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81.
在区域成矿环境及典型矿床研究的基础上,系统总结了黑龙江沉积变质型晶质石墨矿成矿特征,深入分析了成矿地质作用及控矿因素。建立了柳毛式沉积变质型晶质石墨典型矿床区域预测模型,在预测工作区圈定和优选了217个最小预测区,采用地质体积法估算石墨矿物的预测资源量。指出黑龙江石墨找矿潜力大,为今后石墨矿勘查部署提供了重要的地质依据。 相似文献
82.
为了解富锦隆起的构造演化,研究了佳木斯地块东北部富锦隆起地区一套含砾粗砂岩-石英砂与花岗片麻岩不整合面。LA-ICP-MS锆石U-Pb年代学结果表明,花岗片麻岩的加权平均年龄为495±5 Ma,石英砂岩中的碎屑锆石年龄均480 Ma,其中以480~520 Ma的年龄组为主体,并含有少量年龄800 Ma的锆石。角度不整合及年代学证据充分表明,富锦隆起是佳木斯地块的组成部分。鉴于佳木斯地块缺失奥陶纪—志留纪沉积,推测这套含砾粗砂岩-石英砂岩的形成时代为泥盆纪。结合区域资料,认为佳木斯地块的变质结晶基底形成后,经历了长期的隆升剥蚀,到早泥盆世,其东部整体转为被动大陆边缘。 相似文献
83.
84.
科学钻探深井结晶岩处在高地应力、高地层压力和高地温的“三高”环境中,自身的结构特征和物化特性会发生根本性变化,因温度变化引起的应力变化极易导致井壁失稳。本文依据温压耦合影响下坍塌压力和破裂压力计算模式,确定不同井壁温度下的安全钻井液密度窗口,通过FLAC3D开展温压耦合影响下井壁稳定数值模拟,分析在不同钻井液密度下井眼打开后不同时间的井壁周边温度和井壁稳定变化情况。结果表明:地层弹性参数对地层破裂压力的影响较大,对于花岗岩此类弹性模量较大的结晶岩,温度变化对破裂压力影响更大;井壁处附加应力受温度变化的影响程度:附加周向应力>附加径向应力>附加垂向应力;在最小主应力方向的井壁周边地层等效应力与钻井液密度呈正比关系,在最大主应力方向呈反比关系。 相似文献
85.
According to the geological and seismic reflection data of the Chinese Continental Scientific Drilling (CCSD) main-hole (MH), and the anomalies of CH4, CO2, and He are correlated to the three-component seismic reflectors, especially in horizontal component profiles. However, the seismic response is dif-ficult to be explained as the porosity of crystalline rocks is only about 1% in well section where the gas anomalies occur. Seismic velocity measurement of the MH cores indicated that compared with wa-ter-saturated rock samples, seismic velocity (especially the S-wave) could be distinctly decreased by gas contained in tiny cracks despite of the low porosity, and then notable seismic response could be induced in gas-filled crystalline rocks. It could be predicated that if the porosity of certain rocks in the middle crust rose due to water-rock interaction and had natural gas filled, then there would be more probability for natural gas in top of the mid-crust to fill in the crystalline rocks with increased porosity. In such case, based on the decrease of Swave velocity in crystalline rocks, seismic method could be applied in the future to explore natural gas reservoirs in the middle crust. 相似文献
86.
基于DCT的重力异常数据处理正、反演方法具有较高的精度,计算方法稳定性优良。将基于DCT的重力异常水平一阶导数、垂向一阶导数、常密度单界面异常反演和Euler反褶积等正、反演方法用于大庆探区外围虎林盆地DB1线重力异常数据处理中,综合分析了该线重力场特征。利用基于DCT的Euler反褶积法反演出断层14条,分析了其中7条较深大断裂的性质。根据反演的结晶基底起伏情况和断裂构造剖面轨迹的基本特征,将DB1线划分为两隆两坳的构造格局,其中七虎林河断陷是由古新纪(E)断陷与早白垩纪(K1)残余盆地组成的2个旋回(E+ K1)的叠合盆地,而凯北坳陷为早白垩纪(K1)的残余盆地。把敦密南北支2条断裂确定为虎林盆地控盆断裂,阐述了控盆断裂的动力学特征。 相似文献
87.
Philippe Négrel 《Aquatic Geochemistry》1999,5(2):125-165
A small watershed (89 km2) underlain by granite or granite-gneiss in the Margeride mountains, southern Massif Central (France),
has been studied using the chemical and isotopic composition of its dissolved load, bed sediments and soils. Dissolved concentrations
of major ions (Cl, SO4, NO3, HCO3, Ca, Na, Mg, K, Al and Si), trace elements (Rb and Sr) and strontium isotopes have been
determined for three different hydrologic periods in the main stream of the Desges river and its tributaries.
