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91.
CSA mine exploits a ‘Cobar-type’ Cu–Pb–Zn±Au±Ag deposit within a cleaved and metamorphosed portion of the Cobar Supergroup, central New South Wales. The deposit comprises systems of ‘lenses’ that encompass veins, disseminations and semi-massive to massive Cu–Pb–Zn ores. The systems and contained lenses truncate bedding, are approximately coplanar with regional cleavage and similarly oriented shear zones and plunge parallel to the elongation lineation. Systems have extreme vertical continuity (>1000 m), short strike length (400 m) and narrow width (100 m), exhibit vertical and lateral ore-type variation and have alteration haloes. Models of ore formation include classical hydrothermalism, structurally controlled remobilisation and polymodal concepts; syntectonic emplacement now holds sway.Fluid inclusions were examined from quartz±sulphide veins adjacent to now-extracted ore, from coexisting quartz–sulphide within ore, and from vughs in barren quartz veins. Lack of early primary inclusions precluded direct determination of fluids associated with D2–D3 ore and vein emplacement. Similarly, decrepitation (by near-isobaric heating) of the two oldest secondary populations precluded direct determination of fluid phases immediately following D2–D3 ore and vein emplacement. Post-decrepitation outflow (late D3 to early post-D3) is recorded by monophase CH4 inclusions. Entrained outflow of deeply circulated meteoric fluid modified the CH4 system; modification is recorded by H2O+CH4 and H2O+(trace CH4) secondary populations and by an H2O+(trace CH4) primary population. The contractional tectonics (D2–D3) of ore emplacement was superseded by relaxational tectonics (D4P) that facilitated meteoric water penetration and return flow.Under D2 prograde metamorphism, entrapment temperatures (Tt) and pressures (Pt) for pre-decrepitation secondary inclusions are estimated as Tt300–330 °C and Pt1.5–2 kbar≈Plith (the lithostatic pressure). Decrepitation accompanied peak metamorphism (T350–380 °C) in mid- to late-D3, while in late-D3 to early post-D3, essentially monophase CH4 secondary inclusions were entrapped at Tt350 °C and Pt=1.5–2 kbar≈Plith. Subsequently, abundant CH4 and entrained meteoric water were entrapped as H2O+CH4 secondaries under slowly decreasing temperature (Tt330–350 °C) and constant pressure (Pt1.5–2 kbar). Finally, with increasingly dominant meteoric outflow, H2O+(trace CH4) populations record decreasing temperatures (Tt>300 to <350 down to 275–300 °C) at pressures of Phydrostatic<Pt (1 kbar) <Plith (1.5 kbar).The populations of inclusions provide insight into fluid types, flow regimes and P–T conditions during parts of the deposit's evolution. They indirectly support the role of basin-derived CH4 fluids in ore formation, but provide no insight into a basement-sourced ore-forming fluid. They fully support post-ore involvement of meteoric water. The poorly constrained entrapment history is believed to span 10 Ma from 395 to 385 Ma. 相似文献
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高坪-吉心段公路喀斯特工程地质综合勘察 总被引:1,自引:0,他引:1
以沪蓉国道主干线湖北省高坪-吉心段的喀斯特地质勘察工作为例,探讨喀斯特地区公路工程地质综合勘察的基本方法。在喀斯特地区运用遥感和地理信息技术技术、地质测绘、综合物探以及地质钻探等勘察手段,通过综合分析各种勘探成果,能够较准确地查明可溶岩的分布、喀斯特形态类型、分布规律、控制因素以及喀斯特水的赋存、分布和运移规律等,并根据不同的喀斯特地貌提出了有针对性的处理对策。通过不断的实践和经验总结。针对喀斯特工程地质问题合理运用综合工程勘察方法,能做出科学的分析评价,可以适应喀斯特区公路建设的需要,并且供今后在喀斯特地区修建公路时参考和借鉴。 相似文献
94.
About 70% of its land area as mountains and plateaus,China is the largest mountain countryin the world.Thanks to its vast territory (9.6 million km2),outstanding relief and varied climates,China boasts extremely plenty of ecosystems and landscapes.From south to north,it traverses almostall the temporal zones from tropical rainforest in the southernmost to frigid-temperate needle-leavedforest in the northernmost; from east to west,it sees a gradual transition fro humid forest landscape toextremely arid desert landscape; vertical change of landscapes is most striking owing to the existenceof many high mountains (above 6000-7000 m,e.g.,the Himalayas,the Kunlun,the Tianshan,theHengduan,etc.) and plateaus,especially the immense Tibetan Plateau (averagely 4500 m above sealevel).All of this give rise to the richness and diversity of ecosystems and landscape in China.Some ofthe ecosystems are endemic to China,e.g.,alpine desert and alpine steppe in the Tibetan Plateau.As aresult,China bears a great responsibility in the protection of global ecosystems and landscape. 相似文献
95.
以2000网为例,根据1991~2001年累积的GPS重复观测资料,利用GIPSY软件建立具有1115个测点的地壳运动模型。在此基础上,采用双三次样条函数数值拟合法,模拟出2000网网点相对西安基准站的地壳形变改正值,并给出了效果图。 相似文献
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Liu Xiqiang 《中国地震研究》2005,19(3):269-281
INTRODUCTIONThe structural mine earthquake in coal mines refers to the quake induced by excavationengineeringthatleadstorupturingor change of geological structure and weakness surfaceintheinteriorof rock mass.According to the origin,mine earthquakes can b… 相似文献
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为探明宁东煤田枣泉矿井首采区煤层自然范围及充水性,根据采区内地球物理物征,采用高精度磁法,直流电测深法和激发极化法进行综合勘探。在磁法勘探中结合测区曲线特征,建立数据体模型,正演计算烧变岩边界;电法勘探利用烧变岩含水后电阻率降低的特征确定其含水范围及富水性。 相似文献
100.
This paper concerns the performance of national war memory at the Changi Chapel and Museum, a site honouring the many prisoners interned in Japanese-Occupied Singapore—especially at Changi—during the Second World War. In the light of the global nature of ‘the Changi story’, and the predominantly transnational nature of its present in situ memorialisation, we first examine how the Singapore state has sought to ‘localise’ the site to make it equally appealing to Singaporeans, as a place where a sense of their ‘shared history’ may be invoked. We then explore the Singaporeans' views about the site and its reconfiguration as a national icon, arguing how the state's task of ‘localising’ the site has been a vexed process due to myriad factors such as ethnic and religious plurality, and the already foreign-centric bias of prevailing knowledge about Changi. Following that, we show how this performance of national memory is also inflected by Australia's national remembrance of the same event. More broadly, we highlight the contested process of ‘localising’ such war memoryscapes as national iconography, suggesting how it may be more fruitful to conceive them as ‘international memoryscapes’, or places to which all individuals can relate regardless of race or national affiliations. 相似文献