碱性玄武岩中幔源岩石包体内尖晶石成分特征及其岩石学成因意义   总被引：4，自引：2，他引：2  

董振信  陈立辉 《岩石学报》1999,15(4):607-615

通过对我国东部北起黑龙江省南至海南省３１个产地的新生代碱性玄武岩中橄榄岩类 （纯橄岩、方辉橄榄岩及二辉橄榄岩） 包体和辉石岩类包体中的１６０ 多个尖晶石电子探针分析数据, 论述了尖晶石的Ｃｒ－Ａｌ, Ｆｅ－Ｍｇ, Ｎｉ－Ｍｇ 主元素及有关比值和端员组分之间的关系, 分析研究了不同岩类包体中尖晶石的颜色、成分及成因之间的联系。并利用所分析的有关橄榄石、斜方辉石、单斜辉石共生矿物的电子探针分析数据, 采用新的、较合理的Ｂｒｅｙ－Ｋｏｈｌｅｒ温度计及Ｋｏｈｌｅｒ－Ｂｒｅｙ 压力计和Ｂａｌｌｈａｕｓ ｅｔａｌ． 氧逸度计算方法进行了计算, 探讨了尖晶石成分与其形成温度、压力和氧逸度状态的关系, 指出了尖晶石成分所反映的地幔亏损程度及部分熔融程度的变化规律及尖晶石 （相） 稳定的温度、压力和氧逸度范围。  相似文献   

伟晶岩绿柱石矿物学及其通道水氢同位素研究进展   总被引：4，自引：0，他引：4  

张辉  刘丛强  马英军 《矿物学报》1999,19(3):370-378

自然界绿柱石存在三个类质同象系列,即“八面体”绿柱石（ｃ／ａ＝０．９９１￣０．９９６）,“正常”绿柱石和“四面体”绿柱石。绿柱石矿物精细结构研究表明,二价离子置换八面体中Ａｌ,Ｌｉ置换四面体中Ｂｅ,而碱离子被绿柱石通道所容纳,用于补偿低价阳离子置换Ａｌ八面体和Ｂｅ四面体引起的电价不足。伟晶岩绿柱石通常含有〉１．６ｗｔ％的通道水,而包裹体中流体仅为０．１５ｗｔ％左右。室温下绿柱石通道中存在１型和Ⅱ  相似文献   

Preliminary study on weathering and pedogenesis of carbonate rock   总被引：23，自引：0，他引：23  

Shijie Wang  Hongbing Ji  Ziyuan Ouyang  Dequan Zhou  Leping Zhen  Tingyu Li 《中国科学D辑(英文版)》1999,42(6):572-581

South China is the largest continuous distribution area of carbonate rock in the world. The origin of the soils over the bedrock carbonate rock has long been a controversial topic. Here further exploration is made by taking five soil profiles as examples, which are developed over the bedrock dolomitite and limestone and morphologically located in upland in karst terrain in the central, west and north Guizhou as well as west Hunan, and proved to be the weathering profiles of carbonate rock by the research results of acid-dissolved extraction experiment of bedrock, mineralogy and trace element geochemistry. Field, mineralogical and trace element geochemical characteristics of weathering and pedogenesis for carbonate rock are discussed in detail. It is pointed out that weathering and pedogenesis of carbonate rock are important pedogenetic mechanisms for soil resources in karst area, providing a basis for further researches on the origin of soils widely overlying bedrock carbonate rocks in South China. Project supported by the National Natural Science Foundation of China (Grant No. 498330003) and National Key Basic Research Project (Grant No. 95pre-39).  相似文献   

Anatomically preserved plants in siderite concretions in the shale split of the Foord Seam: mineralogy, geochemistry, genesis (Upper Carboniferous, Canada)     

Erwin L. Zodrow  Christopher J. Cleal 《International Journal of Coal Geology》1999,41(4):248

