Study　on　Fine　Crustal　Structure　of　the　Sanhe-Pinggu　Earthquake　（M8.0）　Region　by　Deep　Seismic　Reflection　Profiling   总被引：2，自引：1，他引：2  

Zhang Xiankang  Zhao Jinren  Liu Guohu  Song Wenrong  Liu Baojin  Zhao Chengbin  Cheng Shuangxi  Liu Jian  Gu Menglin  Sun Zhenguo 《中国地震研究》2003,17(2):122-133

Two near-vertical deep seismic reflection profiles (140km-long, 24-fold) were completed in the 1679 Sanhe-Pinggu earthquake (M8.0) region. The profiles ran through the Xiadian fault and the Ershilichangshan fault. The profiling result shows that the crust in this region is divided into the upper crust, the lower crust and the crust-mantle transitional zone by two powerful laminated reflectors: one at the two-way travel-time of about 7.0s (21 km), the other at about11.0～12.5s (33～37km). Crustal structure varies significantly in vertical direction. The shallow part is characterized by obvious stratification, multilayers and complexity. The upper crust on the whole features reflection “transparency“, while the lower crust features distinct reflectivity. Crustal structure also varies a lot in the lateral direction. The main fracture in this region is the deep fault under the Xiadian fault. This deep fault is steeply inclined (nearly vertical), and is supposed to be the causative fault of the Sanhe-Pinggu MS.0 earthquake. The two profiles respectively reveal the existence of local strong reflectivity in the lower crust and the lower part of the upper crust, which is assumed to be a dike or rock mass formed by the upwelling and cooling down of materials from the upper mantle. Magmatic activity in this part brought about differences in regional stress distribution, which then gave rise to the formation of the deep fault. That is supposed to be the deep structural setting for the Sanhe-Pinggu M8.0 earthquake.  相似文献   

太原市汾河断裂浅层高分辩率地震探测          下载免费PDF全文

尤惠川  何正勤等 《地震地质》2002,24(4):583-592

通过浅层高分辩率地震探测，结合钻孔资料，获得了测线处汾河断裂的准确位置，几何结构，活动性质、时代和速率等参数，并对其动力学属性进行了初步的讨论。地震探测揭露出汾河断裂的西支断层，为高角度东倾的斜滑断层，切割了第四系下部，上断点位于地下约70m处。据钻孔剖面推断有2条高角度相向而倾的斜滑断层，东支位于汾河东岸，断至全新统-上更新统，其底界面垂直错距约8m。断裂北段另一个钻孔剖面表明，西支断层切割了全新统-上更新统，底界面垂直错距约6m。汾河断裂晚更新世以来的平均垂直滑动速率为0.06-0.08mm/a，大震平均重复间隔为5.0-6.7ka。  相似文献   

Electrons in feldspar I: on the wavefunction of electrons trapped at simple lattice defects     

N. R. J. Poolton  J. Wallinga  A. S. Murray  E. Bulur  L. Bøtter-Jensen 《Physics and Chemistry of Minerals》2002,29(3):210-216

 The purpose of this article is to make an initial consideration of the physical properties of electrons trapped at classic hydrogenic lattice defects in feldspar. We are particularly interested to determine the radial extent of the electron wavefunctions in the ground and excited states. It is shown that for NaAlSi₃O₈, the ground-state wavefunction is expected to be confined well within a single lattice unit cell, but the first excited state is far more extensive, being spread over several unit cells. This aspect is of direct relevance to understanding the nature of various luminescence processes in the materials. Under low-energy optical stimulation (hν∼ 1.4 eV), luminescence can be a competitive process between direct electron-hole tunnelling recombination (with the charge still trapped at the defect sites), and free-to-bound recombination (after the excited state electron accesses the conduction band). We show that analysis of the thermal behaviour of the luminescence can be used to separate the two processes. Received: 6 March 2001 / Accepted: 6 September 2001  相似文献   

A Comparison of the Moho Interpreted From Gravity Data and From Deep Seismic Reflection Data In the Northern North Sea   总被引：1，自引：0，他引：1  

Klaus Holliger  Simon L. Klemperer 《Geophysical Journal International》1989,97(2):247-258

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提高海上单道反射地震记录信噪比和分辨率的方法技术     

刘建勋 《物探化探计算技术》2007,(Z1)

海上浅层单道反射地震的数据不需要水平叠加处理,该方法在更容易获得较好的保真度、较高分辨率剖面的同时,要求有高信噪比的地震记录为基础。通过对野外数据采集过程中噪声干扰情况的分析,合理地选择激发震源、检波器因素及仪器参数,不仅能够得到频带较宽、主频较高的高分辨率地震时间剖面,而且能够压制部分随机噪声;在资料处理流程中,采用有效的方法技术对数据进行信噪分离,削弱多次及绕射等干扰波的影响,可进一步提高单道地震记录的信噪比和分辨率。  相似文献   

