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1.
蒙花岭组是新建的岩石地层单位,指定蒙花岭剖面为正层型剖面。岩性为一套高绿片岩相的变质岩,由变质石英细砂岩、各类片岩、绢云千枚岩夹细粒石英岩及数层变质基性―酸性火山岩组成。在剖面的下部第8层及上部第24层含丰富的藻类化石,地质时代为寒武纪;在剖面中部第16层变质火山岩中采人工重砂样、锆石U-Pb测年结果为499±6Ma~527±48Ma,地质时代为寒武纪中晚期。故将蒙花岭组划寒武系黔东统(∈2)到芙蓉统(∈4)。  相似文献   
2.
位于海南岛西南部的抱伦金矿产于尖峰岩体外接触带,与辉绿岩脉密切伴生,这些侵入岩蕴含了金矿成矿作用与岩浆活动-构造演化-成矿体系关系的重要信息。文章报道了对抱伦尖峰花岗岩和辉绿岩开展岩石学、锆石U-Pb年代学、元素和Sm-Nd同位素地球化学研究的成果。本次工作获得了尖峰花岗岩的LA-ICP-MS方法锆石U-Pb年龄为(234.9±2.8)Ma,与辉绿岩构成双峰式侵入杂岩组合。辉绿岩属亚碱性玄武岩系列,相对富集Th、Nb、Ta等强不相容元素,无Nb、Ta、Ti亏损,显示与富集洋中脊玄武岩(E-MORB)相似的地球化学特征,其εNd(t)值为4.11,指示了亏损的源区性质;尖峰花岗岩属高钾钙碱性岩系的铝质A型花岗岩,相对富集K、Rb、Th、Ce等元素,相对亏损Sr、Ba、Nb、Ta、P、Ti等元素,其εNd(t)值为-7.61~-7.80,指示了再循环地壳源区。抱伦辉绿岩为交代型地幔降压熔融的产物,而尖峰花岗岩起源于中元古界泥质和杂砂岩地壳源岩于低压、高温环境下的部分熔融,该双峰式侵入杂岩与金成矿作用形成于造山后伸展-减薄构造背景。双峰式侵入杂岩的...  相似文献   
3.
胡军  徐德明  张鲲  王磊  陈沐龙  云平 《矿床地质》2017,36(2):303-316
新村钼矿床是海南省近年来发现的具中型规模的钼矿床。文章对赋矿二长花岗岩进行LA-ICP-MS锆石U-Pb同位素测年,获得~(206)Pb/~(238)U年龄加权平均值为(102.0±1.5)Ma(MSWD=2.3);对辉钼矿进行Re-Os同位素定年,获得5件样品的模式年龄范围为(97.29±1.43)Ma~(98.52±1.55)Ma,加权平均年龄为(97.84±0.64)Ma,等时线年龄为(98.90±3.40)Ma,成岩年龄与成矿年龄在误差范围内一致。辉钼矿的Re含量和锆石Hf同位素特征指示新村钼矿的成岩成矿物质来自于壳幔混源。新村钼矿床的成岩成矿年龄与海南岛最重要的钼成矿期(95~105 Ma)一致,属中国东部早白垩世晚期—晚白垩世早期钼成矿事件的一部分,与该时期岩石圈大规模拉伸减薄、软流圈上涌及强烈壳-幔作用密切相关。  相似文献   
4.
In order to understand the response of authigenic pyrite to gas hydrate geo-systems, pyrite tubes or rods at the sulfate–methane transition (SMT) zone of core GC10 from the northern continental slope of the South China Sea (SCS) were investigated. In situ X-ray diffraction (XRD) results show that the pyrite tube consists of pyrite micro-crystals with trace amount of graphite in the inner tube. Scanning electron microscope (SEM) observations of pyrite tubes indicate various aggregations in the form of framboidal, euhedral, and colloidal pyrite microcrystals. Typical framboidal pyrite is considered as packing of octahedral microcrystals. Interestingly, many framboids in the tubes consist of round or irregular microcrystals and have an outer crust that consists of secondary pyrite. The size of the framboids in the inner wall of the tube is larger than that in the middle wall or foraminifer-filled pyrite. High-resolution transmission electron microscopic (HRTEM) images show marcasite lamellae defects in the spherulitic pyrite crystals, which reveal different solution conditions during the pyrite precipitation. Nano-foil-like graphitic carbon was observed to be closely associated with the pyrite spherules. The occurrence of both marcasite layers and nano-foil-like graphitic carbon suggest that the migration of methane from deep sediment. It is suggested that the formation of pyrite serves as a catalyst during the reaction from methane to elemental carbon under the anaerobic oxidation of methane. Meanwhile, this reaction results in local acidification of the solution inside the pyrite tubes, which favors marcasite lamellae growth on the host pyrite substrate.  相似文献   
5.
