Pressure State in Deep Crust and Formation Depth of UHP Metamorphic Rocks     

Lü Guxian 《中国地质大学学报(英文版)》2004,15(2):135-144

INTRODUCTIONSincethediscoveryofeclogiteswithcoesiteanddia mondinclusionsrelatedtothecontinent continentcollision orogenyenvironment,theultrahigh pressuremetamorphism(UHPM )intheDabie Suluhasarousedgreatinterestinmanygeologists (Liouetal .,1994 ;Xuetal.,1992 ) .Experimentalstudieshaveprovedthatsuchmineralsasdia mond ,coesiteandomphaciteoccurredat 2 - 5GPa (andatthecorrespondingtemperatures) (Stevenetal.,1982 ;MirwaldandMasonne ,1980 ) .However,itdoesnotmeanthatthemetamorphicrockscanbe…  相似文献   

复杂环境条件下深基坑综合支护措施的应用          下载免费PDF全文

李江  张明中  陈辉  贾城 《探矿工程》2004,31(8):4-7

北京某交易中心一期基坑工程属大型深基坑工程，各种地下管线和地上建(构)筑物复杂，介绍了针对其复杂环境条件的综合支护措施的设计思路与实际应用效果。  相似文献   

温州世贸中心大厦超深大直径钻孔灌注桩施工技术          下载免费PDF全文

徐辉雄  张涛  晏军  杨建林  鄢泰宁  蒋国盛 《探矿工程》2004,31(9):35-37

介绍了超深大直径钻孔灌注桩在温州世贸中心大厦桩基工程中的应用情况，对其施工中出现的主要问题进行了分析和处理，并提出了解决措施。  相似文献   

大功率激电测深法寻找焦家式深部金矿床的试验应用研究     

牛如宝  陈长峰  宋海平  王友芳  王轮吉 《应用地球物理》2005,2(1):51-55

利用大功率的激电测深法可以寻找焦家式深部金 矿。首先,由物理和数学推导建立多层极化体的数 理模型,其数理模型产生的极化场可由多层若干 个极化单元场相叠加而成。由多次去除极化单元 场的原理而导出大功率激电测深资料进行消除浅 部强激电干扰异常的数据处理公式,从而突出了 深部矿床的激电异常。并利用处理后的激电测深 曲线,定量求取了深部金矿蚀变矿化带的顶界面 埋深。  相似文献   

深基坑支护方案的分析与优化   总被引：3，自引：0，他引：3  

尹双  张仲先  王勇 《岩土工程技术》2005,19(3):152-154,F003

针对武汉市南湖岸边复杂的地质条件及周边环境,在某高层建筑的深基坑支护结构设计中,结合实际因地制宜地对基坑的支护方法进行了分析比较。支护效果及实测数据表明,该工程所采用的混合式支护实施方案技术安全可靠,经济合理,可为同类型基坑工程设计提供借鉴。  相似文献   

Chemistry and Sulfur Isotopes in a Chert-dominant Sequence around the Stratiform Manganese Deposit of the Noda-Tamagawa Mine, Northern Kitakami Terrane, Northeast Japan: Implication for Paleoceanographic Environmental Setting     

Kosei Komuro    Katsuyuki Yamaguchi  Yoshimichi Kajiwara 《Resource Geology》2005,55(4):337-351

Abstract. Chemistry and sulfur isotopes are analyzed for a series of rocks in the chert‐dominant sequence around the stratiform manganese ore deposit of the Noda‐Tamagawa mine in the northern Kitakami Terrane, northeast Japan. The sequence is litholog‐ically classified into six units in ascending order: lower bedded chert, lower black shale, massive chert, manganese ore, upper black shale, and upper bedded chert. The rocks around the manganese ore deposit exhibit anomalous enrichment in Ni (max. 337 ppm), Zn (102) and U (30) in the upper part of lower bedded chert, Mo (122), Tl (79) and Pb (33) in the lower black shale, MnO, Cu (786) and Co (62) in the manganese ore, and As (247) and Sb (17) in the upper black shale. The aluminum‐normalized profiles reveal zonal enrichment of redox‐sensitive elements around the manganese bed: Zn‐Ni‐Fe‐Mo‐U(‐Co), Tl‐Pb(‐Mo), Mn‐Fe‐Cu‐V‐Cr‐Co(‐Zn) and As‐Sb in ascending order. The uppermost part of the lower bedded chert and black shale exhibit negative Ce/Ce* values, whereas the massive chert, manganese ore and lower part of the upper bedded chert display positive values. The isotopic δ³⁴S values are 0±6 % in the lower part of the lower bedded chert, ‐19 to ‐42 % in the upper part of the lower bedded chert, ‐36 to ‐42 % in the lower black shale, ‐28 to ‐35 % in the massive chert, manganese ore and upper black shale, and ‐23±5 % in the upper bedded chert. Thus, there is a marked negative shift in δ³⁴S values in the lower bedded chert, and an upward‐increasing trend in δ³⁴S through the manganese ore horizon. The present data provide evidence for a change in the paleoceanographic environmental resulting from inflow of oxic deepwater into the stagnant anoxic ocean floor below the manganese ore horizon. This event is likely to have triggered the precipitation of manganese oxyhydroxides. The redistribution of redox‐sensitive elements through the formation of metalliferous black shale and manganese carbonate ore may have occurred in association with bacterial decomposition of organic matter during early diagenesis of initial manganese oxyhydroxides.  相似文献   

