Variable Impact of the Subducted Slab on Aleutian Island Arc Magma Sources: Evidence from Sr, Nd, Pb, and Hf Isotopes and Trace Element Abundances

Major and trace element compositions and Sr, Nd, Pb, and Hfisotope ratios of Aleutian island arc lavas from Kanaga, Roundhead,Seguam, and Shishaldin volcanoes provide constraints on thecomposition and origin of the material transferred from thesubducted slab to the mantle wedge. ⁴⁰Ar/³⁹Ar dating indicatesthat the lavas erupted mainly during the last     

多光谱遥感异常提取技术方法体系研究

详细介绍了多光谱遥感异常提取方法体系——“去干扰（或称掩模）-主成分分析-异常筛选”（De-interfered Anomalous Principal Component Anomaly Filtration，以下简称DPF技术）的内容及工作方法，指出了技术体系应用时需要注意的问题。该 技术体系包括数据预处理、干扰去除、异常提取、异常后处理、异常筛选与推荐等5部分。在天山—北山、昆仑及冈底斯成矿带的 应用证明，该方法体系成效显著。     

Study of techniques of identifying the earthquake precursory anomalies in terms of mathematical modeling

IntroductionGenerallyspeaking,thedataofprecursorymonitoringwhichmightbeassociatedwiththepreparationofthefutureearthquakes,couldberepresentedbyatimeseries.There,however,wouldbenotonlyanomalouschangesassociatedwiththeearthquakeoccurrences,butalsosomechangeswhichwouldberelatedtosourcesotherthantheearthquakepreparation,eitherknownorunknowntotheinvestigatorsandbecalledas(thechangesfromnon-earthquakeeffects(,inthetimeseries,inpractice,tillnow.ItistosaythatthetimeseriesF(t)showingthetemporalchangesof…     

永善水氡异常特征及其预报意义

通过对永善地震台８年的水氡资料进行了数学处理，发现水氡异常与地震对应率较高。并对水氡异常特征及其机理作了分析．从而讨论了利用水氡资料对本地区短临地震监测的预测意义。     

地震地电阻率前兆异常特征及其机理研究

本文在全面整理我国大陆二十余年来的地电阻率观测资料的基础上,分析了地电阻率前兆异常特征及其与地震三要素之间的关系,给出地震强度(震级)与异常时间和震中距乘积的对数呈线性关系的实用结果,研究了不同类型地震地电阻率短临前兆特征及其在地震预报中的应用,探讨了地电阻率前兆变化的机理。     

The chemical anomalous behaviors of water-marble rock system under action of ultrasound

By the experiment, it is confirmed that water-marble rock system shows obviously chemical anomalous behaviors: the relevant minerals which formed marble rock are resolved fast, water becomes alkaline, meanwhile H₂ emission appears under action of ultrasound; based on rock identification by microscope and chemical analysis of water and rock, the mechanism of above chemical reaction is analyzed and discussed. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15 498–507, 1993. This study was supported by the Chinese Joint Seismological Science Foundation.     

Redox state of amphibole-bearing mantle peridotite from Nüshan, Anhui Province in eastern China and its implications

Using secondary spinel standard method, we have measured precisely the compositions of spinels of amphibole-bearing mantle peridotite xenoliths from Nüshan in eastern China, and calculated the mantle oxygen fugacities recorded by the xenoliths. Results indicate that the mantle metasomatism for forming amphiboles in Nüshan region of Anhui has resulted in the decrease of mantle redox, which is in contrast with theoretical estimation and previous research results from other areas around the world. Combining with related studies on the mantle of eastern China, we give a reasonable explanation to the ‘new finding’ and further elucidate the compositions and nature of mantle fluids in eastern China.     

MDCB型地震前兆监测仪的前兆异常与岫岩地震

以岫岩地震为例，介绍了MDCB－3型地震前兆仪所形成的异常形态不同，映震规律也不尽相同。从岫岩偏岭两次地震的前兆特征，对该仪器预测地震三要素做了初步探索。     

Three-dimensional primary instabilities of a stratified,dissipative, parallel flow

Abstract

We demonstrate the existence of a class of dissipative, stratified, parallel shear flows which, as a consequence of linear supercritical instability, evolve directly into three-dimensional flows without the requirement for an intermediate two-dimensional finite-amplitude state. This represents a counter-example to a common misinterpretation of Squire's theorm, namely that the fastest-growing unstable mode of a dissipative parallel shear flow must be two-dimensional.     

Deformation mechanisms and fluid behavior in a shallow, brittle fault zone during coseismic and interseismic periods: Results from drill core penetrating the Nojima Fault, Japan

Abstract This paper describes the results of petrographical and meso- to microstructural observations of brittle fault rocks in cores obtained by drilling through the Nojima Fault at a drilling depth of 389.52 m. The zonation of deformation and alteration in the central zone of the fault is clearly seen in cores of granite from the hanging wall, in the following order: (i) host rock, which is characterized by some intragranular microcracks and in situ alteration of mafic minerals and feldspars; (ii) weakly deformed and altered rocks, which are characterized by transgranular cracks and the dissolution of mafic minerals, and by the precipitation of zeolites and iron hydroxide materials; (iii) random fabric fault breccia, which is characterized by fragmentation, by anastomosing networks of transgranular cracks, and by the precipitation of zeolites and iron hydroxide materials; and (iv) fault gouge, which is characterized by the precipitation of smectite and localized cataclastic flow. This zonation implies that the fault has been weakened gradually by fluid-related fracturing over time. In the footwall, a gouge layer measuring only 15 mm thick is present just below the surface of the Nojima Fault. These observations are the basis for a model of fluid behavior along the Nojima Fault. The model invokes the percolation of meteoric fluids through cracks in the hanging wall fault zone during interseismic periods, resulting in chemical reactions in the fault gouge layer to form smectite. The low permeability clay-rich gouge layer sealed the footwall. The fault gouge was brecciated during coseismic or postseismic periods, breaking the seal and allowing fluids to readily flow into the footwall, thus causing a slight alteration. Chemical reactions between fluids and the fault breccia and gouge generated new fault gouge, which resealed the footwall, resulting in a low fluid condition in the footwall during interseismic periods.