The Valanginian history of the eastern part of the Getic Carbonate Platform (Southern Carpathians,Romania): Evidence for emergence and drowning of the platform

Lower Cretaceous successions that crop out in the eastern part of the Getic Carbonate Platform (Southern Carpathians, Romania) preserve records of the Valanginian events in different settings of the platform. The integrated sedimentological, biostratigraphical, geochemical and mineralogical analysis of the upper Berriasian–Valanginian successions reveal successive stages in the evolution of the carbonate platform: (a) pre-drowning stage of the shallow-shelf and slope settings of the platform; (b) subaerial exposure and karstification; and (c) incipient flooding and drowning of the carbonate platform. Following the subaerial exposure, starting in the middle early Valanginian, the eastern part of the Getic Carbonate Platform experienced a drowning phase documented by iron oxyhydroxides, phosphate and glaucony mineralized discontinuity surface and glaucony-rich sediments disposed on the discontinuity surface. Recognition of the diachronous intra-Valanginian discontinuity surface within the studied successions is based on clear evidences (facies contrast, depositional and diagenetic features, biostratigraphic and taphonomic data, and geometrical relations). The negative–positive carbon isotope excursion is correlated with the global perturbations of the carbon cycle related to the Valanginian “Weissert” episode, and it is documented for the first time in the shallowest parts of the Getic Carbonate Platform. Tectonic activity and eustatic sea-level fluctuations were most probably the main factors that led to fault-block tilting, local emersion and subsequent drowning of the eastern part of the Getic Carbonate Platform during the Early Cretaceous. We infer that the eastern part of the Getic Carbonate Platform was affected by late Berriasian–early Hauterivian extensional tectonics that could be related to the Neo-Cimmerian movements with effects generally recognized in the northern peri-Tethyan areas.     

深圳市地理信息共享服务的关键技术

目前,地理信息共享是政府部门、工业界和学术界讨论的热点话题。地理信息共享层次和方式存在多种解决方案。本文遵循SOA思想和技术架构,立足于数字深圳空间基础信息平台的技术实践,深入剖析其技术架构和功能特征,致力于以标准化的空间Web服务为核心,建立满足多层次需求的多途径的地理信息在线共享服务模式。通过提供多个应用实例,进而为政府部门之间基于地理信息的电子政务建设提供新思路。     

Early to mid-Viséan shallow water platform buildups,north Co. Dublin,Ireland

A number of carbonate buildups in north Co. Dublin, long assigned to the late Viséan (Asbian), are shown on the basis of coral, foraminiferal and algal evidence to be early to mid-Viséan (late Chadian to Holkerian) in age. They are equivalent in age to beds ranging from the upper part of the Lane Formation to the top of the Holmpatrick Formation. The buildups are poorly exposed and relatively small, probably only a few tens of metres across at most. Buildup sediments are massive to crudely bedded and dominated by peloidal, clotted and dense uniform micrites displaying lime mudstone and bioclastic wackestone textures. Dasycladacean algae are common in the buildups and cryptalgal fabrics are locally important. Cavities in the buildups are generally small (< 5 cm) and lined with inclusion-rich radiaxial calcite cements. Micritization of bioclasts and cements is ubiquitous. Enclosing off-buildup limestones are skeletal and intraclastic grainstones possessing sedimentary structures indicative of deposition in moderate to high energy environments. Fossil and petrographic evidence from the buildups also indicate a shallow water origin for the north Co. Dublin buildups. Compared with the slightly older Tournaisian (Courceyan to early Chadian) Waulsortian buildups which developed extensively in the Dublin Basin, these younger platform buildups are smaller and more isolated and possess a diverse suite of algal components and cryptalgal fabrics. Nevertheless, components in the north Co. Dublin buildups most closely resemble the shallowest phase D Waulsortian buildups, particularly in the presence of abundant peloids and micritized cements. The north Co. Dublin buildups developed on a carbonate platform (the Milverton Platform), adjacent to the Dublin Basin, whereas the Waulsortian developed in a deeper ramp setting. Following the demise of the Waulsortian in early Chadian time carbonate buildups established themselves on the shallow platforms. It is suggested that the microbial communities responsible for these buildups may have ‘evolved’ from older phase D Waulsortian communities and that he north Co. Dublin platform buildups represent the shallow water end of a spectrum of Viséan buildups.     

