新疆阜康断裂带中段大黄山探槽晚第四纪沉积物的光释光测年

对新疆阜康断裂带中段大黄山探槽的23个样品进行了细颗粒石英光释光简单多片再生法测年。样品LED12-297等效剂量的预热坪实验结果表明,在220~260℃的预热温度范围内均能获得基本一致的等效剂量值。测年结果显示,样品年龄与地层的时序性一致,表明阜康断裂带为全新世活动断层。根据探槽剖面错断的最新地层及其上覆地层的光释光年龄判断,断层的最新1次古地震事件发生在距今(1.90±0.14)ka~(3.47±0.17)ka。根据地层的垂直位移量与测年结果得到,阜康断层大黄山段的垂直滑动速率为0.17mm/a。     

西南天山明尧勒背斜河流阶地沉积物的光释光测年

晚第四纪细颗粒河流阶地沉积物的准确定年是当前光释光测年研究中的一个难点。利用简单多片再生法(SMAR)、单片再生法(SAR)等对新疆西南天山喀什前陆盆地明尧勒背斜喀浪勾律克河阶地沉积物样品的细颗粒石英光释光(BLSL)信号、混合矿物红外释光信号(IRSL)和红外后蓝光释光信号([Post-IR]OSL)进行测量。通过对比同一样品的细颗粒石英BLSL、混合矿物IRSL和[Post-IR]OSL的等效剂量值,认为细颗粒石英简单多片再生法是河流阶地沉积物释光测年最为适用的方法之一。对于细颗粒混合矿物而言,由于长石矿物的异常衰退,对于等效剂量De>70Gy的样品,其IRSL等效剂量值均偏小;其[Post-IR]OSL等效剂量值仍需慎重使用。通过对同一样品细颗粒石英多个测片的单片再生法等效剂量值分布以及简单多片再生法多个测片校正后天然释光信号强度的一致性判断,认为样品LEDL03-87q,LEDL03-86q和LEDL04-54q在沉积时的光晒退是不均匀的,采用最小等效剂量组分来计算沉积年龄     

香山-天景山断裂活动时代的光释光测年

在青藏高原东北隅发育一系列向北东凸出的弧形断裂带．其中最主要的三条断裂带从北到南分别为牛首山-罗山断裂带、香山-天景山断裂带和天祝一海原断裂带。香山-天景山断裂带从上世新以来一直有过活动,并在1709年发生了中卫南7t／2级地震。近期,宁夏地震局在孟家湾村南开挖了一个探槽．揭露出石炭纪的煤系地层逆冲于晚更新世风成沙之上．根据风成沙光释光测年结果表明。此探槽显示的断裂活动时代在距今约26．14±1．08ka．极有可能为22．09±0．4ka与26．14±1．08ka之间．     

汶川8.0级地震小鱼洞地表破裂带古地震事件的光释光测年

小鱼洞地震地表破裂带罗元村探槽剖面揭示了汶川8.0级大地震之前的1次同等规模的古地震事件.文中对采自小鱼洞破裂带罗元村古地震探槽的7个冲洪积物样品进行了细颗粒石英简单多片再生法和单测片再生法光释光测年研究.LED08-212样品SAR法预热坪实验表明预热温度坪区间为180～240℃,在此温度下热转移量小于等效剂量的1%...     

滨海断裂北带何在——~(14)C测年资料在工程地震中的应用

本文研究了珠海西区三处大型工程场址的资料,结果表明,在珠海西区的近海海城,滨海断裂带并不明显,而北西向西江断裂带的近期活动性却有自西而东增强的趋势,其活动性最强的部位是在磨刀门地区。     

乌兰巴托以西断裂活动时代的光释光年代学研究

蒙古乌兰巴托周边发育了多条活动断裂.以乌兰巴托以西的Emeeh和Hustai断裂为例,对相关断层开挖探槽,进行年代学研究.结果表明,Emeeh断裂以走滑运动为主,根据剖面错断地层和其上覆、下伏地层的光释光年代学研究结果,推断出该断层最新活动时间介于距今(9.6±1.0)ka和(11.3±1.3)ka之间;对Hustai断裂开挖的新鲜剖面显示其为正断层,通过分析错断地层和其上覆堆积物的光释光定年结果,推断该断裂最新活动时间介于距今(0.87±0.08) ka和(24.2±4.9) ka之间,且可能更接近距今(0.87±0.08)ka.     

