珠江口盆地荔湾凹陷上渐新统—早中新统物源特征及其对沉积充填的影响          下载免费PDF全文

邢作昌  张忠涛  林畅松  张博  洪方浩  张正涛 《中国地质》2020,47(5):1577-1588

利用化学蚀变指数法恢复物源区的风化历史及沉积物通量是一种经济实用、行之有效的方法。前人对珠江口盆地荔湾凹陷对应物源区的研究相对薄弱。本文通过对区内岩心测试数据进行化学蚀变指数分析,恢复晚渐新世—早中新世物源区的风化历史,并进行沉积物通量的估算,在此基础上探讨物源特征对研究区内沉积充填的控制作用。研究表明,晚渐新世研究区对应物源区经历了强烈风化阶段,该阶段产生的丰富的沉积物供给是研究区西北部快速进积、规模壮观的陆架边缘三角洲及斜坡重力流沉积体系发育的重要控制因素之一;早中新世,西北物源区风化减弱,沉积供给减少,但研究区东部沉积物供应较西部要充分得多,表明早中新世,研究区南部除了来自西北部的主要物源外,局部物源对该时期的沉积具有重要影响;推测东部物源(东部古隆起、兴宁古隆起)的突然复活是促进研究区东部早中新世沟槽形成发育的重要原因之一。在超深水区进行沉积物源区的研究中,这种半定量的方法对盆内局部物源的确定具有重要的指示意义。  相似文献   

大兴安岭北段富林矽卡岩铜矿床成因:印支期含矿岩浆源区特征、蚀变矿物学及勘查意义     

赵超  宋国学  秦克章  李光明  李真真  金露英  孟昭君  张夏楠 《岩石学报》2017,33(2):455-475

新近发现的印支期富林矽卡岩铜矿床位于大兴安岭北段新林区新林镇东约90km。矿区发育与成矿直接相关的花岗岩和侵入花岗岩中的花岗斑岩,矿体主要赋存于花岗岩与古元古代兴安桥组大理岩和早奥陶世黄斑脊山组钙质粉砂岩接触带内。富林矿床矿化与矽卡岩密切相关,整个矿化过程可分为两期:矽卡岩期和石英-硫化物期,5个阶段:早期矽卡岩阶段、退化蚀变阶段、氧化物阶段、早期硫化物阶段和晚期硫化物阶段,其中铜矿化主要发生在早期硫化物阶段。硫化物主要包括黄铜矿和黄铁矿,并含少量闪锌矿、方铅矿、斑铜矿等。蚀变类型包括石榴子石-透辉石矽卡岩化、阳起石-透闪石矽卡岩化、绿帘石矽卡岩化、绿泥石化、绢云母-粘土化、钾长石化和局部角岩化。电子探针分析(EMPA)结果表明:矿区内的石榴子石属钙铝-钙铁榴石系列,主要为钙铁榴石,辉石为透辉石-钙铁辉石系列,以透辉石为主,闪石主要为透闪石、阳起石以及少量镁绿钙闪石和铁浅闪石,帘石为黝帘石-绿帘石系列。黑云母以镁铁黑云母和铁叶云母为主,绿泥石主要为密绿泥石和铁叶绿泥石,长石以正长石和钠长石为主。石榴子石成分剖面显示从核部到边部,石榴子石呈现出钙铝榴石和钙铁榴石交替变化的环带特征,且Fe~(3+)含量的逐渐升高暗示后期成矿流体氧逸度升高,结合黑云母Mg-Fe~(3+)-Fe~(2+)图解,说明富林矽卡岩型铜矿床形成于较强的氧化环境。锆石LA-ICP-MS U-Pb测年结果显示花岗岩形成于~253Ma,花岗斑岩形成于~244Ma,为大兴安岭地区一期新的成矿事件。锆石原位Hf同位素测试结果表明,花岗岩εHf(t)介于-1.60~2.23,花岗斑岩εHf(t)介于-3.53~1.90,二者均具有古老的两阶段模式年龄,结合前人对区域构造背景的研究,认为富林花岗质岩石可能来自于松辽地块和兴安地块后碰撞背景下俯冲板片断离软溜圈上涌导致古老下地壳的部分熔融并卷入少量地幔物质而形成的岩浆。花岗斑岩及与斑岩有关的脉状矿化和蚀变的出现暗示富林地区可能存在印支期的斑岩型矿床,此外结合石榴子石、辉石成分特征以及辉石Mn/Fe比值与世界矽卡岩矿床对比,指出富林矿区外围找矿应综合考虑铜、钼、铁、金、铅、锌等矿化组合。  相似文献   

云南宝兴厂金多金属矿床成矿地质条件     

王绍明  涂国府 《云南地质》2009,28(4):374-379

矿区金、铜、钼矿化与碱性斑岩相关,向阳组碎屑岩是主要矿源层及赋矿地层,北东向响水断裂控矿,近东西向次级断裂及层间断裂为储（容）矿构造。多种条件耦合成矿。  相似文献   

