Genesis of the Ciemas Gold Deposit and Relationship with Epithermal Deposits in West Java, Indonesia: Constraints from Fluid Inclusions and Stable Isotopes     

ZHENG Chaofei  ZHANG Zhengwei  WU Chengquan  YAO Junhua 《《地质学报》英文版》2017,91(3):1025-1040

The Ciemas gold deposit is located in West Java of Indonesia,which is a Cenozoic magmatism belt resulting from the Indo-Australian plate subducting under the Eurasian plate.Two different volcanic rock belts and associated epithermal deposits are distributed in West Java:the younger late Miocene-Pliocene magmatic belt generated the Pliocene-Pleistocene epithermal deposits,while the older late Eocene-early Miocene magmatic belt generated the Miocene epithermal deposits.To constrain the physico-chemical conditions and the origin of the ore fluid in Ciemas,a detailed study of ore petrography,fluid inclusions,laser Raman spectroscopy,oxygen-hydrogen isotopes for quartz was conducted.The results show that hydrothermal pyrite and quartz are widespread,hydrothermal alteration is well developed,and that leaching structures such as vuggy rocks and extension structures such as comb quartz are common.Fluid inclusions in quartz are mainly liquid-rich two phase inclusions,with fluid compositions in the NaCl-H20 fluid system,and contain no or little CO_2.Their homogenization temperatures cluster around 240℃-320℃,the salinities lie in the range of 14-17 wt.%NaCl equiv,and the calculated fluid densities are 0.65-1.00 g/cm~3.The values of δ~(18)O_(H2O-VSMOW)for quartz range from +5.5‰ to +7.7‰,the δD_(VSMOW) of fluid inclusions in quartz ranges from-70‰ to-115‰.All of these data indicate that mixing of magmatic fluid with meteoric water resulted in the formation of the Ciemas deposit.A comparison among gold deposits of West Java suggests that Miocene epithermal ore deposits in the southernmost part of West Java were more affected by magmatic fluids and exhibit a higher degree of sulfldation than those of Pliocene-Pleistocene.  相似文献   

Tropical coral reef coral patterns in Indonesian shallow water areas close to underwater volcanic vents at Minahasa Seashore,and Mahengetang and Gunung Api Islands          下载免费PDF全文

Hedi I. Januar  Neviaty P. Zamani  Dedi Soedarma  Ekowati Chasanah  Anthony D. Wright 《Marine Ecology》2017,38(2)

Coral community patterns on some Indonesian reefs influenced by CO₂ from underwater volcanic vents and nutrients from eutrophication pressures were examined. The overall aim of the study was to provide an insight into the significance of future ocean acidification compared to eutrophication pressures on tropical coral communities. Coral cover and seawater characteristics at acidified sites (with varied levels of eutrophication), i.e., moderate acidification (pH: 7.87 ± 0.04), low acidification (pH: 8.01 ± 0.04) and reference (pH: 8.2 ± 0.02), were observed at reefs associated with Minahasa Seashore, and Mahengetang and Gunung Api Islands. Results showed that coral community patterns varied among locations and acidified sites, e.g., domination of families such as Alcyoniidae, Acroporidae, Poritidae and Heliporidae, and with different levels of abiotic cover. Surprisingly, pH was not detected as the major determining factor. This finding probably relates to tropical seawater temperatures being high enough to still allow for aragonite deposition even at pH values down to 7.8. Nutrients (phosphate and dissolved inorganic nitrogen) were shown to be the main determining factors that influenced community patterns on the observed coral reefs. Overall, the results indicate that tropical coral reef community patterns will continue to vary as pH decreases to the predicted oceanic value of pH 7.8 over the next 100 years, and bio‐geo‐ecological characteristics and anthropogenic pressures will be the major factors determining Indonesian tropical coral community structure, compared to pH.  相似文献   