A shale split in the well-studied Foord Seam (Upper Carboniferous), Stellarton Basin, Nova Scotia, provides a rare opportunity to study little known siderite concretions with anatomically preserved plants from a limnic basin. Siderite concretions occur throughout the split, commonly as sheet-like, inter-connected lepidodendrid logs, or less frequently as spherical masses; they are typically vuggy. A sample of 14 stratigraphically oriented concretions in the split shows that primary siderite varies from 45% to 80% (wt.%) due to selective replacement by 5% to 40% ferroan dolomite or ankerite in plant tissues. These two minerals show large Mg/Fe and Mg/Ca variability and are Fezoned. Clay content ranges from trace to 20%, and quartz from 5% to 10%. Partial cell-wall destruction by erosion and changeable oxic/anoxic conditions, prior to siderite permineralization, resulted in preservation mainly of the more resistant plant tissues. On average, carbon from siderite is isotopically heavier (+4.8±1.9 0/00) than that from ‘dolomite' (−7.2±1.1 0/00). The distribution of and the positive correlation between δ¹³C and δ¹⁸O probably reflects the two fractionation processes associated with methanogenesis and ‘dolomitization', respectively, in the genetic history of the siderite concretions in the split. Siderite concretions formed diagenetically early from bicarbonate under reducing conditions in a slightly alkaline freshwater environment that precluded calcite deposition.  相似文献   

白云鄂博矿物岩石研究的新进展     

张培善  陶克捷  杨主明 《岩石矿物学杂志》1991,10(3):265-270

本文论述了近年来白云鄂博矿区在旷物学、岩石学、地球化学和矿床成因研究方面的进展。在矿物学研究方面,除以往研究过的一百多种矿物外,八十年代中期以后,又相继发现并研究了含铌锐钛矿、含铌钙钛矿、锶铁钛石、水磷钙钍石、白云鄂博矿、未命名氟碳酸盐新种矿物、珀硅钛铈铁矿、硅钡镁石、带云母等矿物;发现了矿物间的共生和交代关系。在岩石学研究方面,找到了霓长岩,发现了霓长岩化作用,确定了火成碳酸岩岩石的存在。在地球化学和矿床成因方面,提出了稀土稀有金属矿化与火成碳酸岩岩浆活动有成因联系的见解。  相似文献   

月球辐射状撞击坑经度方向分布特征与同步旋转轨道状态模拟分析          下载免费PDF全文

邵先远  李斐  鄢建国  叶茂  郝卫峰 《地球物理学报》2017,60(4):1321-1331

月球目前的同步旋转轨道状态使得形成的撞击坑分布满足一定的不对称性.本文利用最新的LRO影像和地形数据,结合早期的Clementine影响数据,分析了月球辐射状撞击坑经度方向成坑率分布,结果表明所识别的辐射状撞击坑的.年龄为O.9 Ga内,西一东半球方向存在明显不对称性,比值约为1.35~1.53;同时利用辐射状撞击坑模拟了0.9 Ga内的同步旋转轨道的平均状态,得到该时间内月球的向点-背点为70°W—110°E附近;最后利用撞击坑数据库资料对月球形成以来各地质世纪时间尺度内的撞击坑进行了成坑率分布分析,结论表明月球在大爆炸中后期间可能处于过近似的同步轨道旋转状态,但是与现在的轨道运行状态相反,月球在之后的地质时期内经历了翻转,其诱因可能是雨海和东方海盆地遭受的撞击.  相似文献   

邯邢地区中生代侵入岩中磷灰石的成因矿物学研究     

梁贤 《地质与勘探》2020,56(5):969-984

氧逸度为有效的氧分压,是实验岩石学中重要的研究课题,岩浆的氧逸度是继温度、压力、浓度等影响成岩成矿过程的关键性物理化学参数。本文利用磷灰石的氧逸度计,对邯邢地区六大主要岩体的岩浆氧逸度进行了计算。研究结果显示,样品中的磷灰石主要为羟-氟磷灰石,磷灰石的形态、成分和结构特征指示其为岩浆成因。磷灰石中的Mn元素在晶格中有两种方式,多以Mn3＋和Mn5＋的方式进入晶格。磷灰石氧逸度计计算的logfo2为-12.31~-9.75,均值-11.02。参考与磷灰石共生角闪石的形成温度,认为邯邢地区岩浆岩普遍具有较高的氧逸度。根据磷灰石氧逸度值与矿床规模的填图结果,认为并非氧逸度越高越有利于邯邢式铁矿的形成。结合矿物学填图等值线闭合的趋势,进而推断邯邢地区中部的符山和武安岩体深部可能仍存在较好的找矿远景。  相似文献   

