在我国首次发现的三种磷酸锌矿物

在广东某锰矿区的南部,笔者发现三种罕见的磷酸锌矿物——副磷锌矿、磷钙锌矿、三斜磷锌矿。这三种矿物在我国均属首次发现。笔者对这三种矿物作了物理性质、化学性质、晶体光学性质、晶体结构、红外吸收光谱、差热分析等方面的测试,所得数据与国外资料对比基本相同。但经多次测定,该副磷锌矿为二轴晶负光性而与丹纳氏矿物学描述不同。本文较详细地描述了这些矿物的光性特征。另外,补充了这三个矿物的红外吸收光谱、差热分析数据和三种矿物的鉴定特征。     

宝坑锰矿床中的磷酸锌矿物

宝坑锰矿为一次生氧化锰矿床.在矿区的南部发现三种罕见的磷酸锌矿物——付磷锌矿、磷钙锌矿、三斜磷锌矿.这些矿物与微晶磷灰石、锰土、褐铁矿等伴生,组成块状高磷富锌的氧化矿石.这些矿石与氧化锰矿石、褐铁矿石及各种成分的砂、砾石堆积于山坡上,由于雨水冲刷而裸露地表.发现有七块直径为30～60厘米大小的这种矿石.据R.丁希尔(Min Mag1974 684—95)报导,澳大利亚的利福希尔锌矿区的铁锰帽带曾发现有这三种矿物共生的产状.     

硅铁灰石在我国的首次发现

硅铁灰石是一种罕见的单链硅酸盐矿物，产于矿体围岩的晚期热液脉中，其晶体呈厚板状或矛头状，颗粒大小０．１ｍｍ—０．５ｍｍ，日光下呈黑色，强光源下呈浓茶绿色─棕色，玻璃光泽，条痕淡灰绿色，透明─半透明，维克显微硬度Ｈｖ１００ｇ＝３５９ｋｇ·ｍｍ－２，实测密度３．３５ｇ·ｃｍ－３，计算密度为３．３２ｇ·ｃｍ－３。偏光显微镜下显正高突起，具强多色性，Ｎｇ浅黄棕色、Ｎｐ暗绿色，二轴晶正光性，ＺＶ（＋）＝７６（１）°，折射率Ｎｇ＝１．７５９，Ｎｍ＝１．７３７，Ｎｐ＝１．７２８．Ｘ射线单晶衍射表明，硅铁灰石属三斜晶系，空间群为Ｐ１。由Ｘ射线粉晶衍射数据计算出晶胞参数ａ＝０．７４７５（１）ｎｍ，ｂ＝１．１８４４（１）ｎｍ，ｃ＝０．６６７９（１）ｎｍ，α＝９１°３４（３）′，β＝９３°４５（１）′，γ＝１０３°１９（１）′。硅铁灰石的晶体化学式为（Ｃａ２．０７１Ｎａ０．００７Ｋ０．００１）２．０７９（ＦｅＭｎＭ０．１７１）０．９９１（ＦｅＡｌＴｉ０．００２）１．０２１［（Ｓｉ４．９８９　Ａｌ０．０１１）５．０００Ｏ１４．１０１（ＯＨ）０．８９９］。硅铁灰石是酸式硅酸盐，不存在与阳离子结合的ＯＨ－离子，因而在红外光谱中缺失３４     

天然矿物Wadsleyite在我国首次发现

对于在毫县陨石中发现的Ｘ矿物，本文用电子探针获得了其化学成分：ＳｉＯ４，用Ｘ射线微区衍射得到了其结构参数。该矿物属斜方晶系，晶胞参数ａ＝０．８２６４，ｂ＝１．１４４８，ｃ＝０．５７０４ｎｍ。这些结果证明了它是Ｗａｄｓｌｅｙｉｔｅ，是橄榄石的高压相－β－（Ｍｇ，Ｆｅ）２ＳｉＯ４由冲击变质作用形成的。该矿物呈包裹体产出，在我国属首次发现。     

