马兰黄土的热释光年龄

我国黄土分布十分广泛,其中马兰黄土所占面积最大。自三十年代以来,马兰黄土便成为华北晚更新世标准地层。马兰黄土与国民经济有着密切的关系,对它的研究既有理论意义又有实践意义。因此,长期以来吸引着许多学者去进行研究,并已获得了可喜的成果。但年代学工作却作得较少。随着研究工作的深入,了解马兰黄土堆积的年龄值颇为重要。本文主要叙述马兰黄土堆积的起始年龄及其地层意义     

云南腾冲马鞍山最后一次喷发的热释光年龄

云南腾冲火山区是我国少数几个近代有火山活动的地区之一,它由多座第四纪火山组成。其中马鞍山是规模较大,可能喷发较晚的一处火山。从马鞍山火山锥附近采集了２个火山岩样品,进行了热释光测年分析。热释光年龄表明马鞍山最后一次大规模的火山喷发发生在全新世,可能距今约２５００～３５００年。     

五大连池火山群老黑山火烧山熔岩流流动特征及其形成动力过程

从火山灾害的预测预防角度出发，叙述了五大连池火山群老黑山、火烧山近代火山喷发所形成的熔岩流产物——熔岩的分布，表面特征，流动过程。讨论了漫流、溪谷熔岩流和潜流三种流动方式。对结壳熔岩、渣状熔岩、块状熔岩、喷气锥、熔岩遂道等的形成动力过程以及对古地形古环境条件的制约做了深入的讨论，提出新的形成模式和一些新的认识。     

SOLAR ACTIVITY VARIATIONS RECORDED IN VARVED SEDIMENTS FROM THE CRATER LAKE OF HOLZMAAR – A MAAR LAKE IN THE WESTEIFEL VOLCANIC FIELD, GERMANY

Annually laminated sediments from Lake Holzmaar (Germany) provide high resolution sedimentological and palaeoenvironmental data of the last 22,500 years. Weichselian periglacial varves and Holocene organic varves indicate different depositional environments. For the best preserved sections from both parts, spectral analyses were performed in order to detect cyclic fluctuations in varve thickness. Weichselian varves are dominated by an 88 year periodicity. Linear spectral analysis of Holocene varves provides no significant cyclicity. But, supposing nonlinear transformations of the solar signal through the Lake Holzmaar ecosystem during the Holocene, an adequate nonlinear spectral analysis method was able to detect periodicities of 11, 88, and 208 years. The existence of these cyclicities, comparable to the solar activity fluctuations, give further evidence for the existence of a sun-climate relationship, based on a not yet completely understood mechanism.     

EARTHQUAKE-CAUSED SEISMIC VOLCANIC ROCKS AND THIXOTROPIC DEFORMATION OF SOFT SEDIMENTS IN THE UPPER CRETACEOUS SHIJIATUN MEMBER,JIAOZHOU CITY

A lot of seismic volcanic rocks and strong earthquake-induced thixotropic deformation structures in soft mud-sandy sediments(seismites)were identified from the Upper Cretaceous Shijiatun Member of the Hongtuya Formation for the first time in Jiaozhou City of the Zhucheng Sag, eastern China. Seismic volcanic rocks are volcanic rocks with co-seismic deformation structures which were produced by major earthquakes destroying volcano ejecta. Seismites are sediment layers with soft-sediment deformation structures formed by strong earthquake triggering saturated or semi-consolidated soft sediments to produce liquefaction, thixotropy, faults, cracks and filling and so forth. The Shijiatun Member of the Hongtuya Formation mainly consists of basaltic volcano rocks interbedded with mud-sandy(muddy sand and sandy mud)deposition layers of the river-lake facies. In the Shijiatun Member, main types of seismic volcanic rocks are shattered basalts with co-seismic fissures and seismic basaltic breccias. The thixotropic deformations of soft mud-sandy sediments mainly include thixotropic mud-sandy veins and thixotropic mud-sandy layers with tortuous boundaries. Under the strong earthquake action, saturated mud-sandy sediments could not be liquefied, instead resulting in thixotropy, i.e. their texture can be damaged and their flow-ability or rheology becomes strong. Because basaltic volcano rocks were damaged(shattered, seismic broken), a major earthquake can lead to thixotropic mud-sandy sediments flowing along seismic fissures in basalts, resulting in the formation of deformation structure of thixotropic veins, and boundaries between volcano rock and mud-sand layer became quite winding. Under the koinonia of gravity and vibration force, seismic breccia blocks sunk into thixotropic mud-sandy layers, resulting in the formation of inclusions of thixotropic mud-sandy sediments. Seismic intensity reflected by these strong earthquake records during the end stage of the Late Cretaceous was about Ⅶ to more than X degrees. The Shijiatun Member is mainly distributed in the south of the Baichihe fault in the northern Zhucheng Sag, and the fault has generated many strong tectonic and earthquake activities at the end of the late Cretaceous, also provided the channel for intrusion and eruption of basaltic magma then. At the end of the late Cretaceous, intermittent intrusion and eruption of basaltic magma took place along the Baichihe fault, meanwhile the volcano earthquakes took place or tectonic earthquakes were generated by the Baichihe fault which caused the deformation of the volcano lava and underlying strata of red saturated muddy-sand, resulting in the formation of various seismo-genesis deformations of volcanic rocks interbedded with mud-sandy sediment layers. Therefore, strong seismic events recorded by them should be responses to strong tectonic taphrogenesis of the Zhucheng Sag and intense activity of the Baichihe fault in the end of Late Cretaceous. In addition, these seismogenic deformation structures of rock-soil layers provide new data for the analysis of the failure effect produced by seismic force in similar rock-soil foundations.     