长白山天池火山炭化木的~(14)C年代及其意义

对长白山天池火山喷发形成的灰白色空降浮石层、黑色熔结凝灰角砾层和火山碎屑堆积物中 16个炭化木作了系统的14C年龄测定,结果表明天池火山喷发年代为 (1215±15)AD。从火山碎屑堆积中采集的炭化木测定的14C年代要比火山喷发年代偏老,最大可偏离 800a;炭化木树皮的测定结果比较接近火山喷发年代;黑石河、浮石林、锦江大峡谷等地的黑色熔结凝灰角砾层的14C年代结果表明它们也属于(1215±15)AD大喷发的产物     

THE CHARACTERISTICS OF VOLCANIC ROCKS STRUCTURE AND LITHOFACIES OF DALIUCHONG VOLCANO IN THE TENGCHONG VOLCANIC FIELD,YUNNAN PROVINCE

A set of grey-purple layered volcanic rocks are found widely distributed from the mountain flank to the main peak of Daliuchong volcano, but it's difficult to identify whether they are volcaniclastic rock or lava rock just by field investigation and the crystal structure observation under microscope. The study of matrix microstructure of the volcanic rocks can help to identify the volcanic facies. We recognize the eruptive facies rocks through observation of the matrix microstructure and pore shape with comparison to those of the volcanic vent facies, extrusive facies and effusive facies rocks under microscope, thus the mentioned layered volcanic rocks could be named as dacitic crystal fragment tuff. Combining the joint work of field investigation, systematic sampling, chemical analyzing and microscopic observation, we summary the Daliuchong volcanic facies as follows:1. The effusive facies lava constitutes the base of Daliuchong volcano and was produced by early eruption.2. The explosive facies is composed of dacite crystal fragment welded tuff and volcanic breccia and mainly distributes on the W, S and NE flank of the volcanic cone.3. The volcanic conduit with its diameter more than one hundred meters is located about 100 meters south of the main peak of the Daliuchong volcano.4. The extrusive facies rock is only exposed near the peak of Daliuchong volcano.Therefore, the volcanism of Daliuchong volcano can be speculated as:Large-scale lava overflowing occurred in the early eruption period; then explosive eruptions happened; at last, the volcanisms ceased marked with magma extrusion as lava dome and plug.     

阿尔金断裂带东段晚更新世阶地沉积物红外释光测年及其构造意义

对流经阿尔金断裂带东段的段家沙河、疏勒河和踏实河的阶地沉积物进行了细颗粒多测片红外释光(IRSL)测年,初步确定了晚第四纪各级阶地的形成年代和构造抬升速率。疏勒河在昌马盆地南缘发育7级阶地,光释光测年结果显示这些总高度超过100m的阶地可能主要形成于数万年以内,抬升速率约为2.5mm/a;照壁山峡谷疏勒河保留有5级阶地,大致形成于20万年前,阶地的抬升速率约为0.7mm/a;段家沙河在红柳峡上形成4级阶地,形成于距今7万年以来,其抬升速率约为06mm/a     

海原断裂带刺儿沟剖面烘烤次生黄土的光释光测年及其地质意义

选择海原活动断裂带刺儿沟剖面2个烘烤次生黄土样品LEDL0588H和LEDL0365的细颗粒石英,采用改进后的单测片再生法(SAR)和简单多测片再生剂量法(SMAR)进行了一系列实验研究。2个样品细颗粒石英的光释光信号均以快速组分为主,其等效剂量(DE)的预热坪实验表明,在180～260℃的预热温度范围内均能获得基本一致的DE值。SAR法测量不同预热温度下的释光感量变化、剂量恢复实验和LN/TN比值的关系以及SMAR法测量中LN/TN比值与预热温度的关系的研究表明,文中所采用的流程能有效地校正测量过程中释光信号感量变化。2种方法均适用于采自不同层位的2个烘烤样品细颗粒石英的OSL测年,并获得了非常接近的OSL年龄。2个样品最后一次被烘烤的时间可能代表的是同一时期的人类活动     