褐铊矿在我国的首次发现

褐铊矿是一种罕见的稀有分散元素铊的矿物,产于西藏洛隆县斯拉沟的天然河流重砂中。与其共生的矿物还有方铅矿、白铅矿,黄铁矿、白钨矿、锆石、锐钛矿、赤铁矿、钛铁矿、重晶石、榍石等。三个颗粒的17个不同部位的电子探针定量分析结果的平均值为:Tl_2O_398.53%,SiO_2 1.09%,Al_2O_3 0.19%,Fe_2O_3 0.16%,总量99.97%。属等轴晶系,空间群,T~5-I2_13,晶胞参数a=10.55,Z=16。     

硅硼镁铝矿在我国的首次发现

硅硼镁铝矿(Grandidierite)为一罕见矿物.国外由M.A.Lacroix于1902年在马达加斯加花岗岩中首次发现,1918年在匈牙利又有发现,此后国内外一直未见报道.1985年笔者在对黑龙江鸡西三道沟矽线石矿床研究中,发现了硅硼镁铝矿.它产于麻山群斜长片麻岩内,与培长石、柱晶石、矽线石、电气石、石墨等共生,含量占7－8%.硅硼镁铝矿呈蓝绿色、长柱状,粒度0．1×0.2×0.8~0.5 ×1.0 × 4.omm.相对密度为3.016g/cm~3,摩氏硬度7.5.矿物难溶于盐酸、硫酸及氢氟酸.     

狄更逊虫类化石在我国的首次发现

狄更逊虫类化石是新元古埃迪卡拉动物群中的重要分子。本文首次报道了产于安微寿县八公山淮南群刘老碑组（８４０Ｍａ）中的该类化石，是迄今为至世界上后生物实体石化产出的最低层位，具有重要的理论意义和实际价值。     

在我国首次发现的硫铜钾矿

本硫铜钾矿发现于金川铜镍矿床中。据能谱分析及电子探针分析,它主要由钾、镍、铁和硫组成。矿物的X射线分析表明是等轴晶系,晶胞参数α=10.296,格子类型为立方简单格子P。     

狄更逊虫类化石在我国的首次发现

狄更逊虫类化石是新元古埃迪卡拉动物群中的重要分子。本文首次报道了产于安徽寿县八公山淮南群刘老碑组（８４０Ｍａ）中的该类化石，是迄今为止世界上后生动物实体化石产出的最低层位，具有重要的理论意义和实际价值。     

我国首次发现方锑金矿

方锑金矿在我国湖南平江杨山庄金矿床中首次发现。共生矿物有:自然金、辉锑矿、自然锑、毒砂、黄铁矿、车轮矿等。颗粒极细小,直径为0.02—0.05mm,灰黑色,暗淡光泽,不透明,无解理,显微硬度211—246kg/mm~2(20g)。反射色为白色,均质,反射率:63.29(405nm),63.04(480nm),63.00(546nm),62.57(589nm),61.86(656nm)。三个不同颗粒方锑金矿电子探针分析结果:Au 43.04,43.01,42.96;Sb 56.96,56.99,57.04。化学式;Au_(0.93)Sb_2。X射线粉晶分析主要谱线:3.34(60),2.99(70),2.722(60),2.362(70),2.010(100)。     

广东珠海大桥直径2m桥桩孔成孔施工实践

在珠海大桥桥桩孔的成孔施工实践中采用了滚刀钻头、泵吸反循环工艺，施工２．０ｍ和２．２ｍ大口径桥桩孔，对施工工艺参数、水上平台作业对大口径施工机械设备的技术要求、事故处理以及滚刀钻头在软土地层中钻进的可行性等方面进行了探讨。     

