Tephrochronological dating of varved interglacial lake deposits from Piànico‐Sèllere (Southern Alps,Italy) to around 400 ka     

Achim Brauer  Sabine Wulf  Clara Mangili  Andrea Moscariello 《第四纪科学杂志》2007,22(1):85-96

The sediment record from the Piànico palaeolake in the southern Alps is continuously varved, spans more than 15 500 years, and represents a key archive for interglacial climate variability at seasonal resolution. The stratigraphic position of the Piànico Interglacial has been controversial in the past. The identification of two volcanic ash layers and their microscopic analysis provides distinct marker layers for tephrochronological dating of these interglacial deposits. In addition to micro‐facies analyses reconstructing depositional processes of both tephra layers within the lake environment, their mineralogical and geochemical composition has been determined through major‐element electron probe micro‐analysis on glass shards. Comparison with published tephra data traced the volcanic source regions of the Piànico tephras to the Campanian volcanic complex of Roccamonfina (Italy) and probably the Puy de Sancy volcano in the French Massif Central. Available dating of near‐vent deposits from the Roccamonfina volcano provides a robust tephrochronological anchor point at around 400 ka for the Piànico Interglacial. These deposits correlate with marine oxygen isotope stage (MIS) 11 and thus are younger than Early to Middle Pleistocene previously suggested by K/Ar dating and older than the last interglacial as inferred from macrofloral remains and the geological setting. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

山西五台地区壳内低速体的重力异常的研究   总被引：1，自引：0，他引：1  

方盛明  余钦范 《地震地质》1995,17(2):109-113

运用健全的极大似然法对山西五台地区中、下地壳中存在的低密度（低速度）异常体进行了三维反演，求出该异常体的空间赋存状况，并结合浅层局部重力负异常及其它地球物理特征进行地质解释，还就其形成机制进行了讨论  相似文献   

华北、扬子板块碰撞后热演化史的初步研究   总被引：12，自引：1，他引：12  

李齐  陈文寄  马宝林  王清晨  孙敏 《地震地质》1995,17(3):193-203

对采自苏北－胶南－大别高压变质构造混杂岩带的片麻岩、糜棱岩和郯庐断裂带上的片麻岩中９个钾长石进行了￣４０Ａｒ－￣３９Ａｒ年龄测定和多重扩散域（ＭＤＤ）模式处理，９个样品的热演化史表明上述地区存在５个不同的快速冷却时段，并就其可能的构造含义，提出了华北与扬子板块碰撞后的折返历史过程  相似文献   

雁列式断层变形过程中物理场演化的实验研究（一）   总被引：21，自引：3，他引：21  

马胜利  邓志辉 《地震地质》1995,17(4):327-335

在双轴压缩条件下对挤压型和拉张型雁列式断层变形破坏过程中声发射、断层位移及应变场的时空演化进行了实验研究。研究表明，两类雁列式断层具有类似的变形破坏过程，即前期以雁列区的破裂贯通为主，后期以沿断层的滑动为主。但挤压型雁列区内可积累较高的应变能，有较强的应变释放和声发射活动，雁列区对滑动始终起着阻碍作用；而拉张型雁列区内难以产生快速的应变释放和较强的声发射活动，雁列区对后期的滑动也无明显的阻碍作用。两类雁列区贯通所引起的失稳均有明显的前兆，而在随后滑动过程中失稳前兆的出现，取决于断层不同部位或段落之间是否有应变传递  相似文献   

雁列式断层变形过程中物理场演化的实验研究（二）   总被引：6，自引：1，他引：6  

马胜利  刘力强 《地震地质》1995,17(4):336-343

在双轴压缩条件下对由挤压型和拉张型雁列式断层组合而成的复杂雁列断层系变形过程中声发射、断层位移及应变的时空演化进行了实验研究，结果表明，复杂雁列式断层系的变形过程及相应的物理场演化并非是两种雁列式断层的简单叠加，而是包含着它们之间的相互作用。能量较强的声发射事件成核部位主要集中在应力水平较低的张性雁列区附近的主于断层上，而不是应力水平较高的压性雁列区，但这种事件发生的时间则明显受控于压性雁列区的变形过程  相似文献   