The aim was to characterize the chemical and isotopic signatures of each reservoir in the watershed; signature changes are
interpreted as fluctuations in the different influencing components: rainwater, weathering products and anthropogenic addition.
In the study area, as in other watersheds in granite environments, the only source for input of chemical species into the
dissolved load at high altitude is chemical weathering and atmospheric deposition, whereas at lower altitude, human influence
plays a non-negligible role.
As precipitation is a major vehicle for the addition of dissolved chemical species into the hydrosystem, a systematic rainwater
study using an automatic collector was carried out over one year in order to better constrain rain elemental input. Corrections
for rainwater addition, using chloride as an atmospheric-input reference, were computed for selected elements and for 87Sr/86Sr
ratios. After these correction, the geochemical budget of the watershed was determined and the role of anthropogenic addition
was evaluated based on strontium isotope relationships.
For particulate matter, we used the normalization of chemical species relative to parent rocks and the element ratios which
reflect the depletion or enrichment in soils and sediments. Both the immobile- and mobile-element approaches have been tested,
using Ti/Zr and La/Ce ratios for the former and Ca/Sr, K/Rb, and K/Fe ratios for the latter.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
88.
Yuichi MORISHITA 《Resource Geology》1999,49(4):243-257
Abstract: Predominant Zn-rich ore bodies were found to a deep part of the Sakonishi area in the Kamioka mining district, Japan. The ore mineralization was recognized at 230 to 300m above sea level in the Sakonishi area. Since crystalline limestone is broadly distributed over the area, and the variation in isotopic composition is easily detected, the isotopic prospecting should be powerful in surveying of the extent of the ore bodies and the related hydrothermal system. Although isotopic anomalies have been extracted two-dimensionally so far, three-dimensional information is possibly more powerful. In this paper, Zn-rich ore bodies in the Sakonishi area are treated as hydrothermal ore deposits, and the importance of the activity of hydrothermal fluids during mineralization is emphasized. Oxygen and carbon isotopic ‘iso–surfaces’ are three-dimensionally calculated for the Sakonishi area. The δ18O values of crystalline limestone from the surface and from the drill holes range from +8. 1 to +21. 1% and from –2. 7 to +20. 4%, respectively. The δ13C values of crystalline limestone from the surface and from the drill holes range from –1. 0 to +5. 3% and from –7. 7 to +4. 6%, respectively. The oxygen and carbon iso-topic ratios at the mineralization level are extremely low, but there are exceptions as to carbon isotopes. The oxygen isotopic ratios of crystalline limestone may decrease by isotopic exchange reaction with a hydrothermal fluid, while the carbon isotopic ratios slightly change. Since the precipitated calcite from a hydrothermal fluid has low carbon isotopic ratio and various oxygen isotopic ratio depending on the formation temperature, the bulk sample of crystalline limestone containing the precipitated calcite has oxygen and carbon isotopic ratios of relatively low values accordingly. Thus the decrease mechanism for carbon isotopic ratio of crystalline limestone is different from that for oxygen isotopic ratio. Samples with the carbon isotopic ratio of –4 to –8% are considered to be crystallized from hydrothermal fluids. Since the oxygen and carbon isotopic ratios of crystalline limestone at the ore mineralization level are low, the ore bodies are considered to have formed by a prominent hydrothermal activity. Thus oxygen and carbon isotopic ratios of crystalline limestone can be used as an indicator of the related hydrothermal activity. The alteration such as chloritization is intense near fractures in the Sakonishi area, showing that the hydrothermal system is controlled by a fracture system. It is assumed that the decreased isotopic ratios indicate the high degree of reactivity with hydrothermal fluids, and the depleted zone in oxygen and carbon isotopes may correspond to the conduit of the hydrothermal fluids. 相似文献
89.
90.
中祁连东段湟源群的年代学新证据及其地质意义 总被引:7,自引:0,他引:7
根据新近获得的中祁连地块东段湟源群中变质火山岩(910±6.7)Ma和侵位于湟源群中的响河尔花岗岩(917±12)Ma的单颗粒锆石U-Pb年龄,结合区域地质背景分析认为(1)湟源群时代不是古元古代,而是中晚元古代,上限在900
Ma左右;(2)响河尔花岗岩是晋宁期花岗岩而非中条期花岗岩;(3)湟源群及侵位于其中的晋宁期花岗岩代表了中祁连晋宁旋回结晶基底,并非中条旋回结晶基底。湟源群时代的重新厘定使得已经建立的中祁连地块东段前寒武纪地层格架和中祁连地块性质、归属等问题需要重新审视和研究。 相似文献