山东荣成马草夼橄榄岩矿物地球化学研究

马草夼橄榄岩位于苏鲁超高压变质带山东荣成腾家集附近,其原岩为残余地幔方辉橄榄岩,经历了超高压变质作用和后期麻粒岩-角闪岩相变质作用.对马草夼橄榄岩及侵入于其中的辉石岩脉和角闪岩脉的主要矿物橄榄石、斜方辉石和角闪石做了单矿物微量元素和稀土元素地球化学分析,结果表明Co和Ni在橄榄石中含量最高且富集,在斜方辉石和角闪石中含量低且亏损.由于橄榄石在全岩中含量高达90%以上,因而全岩Co、Ni富集.虽然角闪石在全岩中体积含量仅占3%～8%,但斜方辉石和橄榄石的微量和稀土元素含量远远低于角闪石,故全岩的微量(Co、Ni除外)和稀土元素化学特征受控于角闪石.斜方辉石、橄榄石与角闪石的微量和稀土元素分布特征基本相同,辉石岩脉和角闪岩脉中的角闪石比地幔橄榄岩中的角闪石更富集微量和稀土元素.微量和稀土元素地球化学特征显示马草夼橄榄岩至少受到了含Co、Ni的流体,富含LREE、Ba、Sr、Ta的硅酸盐流体和少量低Th、U的碳酸盐地幔流体的多次交代,流体交代发生于超高压变质后期浅部地幔驻留期间.马草夼橄榄岩所处的氧逸度(相对于FMQ)为+1.0～+2.0,落入正常大陆地幔的范围,在折返过程中未受到壳源流体的影响,保持了地幔氧同位素特征.     

Control of Cl production in carbonaceous shales by phosphate minerals

When using ³⁶Cl to date very old groundwater in regional aquifer systems, knowledge of the subsurface ³⁶Cl input into the aquifer system is essential. Although ³⁶Cl can be produced through nuclear reactions in the subsurface, in many situations, the input of ³⁶Cl into sedimentary aquifer systems by this avenue of production can be neglected. This is a valid assumption when investigating long-flowpath groundwater systems composed of sandstones, limestones, and shales of typical composition. These rock types are not sufficiently enriched in radioactive elements to produce significant ³⁶Cl in the deep subsurface. Carbonaceous shales, on the other hand, can concentrate the radioactive elements necessary to produce significant ³⁶Cl in the deep subsurface. Chlorine-36 ratios (³⁶Cl/Cl) for a suite of Late Devonian and Pennsylvanian carbonaceous shales were calculated from bulk-rock chemistry as well as measured using accelerator mass spectrometry. The poor agreement between calculated and measured ratios is the result of the assumption of chemical homogeneity used by the calculation algorithm, an assumption that was not satisfied by the carbonaceous shales. In these shales, organic matter, clay minerals, and accessory minerals are heterogeneously distributed and are physically distinct on a micron-order scale. Although organic matter and clay minerals constitute the overwhelming bulk of the shales, it is the phosphate minerals that are most important in enhancing, and suppressing, ³⁶Cl production. Minerals such as apatite and carbonate-apatite (francolite)—by including uranium, rare earth elements (REEs), and halogens—have an important impact on both neutron production and thermal neutron absorption. By incorporating both uranium and fluorine, phosphate minerals act as neutron production centers in the shale, increasing the probability of ³⁶Cl production. By incorporating REEs and chlorine, phosphate minerals also act to shield ³⁵Cl from the thermal neutron flux, effectively suppressing the production of ³⁶Cl. To reconcile the measured ³⁶Cl ratios with the ratios calculated assuming chemical homogeneity, the shales were artificially split into three fractions: organic, clay mineral, and phosphate mineral. Neutron production was calculated separately for each fraction, and the calculation results demonstrated that the phosphate fraction exerted much more control on the ³⁶Cl ratio than the organic or clay mineral fractions. By varying the uranium and chlorine contents in the phosphate fraction, a new, heterogeneous ³⁶Cl ratio was calculated that agreed with the measured ratio for the overwhelming majority of the carbonaceous shales. When using rock chemistry to calculate the ³⁶Cl ratio, rock types that show mineralogical heterogeneity on a micron scale can be divided into bulk fractions and accessory fractions for separate calculations of neutron production and neutron absorption. In this manner, a more accurate, heterogeneous ³⁶Cl ratio can be calculated for the rock as a whole.     

