尼日尔三角洲的重力滑动构造

位于南大西洋东岸被动大陆边缘之上的尼日尔三角洲发育一大型重力滑动构造。自非洲大陆向南大西洋方向,该重力滑动构造可以划分出前缘挤压构造变形区和后缘拉张构造变形区。前缘挤压构造变形,形成褶皱冲断带;后缘拉张构造变形,形成堑垒构造;两者之间的过渡带发育滑脱褶皱。三角洲沉积的时代为始新世—第四纪,地层剖面自下而上依次是海相页岩(Akata组)、近海三角洲相砂岩—页岩互层(Agbada组)和陆相冲积砂岩(Benin组)。3个岩石地层单元都是穿时的,向大洋方向变新。重力滑动构造的主滑脱面位于Akata海相页岩中。根据生长地层、不整合以及卷入变形的地层时代,重力滑动构造起始于约12 Ma,伴生有广泛发育的泥构造。重力滑动构造的形成可能与新生代喀麦隆火山带(Cameroon volcanic line)的火山活动有一定的关系。     

Boris Choubert: The forgotten fit of the circum-Atlantic continents

Boris Choubert was a strong supporter of Wegener's continental drift theory. In 1935, he published a very accurate fit of the circum-Atlantic continents, which was based on continental edges instead of coastlines; in the same paper, he interpreted the Palaeozoic belts as the result of horizontal movements of the Precambrian blocks; so, he greatly expanded the role of continental drift through time. This original and very prophetic work was almost completely ignored by his contemporaries. Thirty years later (1965), Bullard, Everett and Smith published in turn a similar but more sophisticated fit; they did not acknowledge Choubert's initial work. Bullard's fit was met with immediate and tremendous success. The present paper analyses the reasons why Boris Choubert was frustrated of his pioneering role. This lack of recognition is related to: (1) a great evolution in the geological concepts between 1935 and 1965, and (2) a poor choice of Choubert, regarding the title of his 1935 article.     

http://dx.doi.org/10.1016/j.gsf.2016.10.005

The Earth was born as a dry planet without atmosphere and ocean components at 4.56 Ga, with subsequent secondary accretion of bio-elements, such as carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) which peaked at 4.37–4.20 Ga. This two-step formation model of the Earth we refer to as the advent of bio-elements model (ABEL Model) and the event of the advent of bio-elements (water component) as ABEL Bombardment. It is clear that the solid Earth originated from enstatite chondrite-like dry material based on the similarity in oxygen isotopic composition and among other isotopes. On the other hand, Earth's water derives primarily from carbonaceous chondrite material based on the hydrogen isotopic ratio. We present our ABEL model to explain this enigma between solid Earth and water, as well as secondary accretion of oxidizing bio-elements, which became a precursor to initiate metabolism to emerge life on a highly reductive planet. If ABEL Bombardment had not occurred, life never would have emerged on the Earth. Therefore, ABEL Bombardment is one of the most important events for this planet to evolve into a habitable planet. The chronology of ABEL Bombardment is informed through previous researches of the late heavy bombardment and the late veneer model. ABEL Bombardment is considered to have occurred during 4.37–4.20 Ga, which is the concept to redefine the standard late heavy bombardment and the late veneer models. Also, ABEL Bombardment is the trigger of the transition from stagnant lid tectonics to plate tectonics on this planet because of the injection of volatiles into the initial dry Earth.     

Contemporaneous assembly of Western Gondwana and final Rodinia break-up: Implications for the supercontinent cycle

Geological, geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana. Although the classical geodynamic scenario assumed for the period 800–700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins, a significantly different tectonic evolution can be inferred for most Western Gondwana cratons. These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension, island arc development and limited formation of oceanic crust in internal oceans. This period was thus characterized by increased crustal growth in Western Gondwana, resulting from addition of juvenile continental crust along convergent margins. In contrast, crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana. The Río de la Plata, Congo-São Francisco, West African and Amazonian cratons collided at ca. 630–600 Ma along the West Gondwana Orogen. These events overlap in time with the onset of the opening of the Iapetus Ocean at ca. 610–600 Ma, which gave rise to the separation of Baltica, Laurentia and Amazonia and resulted from the final Rodinia break-up. The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca. 580 Ma, contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin. However, the Kalahari Craton was lately incorporated during the Late Ediacaran–Early Cambrian. The proposed Gondwana evolution rules out the existence of Pannotia, as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia. Additionally, a combination of introversion and extroversion is proposed for the assembly of Gondwana. The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the supercontinent cycle, as supercontinent amalgamation and break-up do not necessarily represent alternating episodic processes but overlap in time.     