Chemical Profiles across a Jurassic Stratiform Manganese Deposit at Katsuyama in the Mino Terrane of Central Japan: Implications for Depositional Environment, Diagenetic Metal Redistribution and Paleoceanography     

Kosei Komuro  Koji Wakita 《Resource Geology》2005,55(4):321-336

Abstract. Inorganic chemical compositions are determined for a series of rocks crossing an Early Jurassic stratiform manganese ore deposit in a chert‐dominant sequence at Katsuyama, in the Mino Terrane of central Japan. The lithology in the vicinity of the manganese ore bed is classified into lower bedded chert, black shale, massive chert, manganese ore and upper bedded chert, in ascending order. The rocks surrounding the manganese deposit are anomalously high in certain elements: Pb (max. 29 ppm), Ni (1140) and Co (336) in the lower bedded chert, Mo (438), As (149), Tl (29) and U (12) in the black shales, V (210) and Cr (87) in the massive chert, and MnO and W (24) in the manganese ore. The aluminum‐normalized profiles reveal a distinct zonation of redox‐sensitive elements: Pb‐Zn, Ni‐Co‐Cu(‐Zn) and U‐Cr in the lower bedded chert, Mo‐As‐Tl in the black shale, V(‐Cr) in the massive chert, and Mn‐Fe‐Ba‐W in the manganese ore, in ascending order. The lower and upper bedded cherts and manganese ore generally exhibit flat rare earth element patterns with positive Ce anomalies, whereas the uppermost part of the lower bedded chert, the black shale and massive chert have flat patterns with weak or nonexistent negative Ce anomalies and weak positive Eu anomalies. The strong enrichment in Ni, Co, W, Tl and As detected in the Katsuyama section is not recognized in other sediments, including those of anoxic deposition origin, but is identified in modern ferromanganese nodules, suggesting that metal enrichment in the Katsuyama section is essentially due to the formation of ferromanganese nodules rather than to deposition in an anoxic environment. The observed elemental zonation is well explained by equilibrium calculations, reflecting early diagenetic formation and associated gradual reduction with depth. The concentration profiles in combination with litho‐ and biostratigraphical features suggest that formation of these bedded manganese deposits was triggered by an influx of warm, saline and oxic water into a stagnant deep ocean floor basin in Panthalassa at the end of the middle Early Jurassic. Paleoceanographic environmental controls thus appear to be important factors in the formation and preservation of this type of stratiform manganese deposit.  相似文献   

深圳市某建筑深基坑支护滑塌事故剖析     

黄圭峰 《地质科技情报》2005,24(Z1):65-68

以深圳某建筑深基坑滑塌为例,在现场实物和相关资料调查的基础上,从基坑支护的设计、施工、监测以及质量安全管理等方面对基坑滑塌事故的原因进行了较为全面的分析和探讨,认为导致该基坑支护工程滑塌的主要原因是土钉和锚索抗拔力不足.最后针对目前深基坑工程中普遍存在的问题提出了加强设计方案的审查、加强施工管理、加强土钉墙研究的建议.  相似文献   

佳木斯地块西缘金矿带构造效应与壳幔作用--以鹤岗隆起为例     

徐受民赵海滨  于荣文 《华东地质学院学报》2005,28(4):325-328

佳木斯地块西缘金矿带的形成受左行走滑断裂带和深部流体控制，壳-幔作用和地球动力体制转换是成矿物质活化→运移→聚集→成矿的基本动力学保障，构造应力场转换是其重要表现形式。深切地幔牡丹江岩石圈断裂的活动发生了深熔作用，使成矿物质得以活化、运移的重要驱动力，是成岩成矿作用发生的根本原因之一。地幔流体通过壳-幔相互作用形成了含矿流体，为流体成矿作用提供了矿源，并沿深断裂运移到更高的层位，在物理化学条件发生改变时沉积成矿。佳木斯地块西缘金矿带是受深断裂控制的，矿床之间是相互联系的，是在一个构造应力体制下完成它们的成矿作用的。北北东向和伴生的北西西向断裂，并有中生代浅成-超浅成岩体或脉岩侵位是今后找矿的方向。  相似文献   

深直井旋转钻柱空转功率消耗的数学建模          下载免费PDF全文

吕建国  陈敏  刘宝林  肖天鹏 《探矿工程》2005,32(10):42-44

通过对深井旋转钻柱空转功率消耗因素的分析，考虑空转时离心力作用在井壁上引起的摩擦力导致的功率消耗，并将钻井液视为牛顿液体，运用柱坐标系建立了旋转钻柱在深井作业条件下空转功率消耗的分析模型。综合考虑空转功率与钻柱旋转的角速度、钻柱与井眼结构参数、钻井液粘度系数等因素间的关系，即旋转钻柱运动过程中的离心力和钻井液作用在钻柱上的剪切应力对功率的影响，建立了更加符合实际工况的数学模型。  相似文献