Coal seam gas distribution and hydrodynamics of the Sydney Basin,NSW, Australia     

A. Burra  J. S. Esterle  S. D. Golding 《Australian Journal of Earth Sciences》2014,61(3):427-451

This paper reviews various coal seam gas (CSG) models that have been developed for the Sydney Basin, and provides an alternative interpretation for gas composition layering and deep-seated CO₂ origins. Open file CSG wells, supplemented by mine-scale information, were used to examine trends in gas content and composition at locations from the margin to the centre of the basin. Regionally available hydrochemistry data and interpretations of hydrodynamics were incorporated with conventional petroleum well data on porosity and permeability. The synthesised gas and groundwater model presented in this paper suggests that meteoric water flow under hydrostatic pressure transports methanogenic consortia into the subsurface and that water chemistry evolves during migration from calcium-rich freshwaters in inland recharge areas towards sodium-rich brackish water down-gradient and with depth. Groundwater chemistry changes result in the dissolution and precipitation of minerals as well as affecting the behaviour of dissolved gases such as CO₂. Mixing of carbonate-rich waters with waters of significantly different chemistries at depth causes the liberation of CO₂ gas from the solution that is adsorbed into the coal matrix in hydrodynamically closed terrains. In more open systems, excess CO₂ in the groundwater (carried as bicarbonate) may lead to precipitation of calcite in the host strata. As a result, areas in the central and eastern parts of the basin do not host spatially extensive CO₂ gas accumulations but experience more widespread calcite mineralisation, with gas compositions dominated by hydrocarbons, including wet gases. Basin boundary areas (commonly topographic and/or structural highs) in the northern, western and southern parts of the basin commonly contain CO₂-rich gases at depth. This deep-seated CO₂-rich gas is generally thought to derive from local to continental scale magmatic intrusions, but could also be the product of carbonate dissolution or acetate fermentation.  相似文献   

Isotopic Composition of Dissolved Carbonates Meromictic Soda Lake Doroninskoe(Eastern Transbaikalia,Russia)   总被引：1，自引：0，他引：1  

Leonid V. ZAMANA  Svetlana V. BORZENKO 《《地质学报》英文版》2014,88(Z1):395-397

正1 Introduction Meromictic soda Lake Doroninskoe localized in the intermountain area,filled with continental sediments of the Mesozoic,in the upper basin of the river Amur.Coordinates of its location are N51°14'42"E112°14'40",  相似文献   

Primary carbonate/CO₂ inclusions in sapphirine-bearing granulites from central Sri Lanka     

Bolder-Schrijver  Kriegsman  & Touret 《Journal of Metamorphic Geology》2000,18(3):259-269.

High-density CO₂-rich fluid inclusions from a sapphirine-bearing granulite (Hakurutale, Sri Lanka) have been studied by microthermometry, Raman spectrometry and SEM analysis. Based on textural evidence, two groups of inclusions can be identified: primary, negative crystal shaped inclusions (group I) and pseudo-secondary inclusions, which experienced a local, limited post-trapping modification (group II). Both groups contain magnesite as a daughter mineral, occurring in a relatively constant fluid/solid inclusion volume ratio (vol_solid =0.15 total volume). CO₂ densities for group I and II differ only slightly. Both groups contain a fluid, which was initially trapped at peak metamorphic conditions as a homogeneous (CO₂+MgCO₃) mixture. Thermodynamic calculations suggest that such a fluid (CO₂+15 vol% MgCO₃) is stable under granulite facies conditions. After trapping, magnesite separated upon cooling, while the remaining CO₂ density suffered minor re-adjustments. A model isochore based on the integration of the magnesite molar volume in the CO₂ fluid passes about 1.5–2 kbar below peak metamorphic conditions. This remaining discrepancy can be explained by the possible role of a small quantity of additional water.  相似文献   

Superposition of gold mineralisation on pre‐existing carbonate alteration: Structural evidence from the Mulgarrie gold deposit,Yilgarn Craton     