豫西嵩县盆地周边地区地震空区地质环境初探     

韩德润  苏怡之 《地震地质》1995,17(4):432-438

通过时豫西嵩县中～新生代断陷盆地构造类型、断裂发育及其活动程度的初步分析，认为该盆地及其邻区具有断裂发育规模小、新构造活动程度低、盆内无次级断裂及其所围限的地堑和地垒断块构造发育等特征，从而形成了被深断裂割开的地震空区  相似文献   

Performance of the stereoscopic system of the HEGRA imaging air erenkov telescopes: Monte Carlo simulations and observations     

《Astroparticle Physics》1999,10(4):886

Based on the Monte Carlo simulations we have studied the performance of the HEGRA system of imaging air erenkov telescopes (IACTs) in its present configuration of 4 IACTs as well as in its future final configuration of 5 IACTs. Here we present the results on the basic characteristics of the IACT system which are used in the standard data analysis procedure, i.e., the collection areas, the detection rates, the angular resolution, the energy resolution, and the γ/hadron-separation efficiency. By comparing several key Monte Carlo predictions with experimental results it is possible to check the accuracy of the simulations. The Monte Carlo results concerning hadron-nuclear showers are tested with the recorded cosmic ray events and the results concerning photon-induced showers are tested with a large data sample of γ-rays observed from BL Lac object Mkn 501 during its high flaring activity in 1997. Summarizing the simulations and current observations we give the basic recommendations of using the instrument and the major values of its sensitivity.  相似文献   

滇西北兰坪盆地金满脉状铜矿床绢云母^40Ar-^39Ar年龄对成矿时代的约束   总被引：4，自引：0，他引：4  

王彦斌陈文  曾普胜 《地质通报》2005,24(2):181-184

处于印度大陆与亚洲大陆主碰撞带北东侧的兰坪盆地西缘的金满铜矿床，产于中生代陆相沉积砂岩、泥岩中，以其属新类型陆相喷流铜矿床而引起人们的关注。关于其成矿时代至今仍然存在争论。采用常规^40Ar/^39Ar阶段升温测年法对金满铜矿床主矿体旁侧的含铜热液蚀变矿物绢云母进行了测试，获得3组视平均年龄分别为88Ma、67Ma、37Ma。结合兰坪盆地区域地质成矿背景，认为金满铜矿成矿经历了早期67Ma的成矿作用和晚期37Ma的成矿叠加作用，后者代表了金满铜矿的主要形成年龄。金满铜矿床的2期成矿年龄可能是印～藏碰撞(古新世)和走滑～拉分(始新世)等重大地质构造事件在矿床中留下的同位素年龄信息．暗示着古新世时期的构造作用和始新世时期的构造-岩浆-成矿活动对兰坪盆地的作用。  相似文献   

High-altitude Plio–Quaternary fluvial deposits and their implication on the tilt of a horst, western Anatolia, Turkey     

M.L. Süzen  V. Toprak  B. Rojay 《Geomorphology》2006,74(1-4):80-99

This study investigates the origin and regional tectonic implications of high-altitude Plio (?)–Quaternary fluvial deposits developed over the Bozdağ horst which is an important structural element within the horst–graben system of western Anatolia, Turkey.A total of 23 deposits occur near the modern drainage divide comprising fluvial to occasionally lacustrine deposits. The deposits are all elongated in N–S direction with a width / length ratio of 1 / 10. The largest of them is of 13 km in length with a maximum observable thickness of about 100–110 m. Morphological, lithological, deformational characteristics of these deposits and the drainage system of the area all suggest that the deposits were formed due to uplift and southward tilting of the Bozdağ horst. This tilting which is estimated as 1.2° to 2.2° caused accumulation of the stream load along channels flowing from south to north. All the deposits were later dissected by the same streams with the exception of one deposit which still preserves its original lake form. These deposits are of Quaternary age, which corresponds to the latest N–S directed extensional tectonic phase in the region.  相似文献   

成都市数字化地震及前兆观测网建设和展望     

袁海良  宋杰 《四川地震》2006,(3):15-22

本文着重介绍了成都市的地震监测工作状况。在“九五”、“十五”期间,成都市加大了对地震监测基础设施建设的投入,先后建成了成都市数字遥测地震台网(含一期工程、二期工程)和成都市数字电磁波观测台网,改造了成都市地震监测中心。根据成都市现有地震监(观)测能力,“十一五”期间,将继续加强成都市的地震监(观)测工作,从防震减灾的角度提升成都市的综合竞争力。  相似文献