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大别山北部榴辉岩的大地构造属性及冷却史 总被引：12，自引：0，他引：12
岩石地球化学及同位素年代学研究表明，大别山北部榴辉岩的大部分属印支期扬子俯冲陆壳（下地壳）的一部分；大致沿磨子潭－晓天断裂附近分布的含榴辉岩、大理岩和变质橄榄岩的镁铁－超镁失质岩带可能代表扬子与华北2个大陆板块之间的变质构造混杂岩带，它应接近于扬子与华北2个大陆板块之间的缝合线（镁铁－超镁铁质岩带以北），而五河－水吼剪切带则可能代表扬子腐冲陆壳内部的1条拆离带或滑脱带。冷却史研究表明，大别山北部榴辉岩峰期变质后初期（230－210Ma)仅抬升到下地壳水平，因而未经历降温过程并具有比大别山南部榴辉岩较低的抬升速率，峰期变质后较慢的抬升速率及相应的近于等温或局部升温阶段也许是造成大别山北部榴辉岩与南部超高压带中榴辉岩差异的重要原因之一；同时，也许是研究区榴辉岩很少见有保留早期超高压变质证据的重要原因。 相似文献
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大别山北部漫水河灰色片麻岩的锆石UPb年龄及其地质意义 总被引：11，自引：2，他引：11
北大别杂岩主要由灰色片麻岩和斜长解闪岩组成。通过对大别山北部霍山漫水河花岗闪长片麻岩的锆石U-Pb年龄测定，得到中元古代、早三叠世和晚侏罗世3组年龄数据。中元古代的年龄老于灰色片麻岩集中在新元古代的锆石U-Pb上交点年龄，指示漫水河北部片麻岩中有古老锆石捕掳晶；早三叠世年龄指示该片麻岩中有印支期变质作用形成的锆石；晚侏罗世年龄表明灰色片麻岩中有燕山早期形成的岩浆锆石。根据北大别杂岩的构造背景、变质作用及地球化学特征，认为北大别杂岩中的部分灰色片麻岩形成于燕山早期的花岗闪长岩，它们可能源自或混染了经过早三叠世变质作用的扬子陆块俯冲基底。本文的结果表明，北大别杂岩既不是形成于白垩纪的岩浆杂岩，也不完全是形成于新元古代的TTG岩系，其中的部分灰色片麻岩为形成于燕山早期的花岗闪长岩，即在白垩纪大规模岩浆作用前的燕山早期，北大别曾有过一次岩浆作用。 相似文献
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根据构造地貌遥感解析,发现郯庐断裂带沿庐江白山到桐城卅铺一线显示1组平行断层,现场地震地质调查验证其为1组活动断层。通过断层剖面观测、样品采集及样品测试分析和宏微观构造分析,结果表明,郯庐断裂带在白山—卅铺一带第四纪以来仍具有黏滑、蠕滑交替的变形活动。其中,在柯坦—卅铺一带,最年轻的水系被NE向断层组右旋扭折,其断层物质的微观观测和测龄结果表明该断裂段第四纪时的活动具有脆、塑性过渡变形特征,强烈活动时间处于早、中更新世;而白山剖面断层泥年龄测试结果则反映相应断层段在中、晚更新世曾有过较强烈的活动。断层泥超微(SEM)和显微观测结果亦表明该断裂段曾发生黏滑、蠕滑交替的构造变形事件,且表现为先黏滑后蠕滑;结合水系呈现缓慢扭折表征,近年来沿断裂有不少微震发生,表明郯庐断裂带在白山—卅铺段的最新滑移方式主要表现为蠕滑,也就是说,该段积累的应力以蠕滑或微震等方式缓慢释放,据此推测未来一定时期内不易孕育强烈地震 相似文献
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由美国北卡罗来纳大学全球能源及环境系统学院（GLEES）主办,国际环境地学技术协会（ISEG）、UNESCO、全球减灾联合会等17家组织机构协办的国际能源环境与灾害学术大会（INTERNATIONAL CONFERENCE ON ENERGY,ENVIRONMENT AND DISASTERS,即INCEED2005）于2005年7月24日至30日在美国北卡罗来纳州的夏洛特（CHARLOTTE）召开。 相似文献
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Recently acquired (2005) multi-beam bathymetric and high-resolution seismic reflection data from the E–W-oriented Gulf of Gökova off SW Anatolia were evaluated in order to assess the uneven seafloor morphology and its evolution in terms of present-day active regional tectonics. Stratigraphically, the three identified seismic units, i.e., the basement, deltaic sediments deposited during Quaternary glacial periods, and modern gulf deposits, are consistent with those observed in previous studies. Structurally, the folds and faults with strike-slip and reverse components have been regionally mapped for the first time. Of these, NE–SW-oriented left-lateral strike-slip faults with compressional components forming the so-called Gökova Fault Zone intersect and displace two WNW–ESE-oriented submarine ridges and deep submarine plains. Thus, strike-slip faults are the youngest major structures in the gulf, and control present-day active tectonism. E–W-oriented folds on the inner and outer shelf, which are generally accompanied by reverse faults, delimit the margins of these submarine ridges, and deform the young basin deposits. These features also reveal the concomitant existence of a compressional tectonic regime. The compressional structures probably represent pressure ridges along left-lateral strike-slip fault segments. However, some E–W-oriented normal faults occur on the northwestern and partly also southern shelf, and along the borders of the adjacent deep submarine plains. They are intersected and displaced by the strike-slip faults. The lower seismicity along the normal faults relative to the NE–SW-oriented strike-slip faults suggests that the former are at present inactive or at least less active. 相似文献
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The sign and the magnitude of the zeta potential must be known for many engineering applications. For clay soils, it is usually
negative, but it is strongly dependent on the pore fluid chemistry. However, measurement of zeta potential time is time-consuming
and requires special and expensive equipment. In this study, the prediction of zeta potential of kaolinite has been investigated
by artificial neural networks (ANNs) and multiple regression analyses (MRAs). To achieve this, ANN and MRA models based on
zeta potential measurements of kaolinite in the presence of salt and heavy metal cations at different pH values have been
developed. The results of the models were compared with the experimental results. The performance indices, including coefficient
of determination, root mean square error, mean absolute error, and variance, were used to assess the performance of the prediction
capacity of the models developed in this study. The obtained indices make it clear that the constructed ANN models were able
to predict zeta potential of kaolinite quite efficiently and outperformed the MRA models. Results showed that ANN models can
be used satisfactorily to predict zeta potential of kaolinite as a rapid inexpensive substitute for laboratory techniques. 相似文献
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高低空急流耦合对长江中游强暴雨形成的机理研究 总被引：25，自引：1，他引：25
对1998－07－22T08－14发生于武汉附近的一次强暴雨过程的分析发现，这次强暴雨发生于南方暖区与北方冷空气脱离的孤立系统中，副热带经圈环流上升支是暴雨发生的大尺度背景场，它的低空入流和高空出流对大尺度雨区的生成与维持具有重要作用。边界层南风急流、低空西风急流和高空西风急流上下的耦合作用理强暴雨发生的重要原因。925hPa上边界层偏南风急流是暴雨区所需水汽的最大提供者和暴雨区对流不稳定能量释放的触发者，850hPa上低空偏西风急流的主要作用是建立和维持了暴雨区中低空的对流不稳定，200hPa上中纬高空西风急流的主要作用是建立和维持了暴雨区高空的条件对称不稳定，三者上下耦合使得中低空对流上升运动得以向上发展和加强，从而产生强暴雨。 相似文献