恰地区早侏罗世康苏组沼泽相砂岩层中,发现并识别出软沉积物液化变形层,变形包括负载构造,球-枕构造及卷曲变形构造。通过模拟试验的对比研究认为,该软沉积物变形机制与液化作用有关,触发沉积物液化的动力是古地震,并且根据地震震级与液化最大震中距的关系,推测出造成早侏罗世软沉积物变形的里氏地震震级为6相似文献   

Mesoproterozoic Earthquake Events and Breakup of the Sino-Korean Plate

In the Mesoproterozoic time, the northern part of the Sino-Korean Plate experienced a period of intensive tectonic extension and breakup. 1. An abundance of sedimentary earthquake records is preserved in the Chuanlinggou, Tuanshanzi and Gaoyuzhuang formations in the Mesoproterozoic Changcheng System （1800-1400 Ma） and in the Mesoproterozoic Wumishan Formation of the Jixian System （1400-1000 Ma）. These earthquake records are characterized by various liquefied sand-veins, carbonate microspar and coarser spar veins, limestone dikes, liquefied breccia and various forms of liquefied contorted bedding. This deformation is always associated with synsedimentary faults and igneous activity. 2. Three liquefaction models for soft carbonate sediments are recognized, including liquefaction in laminated carbonate rocks, liquefaction in thin-bedded carbonates and large-scale liquefaction along huge carbonate dikes. 3. Based on the record of earthquake and volcanic activities, the Sino-Korean Plate experienced at least twice intraplate breakups. One occurred between 1800-1400 Ma, and the other occurred at about 1200 Ma. The last breakup resulted in formation of the Yan-Liao aulacogen, a tectonic zone characterized by deeper material vibrancy, active faults, major igneous activity and frequent earthquakes.     

Storm Deposits of the Sinian Zhangqu Formation in Northern Anhui — An Upward Shallowing Carbonate Sequence1

Abstract This paper studies, for the first time, the storm deposits of a carbonate sequence in the Sinian Zhangqu Formation in northern Anhui. In the formation, a great number of calcareous trider sponge spicules were discovered in a distal storm turbidity sequence, which have provided further evidence for the correlation of the Sinian Systems in North and South China from a view point of palaeontology.     

Seismic Sequence in Carbonate Rocks By Vibrational Liquefaction1

Abstract On the basis of the records of strong seismic events taking place in soft carbonate sediments, a new seismic sequence system of vibrational liquefaction is established, which consists of a series of units, such as escaped structure of micrite veins and liquefied deformation formed in the period of seismic liquefaction, land subsidence structure after liquefaction, tsunamic hummocky and turbidite produced by seismic events, This sequence is a generalization and summation of field observation in vast areas, which shows the whole process of a strong seismic event and provides an unified theoretical explanation. The pattern of the seismic sequence by vibrational liquefaction provides one of correlation standards for geologists in the field to discriminate events in carbonate sequences. Based on the pattern of seismic sequence, the authors first advance a new conception of the Palaeo - Tanlu (Tancheng - Lujiang) Zone and discuss primarily its geological significations.     

浑江末前寒武纪丝状藻类及其环境意义

本文初步探讨了吉林浑江晚前寒武纪丝状藻类与沉积环境的关系。这些丝状藻类产自晚前寒武纪不同层位,大多属蓝绿藻类。通过对丝状藻类整体面貌和个体丰度的分析,笔者将其划分为三类即:藻席型、孤立生存型和其间的过渡类型。根据对现代丝状藻类生态及环境的研究,采取比较古生物学的方法,具体讨论了浑江地区晚前寒武纪丝状藻类的指相意义。根据沉积学与事件地层记录分析的沉积环境模式与对丝状藻类环境分析的结果是一致的。     

直接测定内蒙古腮林忽洞组碳酸盐岩Pb－Pb同位素年龄

碳酸盐岩Ｐｂ－Ｐｂ同位素测年是地质年代学一个新的分支，本文利用这一技术，直接测定了内蒙古地区腮林忽洞组年龄，是本区首次直接获得地质年龄，不仅为碳酸盐地区确定地质年代提供了新的方法，同时对本区地层研究提供了新的数据。本文期待引起同行讨论，使这一新方法在地质研究应用中臻于完善。     

