Stratigraphic subdivision and correlation of the Carboniferous System in South China

The Carboniferous System of South China is famous for its well-developed rock sequence, variety of depositional types, and abundant fossils. Three established Global Boundary Stratotype Section and Point (GSSP) markers have been identified in several sections in South China. Of these sections, the Pengchong section is the GSSP for the base of the Visean Stage, whereas the Dapoushang and Naqing (Nashui) sections are excellent reference sections for the bases of the Tournaisian and Bashkirian stages, respectively. Other sections have good potential for the four unestablished GSSPs and the Devonian–Carboniferous boundary in South China. The Naqing (Nashui) section is a candidate for the GSSPs of four stages: the Serpukhovian, Moscovian, Kasimovian, and Gzhelian stages. The regional stages of China include the Tangbagouan, Jiusian, Shangsian, Dewuan, Luosuan, Huashibanian, Dalaun, and Xiaodushanian. The history, definitions, reference sections, sedimentary characteristics, biostratigraphy, and correlations of these Chinese regional stages are summarized. A Carboniferous stratigraphic chart of South China is provided, showing the correlation of global chronostratigraphic and biostratigraphic units with those in South China and the lithostratigraphic units of various areas in South China. The chart is presented as a new practical framework for the stratigraphic subdivision and correlation of the Carboniferous System in South China.     

青藏高原困难地区开展区域重力调查工作遇到的问题与对策

青藏高原的大部分地区自然条件恶劣、人口稀少、交通不便、基础测绘程度低、通讯条件极其落后,属于典型的开展区域重力调查工作的困难地区.在这些地区开展区域重力调查工作,在重力仪选择及标定、GPS控制点的建立及其控制范围、重力测点水准高程求取,以及近区地形改正、物性标本采集等方面都会遇到很多与内地一般地区工作时不一样的问题.笔者通过对青藏高原地区开展的多个1∶20万区域重力调查项目的野外工作过程进行总结,分析了困难地区区域重力调查项目实施过程中遇到的一些技术问题,认为可通过尽量选择高精度、稳定性好的重力仪,合理延长闭合时间,采用CQG2000似大地水准面模型求取测点水准高程,扩大GPS基准站的控制半径等办法解决.这些措施可作为以后在青藏高原地区及国内其他困难地区开展区域重力调查工作时的参考.     

Regional Distribution and Prospects of Potash in China

China was formed by amalgamation of several small continental blocks (cratons), micro, blocks and orogenic belts in different paleoclimatic settings. It may be correlated with other continental blocks but has its own specific characteristics; therefore the tectonic environments of China’s marine and continental saline basins and salt, and potash, forming environment have some specific characteristics: multiple phases of salt formation, difference in salt, forming ages, migration and concentration of salt, forming processes and diversity of component materials, as well as small sizes of marine saline basins and great changes of saline basins in the late stage and occurrence of abundant liquid mineral resources. The nature of the tectonic basement exerted a key controlling effect on the formation of potash basins. The stable tectonic region was favorable for potash concentration in a quasi, stable region, and quasi, and the quasi-stable region was favorable for salt concentration and potash formation in a local stable tectonic region. Most China’s major ancient saline basins occur in “quasi, cratons (continental block)”; especially all the marine saline basins occur in continental blocks with the Precambrian basement. These regions are the key ones for potash search. Most relatively large, scale soluble salt deposits are developed in relatively stable continental nuclei. According to the characteristics of the tectonic domains where China’s salt, forming basins are located, the North China, Yangtze and Tarim, Qaidam salt minerogenetic domains and the northern Qiangtang, western Yunnan salt minerogenetic belt may be distinguished. Their salt and potash prospects will be discussed separately.     

Transnational Corporations and Local Embeddedness: Company Case Studies from Shanghai,China

Many factors impinge on local involvement in transnational corporation (TNC) networks. Two factors have not been explored, the previous economic strength of local partners and the large domestic market. This study employs site interviews and survey data in Shanghai to demonstrate that these two factors do affect the local involvement in management, industrial linkages, and technology transfer. The paper discusses China's cultural and political background, TNC's market‐capture motive, and equity joint ventures as the most common entry modes. The influence appears more evident when the two factors come together in joint ventures. Evidence also suggests that the overall localization level in Shanghai is lower than in some other developing countries because of the novelty of TNC investment in the city. On this account, as joint ventures constitute the main mode of TNC investment, increasing localization is anticipated in the years ahead.     

粤东梅州地区1：5万区调主要成果与进展

在粤东梅州地区完成的1：5万区域地质调查,对区内地层进行了多重划分和对比研究,理清了地层层序;将“兴梅混合岩田”解体为变质表壳岩和变质深成岩;采用双重填图法,查明了火山岩相、火山机构分布特征,划分了火山活动旋回;对侵入岩进行重新划分和研究,首次将永和北．三枫侵入体解体为超基性、中性和中酸性侵入岩;对构造形迹进行调查研究...     