THE HISTORICAL RECORDS OF VOLCANIC ERUPTION IN THE KOREAN PENINSULA

The historical document record is of vital significance to determine the volcanic eruption history age in the volcanology research and it cannot be replaced by ¹⁴C dating and other methods. The volcanoes are widely distributed in the northeast area of China, but there is lack of relevant historical records. However, there are the records of the volcanic eruption in the historical documents of Goryeo Dynasty(AD918-1392)and Joseon Dynasty(AD1391-1910)in the Korean Peninsula which is separated by a river with China only. Some of the records have been widely used as important information to the research of Changbaishan Tianchi volcano eruption history by researchers both at home and abroad, but they have different opinions. On the basis of the historical documents in the Korean Peninsula, that is, the History of Goryeo Dynasty and the Annals of the Joseon Dynasty so on, the phenomena of volcanic eruptions, including the intuitive eruptive events and the doubtful volcanic eruption phenomenon such as "the ash fall", "the white hair fall", "the sky fire", "the dust fall" are investigated and put in order systematically in this paper. The results are as follows:1)The intuitive eruptive events are the 1002AD eruption of Mt. Halla volcano on Jeju Island, Korea Peninsula, and the 1007AD volcanic eruption offshore to the west of Jeju Island, Korea Peninsula, as well as the 1597AD eruption of Mt. Wangtian'e volcano in Changbai County, Jilin Province, China; 2)"The ash fall" is airborne volcanic ash, and those "ash falls" happening in 1265, 1401-1405, 1668, 1673 and 1702AD are possibly the tephra of Changbaishan Tianchi volcano; 3)"The white hair fall" is Pele's hair and it is speculated that the "white hair fall "happening in 1737AD is related to Changbaishan Tianchi volcanic eruption; 4)If regarding "the sky fire" as the volcanic eruption phenomenon, "the sky fire" happening in 1533AD is possibly the Changbaishan volcanic eruption event, and "the sky fire" in 1601-1609AD may be the eruptive event of the Longgang volcano in Jilin Province, China or Changbaishan Tianchi volcano; 5)"The dust fall" is recorded in many historical documents. However, "the dust fall" is not the volcanic ash fall but the phenomenon of loess fall. So, it is improper to determine the eruptive events of Changbaishan Tianchi volcano on the basis of "the dust fall".     

白头山火山地震特征

白头山火山地震分为四种类型,其地震特点是频度高、强度低震源集中。活动强度在时间分布上具有明显的规律性,虽然白头山火山活动目前处于平静状态,仍应注意监视。     

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.     

腾冲火山岩矿物化学研究

通过电子探针分析,系统研究了腾冲火山岩１０５个造岩矿物的化学成分。研究表明：本区熔岩中的橄榄石为贵橄榄石兼少量透铁橄榄石,斜方石为古铜辉石兼紫苏辉石,单斜辉石为普通辉石兼少量 质透石,斜长石为拉长石兼部分中长石和少量更长石,角闪石为低铁普通角闪石,黑云母为钛铁黑云母为钛铁黑云母为钛铁黑云母兼富铁黑云母。     

第四纪松散沉积物中隐性活断层的显微构造特征

第四纪松散沉积物中普遍存在断层的隐性现象 ,包括断层的隐形和尖灭 ,给古地震研究带来了复杂性和多解性。选择了一些典型古地震剖面 ,对涉及到断层隐形或尖灭的部位 ,进行了定向原状样品采集 ,通过室内样品固结 ,显微薄片制作和显微构造现象观察 ,从显微域里找到了鉴定隐形断层的许多标志 ,并对断层尖灭机制进行了研究。认为通过显微构造分析 ,排除或肯定隐形断层的存在 ,或者追踪断层尖灭的层位 ,结合宏观剖面研究和年代测定 ,可以使古地震时代和期次判定更准确     

五大连池火山群最新喷发时间的热释光(TL)年代学证据

首次利用ＴＬ测年技术,测定了五大连池火山群中两座最新喷发的火山熔岩中的烘烤捕虏体的年代。测定结果（（２６４±１９）ａＢ．Ｐ．,（２７３±１９）ａＢ．Ｐ．）在误差范围内与喷发的历史记载（１７１９～１７２１年）一致,表明这两座火山是同期喷发的产物,同时也表明利用ＴＬ测年技术能比较准确地测定年轻火山活动的年代,它为恢复火山最新喷发历史的研究提供了一种比较可靠的年代测定途径