岩石地球化学剖面测量在找矿实践中的应用——以新疆哈密市白山北坡HS-2异常为例     

王满仓  李维成  张飚  崔继岗  王小平  王北颖 《西北地质》2007,40(4):43-52

在1∶5万区域地质矿产调查的基础上,对新疆哈密市白山北坡HS-2异常区钨矿点实施1∶1万岩石地球化学剖面测量,并对其地质、地球化学特征进行综合研究,圈定了两个钨矿化蚀变带,初步判断有工业矿体存在。在此基础上肯定了异常区的找矿前景,并指出了找矿重点地段。  相似文献   

Optical dating of liquefaction features to constrain prehistoric earthquakes in Upper Assam, NE India—some preliminary results     

Puthusserry J. Thomas  Dontireddy V. Reddy  Devender Kumar  Pasupuleti Nagabhushanam  Balbir S. Sukhija  Radhendra N. Sahoo 《Quaternary Geochronology》2007,2(1-4):278-283

Optical dating of liquefied sand structures formed during major earthquakes in Upper Assam, northeast of India, has been carried out to constrain the timing of prehistoric earthquakes in this seismically active region. The bleaching of source material and of the same material during the creation of a liquefaction feature was tested using quartz extracted from 21 samples associated with two different liquefaction structures in Upper Assam. Due to the poor sensitivity of quartz from this region, a sensitisation procedure was used in our SAR protocol to reduce the scatter in optical ages. Various internal consistency tests of the measurement protocol and the excellent reproducibility of the OSL ages indicate that the dose estimates from the quartz are accurate and the optical ages reliable. The preliminary OSL ages indicate that the liquefaction features were formed between 1430 AD and 1630 AD. This study demonstrates that using OSL, ‘direct dating’ of prehistoric earthquakes may be possible, if sand blows from liquefied dykes are preserved.  相似文献   

Late Holocene Mediterranean coastal change along the Tiber Delta and Roman occupation of the Laurentine shore, central Italy     

Helen M. Rendell  Amanda J. Claridge  Michle L. Clarke 《Quaternary Geochronology》2007,2(1-4):83-88

A line of Roman villas once dominated the Mediterranean coastline to the south of the Tiber river mouth near Ostia in central Italy. The Roman remains, which were constructed within a series of dune ridges, now lie up to 900 m from the current shoreline as a result of the continued evolution of the Tiber delta in response to postglacial sea level rise, sediment inputs from the Tiber river catchment and tectonic uplift. Infrared stimulated luminescence (IRSL) ages of potassium-rich feldspars extracted from dune sands are in good agreement with the independent age control provided by the Roman structures and allow us to hypothesise an increase in aggradation rates of five times since the end of the period of Roman occupation compared with the earlier Holocene.  相似文献   

Testing the accuracy of quartz OSL dating using a known-age Eemian site on the river Sula, northern Russia   总被引：1，自引：0，他引：1  

A.S. Murray  J.I. Svendsen  J. Mangerud  V.I. Astakhov 《Quaternary Geochronology》2007,2(1-4):102-109

Quartz optically stimulated luminescence (OSL) forms the basis for the chronology of Weichselian ice advances in Arctic Eurasia developed over the last few years. There is almost no age control on this chronology before 40 ka, except for some marine sediments correlated with marine isotope stage (MIS) 5e on the basis of their palaeofauna. Results from more southern latitudes have shown that dose estimates based on quartz OSL and the single aliquot regenerative (SAR) dose procedure may underestimate the age of MIS 5e deposits. Here we use the same method to date well-described marine sediments, thought to have been deposited during the very beginning of the Eemian interglacial at 130 ka, and exposed in two sections on the river Sula in northern Russia. Various quality-control checks are used to show that the OSL behaviour is satisfactory; the mean of 16 ages is 112±2 ka (σ=9 ka). This represents an underestimate of 14% compared to the expected age, a discrepancy similar to that reported elsewhere. In contrast to SAR, the single aliquot regeneration and added (SARA) dose procedure corrects for any change in sensitivity during the first OSL measurement. The SARA results are shown to be 10% older than those from SAR, confirming the geological age estimate and suggesting that SAR ages may underestimate older ages (larger doses), despite their good performance in the younger age range.  相似文献   

Treatment of broad palaeodose distributions in OSL dating of dune sands from the western Murray Basin, South Australia     

J. Lomax  A. Hilgers  C.R. Twidale  J.A. Bourne  U. Radtke 《Quaternary Geochronology》2007,2(1-4):51-56

Preliminary results of an optically stimulated luminescence dating study in the western Murray Basin in semi-arid south-eastern Australia are presented. The ultimate objective of the dating study is a reconstruction of dune formation indicative of palaeoclimatic changes in this region. So far, one site has been dated using the single-aliquot regenerative (SAR) dose protocol for quartz. A high scatter in individual palaeodoses was observed, which is unexpected in supposedly well bleached aeolian deposits. Therefore other sources of variability such as microdosimetry and bioturbation have to be taken into account. Nevertheless, the resulting ages are in chronostratigraphic order and document a long aeolian record from 180 to 9 ka.  相似文献