A New Coastal Marine Ecosystem Model Study Coupled with Hydrodynamics and Tidal Flat Ecosystem Effect

A new coastal marine ecosystem model was developed, which was composed of pelagic and benthic ecosystems, and was applied to Mikawa Bay, Japan. This model deals with variations of biochemical and physical interactions among dissolved oxygen and C–N–P species (composition formed out of carbon, nitrogen and phosphorus elements) so that it resolves the flux dynamics of carbon, nitrogen, phosphorus and oxygen elements. The physical and biochemical mechanism figured in this model is constructed for the purpose of simulating the estuarine lower trophic ecosystem, in areas where the sea was too deep for light to reach the sea-bottom. As a result of coupling the benthic with pelagic system, the effect of process of sedimentation and nutrient diffusion back to the pelagic system could be indicated. In addition, by implementing the tidal flat ecosystem model's calculation result, the integrated model can include the effect of water purification in tidal flats where the light can reach the sea-bottom, and where sea-weed, sea grass and benthic algae exist. In this study, the model indicates that oxygen-depleted water exists at the sea-bottom especially in summer mainly caused by an increase of oxygen consumption in the benthic system and a decrease of the vertical mixing water process. Furthermore, by comparing the case – with the tidal flat ecosystem model and the case without it, the effect of water purification of tidal flat estuaries was indicated. From the viewpoint of a short time scale, the tidal flat has the potential to restrict red tide (rapid increase of phytoplankton), and from the viewpoint of a long time scale, it restricts the sedimentation of detritus. Restricting the sedimentation prevents oxygen-depleted water occurring in the coastal marine system of Mikawa Bay.     

Three-dimensional Q structure in Jiashi earthquake region of Xinjiang

3-D S-waveQ structure in Jiashi earthquake region is inverted based on the attenuation of seismic waves recorded from earthquakes in this region in 1998 by the Research Center of Exploration Geophysics (RCEG), CSB, and a rough configuration of deep crustal faults in the earthquake region is presented. First, amplitude spectra of S-waves are extracted from 450 carefully-chosen earthquake records, called observed amplitude spectra. Then, after instrumental and site effect correction, theoretical amplitude spectra are made to fit observed amplitude spectra with nonlinear damped least-squares method to get the observed travel time overQ, provided that earthquake sources conform to Brune’s disk dislocation model. Finally, by 3-D ray tracing method, theoretical travel time overQ is made to fit observed travel time overQ with nonlinear damped least-squares method. In the course of fitting, the velocity model, which is obtained by 3-D travel time tomography, remains unchanged, while onlyQ model is modified. When fitting came to the given accuracy, the ultimateQ model is obtained. The result shows that an NE-trending lowQ zone exists at the depths of 10–18 km, and an NW-trending lowQ zone exists at the depths of 12–18 km. These roughly coincide with the NE-trending and the NW-trending low velocity zones revealed by other scientists. The difference is that the lowQ zones have a wider range than the low velocity zones. Foundation item: Joint Seismological Science Foundation of China (957-07-414) and State Key Basic Research Development and Programming Project (95-13-02-02). Contribution No. RCEG200105, Research Center of Exploration Geophysics, China Seismological Bureau.     

Seismo-tectonic divisions of strong earthquakes with M S≥7.0 and their tectonic geomorphology along Xianshuihe-Xiaojiang fault zone

Seismo-tectonic areas of historical strong earthquakes with M _S≥7 along Xianshuihe-Xiaojiang fault zone are divided, and their individual fault-pattern and tectonic geomorphology are analyzed. Those strong-earthquake areas are located in some special parts of the fault zone, where the major branch-faults of the fault zone form left stepping, parallel, and fork-like patterns. In the strong-earthquake areas structurally complicated basins are developed, such as pull-apart basins in fork-like area, in double stepping area, and in stepping and fork-like areas. Foundation item: Chinese Joint Seismological Science Foundation (9507424). Contribution No. 2001A003, Institute of Crustal Dynamics, China Seismological Bureau.     