B. K. Davis  K. A. Hickey  S. Rose 《Australian Journal of Earth Sciences》2013,60(1):131-149

Carbonate alteration at the Mulgarrie gold mine in the Eastern Goldfields of Western Australia, is represented by porphyroblasts, veins and pervasive, texturally destructive, carbonatisation. Two foliations, S_1M and S_2M, were produced by two separate deformation events at the mine‐scale, D_1M and D_2M. D_1M and D_2M both occurred in response to regional D₂ tectonism. Carbonate alteration was the product of two separate episodes of fluid ingress: the earlier produced magnesite and the latter Fe‐dolomite. Both periods of carbonate alteration occurred pre‐ to early syn‐D_2M, when mafic to ultramafic komatiitic rocks reacted with fluids that moved along regional faults and pre‐date the alteration associated with regional peak metamorphism. Gold at Mulgarrie overprints pre‐ and late syn‐D₂ quartz veins in zones of massive carbonate alteration, suggesting it has a late‐ to post‐D₂ timing. This late timing agrees with the generally accepted syn‐D₃ (and younger) age for gold mineralisation in the Eastern Goldfields. We suggest that carbonate alteration at Mulgarrie is not a product of the hydrothermal event responsible for the gold mineralisation. Rather, the different relative timing of magnesite, Fe‐dolomite and gold indicates there were two carbonate‐producing fluid systems and a fluid transporting the gold overprinted these. Similarly, early carbonate alteration may play a role in localising auriferous vein deposits throughout the Yilgarn and other Archaean cratons.  相似文献   

Transfort of oxygen,nutrients and carbonates by the Kuroshio Current   总被引：1，自引：0，他引：1  

C. T. A. Chen  C. T. Liu  S. C. Pai 《中国海洋湖沼学报》1994,12(3):220-227

Measured concentrations of dissolved oxygen, phosphate, silicate, total alkalinity and calculated total CO₂ in a section between 121° E and 125° E across the Kuroshio near 22° N off Taiwan and the geostrophic velocity were used to estimate the gross transport of oxygen, nutrients and carbonates. The flux of dissolved oxygen is 6.7×10⁶ mol/s northward and 0.9×10⁶ mol/s southward. The net flux equals 5.8×10⁶ mol/s down-stream. The northward flux of phosphate is 22.6×10³ mol/s; the southward flux is 1.4×10³ mol/s. The net phosphate flux is 21.2×10³ mol/s northward. The flux of silicate is 967×10³ northward and 59×10³ mol/s southward; the net transport is 908×10³ mol/s down-stream. The flux of alkalinity is 75.5×10⁶ mol/s northward, and 10.8×10⁶ mol/s southward, the net flux is 64.7×10⁶ mol/s northward. For total CO₂ the transport is 73.4×10⁶ mol/s northward and 10.8×10⁶ mol/s southward, or a net transport of 62.6×10⁶ mol/s horthward.  相似文献   

碳酸盐矿物激光原位U-Pb定年基本原理、分析方法与地学应用     

高伊雪  邱昆峰  于皓丞  侯照亮  魏瑜吉 《岩石矿物学杂志》2022,41(4):786-803

碳酸盐矿物作为地壳中沉积作用与流体活动的直接产物,记录了沉积、热事件的全过程,是进行同位素年代学研究的理想矿物。碳酸盐矿物传统的U系列定年法、同位素稀释法定年体系成功率低,耗时长,导致定年难度大,限制了碳酸盐矿物地质年代学的发展。近年来,碳酸盐矿物激光原位U-Pb定年技术取得重要进展,使低U碳酸盐矿物地质年代的精确测定成为了可能。碳酸盐矿物LA-ICP-MS U-Pb年代学具有空间分辨率高、耗时短等显著优势,被广泛应用于地学研究中。文章归纳总结了碳酸盐矿物同位素定年体系的基本原理及分析方法,回顾了近5年碳酸盐矿物LA-ICP-MS U-Pb年代学应用的研究进展,重点论述该方法在确定脆性变形时代、岩石破裂以及盆地流体流动时限、碳酸盐地层的成岩时代和成矿热液活动时限4个方面的应用,并梳理了该方法尝试解决的科学问题和取得的新认识。碳酸盐矿物定年方法的发展和应用,增强了人们对地壳变形和演化的理解,解决了部分迄今为止难以确定的地质体历史演化问题,为未来地质年代学的研究提供了新思路,在地球科学研究中具有重要潜力。  相似文献   

Hydrocarbon Inclusion Characteristics in the Cambrian-Ordovician Carbonates of the TS2 Well: Implication for Deep Hydrocarbon Exploration in the Tahe Oilfield,Tarim Basin,Northwest China     