宁波地震台水位、地倾斜在印尼8.7、8.5级地震中的同震变化现象     

邱永平 《内陆地震》2006,20(4):336-341

分析了浙江省宁波地震台ZK03井动水位、VS垂直摆倾斜仪资料出现的异常,认为这些异常可能是印尼8.7、8.5级地震的同震变化现象。8.7级地震后,动水位表现为水震波引起的脉冲和阶跃变化并抬高水位。垂直摆倾斜仪资料表现为形变波引起的脉冲和阶跃变化,EW向出现最大幅度约为408.328 2×10-3″的脉冲式向东振荡波,并向西出现阶跃变化;NS向出现最大幅度约为295.191 7×10-3″的脉冲式向北振荡波,并产生向北阶跃变化。8.5级地震后,动水位表现为水震波引起的脉冲。垂直摆倾斜仪资料表现为形变波引起的脉冲和阶跃变化,EW向出现最大幅度约为306.280 9×10-3″的脉冲式向东振荡波,并向西出现阶跃变化;NS向出现最大幅度约为261.565 9×10-3″的脉冲式向北振荡波。  相似文献   

Rise and fall of the Eastern Great Indonesian arc recorded by the assembly, dispersion and accretion of the Banda Terrane, Timor     

Ron   《Gondwana Research》2006,10(3-4):207-231

New age, petrochemical and structural data indicate that the Banda Terrane is a remnant of a Jurassic to Eocene arc–trench system that formed the eastern part of the Great Indonesian arc. The arc system rifted apart during Eocene to Miocene supra-subduction zone sea floor spreading, which dispersed ridges of Banda Terrane embedded in young oceanic crust as far south as Sumba and Timor. In Timor the Banda Terrane is well exposed as high-level thrust sheets that were detached from the edge of the Banda Sea upper plate and uplifted by collision with the passive margin of NW Australia. The thrust sheets contain a distinctive assemblage of medium grade metamorphic rocks overlain by Cretaceous to Miocene forearc basin deposits. New U/Pb age data presented here indicate igneous zircons are less than 162 Ma with a cluster of ages at 83 Ma and 35 Ma. ⁴⁰Ar/³⁹Ar plateau ages of various mineral phases from metamorphic units all cluster at between 32–38 Ma. These data yield a cooling curve that shows exhumation from around 550 °C to the surface between 36–28 Ma. After this time there is no evidence of metamorphism of the Banda Terrane, including its accretion to the edge of the Australian continental margin during the Pliocene. These data link the Banda Terrane to similar rocks and events documented throughout the eastern edge of the Sunda Shelf and the Banda Sea floor.  相似文献   

Tropical forest monitoring and remote sensing: A new era of transparency in forest governance?   总被引：3，自引：0，他引：3  

Douglas O. Fuller 《Singapore journal of tropical geography》2006,27(1):15-29

The extent of tropical deforestation is now being tracked by actors in the nongovernmental, academic, private and government sectors using several different sources of satellite imagery. This paper presents an overview of the satellite systems that can be used for operational forest monitoring in the tropics and examines some recent trends in their use. It also reviews various satellite-based studies to map moist tropical forests and draws upon lessons learned from land cover mapping projects in several countries and regions. The case of Indonesia, examined as a nation undergoing rapid conversion of forest to other land uses, is contrasted with Brazil where satellite-based deforestation monitoring is fully operational. In Indonesia, the paper argues, the creation of a national monitoring system for tropical forest conversion is needed to create a source of transparent, reliable information on forest cover and condition. Such a system is likely to succeed if based on multitemporal, moderate-resolution optical data such as imagery provided by MODIS (Moderate Resolution Imaging Spectrometer). When MODIS images are complemented by radar and fine-resolution imagery from sensors such as IKONOS and QuickBird, areas of abrupt change can be identified and the causes potentially discerned. Thus, satellite imagery at multiple temporal and spatial resolutions can effectively increase transparency in the forestry sector by revealing the rate and extent of deforestation on an annual basis and identifying potential areas of illegal logging.  相似文献   

Livelihoods, fire and policy in eastern Indonesia   总被引：2，自引：0，他引：2  

Luca Tacconi  Yayat Ruchiat 《Singapore journal of tropical geography》2006,27(1):67-81