云南双江白水河金矿成矿地质特征     

张保龙  徐荣  李高良  李小宽  文杰 《云南地质》2012,(3):297-300

白水河金矿属断裂构造控制的热液蚀变型金矿床,金矿体产于新元古界澜沧群变质岩区多期断裂的次级分支断裂破碎带内。沿构造带有辉绿岩脉、石英斑岩脉、煌斑岩脉侵入,首次在临沧地区新元古界澜沧群变质岩区找到金矿。  相似文献   

空间U统计量法在遥感蚀变信息提取中的应用研究   总被引：2，自引：0，他引：2  

胡波  朱谷昌  张远飞  肖燃 《国土资源遥感》2011,(3):71-76

鉴于传统蚀变异常信息提取方法的局限性,试图在二维光谱特征空间(即散点图)中研究遥感蚀变信息的提取方法.在二维散点图中,两个波段灰度值的联合分布体现了各向异性的特点,聚类常呈类似椭圆形分布.对散点图中点的频数使用空间U统计量法逐个获得地物聚类的椭圆参数,将每个椭圆内的点映射到遥感图像上,经过目视解译,最终获得蚀变异常信息...  相似文献   

云南保山从干树金矿控矿条件及矿床成因讨论     

李先棋  涂向衡  杜彦强  李琼仙 《云南地质》2011,30(2):130-133,140

从干树金矿赋存于怒江构造带高黎贡山岩群变质岩系中,有两个明显的次级矿化带,具多期次成矿作用特点:前期可能为沉积变质赋矿,后期为剪切(构造热液)成矿。晚期在浅部风化淋滤富集。剪切作用形成的金矿是主体。  相似文献   

云南沧源羊缅金矿成因     

高李阳  王爱萍 《云南地质》2011,30(3):273-274

羊缅金矿位于昌宁-孟连有色金属贵金属成矿带,金矿受压扭性断裂控制,分布于变余辉长辉绿岩中,典型的低温热液蚀变型金矿床。  相似文献   

An SVM-based machine learning method for the separation of alteration zones in Sungun porphyry copper deposit     

Maliheh Abbaszadeh  Ardeshir Hezarkhani  Saeed Soltani-Mohammadi 《Chemie der Erde / Geochemistry》2013

Sungun porphyry copper deposit is in East Azarbaijan province, NW of Iran. There exist four hypogene alteration types in Sungun: potassic, propylitic, potassic–phyllic, and phyllic. Copper mineralization is essentially associated more with the potassic and less with the phyllic alterations and their separation is, therefore, quite important. This research has tried to separate these two alteration zones in Sungun porphyry copper deposit using the Support Vector Machine (SVM) method based on the fluid inclusion data, and seven variables including homogenization temperatures, salinity, pressure, depth, density and the Cu grade have been measured and calculated for each separate sample. To apply this method, use is made of the radial basis function (RBF) as the kernel function. The best values for λ and C (the most important SVM parameters) that perform well in the training and test data are 0.0001 and 1, respectively. If these values for λ and C are applied, the phyllic and potassic alteration zones in the training and test data will be separated with an accuracy of about 95% and 100%, respectively. This method can help geochemists in separating the alteration zones because classifying and separating samples microscopically is not only very hard, but also quite time and money consuming.  相似文献   

An Improved Crosta Technique for Alteration Information Extraction Based on Local Variable Window     

PENG Guangxiong  LI Shanping 《《地质学报》英文版》2013,87(Z1):758-760

  相似文献   

Hydrothermal alteration processes in the giant Dahutang tungsten deposit,South China: Implications from litho-geochemistry and mass balance calculation     

Hai-Bo Zhao  Yong Zhang  Lei Liu 《China Geology》2021,4(2):230-244

The giant Dahutang tungsten (W) deposit has a total reserve of more than 1.31 Mt WO₃. Veinlet-disseminated scheelite and vein type wolframite mineralization are developed in this deposit, which are related to Late Mesozoic biotite granite. Four major types of alterations, which include albitization, potassic-alteration, and greisenization, and overprinted silicification developed in contact zone. The mass balance calculate of the four alteration types were used to further understanding of the mineralization process. The fresh porphyritic biotite granite has high Nb, Ta, and W, but low Ca and Sr while the Jiuling granodiorite has high Ca and Sr, but low Nb, Ta, and W concentrations. The altered porphyritic biotite granite indicated that the Nb, Ta, and W were leached out from the fresh porphyritic biotite granite, especially by sodic alteration. The low Ca and Sr contents of the altered Neoproterozoic Jiuling granodiorite indicate that Ca and Sr had been leached out from the fresh granodiorite by the fluid from Mesozoic porphyritic biotite granites. The metal W of the Dahutang deposit was mainly derived from the fluid exsolution from the melt and alteration of W-bearing granites. This study of alteration presents a new hydrothermal circulation model to understand tungsten mineralization in the Dahutang deposit.  相似文献