溶剂萃取—苯芴酮石墨炉原子吸收法连续测定岩石矿物中锗,铟,镓

甲基异丁基甲酮(MIBK)—苯芴酮同时萃取,利用自制的简易石墨炉平台,以镍和钒作基体改进剂测定锗、铟和镓。方法简便、快速,适合于岩石矿物中锗、铟、镓的连续测定。     

Sedimentary and biotic evidence of a warm-water enclave in the cooler oceans of the latest Ordovician glacial phase, Yangtze Platform, South China block

Abstract   During the Hirnantian period, the Yangtze Platform was situated in the western part of the South China block (SCB) before its later rotation, in the middle–low paleolatitudes of the southern hemisphere in the northeast side of peri-Gondwana. It is part of the Kosov faunal province as indicated by the Hirnantia fauna. Sedimentary evidence shows the domination of cool ventilated marine water from its offshore ramp and shelf. Hirnantian shallow-water carbonate facies (Kuanyinchiao Bed) overlie earlier Ashgill graptolitic black shales (Wufeng Formation) as a result of marine regression. In the Yangtze Platform, however, we have found local areas of intertidal to nearshore facies that lack the typical highly diverse Hirnantia fauna. Some warm-water features (radial oolites, peloids, diverse solitary rugose corals and other benthic shelly fauna) occur commonly in some limited shallow areas, forming grainstones and packstones. Although interglacial episodes within the Hirnantian glaciation could be responsible for these features, their limited occurrence within the interior of the platform leads us to interpret the deposits as indicating that cold-water currents from the southeastern high latitudes were partly excluded from the nearshore area of the Yangtze Platform. The landmass of the eastern SCB in the Hirnantian epoch prevented access to some areas of the cold marine water masses that flowed from higher latitudes of Gondwana; the result was a persistence of warm-water shallow marine facies in some areas.     

Evolution of the Bükk Mountains (NE Hungary) during the Middle–Late Triassic asymmetric rifting of the Vardar-Meliata branch of the Neotethys Ocean

Based on sedimentological and biostratigraphic investigations of the Middle–Late Triassic successions of the Bükk Mountains, the evolution of an upper plate margin of a rifting area was reconstructed. The Middle Anisian shallow water carbonates are succeeded by terrestrial sediments. Simultaneously with the uplift, volcanic activity starts, indicating the beginning of the rifting. The emersion was followed by rapid subsidence in the Late Anisian–Early Ladinian which corresponds to the synrift stage. Based on facies distribution of Ladinian–Carnian sediments, the half-graben structure of the basement can be outlined. Coeval existence of platforms and basins is characteristic of this period. From the end of the Fassanian, the subsidence slows down: postrift stage. At this time the thermal cooling controls the subsidence of the area. During the Late Triassic, the edges of the platforms were gradually drowned and basins conquered bigger and bigger areas. Sediments deposited on the southern shelf of the opening Vardar-Meliata branch of the Neotethys Ocean show features characteristic to the upper plate part of a rifting area, whereas sediments of the northern shelf show features characteristic to the lower plate. The opening of the Vardar-Meliata branch of the Neotethys Ocean follows the asymmetric rifting model of Wernicke (Can J Earth Sci 22:108–125, 1985) and Dixon et al. (Tectonics 8(6):1193–1216, 1989).     

Stratigraphic variation of complex impurities in platform limestones and possible significance of atmospheric dust: a study with emphasis on gamma-ray spectrometry and magnetic susceptibility outcrop logging (Eifelian-Frasnian, Moravia, Czech Republic)

Mineral dust and other constituents of Devonian atmospheric aerosols together with certain amounts of aquatic suspensions of riverine detrital origin, colloidal particle dispersions and seawater solutes were embedded in ~95–98% (or purer) limestones on a consistently subsiding isolated carbonate platform where they formed very complex impurity systems. Very low Th/U values, relative abundance of Fe but a slight excess of K typically characterize these ultrafine impurities which are mineralogically dominated by smectite–illite and mica (sericite) together with goethite. In vertical section, these impurities are arranged like incremental series of light and dense bands. The combined method of natural gamma-ray spectrometric and magnetic susceptibility measurements (GRS–MS) together with background of major and trace element analyses provided first systematic insights into fine-scale variability of these impurities in a pile of pure carbonate platform beds, mostly in inner platform Amphipora limestone facies. These carbonates were deposited close to sea level but far from river mouths, and they represented a certain sort of a relatively “independent” medium that was primarily sensitive to climatically (and by rare events) controlled input of atmospheric dust. A remarkable similarity of MS stratigraphic patterns that reflect the quantity and quality of embedded impurities in very distant and paleogeographically separated Devonian basins might be seen as supporting this viewpoint. A long composite stratigraphic section of the Moravian Karst ranges from mid-Eifelian to end-Frasnian levels and yields a number of time characterizing GRS–MS variations that can potentially serve as templates for high-resolution stratigraphic correlations over long distances.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