Response of detrital zircon and monazite,and their U–Pb isotopic systems,to regional metamorphism and host‐rock partial melting,Cooma Complex,southeastern Australia

Progressive Early Silurian low‐pressure greenschist to granulite facies regional metamorphism of Ordovician flysch at Cooma, southeastern Australia, had different effects on detrital zircon and monazite and their U–Pb isotopic systems. Monazite began to dissolve at lower amphibolite facies, virtually disappearing by upper amphibolite facies, above which it began to regrow, becoming most coarsely grained in migmatite leucosome and the anatectic Cooma Granodiorite. Detrital monazite U–Pb ages survived through mid‐amphibolite facies, but not to higher grade. Monazite in the migmatite and granodiorite records only metamorphism and granite genesis at 432.8 ± 3.5 Ma. Detrital zircon was unaffected by metamorphism until the inception of partial melting, when platelets of new zircon precipitated in preferred orientations on the surface of the grains. These amalgamated to wholly enclose the grains in new growth, characterised by the development of {211} crystal faces, in the migmatite and granodiorite. New growth, although maximum in the leucosome, was best dated in the granodiorite at 435.2 ± 6.3 Ma. The combined best estimate for the age of metamorphism and granite genesis is 433.4 ± 3.1 Ma. Detrital zircon U–Pb ages were preserved unmodified throughout metamorphism and magma genesis and indicate derivation of the Cooma Granodiorite from Lower Palaeozoic source rocks with the same protolith as the Ordovician sediments, not Precambrian basement. Cooling of the metamorphic complex was relatively slow (average ～12°C/10⁶y from ～730 to ～170°C), more consistent with the unroofing of a regional thermal high than cooling of an igneous intrusion. The ages of detrital zircon and monazite from the Ordovician flysch (dominantly composite populations 600–500 Ma and 1.2–0.9 Ga old) indicate its derivation from a source remote from the Australian craton.     

Rb‐Sr geochronology and Sr isotopic composition of Devonian granitoids,eastern Tasmania

Biotite igneous ages and well‐defined isochron ages of plutons from the composite Blue Tier Batholith and the Coles Bay area in northeastern Tasmania range from 395 to 370 Ma. The older limit of this range, for the George River granodiorite, is considerably older than any age previously recorded for NE Tasmania. The ages of the youngest plutons (Mt Paris and Anchor granites), which host cassiterite ores, record pervasive hydrothermal alteration events. The initial ⁸⁷Sr/⁸⁰Sr ratios of the granitoids range from 0.7061 to 0.7136 and suggest different protolith compositions, consistent with mineralogical and geochemical characteristics of each pluton. The S‐type garnetbiotite granites (Ansons Bay and Booby alia granites) have initial ratios greater than 0.7119, indicative of enriched, high Rb/Sr ratio, crustal source‐rocks of Proterozoic age (1700–800 Ma). The S‐type biotite granites (Poimena and Pearson granites) have relatively high initial ⁸⁷Sr/⁸⁶Sr ratios (0.7070, 0.7105) but overlap with those of the I‐type granodiorites (George River, Scamander Tier, Pyengana and Coles Bay granodiorites) which are in the range of 0.7061 to 0.7073. The initial ratios of the enriched altered plutons are poorly constrained, and on both hand‐specimen and thin‐section scales, reveal open‐system Sr isotopic patterns.

Isochron ages for the arenite‐lutite and lutite sedimentary associations of the Mathinna Beds, which are intruded by the granitoids, reflect an approach to Sr isotopic equilibrium during regional metamorphism. The metamorphic age (401 ± 7 Ma) of the early Pragian arenite‐lutite association indicates a relatively small time interval between deposition, regional metamorphism and granitoid intrusion. The isotopic age for the lutite sedimentary association (423 ± 22 Ma) is tentatively correlated with a Benambran‐age burial metamorphic event that has not previously been recorded in Tasmania.     

神经网络在镇扬大桥工程区区域稳定性评价中的应用

基于优势面区域稳定性评价理论，运用ANN优势断裂评价模型来研究镇扬大桥工程区区域稳定性，取得了较好的效果，实践表明基于ANN找寻和评价优势断裂是可行的和有效的。     

黑河流域张掖市物质流账户体系的初步构建

物质流核算与分析(MFA)以重量形式测度经济系统的代谢规模——吞吐量,反映人类活动对环境压力的直观信息,也是生态可持续性的有效衡量.建立包括MFA在内的实物账户,成为研究区域环境经济综合核算的基础.介绍了MFA的理论背景以及区域物质流账户的基本框架及其衍生的指标体系,参照欧盟统计局《物质流指导手册》,以甘肃省张掖市为例,初步构建了中观尺度上的区域物质流账户.结果表明:张掖市物质需求总量(TMR)中生态包袱比例高达86.5%,其中最大的是煤炭及矿物和建材开采所产生的生态包袱,占TMR的65.2%,经济发展对自然环境的扰动破坏影响十分显著,资源开发粗放,利用效率低下.张掖市目前经济发展水平和产业结构特征,决定了张掖市经济系统物质资源的需求结构中相对较高的基础原材料投入,缓解环境压力的根本途径在于促进产业结构的升级调整.     

基于岩体塑性位错理论的龙门山区域构造系统演化过程

青藏高原对四川盆地的挤压作用导致了龙门山断裂带的形成及其山脉的隆起。本文以龙门山附近区域板块运动以及深部岩体力学特性为背景,采用FLAC3D软件模拟再现了时间跨度为700万年的龙门山区域构造系统演化过程。研究结果表明:在板块运动作用下,F1、F2和F3断层依次形成,贯通的断层对地表的抬升具有较强的控制作用,当断层贯通于地表后,龙门山及其以西的川西高原持续隆起,平均抬升速率约为1.38mm/yr,而龙门山断裂带以东的川西坳陷只有较小的抬升量,从而导致川西高原抬升8996 m,致使该区域产生6000m左右的落差,模拟的地形特征与目前的龙门山地形地貌基本相似。依据模拟结果与实测资料,绘制了龙门山断裂带形成及其附近区域地形地貌的演化过程图,呈现了板块挤压、断层塑性位错、地表侵蚀和沉积作用等因素共同作用对地形地貌的塑造过程。