Multiple remote sensing techniques as a tool for reconstructing late Quaternary drainage in the Amazon lowland

Morphologies related to paleochannels are widespread through large areas of the Brazilian Amazonia. Despite the relevance for reconstructing the evolution of the largest fluvial system on Earth, detailed mapping of most of these features is still unavailable. The lack of works emphasizing Amazonian paleochannels represents an enormous bias toward the understanding of both migrating dynamics of Amazonian rivers through time and processes (e.g. tectonics, climate, sea‐level fluctuation) that might have promoted channel abandonment. A few previous studies have demonstrated the successful application of digital elevation model (DEM) collected during the Shuttle Radar Topography Mission (SRTM) for mapping morphologies related to paleochannels still preserved under forested lowland Amazonian areas. The present study applies different remote sensing techniques, including JERS‐1 90m, SAR/SIPAM‐6m, Landsat, and ASTER, to successfully unravel a myriad of paleochannels in Marajó Island (Amazon mouth), which were previously undetected using solely SRTM data. The results presented in this work are promising for mapping paleodrainage in other forested areas of the Amazonas basin. Considering the several problems involved on data acquisition aiming to approach the evolution of Amazonian rivers in space and time (e.g. large dimension, lack of natural geological exposures, difficult access, dense forest cover, and high cloud volume), a proper mapping of Amazonas paleodrainage using different remote sensing techniques is crucial to visualize potential paleochannel morphologies and patterns that are of high relevance for reconstructing the Amazonian fluvial dynamics through time. Copyright © 2010 John Wiley & Sons, Ltd.     

应用遥感构造解析方法分析汶川和玉树地震的构造活动过程———试作区域性地震活动预测分析

每次地震都是一次岩石圈表层的构造变形与位移,一组时空相近而有成生联系的地震,代表着某种方式与方向的地壳运动,即每次地震均可视为一次“地震—构造事件”。应用遥感构造解析方法,将地震视为“地震—构造事件”,对中国近20年来的地震活动进行分析和危险区评估,结果比较合乎实际。据此,对未来5~10年中国东部地区的地震活动趋势进行了预测,认为:两广及其沿海地带和华北平原中部存在发生强破坏性地震的较大风险。      

辽阳河栏地区辽河群中变质基性熔岩的锆石U-Pb年龄与形成构造背景

在海城－草河口的北辽河群中分布大量变质基性火山岩和基性岩墙,其中辽阳河栏镇南部大石桥组中的基性火山岩保存有良好的枕状构造。这些变质枕状熔岩化学成分上低碱低钾富铁,具有岛弧拉斑玄武岩的特征,岩石稀土和微量元素特征指示变质枕状熔岩形成于与岛弧相关的构造背景,很可能是弧后盆地环境的产物,而非大陆裂谷。锆石年代学研究显示：变质枕状熔岩的锆石SHRIMP U-Pb年龄为（1 869±28） Ma;变辉绿岩墙的形成年龄为（1 828±13） Ma,并有一组~2 080 Ma的捕获锆石年龄;花岗伟晶岩锆石U-Pb年龄为（1 869.7±7.6） Ma。结合岩石的产出状态和前人研究资料:推测变质枕状熔岩形成年龄为~1 880 Ma,可以代表北大石桥组的形成时代;花岗伟晶岩的年龄为~1 860 Ma,可作为造山作用结束的标志;变基性岩墙为~1 830 Ma,可作为后造山伸展张裂的标志。     

六盘山断裂带构造活动特征及流域盆地地貌响应

通过航卫片解译和野外实地调查,对六盘山断裂带新活动特征开展详细研究。调查发现六盘山东麓断裂为一条全新世活动的逆左旋走滑断裂,而六盘山西麓断裂为晚更新世活动的挤压逆冲断裂,二者的构造活动控制和影响了本区的地貌发育和地震活动。同时利用SRTM数据提取六盘山东西两侧泾河和水洛河上游流域盆地水系,得到流域盆地面积-高程积分值(HI值)分布图,探讨本区活动构造和地貌的响应关系。分析结果表明,在相同的岩性条件下六盘山东侧的HI值要低于西侧,反映了活动断裂对本地区地貌演化特征的不同影响。上述地貌分析研究为认识和理解六盘山地区地貌演化以及控制因素提供了基础数据和思路。     

一个重力滑动构造的范例——介绍河南芦店滑动构造

芦店滑动构造是河南省西部嵩（山）箕（山）地区滑动构造群中的一个典型实例。其主要表现为双期相向滑动的叠加、两类滑动构造模型的拚合及两种动力因素的作用。通过对其综合研究得出滑动构造是正断层演化的结果,属于正断层的一种类型的新认识。认知滑动构造的意义在于：可在较新地层下寻找、预测埋藏较浅的煤层,如芦店滑动构造区。若按传统构造解释,芦店地区地表出露为中生界三叠系红层,其下伏主采二1煤埋深一般在1 400m左右,超过现行勘查规范资源储量估算垂深1 200m以浅的要求,但利用滑动构造观点客观、合理解释后,煤层埋藏深度最浅处只有几十m。芦店滑动构造的解释成为利用新理论找煤的一个典型范例。     

The Penzhina-West Kamchatka folded zone and the Ukelayat-Sredinnyi block in the structure of the Koryak Highland and Kamchatka

The regional tectonic structure is considered with characterizing the Penzhina-West Kamchatka folded zone as an intracontinental rift and the Ukelayat-Sredinnyi block as a separated part of the Omolon Massif. It is assumed that the Malka-Petropavlovsk (Nachiki) zone of transverse uplifts is a southern continuation of the Penzhina-West Kamchatka folded zone.