中国西北盆山地区地壳结构及其演化

根据新疆及其它相关地学断面所获资料，论述了中国西北盆山构造地区的地壳结构，已有资料表明，在中国西北盆山地区，山脉和盆地具有明显不同的地壳结构，它们的地壳厚度不同，表现为山区地壳厚，具有明显的山根：盆地区地壳厚度小，同时地壳分层和各层的组分也有所差异，这些地壳本身结构性的差异，以及它们所受到的应力状态和热状态的不同，就是小区各种构造活动产生的根源，最后从区内地质构造形成过程讨论了区内地壳不同结构形成的演化历史。     

碎石桩复合地基的抗液化特性探讨

饱和砂土地震液化问题是岩土地震工程中一个重要的研究课题。在多种可行的防治液化措施中 ,最普遍的方法是采用碎石桩复合地基。本文结合目前国内外碎石桩复合地基的抗液化研究的最新进展 ,对碎石桩的密实、排水减压和减震作用做了较详细的评述 ,最后还提出碎石桩复合地基抗液化特性需要进一步研究的问题     

Aggregate resources: Production and environmental constraints

Aggregates are produced from sand and gravel deposits or from bedrock sources. Production sites are numerous to minimize transport and are more and more in a competing land use position. Urbanization, while creating a market, also sterilizes deposits and pressures producers to relocate further from populated areas. Regulating and permitting quarries is an issue in regions with growing populations. This regulatory environment may cause exploitation schemes to evolve towards greater recycling, importing, and marine production, for example. These changes may be entirely attributable to increased environmental constraints on producing operations and not on conventional mining constraints such as overburden, ore grade, and costs of operation.     

对“康滇地轴”轴成矿环境的初步探讨

本文是根据“康滇地轴”的地壳演化历史和铀的地球化学特性来探讨“康滇地轴”的铀成矿环境,认为“康滇地轴”既有有利于铀成矿的地质环境和条件,又有不利的因素,因此,应加强基础地质研究,以各种成矿理论为指导选择有利地段,对“康滇地轴”进行第2轮找矿。     

邯峰矿区古构造应力场与构造演化

采用共轭剪节理应力反演方法,恢复了邯郸-峰峰矿区晚古生代以来的3期古构造应力场,进而探讨了煤田构造的演化历史,将其分为4大阶段：①中生代早期近NS向挤压,煤系后期改造初动期;②中生代晚期SE-NW向挤压,奠定煤田构造格架的基础;③中生代末至古近纪NW-SE向拉张,煤田构造格架定型;④新近纪以来近东西向拉张,煤田构造的现代活动.     

Late Cenozoic Sedimentary Evolution of Pagri‐Duoqing Co graben,Southern End of Yadong‐Gulu Rift,Southern Tibet

The north trending rifts in southern Tibet represent the E–W extension of the plateau and confirming the initial rifting age is key to the study of mechanics of these rifts. Pagri–Duoqing Co graben is located at southern end of Yadong–Gulu rift, where the late Cenozoic sediments is predominately composed of fluvio-lacustrine and moraine. Based on the sedimentary composition and structures, the fluvio-lacustrine could be divided into three facies, namely, lacustrine, lacustrine fan delta and alluvial fan. The presence of paleo-currents and conglomerate components and the provenance of the strata around the graben indicate that it was Tethys Himalaya and High Himalaya. Electron spin resonance (ESR) dating and paleo-magnetic dating suggest that the age of the strata ranges from ca. 1.2 Ma to ca. 8 Ma. Optically stimulated luminescence (OSL) dating showed that moraine in the graben mainly developed from around 181–109 ka (late Middle Pleistocene). Combining previous data about the Late Cenozoic strata in other basins, it is suggested that 8–15 Ma may be the initial rifting time. Together with sediment distribution and drainage system, the sedimentary evolution of Pagri could be divided into four stages. The graben rifted at around 15–8 Ma due to the eastern graben-boundary fault resulting in the appearance of a paleolake. Following by a geologically quiet period about 8–2.5 Ma, the paleolake expanded from east to west at around 8–6 Ma reaching its maximum at ca. 6 Ma. Then, the graben was broken at about 2.5 Ma. At last, the development of the glacier separated the graben into two parts that were Pagri and Duoqing Co since the later stages of the Middle Pleistocene. The evolution process suggested that the former three stages were related to the tectonic movement, which determined the basement of the graben, while the last stage may have been influenced by glacial activity caused by climate change.     

青藏高原东北缘龙首山晚新生代多阶段构造隆升的盆地记录

龙首山地区位于青藏高原与阿拉善地块的结合部位,其盆山演化过程和断裂带扩展模式的恢复对揭示青藏高原新生代北东向生长具有重要意义。本文基于龙首山南北两麓3个新近系沉积剖面的构造特征和5个砂岩样品的碎屑锆石U-Pb同位素LA-ICP-MS年龄结果,重建了青藏高原东北缘龙首山地区晚新生代的盆山演化过程。研究结果显示,龙首山地区晚新生代沉积-构造演化经历了3个主要阶段：（1）~14Ma,龙首山南缘断裂带活化,阿拉善地块南缘沿此断裂逆冲于张掖盆地之上,张掖盆地开始接收阿拉善地块的物源;（2）~5Ma,龙首山南缘断裂带的次级断裂开始发育,使龙首山南侧山麓白垩系开始剥露并为张掖盆地提供物源,同时,龙首山北缘断裂带活化并导致潮水盆地发生挠曲沉降,接收龙首山的物源;（3）5~2.5Ma,龙首山北缘断裂带的次级断裂开始发育,导致龙首山北麓白垩系开始剥露并为潮水盆地提供物源。通过对龙首山周缘盆地沉积相和物源开展分析,本研究反演了龙首山地区中新世以来的断裂带活动和山体隆升过程,表明在14~2.5Ma,随着龙首山南缘断裂、北缘断裂的活化和次级断裂的发育,龙首山经历了3次强烈的隆升,这对揭示青藏高原北东向的扩展过程具有重要的指示意义。