Indonesian legislation calls for a zero-burning policy. This approach to fire management is largely in response to significant negative impacts on the economy and the environment, not only in Indonesia but also the neighbouring region, that result annually from peat fires in Kalimantan and Sumatra. In this context, the present paper investigates the local use and management of fire in Flores and Sumba islands in eastern Indonesia. Our appraisals show that people's livelihoods depend on fire to maintain grasslands and, therefore, that the national policy and legislation for zero-burning is inappropriate and needs to be revised. This follows from the fact that not all fires cause damage and are unwanted. Through a series of rapid rural appraisal interviews, we found that the fires in grasslands are often lit intentionally to maintain the grasslands that local people use to sustain a variety of livelihood activities such as cattle rearing, hunting and farming. Although fires can damage or destroy remnant dry forests in eastern Indonesia, in order to be effective, future policy formulations need to account for this human livelihood dimension and the geographic variation in fuels, climate and land use.  相似文献   

Review of the source characteristics of the Great Sumatra–Andaman Islands earthquake of 2004     

William Menke  Hannah Abend  Dalia Bach  Kori Newman  Vadim Levin 《Surveys in Geophysics》2006,27(6):603-613

The December 26, 2004 Sumatra–Andaman Island earthquake, which ruptured the Sunda Trench subduction zone, is one of the three largest earthquakes to occur since global monitoring began in the 1890s. Its seismic moment was M ₀ = 1.00 × 10²³–1.15 × 10²³ Nm, corresponding to a moment-magnitude of M _w = 9.3. The rupture propagated from south to north, with the southerly part of fault rupturing at a speed of 2.8 km/s. Rupture propagation appears to have slowed in the northern section, possibly to ∼2.1 km/s, although published estimates have considerable scatter. The average slip is ∼5 m along a shallowly dipping (8°), N31°W striking thrust fault. The majority of slip and moment release appears to have been concentrated in the southern part of the rupture zone, where slip locally exceeded 30 m. Stress loading from this earthquake caused the section of the plate boundary immediately to the south to rupture in a second, somewhat smaller earthquake. This second earthquake occurred on March 28, 2005 and had a moment-magnitude of M _w = 8.5.  相似文献   

2004年印尼9级大震的构造成因及回顾性预测研究          下载免费PDF全文

郭安宁  陈家超  郭增建 《地震工程学报》2006,28(1):56-58

认为2004年12月26日印尼9级大震是印尼弧形深海沟的新扩展引起的。讨论了该震发生年份和具体日期的回顾性预测问题。  相似文献   

印度尼西亚M_w9.0地震序列与增温异常和天体引潮力的相关关系研究   总被引：1，自引：0，他引：1       下载免费PDF全文

马未宇  徐秀登  徐保华  张行才  徐杰 《地震工程学报》2006,28(2):129-133,158

初步分析了2004年印尼苏门答腊岛西海岸Mw9.0大地震的地质构造环境,回顾性研究了震前NCEP增温异常和天体引潮力附加构造应力变化。结果表明:主震临震期间NCEP全球分析温度资料(1 000 hPa)沿岛弧地震构造带具有明显增温异常和清晰的初始增温→加强→高峰→衰减→发震的时空演变规律;地震序列活动与增温异常起伏变化对应良好;主震和强余震皆发生在发震断裂带上的天体引潮力附加应力绝对值最大时段。此典型大震再次说明:NCEP温度资料与天体引潮力结合是地震短临预测的一个有希望的新思路。  相似文献   

福建数字地下流体网对远处大震映震能力分析   总被引：1，自引：0，他引：1  

郑小菁  陈莹 《福建地震》2006,(Z1)

本文收集、整理了2004年12月26日印尼苏门答腊西北近海8.7级地震和2005年印尼的8.5级和巴基斯坦的7.8级地震,我省地下流体数字化监测台网观测到的震时和震后效应。测点以永安-晋江断裂为界线,北边多数表现为水位上升,南边多数为下降。初步分析认为,这种现象可能与现代构造应力场有关。  相似文献