结合海南省保亭县1:5万地质灾害详细调查项目,根据野外实际调查与遥感成果,选取地质构造、地形地貌及人类活动3个大类,构造、工程地质岩组、坡度、坡高、海拔高度、植被覆盖率、河流及公路等8个小类作为地质灾害影响评价因子.在ArcGIS平台上运用AHP法,进行评价因子权重计算并建立评价模型,完成保亭县地质灾害易发程度区划,划分出高、中、低易发区,可为今后地质灾害预测与防治提供科学依据.  相似文献   
6.
通过对丽江井数字化地下水温观测资料进行的初步研究,发现该井在川滇地区发生的多次中强以上地震前有短临异常,异常形态可分为三类:第一类是日潮差变化和温度阶升;第二类是震前水温出现大幅降温;第三类为震前出现水温固体潮汐形态畸变和多次温度突跳。丽江井数字化水温震前的短临异常特征对做好未来地震的短临跟踪及地震预测有着实际应用价值。  相似文献   
7.
本文介绍了一种适用于地震行业的低成本通用地震数据采集器,阐述了该仪器的工作原理、硬件结构和主要功能。  相似文献   
8.
本文介绍了一种高性能时钟芯片x1226的功能,技术参数,阐述了该时钟芯片的工作原理、主要功能;并介绍了此芯片的应用电路、软件流程和代码。  相似文献   
9.
Anaerobic oxidation of ammonium (anammox) is an important process in the marine N cycle. It has been estimated to contribute up to 50% of N loss from the ocean and is especially prevalent within the oxygen minimum zone (OMZ). We studied the presence and distribution of anammox in the extended OMZ of the Eastern Tropical North Pacific (ETNP) using ladderane fatty acids (FAs), specific biomarkers for anammox bacteria. The validity of ladderane FAs as a proxy for anammox bacteria was demonstrated by their excellent correspondence with anammox 16S rRNA functional gene abundances and their expression and intact polar ladderane lipid concentrations in suspended particulate matter (SPM) from the Arabian Sea. In the ETNP, SPM was collected from various water depths at four stations along a northwest to southeast cruise transect and ladderane FAs were analysed at each station. In all SPM samples where ladderanes were detected, C18 ladderane FAs were on average fivefold more abundant than C20 ladderane FAs. Maximum ladderane FA concentrations (1.1–2.3 ng l−1) were recorded at 400–600 m, often corresponding to the depth of the secondary nitrite maximum. At one of the four stations, a second maximum in concentration was noted at a shallower depth (85 m), coinciding with higher nitrite availability at this depth. This suggests that nitrite, along with oxygen, may be a limiting factor for anammox activity in the ETNP. Anammox lipids were abundant within the OMZ at all stations and concentrations were comparable to those in other OMZs, suggesting that anammox may be responsible for a significant loss of N from the OMZ of the ETNP.  相似文献   
10.
通过对浙西南遂昌县玉岩古元古代花岗片麻岩锆石LA-ICP-MS U-Pb年代学研究,以探讨和揭示华夏地区基底的物质组成。玉岩花岗片麻岩锆石可分为两类:第一类锆石年龄相对年轻,其~(207)Pb/~(206)Pb年龄介于597~1917 Ma之间,结合稀土元素特征,表明为变质成因锆石,在锆石谐和图上,15个年轻锆石点整体上构成了一条不一致线,其上交点年龄为1904±19Ma,代表了片麻岩形成的变质时间,表明华夏地区存在古老的古元古代晚期岩浆岩-变质岩基底,下交点年龄为262±47Ma,可能记录了华夏地块晚二叠世―早三叠世构造-变质作用的响应。第二类锆石年龄相对较老,锆石~(207)Pb/~(206)Pb年龄介于2087~2523Ma之间,锆石发育核幔结构并有明显的振荡环带,较老的锆石年龄表明华夏地区可能存在太古宙末至2.5Ga的古老基底物质。  相似文献   
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