LI Chunquan  CHEN Honghan 《《地质学报》英文版》2015,89(3):852-860

Going deep has been the strategy for the sustainable development of the Tahe Oilfield.Following the TS1 well in block 1,which revealed excellent combinations of hydrocarbon generation,migration and accumulation in the deeper parts of the Tarim Basin,the TS2 well was drilled to learn more about the prospectivity in the deeper parts of the main blocks of the Tahe Oilfield.Seventeen core samples were collected to perform fluid inclusion studies,including petrography,fluorescence microspectrometry,and microthermometry.The results show that the deeper parts of the Tahe Oilfield have a good hydrocarbon potential.The Cambrian source rocks can supply sufficient oil for not only the Cambrian reservoirs,but also for the Lower Ordovician reservoirs.The CambrianOrdovician carbonates reservoirs experienced at least three oil charging events and one late gas charging event.Oil accumulations formed in the early stage of basin evolution were likely destroyed in the late stage with deep burial,tectonic movements,or invasion of hydrothermal fluids.Therefore,the deep hydrocarbon exploration of the Tahe Oilfield,even the whole Tarim Basin,should focus on gas accumulations,although oil accumulations,especially in Cambrian reservoirs,cannot be neglected.  相似文献   

Rajkanella hottingerinaformis n. gen., n. sp., a new larger benthic foraminifer from the middle-upper Cenomanian of Kosovo     

《Cretaceous Research》2015

A new larger benthic porcelaneous foraminifer of soritid affinity is described as Rajkanella hottingerinaformis n. gen., n. sp. from the middle-upper Cenomanian of Kosovo. It occurs in foraminiferal packstones and grainstones, in association with cuneolinids, rhapidionids, chrysalidinids, and other benthic foraminifers. Due to its general morphology and superficial chamber subdivision by exoskeletal elements, Rajkanella n. gen. can be compared with the early Paleogene genus Hottingerina Drobne, 1975, from which it mainly differs in its apertural features, ornamented test, and coiled adult stage. Further differences to coeval Pseudorhapydionina De Castro, 1971, Pseudorhipidionina De Castro, 1971, and to other comparable genera, are discussed. The discovery of Rajkanella hottingerinaformis in the middle-upper Cenomanian is a further witness of the significant radiation and blooming of increasingly complex porcelaneous foraminifers in inner platform, shallow-water depositional settings during that period.  相似文献   

Middle and Late Devonian microbial carbonates,reefs and mounds in Guilin,South China and their sequence stratigraphic,paleoenvironmental and paleoclimatic significance   总被引：2，自引：0，他引：2  

Pedoja Kevin 《中国科学D辑(英文版)》2005,48(11):1900-1912

The importance of calcimicrobes and microbialite in carbonate platform and reefal environments has been stressed in recent literature. Burne and Moore[1] introduced the term microbialite to describe the clotted, laminated and undifferentiated fabrics formed by mi-crobial communities. Microbialites are organosedi-mentary deposits that have accreted as a result of ben-thic (prokaryotic or eukaryotic) communities, trapping and binding detrital sediment[1]. Microbial organisms and microbialite are…  相似文献   

NMR Measurements in Carbonate Rocks: Problems and an Approach to a Solution   总被引：2，自引：0，他引：2  

Hildegard?WestphalEmail author  Iris?Surholt  Christian?Kiesl  Holger F. ?Thern  Thomas?Kruspe 《Pure and Applied Geophysics》2005,162(3):549-570

Carbonate rocks are well known for their complex petrophysical behavior where, in contrast to siliciclastic rocks, different parameters, including porosity and permeability, usually are not directly related. This behavior is the result of thorough reorganization of porosity during diagenesis, and it turns prediction of reservoir quality of carbonate rocks into a challenge. The study presented here deals with the problem of utilizing NMR techniques in prediction of petrophysical properties in carbonates.We employ a visual porosity classification as a priori knowledge for better interpreting NMR data for prediction purposes. This allows for choice of suitable T₂ cutoff values to differentiate movable from bound fluids adapted for the specific carbonate rock, thus resulting in better interpretation of NMR data. The approach of using a genetic pore type classification for adapting the conventional method for T₂ cutoff determination, which originally was developed for siliciclastic rocks, is promising. Similarly, for permeability determination on the basis of NMR measurements, the classification of carbonate rocks based on porosity types also shows potential. The approach implemented here has the promise to provide a basis of standardized interpretation of NMR data from carbonate rocks.Acknowledgment We are grateful to Baker Hughes INTEQ, Celle, for permission to publish the results of this work. This study was part of I.S.s Masters Thesis at Hannover University that was carried out in collaboration with Baker Hughes INTEQ, Celle, Germany. We appreciate comments of an anonymous referee and PAGEOPH editor Brian J. Mitchell.  相似文献