     

Cambrian-Early Ordovician intrusive bodies in Dunhuang Block: Records of Paleo-Asian Ocean subduction and implications for regional Early Paleozoic tectonic evolutionSCIEI北大核心CSCD

一直以来,敦煌地块缺少1.6-0.46Ga的地质记录,从而严重制约了对该地块在新元古代和早古生代期间地质构造演化的全面认识。通过1:5万区域地质调查,本次工作在敦煌地块东北缘新发现了寒武纪-早奥陶世小宛山岩体、截山子岩体和小宛南岩体等多个中酸性侵入体,测得其LA-ICP-MS锆石U-Pb年龄分别为517±3Ma、480±3Ma和473±3Ma,由此厘定出敦煌地块目前古生代最古老的侵入岩体及早奥陶世侵入岩体。通过这些岩体的岩石岩相学、岩石地球化学特征、岩石成因及大地构造环境分析,表明它们属于与洋壳俯冲消减作用有关的活动陆缘环境下形成的富钠质I型花岗岩。其中,小宛山花岗闪长质岩体是在低压低温条件下由玄武质地幔楔部分熔融而成,同时受到俯冲流体的强烈交代;截山子岩体和小宛南岩体则是在高压低温富水条件下,由新生镁铁质洋壳发生部分熔融并受到地幔楔强烈混染而形成,虽然它们均属于(类)O型埃达克岩,但其部分熔融的压力及其残留矿物组合不同。上述研究揭示敦煌地块北缘早古生代517Ma就存在俯冲作用,且至少持续了44Myr。结合区域地质资料和以往研究成果,敦煌地块北缘早古生代洋陆转换过程可分为三个阶段:(1)晚震旦世-早寒武世(574-518Ma),敦煌地块北缘被动陆缘演化阶段;(2)寒武纪第二世-早奥陶世(517-471Ma),敦煌地块北缘活动陆缘演化阶段,期间,古亚洲洋南支洋分别向敦煌地块和石板山地块/马鬃山地块发生双向俯冲消减;(3)中奥陶世-早泥盆世(464-412Ma),敦煌地块与石板山地块/马鬃山地块碰撞造山阶段,期间古亚洲洋南支洋闭合。     

Correction of common lead in U-Pb analyses that do not report 204 Pb

During the Early-Middle Proterozoic era, three major lithostratigraphic unit associations, namely Hekou-Dahongshan, Dongchuan, and Kunyang-Huili Groups, were established for the metamorphosed volcanic-sedimentary rocks exposed in the southwestern Yangtze Block (SWYB). The integration of petrology, geochemistry and geochronology constrains tectonic framework and evolution of the SWYB, in which four sets of SHRIMP U-Pb zircon ages were obtained from the volcanic rocks interbedded within the Middle Proterozoic successions: 1800–1600 Ma, 1600–1300 Ma, 1300–1100 Ma, and 1100–1000 Ma. Major and trace elemental analysis indicate that four key tectonic evolutionary stages, each coinciding with the above radiometric age set, of the SWYB during the Early-Middle Mesoproterozoic. The SWYB was characterized by an east-westerly trending rift in the Hekou, Dongshan, and Dongchuan areas, and separate basin-forming events during 1800–1600 Ma and 1600–1300 Ma, respectively. In the SWYB, an intracontinental rift basin and a rift basin occurred in the Caiziyuan-Matang and Laowushan areas, respectively in 1300–1100 Ma ago. During 1100–1000 Ma, the SWYB was characterized by the closure of the Caiziyuan-Matang rift-ocean basin, collision between the Huili Blocks and Kunyang Blocks, and presence of volcanic arcs in the Tianbaoshan and Fulingpen areas. Accordingly, the SWYB represents a new basin that records the relatively complete assembly process of the Rodina during the Early-Middle Mesoproterozoic era.     

露天转井工采场及其覆岩采动响应特征研究

以云南磷化集团有限公司晋宁磷矿为依托背景,借助数字照相量测技术,通过相似材料模拟试验,对20与50两种矿体倾角赋存下,露转井工后,井下采场及其上覆岩层的位移与应力响应特征及动态演化过程进行了系统研究。结果表明：（1）地下采场围岩及覆岩的变形演化过程可划分为局部小范围微动、线性持续增大以及整体非线性剧烈垮塌3个阶段;（2）矿体倾角由20增至50后,边坡与地下采场围岩及覆岩的变形整体趋缓,采动影响范围小幅度缩减,沉降曲线则由非对称槽型变为碗型;（3）采场矿柱回收过程中,地下采场围岩及覆岩发生突发性失稳,呈现出明显的多米诺骨牌效应。相关研究结论可为矿山露天转地下开采后地压管理与边坡维护提供一定的理论参考。