云南省地质灾害预报预警系统

基于云南省地质灾害综合研究成果，架构云南省地质灾害预报预警模型方法，认为：影响地质灾害活动是多种因素叠加，地质灾害系统是一个开放、复杂的灾害系统。在对影响地质灾害发生因素分析的基础上，可以利用相应的预测模型，对给定区域内发生地质灾害的危险度作预测，由此创建概念模型和数学模型，运用VB语言在MapGIS平台上进行二次开发，建立了云南省地质灾害预报预警系统。     

Distribution of Precambrian iron and gold deposits on the southwestern East European Platform reflected in underlying transcrustal structure and current river systems

The East European Platform is underlain by Archaean and Proterozoic complexes of the East European Craton. In the southwest these are locally exposed in the Ukrainian Shield and the Voronezh Massif on either side of the ca. 2000 km long ESE-striking late Palaeozoic Pripyat–Dniepr–Donets rift. Evaluation with Landsat imagery of 1 : 1,000,000 scale published maps of the Precambrian complexes [Zaritsky, A.I., Galetsky, L.S. (Eds.), 1992. Geology and Metallogeny of the Southwest of the East-European Platform Map Series, 1 : 1,000,000, Ukrainian State Committee on Geology and Utilization of Mineral Resources, Kiev.] is largely obstructed by a cover of post-Palaeozoic sediments and soils of variable thickness. This obstruction is aggravated by an almost continuous patchwork of farmlands. However, analysis of the current drainage patterns in the Dniepr River basin and surrounding regions reveals a spatial coincidence of numerous stream courses and watersheds with previously inferred steep, transcrustal discontinuities of most probably Precambrian age.Transcrustal dislocations constituted important pathways for heat and fluids as is indicated by the distribution of a large proportion of assumed Early Proterozoic hydrothermal iron and gold deposits along them. This distribution is underpinned by the spatial coincidence of mineralization and elongate areas of highly irregular magnetization attributed to uneven distribution of hydrothermal magnetite in banded iron formation. In view of the extent of these dislocations, both vertically and laterally, the generation of hydrothermal fluid flow, emplacement of mantle-sourced magma and associated mineral potential away from banded iron formation complexes is likely. A second group of gold deposits, of Archaean age, is known to occur in association with still recognizable volcanic edifices in greenstone complexes. It is not known if and to what extent such Archaean gold deposits are related to these major transcrustal discontinuities. The kinematics and dynamics of these dislocations and pathways appear largely unknown and deserve high-priority investigation. The geological longevity of the transcrustal dislocation framework till the present day inferred from the current drainage systems is corroborated, however, by repeated regional topographical levelling surveys.     

Structure of the Zeya block of Toko Stanovik according to results of magnetotelluric sounding

The paper describes the results of magnetotelluric sounding (MTS) carried out in the Zeya block of the Stanovoi megablock, in the area of its junction with the Aldan Shield. The border between them runs along the Stanovoi fault. Based on the results of interpretation of MTS curves and the gravity, magnetic, and geological data, geological/geophysical sections have been constructed to a depth of 7 km along two ~ 20 km long profiles running across the Stanovoi fault. About 1 km thick and approximately 2 km long conductivity zone has been distinguished beneath the Okonon plateau of Quaternary basalts with electrical resistivity of < 100 Ohmm. This anomaly is associated with ore mineralization in Early Proterozoic gabbro intrusion. A 3D density modeling was performed. High-density bodies of NW strike dip to the northeast to a depth of 25 km in the area of the Okonon basalt plateau.^?Corresponding author.     