华北地台晚古生代地层定量时间分析

以[美]学者Shaw AB法为原理,以地层多重划分研究为基础,对华北地台晚古生代地层进行了定量地层的时间分析,进行了分区内以标准参考剖面(SRS)为准的地层定量的时间分析、区域范围内的复合标准参考剖面(CSRS)的定量地层的时间分析,进而讨论了Shaw法在多重地层划分研究中的意义和作用。     

华北地台北缘东段金矿床氢氧同位素地球化学研究

华北地台北缘与金矿床有关的花岗岩类以贫D为特征,由其衍生的岩浆水δD=—120‰——85‰,δ~(18)O=5.0‰—8.0‰。H,O同位素研究表明,太古宙绿岩建造金矿床成矿流体为地壳深处多源混合水,以δD,δ~(18)O十分稳定为特征;显生宙花岗岩建造金矿床成矿流体为与金铜系列花岗岩再平衡的岩浆水;火山岩建造金矿床成矿流体为大气降水与岩浆水的混合产物,以δ~(18)O的明显漂移为特征;古生代绿岩建造金矿床的成矿流体为被花岗岩侵入体加热的大气降水,以δD特别低为特征。     

贵州新民石门坎三叠系关岭组底部火山凝灰岩锆石U-Pb年龄及意义

华南地区三叠系地层发育,安尼阶底界（即下—中三叠统界线）附近广泛发育浅绿色火山凝灰岩或凝灰质碎屑岩,俗称 “绿豆岩”。国际安尼阶底界界线层型候选剖面——位于南盘江盆地内的贵州关刀剖面和广西湾头剖面,已获得可对比的“绿豆岩”锆石U-Pb年龄,但在相邻的上扬子台地上尚缺少对安尼阶底界测年的可对比数据。笔者采集了贵州省盘州市新民镇石门坎剖面三叠系关岭组底部的多层“绿豆岩”,利用LA-ICP-MS获得锆石的U-Pb年龄。结果显示,石门坎剖面关岭组底部的锆石结晶年龄为246. 9±1. 1 Ma,可与南盘江盆地内及上扬子台地区出露安尼阶底界的剖面相对比。其绝对年龄为上扬子台地区内的安尼阶底界年龄对比提供了参照,有助于限定中三叠世海生爬行动物群所代表的海洋生态系统的复苏时间。石门坎剖面地层沉积连续,未来有望继续开展综合地层学的研究。     

The P-T path of metamorphism and age of migmatites from the northwestern Irkut block (Sharyzhalgai uplift of the Siberian Platform)

We study migmatized aluminous gneisses in the northwest of the Irkut granulite complex in the southeastern Sharyzhalgai uplift of the Siberian Platform basement. Migmatized gneisses with the mineral assemblage Grt + Sil + Bt + Kfs + Pl + Qz (+ Crd + Opx + Spl) contain a leucosome and widespread cordierite-bearing (+ orthopyroxene, quartz, and spinel) symplectites developed after garnet and sillimanite. Study of the microstructural relationships of minerals and modeling using the PERPLEX 672 software have shown a retrograde P-T path of metamorphism for the metasedimentary gneisses, close to the isothermal decompression (ITD). The parameters of the peak of metamorphism are T = 850-870 °C and P > 7 kbar. The weighted average age of zircon from the metasedimentary gneisses (1856 ± 13 Ma, SHRIMP) corresponds to the time of metamorphism. The decompression type of retrograde metamorphism of the rocks in the northwest of the Irkut block indicates their formation in the crust extension and thinning setting. The presence of domal structures in the section of the Irkut block on the shore of Lake Baikal suggests that the dome tectogenesis was involved in the exhumation processes. The Paleoproterozoic metamorphism and granite formation were associated with the same stage of collision processes, when the compression setting was changed by an extension one (1.88-1.85 Ga).     

冀北北岔沟门铅锌矿床中辉钼矿的铼-锇同位素年龄

北岔沟门铅锌矿床是华北地台北缘中段最近发现的一个极具成矿远景的新矿床,对矿床成因和成矿规律 的研究刚刚起步。本文介绍了用同位素稀释－等离子质谱法,直接测定了矿床中辉钼矿的Ｒｅ－Ｏｓ等时线年龄,证明成 矿作用发生在燕山中晚期,其等时线年龄为（１５２ ± ３） Ｍａ。这一年龄反映了成矿与浅成花岗岩浆侵入活动有关,并为区内进一步找矿勘探提供了一定的依据。     

基于J2EE规范可视化EAI平台--Run Agent动态解释性平台

企业应用整合EAI(Enterprise Application Interation)能够将业务流程、应用软件以及各种标准联合起来,在两个或更多的企业应用系统之间实现无缝集成,使它们像一个整体一样进行业务处理和信息共享.Run Agent平台就是基于流程层集成提出了解决EAI的新方案,它是一个通过可视化IDE环境以XML语言形式描述企业流程,集成各个企业应用,存入XML文档库,并在后台运行一个执行代理(或者执行引擎)调用并动态解释该XML文件并执行所描述的流程的企业级平台.     

“数字崇文”建设模式研究与实践

通过介绍北京市崇文区“数字崇文”的建设和应用现状，提出并总结了基于WebGIS技术，以信息资源平台为核心的“数字崇文”建设模式。