北京延庆盆地湖相钙质层的电子自旋共振（ESR）测年研究

北京延庆盆地是一个小型的新生代断陷盆地，第四纪时期曾发育多期湖相层，而对这些湖相层的时代有着不同的认识。应用电子自旋共振（ＥＳＲ）测年方法对采自北京延庆盆地地表湖相沉积层的６个钙质样品作了年龄测定，结果表明，延庆盆地地表出露的较老湖相层的时代属于中更新世     

腾冲火山岩稀土和微量元素地球化学研究

本通过腾冲火山岩稀土和微量元素丰度的测试与分析,结合前人部分资料探讨了该区火山岩的稀土和微量元素地球化学特征：各喷发期火山岩均富集ＬＲＥＥ和Ｒｂ、Ｓｒ、Ｂａ、Ｕ、Ｔｈ等不相容元素;均具极为相似的稀土分配型式和微量元素地球化学模式,这可能反映了各其火山岩初始岩浆的同源性。     

THE INTERPRETATION OF GRAVITATIONAL AND MAGNETIC DATA FOR THE VOLCANIC ROCKS DISTRIBUTION IN KE-BAI FAULT ZONE,JUNGGAR BASIN

This paper firstly discusses the feasibility of delineating the volcanic rocks distribution by gravitational and magnetic methods on the basis of the statistical results of the magnetic susceptibility and density of the different lithologies in the study area. After the separation of gravitational and magnetic fields by bandpass filter, we determined the residual gravitational and magnetic anomalies caused by volcanic rocks. The results of potential field separation show that the residual anomalies are in beaded NE-directed distribution. In the meantime, the boundary enhancement techniques such as horizontal total gradient and vertical derivative are employed to delineate the distribution of the faults, as the result, fifteen faults including four NE-striking main faults which appear as an arc protruding to the southeast and other secondary faults are distinguished. Furthermore, two fault systems with deep and superficial attribution are revealed from the inversed section of the telluric electromagnetic sounding, and their properties, characteristics and roles in the volcanic activity are fully discussed by combining with the tectonic background. Based on the comprehensive analysis of the correlation between the distribution characteristics of the residual gravitational and magnetic anomalies and the location of the faults, three volcanic activity zones are reasonably delineated. Finally, we carry out the inversion of apparent density by taking advantage of the residual gravitational anomalies and acquire the apparent density anomalies of the top part of Paleozoic. Integrated with the apparent density anomalies, the lithologies exposed from the boreholes, the observed density data of different rocks and the residual gravitational-magnetic anomalies, we elaborately delineate the lithologies of the top of Paleozoic and further define the distribution range and the lithology combination of Kekesayi group of Middle Ordovician, Tailegula group of Lower Carboniferous and Jiamuhe group of Lower Permian.     

长白山天池火山气象站期喷发类型研究

全面系统地了解一座活火山的喷发特征与历史,对于预测其未来喷发形式及灾害性具有重要意义.长白山天池火山晚更新世或全新世以来存在3期大规模的喷发活动,天文峰期喷发与千年大喷发皆为典型的大规模的布里尼式爆炸喷发,而气象站期喷发方式却在爆炸式或溢流式的喷发类型上存在着激烈的争论.气象站期喷发物在遥感影像上表现为以气象站为寄生火口,向北流动长约5.4km,形貌上似一条熔岩流,但文中研究认为是小规模的脉冲式爆炸喷发而形成的岩层形态.主要依据为:1)岩石成分为高黏度的酸性岩浆;2)野外露头与剖面的薄层状堆积特征;3)晶屑的棱角状破碎形态;4)岩石的颗粒支撑结构.研究结果表明,气象站期的堆积物是爆炸喷发产生的碎屑物沿山坡以火山灰流的形式快速流动,在高温与高流速的剪切力作用下,火山灰流形成1套薄层状的熔结凝灰岩.因此,长白山天池火山晚更新世或全新世以来3期喷发活动均为爆炸式喷发,而非以前认为的爆炸-溢流-爆炸式喷发.