广西桂林庙头上泥盆统融县组中的灰岩脉和角砾灰岩体及其成因

广西桂林庙头上泥盆统融县组台地边缘相具鸟眼或溶孔砂屑生屑藻粘结灰岩中发育了大量灰岩脉，灰岩脉呈岩墙状近直立地切过围岩，露头上可见连续垂直延伸长度达十余米，脉内仍是上泥盆统融县组灰岩组分，仅比围岩稍晚或同时代的：角砾状退白云石化藻粘结灰岩、角砾状藻粘结灰岩（快速堆积，角砾多数来自围岩）、细鲕粒颗粒灰岩、含钙球砂屑粒泥灰岩、藻砂屑腹足泥粒灰岩（正常沉积或液化变形软沉积流，均高于围岩层位）及大量栉壳状方解石脉（张性环境）等，灰岩脉内可见软沉积物变形痕迹及液化脉（地震液化），晚期灰岩脉可穿插早期灰岩脉；在其西侧同层位共生有一套楔状（地裂缝）、不规则状角砾灰岩体，角砾棱角状，大小不等，成分是灰色中厚层角砾状藻粘结灰岩、含钙球砂屑粒泥灰岩等。笔者等注意到灰岩脉均出露在北东向正断层的下盘（东侧），而角砾灰岩体则均出露在该断层的上盘（西侧），事实上，灰岩脉及角砾灰岩体分布走向与北东向断层走向一致，角砾灰岩体中的角砾成分显示其来自较灰岩脉围岩稍高层位，与灰岩脉内充填岩性相近，因此，是该断层控制了当时的沉积，此断层是晚泥盆世台地边缘同沉积正断层；灰岩脉是与断层伴生的张性裂隙被围岩角砾或稍晚时段的沉积物充填；角砾灰岩体是同沉积正断层形成的断层崖崩落角砾岩，指示一个消失殆尽的晚泥盆世碳酸盐岩同沉积正断层陡崖，因而，桂林台地，至少西段台地边缘，是与右江各孤立台地边缘一样——在地质图上应标示为同沉积正断层边界。其构造意义是：庙头地区的灰岩脉、角砾灰岩体及同沉积断层是桂林台地对晚泥盆世构造伸展作用的响应，从而说明广西晚古生代的板块拉张，不是从二叠纪才开始的，而是至少从晚泥盆世就开始了；晚古生代至早三叠世持续的孤立台地与深水盆地相间的古地理格局，是在晚泥盆世就奠定了基础。     

Advances and Overview of the Study on Paleo-earthquake Events: A Review of Seismites

The distribution and formation mechanisms of typical identified seismites are analyzed based on various factors from plate tectonic positions, types of sedimentary basins and properties of seismogenic faults to focal mechanisms. Especially, structural styles, reserved positions, activity times, formation mechanisms and dynamics of soft-sediment deformation structures triggered by seismic activity are systematically analyzed. According to the genetic types of seismites, we propose 5 categories, including liquefied deformation, thixotropic deformation, hydroplastic deformation, superimposed gravity driving deformation and brittle deformation. Further, based on the main genetic types, composition of sediments and deformation styles, we draw up 35 secondary classifications. To determine paleo-seismic sequences in different times, activities of seismogenic faults, high-resolution tectonic events in one main tectonic movement and paleo-tectonic settings, and to understand the inducing mechanisms of paleo-earthquakes and ecologic environment evolution, researching on seismites are of great significance. Combing multiple approaches to identify the paleoearthquake records, simulating experiments on various soft-sediment deformation structures triggered by different magnitudes of shocking, dating precisely on paleo-seismic events, impacting on paleogeography and biological environment and on energy and resources domain are the frontiers of paleoseismic research.     

固沙常见锦鸡儿属植物的研究

本文对12种固沙常见锦鸡儿属植物的分类、分布、花粉形态进行了比较研究。确定了柠条锦鸡儿、中间锦鸡儿和小叶锦鸡儿三者的亲缘关系,并认为绢毛锦鸡儿是这12种中最原始种,锦鸡儿属可能正象Komapob所说的,是由一个比较原始的祖先种沿着不同的途径衍化而形成目前的许多种。     

山东诸城早白垩世莱阳期古地震事件与恐龙迁移

在诸城断陷皇华镇大山村黄龙沟存在丰富的、多样的恐龙足迹化石,在紧邻化石埋藏层下伏及上覆地层中发现了下白垩统莱阳群杨庄组多套古地震记录,主要包含波状褶皱、底劈构造、液化砂岩脉、液化角砾岩、粒序断层、卷曲变形和震积不整合等塑性、脆性软沉积物变形构造。分析表明初始沉积物、沉积相及构造作用确定了地震活动作用时形成的软沉积物变形构造类型。在早白垩世莱阳群沉积中期,地震活动具有阶段性及频发性,以单向挤压的丘-槽构造及双向挤压的波状变形为主,且后期有构造活动强度加大的特征。根据已识别的古地震记录发育及古地震活动强度分析,推测此时期发震断裂可能是断陷的南缘断裂——五莲断裂。区域构造作用使得该时期沉积环境发生变化,由湖相逐渐过渡到河流相,在突发古地震事件发生之后,在滨浅湖区域留下了丰富的恐龙迁徙足迹。古地震记录的研究,可建立古地震事件与沉积、构造演化的联系,约束构造作用的属性、频次及时限,为确定盆地及周缘构造-沉积演化历史提供证据。