C and Sr isotope chemostratigraphy of Vendian-Lower Cambrian carbonate sequences in the central Siberian Platform

We propose a detailed δ¹³C curve for the Vendian and Lower Cambrian (Tommotian) strata of the central Siberian Platform. Two positive carbon isotope excursions identified near the base of the Yuryakh Formation (up to 5.5‰) and in the lower Bilir Formation (up to 5‰) are assigned to the lowermost and middle Tommotian, respectively. This correlation is supported by paleontological data, specific ⁸⁷Sr/⁸⁶Sr values (0.70845-0.70856), and similar C isotope record in coeval Early Cambrian basins. The documented minor vertical oscillations (a few meters) of these isotope excursions relative to the formation boundaries in remote boreholes is presumably caused by the spatiotemporal migration of facies. A high-amplitude negative δ¹³C excursion (-8 to -11‰) in the upper Nepa Regional Stage putatively corresponds to the global Shuram-Wonoka negative carbon isotope excursion (Middle Ediacaran). Carbonates of the lower Nepa Regional Stage (Besyuryakh Formation) demonstrate positive δ¹³C values (up to 5‰) and minimum ⁸⁷Sr/⁸⁶Sr ratios of 0.70796-0.70832. The C and Sr isotope record of the Nepa Regional Stage provides its robust correlation with the Dal’nyaya Taiga and Zhuya Groups of the Patom Foredeep. Micropaleontological data herein reported and glacial diamictites documented at the base of the Vendian sedimentary cover both in the central Patom Foredeep and on its periphery suggest a full stratigraphic volume of the Ediacaran System in the most stratigraphically complete sections of the central Siberian Platform.     

Growth and demise of the Jurassic carbonate platform in the intracratonic Paris Basin (France): Interplay of climate change,eustasy and tectonics

It is usually very difficult to identify and quantify the relative influence of tectonics, eustasy and climate on carbonate system evolution from sedimentary records. In order to improve our understanding of these mechanisms, we have traced for the first time, the evolution of the eastern Paris Basin platform throughout the entire Jurassic period. This carbonate platform underwent eight successive growth and demise phases, with different depositional profiles ranging from ramps to flat-topped geometries. The eight carbonate growth periods are compared with the standard sea-level curves, local tectonic regimes and recently published oxygen-isotope and/or clay mineralogy databases. Prograding heterozoan facies along ramp profiles mark periods dominated by second-order eustatic sea-level rise, relatively cool sea surface temperatures, and mesotrophic and humid conditions (Hettangian, Pliensbachian, late Oxfordian, Tithonian). During these periods, variable detrital contents in the sedimentary succession hampered the efficiency of shallow-marine carbonate factories. Higher sea surface temperatures, oligotrophic and humid conditions associated with either eustatic sea-level rise or very high local subsidence occurred during the early Bajocian and the mid-Oxfordian. These seawater properties seem to have favoured the aggradation of scleractinian corals forming dome-shaped bioherm buildups. An oolitic and lime-mud carbonate system, deposited during the Bathonian second-order eustatic sea-level fall, is characterised by miliolid-rich micritic facies on a rimmed-ramp under stable, cooler and drier conditions. The second-order maximum flooding associated with a sea surface temperature decline and/or a seawater eutrophication caused at least five carbonate demise periods (i.e. Toarcian, earliest late Bajocian, Callovian/Oxfordian transition, earliest late Oxfordian and Kimmeridgian).     

Natural gas potential of Neoproterozoic and lower Palaeozoic marine shales in the Upper Yangtze Platform,South China: geological and organic geochemical characterization

In this article, we describe the geological features of the Ediacaran (upper Sinian), lower Cambrian and lower Silurian shale intervals in the Upper Yangtze Platform, South China, and report on the gas potential of 53 samples from these major marine shale formations. Reflected light microscopy, total organic carbon (TOC) measurement, Rock-Eval, carbon isotope ratio analysis, thermovaporization gas chromatography (Tvap-GC), and open pyrolysis gas chromatography (open py-GC) were used to characterize the organic matter. Measured TOC in this research is normally >2% and averages 5%. TOC contents are roughly positively correlated with increasing geological age, i.e. lower Silurian shales exhibit generally lower TOC contents than lower Cambrian shales, which in turn commonly have lower TOC contents than Ediacaran shales. Kerogen has evolved to the metagenesis stage, which was demonstrated by the abundant pyrobitumen on microphotographs, the high calculated vitrinite reflectance (R_o = 3%) via bitumen reflectance (R_b), as well as δ¹³ C of gas (methane) inclusions. Pyrolysates from Tvap-GC and open py-GC are quantitatively low and only light hydrocarbons were detected. The lower Silurian shale generally exhibits higher generation of hydrocarbon than the lower Cambrian and Ediacaran shale. Cooles’ method and Claypool’s equations were used to reconstruct the original TOC and Rock-Eval parameters of these overmature samples. Excellent original hydrocarbon generation was revealed in that the original TOC (TOC_o) is between 5% and 23%, and original S1+S2 (S1_o+S2_o) is ranging from 29 to 215 mg HC/g rock.