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91.
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上宫构造蚀变岩型金矿床地质特征及化探找金经验 总被引:1,自引:0,他引:1
上宫金矿位于河南省西部熊耳山北麓,在该区1 020 km2范围内进行了1:5万的地球化学水系沉积物测量,按水系划分取样单元,取样本着"小沟多取,支流放稀,大河不管"的原则进行。本次水系沉积物测量的特点是:取样少,控制面积大,速度快,省钱、省人、省物,找矿效果好、经济效益好。本区水系沉积物测量中所发现的金异常,后经异常检查、地质普查评价及钻探验证,确定为一大型构造蚀变岩型金矿床。 相似文献
94.
Early carbonate cements in the Yanchang Formation sandstones are composed mainly of calcite with relatively heavier carbon isotope (their δ^18O values range from -0.3‰- -0.1‰) and lighter oxygen isotope (their δ^18O values range from -22.1‰- -19.5‰). Generally, they are closely related to the direct precipitation of oversaturated calcium carbonate from alkaline lake water. This kind of cementation plays an important role in enhancing the anti-compaction ability of sandstones, preserving intragranular volume and providing the mass basis for later disso- lution caused by acidic fluid flow to produce secondary porosity. Ferriferous calcites are characterized by relatively light carbon isotope with δ^13C values ranging from -8.02‰ to -3.23‰, and lighter oxygen isotope with δ^18O values ranging from -22.9‰ to -19.7‰, which is obviously related to the decarboxylation of organic matter during the late period of early diagenesis to the early period of late diagenesis. As the mid-late diagenetic products, ferriferous cal- cites in the study area are considered as the characteristic authigenic minerals for indicating large-scaled hydrocarbon influx and migration within the clastic reservoir. The late ankerite is relatively heavy in carbon isotope with δ^13C values ranging from -1.92‰ to -0.84‰, and shows a wide range of variations in oxygen isotopic composition, with δ^18O values ranging from -20.5‰ to -12.6‰. They are believed to have nothing to do with decarboxylation, but the previously formed marine carbonate rock fragments may serve as the chief carbon source for their precipitation, and the alkaline diagenetic environment at the mid-late stage would promote this process. 相似文献
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CHEN Jing'an WANG Fushun WAN Guojiang TANG Degui David Dian ZHANG HUNAG Ronggui LI Jian XIAO Tangfu 《《地质学报》英文版》2008,82(5)
The correlation between theδ~(13)C andδ~(18)O in primary carbonates is affected by several factors such as hydrological balance,total CO_2 concentrations,climatic condition and lake productivity. The influence of these factors on theδ~(13)C-δ~(18)O correlation may be different on different time scales.In this paper,two different-type lakes in southwestern China,Lake Erhai and Lake Chenghai,are selected to investigate the influence of climatic pattern on theδ~(13)C-δ~(18)O correlation and to evaluate the reliability of theδ~(13)C-δ~(18)O covariance as an indicator of hydrological closure.The results show that there exists good correlation between theδ~(13)C andδ~(18)O in Lake Erhai (overflowing open lake) and in Lake Chenghai (closed lake).This suggests that theδ~(13)C-δ~(18)O covariance may be not an effective indicator of hydrological closure for lakes,especially on short time scales.On the one hand,a hydrologically open lake may display covariantδ~(13)C andδ~(18)O as a result of climatic influence.The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of theδ~(13)C-δ~(18)O covariance in Lake Erhai and Lake Chenghai.On the other hand,a hydrologically closed lake unnecessarily displays covariant trends betweenδ~(13)C andδ~(18)O because of the buffering effect of high CO_2 concentration on theδ~(13)C shift in byper-alkaline lakes.We should be prudent when we use the covariance betweenδ~(13)C andδ~(18)O to judge the hydrological closure of lake. 相似文献
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湖子地区位于NNE向诸广-新兴铀成矿带与近EW向大东山-漳州大断裂复合部位,是华南早、晚两期铀成矿热液活动叠加区、放射性高场区,既有"硅化带大脉"型铀矿产出,又有"交点"型铀矿存在,找矿前景良好.文章在论述下庄矿田铀成矿地质环境、铀成矿特征及铀矿定位条件基础上,分析了湖子地区铀成矿条件与找矿前景,指出该区今后铀矿找矿方向是:① 6009号硅化断裂带,在其北段找硅化带大脉型铀矿,在其南段找"交点"型铀矿;②新桥-下庄硅化断裂带和6009号带之间成矿部位,寻找硅化带型和"交点"型铀矿;③NW向、近EW向辉绿岩脉与NNE向、NE向构造交汇部位(交点),寻找"交点"型铀矿. 相似文献
99.
川西坳陷中段天然气碳同位素特征及其成因类型 总被引:3,自引:1,他引:2
川西坳陷中段天然气的组份以烃类气体为主,占气体总体积的98.1%~99.7%;非烃气体以CO,2和N2为主,其含量分别占气体的0.12%~1.32%和0.25%~1.54%;烃类气体中以甲烷占绝对优势,平均含量为95.83%;重烃含量较低,平均为3.21%;干燥系数(C1/C,1-5>)平均为0.97,整体上属典型的干气.川西坳陷中段的所有样品δ13C,2都大于-25.8‰,属于典型的煤型气范畴,天然气的δ13C,1δ'13C,2δ13C,3,呈明显的正序排列,显示出天然气为典型的有机成因.甲烷碳同位素组成,反映了其母质演化程度已处于成熟~高成熟阶段,且以高成熟阶段为主. 相似文献
100.