南阿尔金巴什瓦克基性麻粒岩的变质演化 P- T- t 轨迹     

郭晶  李云帅  张建新 《地质学报》2020,94(9):2698-2711

大陆碰撞造山带中高压麻粒岩的 P- T- t 轨迹研究对于理解造山带的热演化历史及大陆地壳的形成与演化具有重要的意义,然而,如何连接同位素年龄与变质演化过程是恢复和建立 P- T- t 轨迹的重点和难点。本文通过对南阿尔金巴什瓦克地区基性麻粒岩的详细岩相学研究,认为该基性麻粒岩经历了原岩阶段（M1）、峰期变质阶段（M2）、峰后退变质阶段（M3）以及晚期角闪岩相- 绿片岩相退变质阶段（M4）。其中,传统矿物温压计和矿物微量元素温压计获得该基性麻粒岩所记录的峰期变质条件分别为17. 5~22. 6 kbar,901~985℃ 和17~28 kbar,1012~1049℃,退变质阶段的温压条件为7. 6~10. 7 kbar,750~810℃。此外,锆石U- Pb 年代学结果表明基性麻粒岩的变质时代为491±3. 5 Ma (MSWD=0. 62),结合锆石和石榴子石的微量元素分配系数以及前人的实验岩石学数据,认为该变质时代记录了早古生代高压- 超高温的变质事件,进而恢复了南阿尔金基性麻粒岩所记录的顺时针 P- T- t 轨迹。  相似文献   

风险评价与风险控制技术在矿山企业中的应用          下载免费PDF全文

修志伟  姜东泉  王经宇  冯英俊 《山东国土资源》2005,21(8):49-51

为更好地适应新形势下安全生产的需要,矿山企业结合自身的特点,以现代的系统的安全管理模式替代原来传统的管理模式,应用风险评价与风险控制技术,搭建一个以“风险控制为核心”的规范化、结构化、系统化的新的安全管理平台,可以有效地控制风险,防止和遏制各类事故的发生。  相似文献   

Late quaternary glacial stades in the Cordillera Central,Colombia, based on glacial geomorphology,tephra–soil stratigraphy,palynology, and radiocarbon dating     

Jean-Claude Thouret  Thomas Van Der Hammen  Barry Salomons  Etienne Juvign 《第四纪科学杂志》1997,12(5):347-369

Using data from glacial geomorphology, tephra–soil stratigraphy and mineralogy, palynology, and radiocarbon dating, a sequence of glacial and bioclimatic stades and interstades has been identified for the last ca. 50000 yr in the Ruiz-Tolima massif, Cordillera Central, Colombia. Six Pleistocene cold stades separated by warmer interstades occurred: before 48000, between 48000 and 33000, between 28000 and 21000, from ≥16000 to ca. 14000, ca. 13000–12400, and ca. 11000–10000 yr BP. Although these radiocarbon ages are minimum-limiting ages obtained from tephra layers on top of tills, the tills are not significantly older because most are bracketed by dated tephra sets in measured stratigraphic sections. Two minor moraine stages likely reflect glacier standstill during cold intervals ca. 7400 yr BP and slightly earlier. Finally, glaciers readvanced between the seventeenth and nineteenth centuries. In contrast to the ice-clad volcanoes of the massif, ca. 34 km² in area above an altitude of ca. 4800 m, the ice cover expanded to 1200 km² during the Last Glacial Maximum (LGM) and was still 800 km² during Late-glacial time (LGT). Glacier reconstructions based on the moraines suggest depression of the equilibrium line altitude (ELA) by ca. 1100 m during the LGM and 500–600 m during LGT relative to the modern ELA, which lies at ca. 5100 m in the Cordillera Central. Glaciers in this region apparently reached their greatest extent when the climate was cold and wet, e.g. during stades corresponding to Oxygen Isotope Stage 3; glaciers were still expanding during the LGM ca. 28000–21000 yr BP, but they shrank considerably after 21000 yr BP because of greatly reduced precipitation. © 1997 John Wiley & Sons, Ltd.  相似文献