Studies on40Ar/39Ar thermochronology of strike-slip time of the Tan-Lu fault zone and their tectonic implications

Samples of mylonite, ultramylonite and phyllonite were collected from 5 localities in the Anhui part of the Tan-Lu fault zone for⁴⁰Ar/³⁹Ar chronological studies. Among them 4 samples from 3 localities on the eastern margin of the Dabie orogenic belt yielded⁴⁰Ar/³⁹Ar plateau ages of 128 —132 Ma; and 2 samples from the western margin of the Zhangbalin uplift and eastern margin of the Bengbu uplift gave the same⁴⁰Ar/³⁹Ar plateau ages of 120 Ma. Isochron analyses and other lines of evidence suggest that the data are reliable. The data are interpreted as cooling ages of sinistral strike-slip deformation of the Tan-Lu fault zone. The younger ages from the north might be related to slower strike-slip rising. These results indicate that the large-scale left-lateral displacement in the Tan-Lu fault zone took place in the Early Cretaceous, rather than in Late Triassic (Indosinian) as proposed by some geologists. Therefore, this fault zone is an intracontinental wrench fault rather than a transform fault or suture line developed during formation of the Dabie orogenic belt.     

辽宁东胜地区金、银、多金属剪切带矿床控矿构造特征

运用剪切带控矿理论，通过对剪切带内变形岩石的应变测量和不同惊讶的成矿构造研究，阐明了辽宁东胜地区金、银、多金属剪切带矿床的控矿构造特征，探讨了此类矿床控矿构造与矿化的关系。     

锦屏隆里地区剪切构造变形的初步研究

在隆里地区新元古界下江群中发育有剪切变形的构造，形成脆－韧性剪切带（过渡性剪切带）。按其产状可分为切层和顺层过渡性剪切带两类，具有较典型的脆性－韧性变形的宏观和微观特征。此类变形是地壳浅层次剪切构造作用产物，显示了江南造山带外带的特征     

江苏溧阳地震孕育和发生的地质因素剖析

研究和剖析了两次溧阳地震孕育和发生的主要地质因素，新生代茅东裂陷盆地；茅东与南京－溧阳两玄武岩喷发带的交汇；茅东断裂带最活动的上沛带；震源区地壳层圈构造（深、浅变质岩界面和低速层）与茅东部断裂带中、深脆－韧性剪切段的复合。探讨了控制溧阳震震级的因素；茅东断裂带属Ⅱ级断裂，茅东裂陷盆地属中、小型裂陷盆地，因此，决定溧阳地震震级为5．0－6．0的中强地震。     

层间氧化带砂岩型铀矿矿物晕的非常规探测方法

本文以层间氧化带砂岩型铀矿矿物晕的一般特征为依托，介绍几种层间氧化带砂岩型铀矿矿物晕的非常规探测方法。     

吉林通化南岔式金矿地质—地球物理—地球化学综合找矿模型

老岭成矿带为吉林省最重要的贵金属、有色金属成矿带，南岔金矿是该成矿带近几年新发现的金矿床。在阐述南岔金矿成矿地质条件、岩（矿）石物性参数特征、地球物理场、地球化学特征的基础上，归纳并提取了控矿地质因素和物化控找矿标志，从而建立了“南岔式”金矿的地质－地球物理－地球化学找矿模型。     

松辽盆地北部深部层圈结构与成因模式探讨

依据松辽盆地深部地震资料 ,分析了深部地震反射特征及深部层圈结构特征。应用“非对称伸展作用”理论 ,通过对深部层圈结构、基底构造特征、侏罗系断陷构造格局的综合分析 ,建立了松辽盆地北部的盆地成因模式。从该模式可看出 ,基底滑脱拆离断层控制了侏罗系断陷的发育。