31P solid-state nuclear magnetic resonance spectroscopy of aluminum phosphate minerals

This study examines the links between ³¹P solidstate NMR studies of aluminum phosphate minerals and their crystallographic structures. We found that ³¹P isotropic chemical shift values, _iso, carry little information about mineral structures. There seems to be no relation between the chemical shift anisotropy, =₃₃–₁₁ (₃₃>₂₂> ₁₁), and indicies of phosphate-tetrahedra distortion. ³¹P¹H heteronuclear magnetic dipole interactions, on the other hand, carry important information about hydrous phosphate mineral structures, information that should prove to be quite valuable in studies of phosphate adsorbed on mineral surfaces. This interaction can be measured through a variety of qualitative and quantitative experiments. It appears that spin diffusion is so rapid that subtle differences in hydrogen-bonding environments cannot be resolved.     

Fluid inclusion geochemistry in minerals obtained from Zhao-Ye gold metallogenetic belt, Shandong Province

A large number of fluid inclusions are observed in quartz contained in Au ores. A study of the geochemistry of inclusions from the Linglong Au deposit in Shandong Province shows that ore-forming temperature and pressure, frequency of appearance for critical inclusion, and saline halo of the main Au-bearing veins 108 and 51 increase in the direction of Linglong Fault. We concluded accordingly, that: (1) the Linglong Fault was a conduit structure for mineralization and will form a favourable place for prospecting where the fault intersects a host structure trending east-northeast; (2) distinct differences in geochemical characteristics are present in relation to the fluid inclusions contained in Au-bearing quartz veins and barren quartz veins, with the former having higher homogenization temperatures, appearing frequency for critical inclusion, content of CO₂, H₂ and CH₄, and molar concentration ratio of (H₂ + CH₄) to CO₂, than those of the latter; (3) decrepitation curves for the two sorts of quartz veins have obviously different characteristics; and (4) geochemical characteristics of fluid inclusions present in the quartz of quartz-vein-type Au ore deposits demonstrate that its metallogenetic pressure, salinity, and decrepitation temperature all increased progressively towards the deeper part of the quartz vein, approximating those of altered-rock-type Au ore deposits. We already know of some Au mines where quartz-vein-type Au ore deposits are turned at depth into altered-rock-type Au ore deposits. Therefore, attention should be paid to prospecting for altered-rock-type Au ore deposits below the quartz-vein-type. From this study, we believe that the geochemical study of fluid inclusions in minerals is a new and useful exploration approach, which should be further explored and used.     

含金磷酸盐矿物的发现及其地质意义 ——以山东牟平腊子沟金矿为例

山东牟平腊子沟金矿位于华北板块苏鲁造山带胶南-威海隆起区,牟平-乳山金矿成矿带中段,区内岩浆活动频繁,构造活动强烈,成矿地质条件优越。本文通过镜下显微结构观察、电子探针测试分析对腊子沟金矿载金矿物的组成、成分及金的赋存状态进行了研究,首次在该矿区发现含金独居石和含金磷灰石,金含量达到0.283%～0.456%,推测金可能通过类质同象形式替代磷灰石中的Ca2+或独居石中的稀土元素(Ce2+、 La2+)以晶格金的形式存在。前人研究认为成矿流体中金主要以Au[HS]2－和AuCl2－络合物形式进行迁移,本次含金磷酸盐矿物的发现表明：可能部分金以磷酸根络合物形式进行迁移。     

江西赣南风化淋滤型稀土矿床中的粘土矿物研究

对江西赣南6个地区风化淋滤型稀土矿中全风化层的粘土矿物进行了研究,为进一步了解粘土矿物对该类型稀土矿中稀土元素分异的影响奠定了基础。X射线衍射自然定向片、甲酰胺片、饱和乙二醇片和加热片、红外光谱及扫描电镜观察结果表明该区粘土矿物以片状高岭石和针管状7埃洛石为主,其中坳背塘、长坑屋、上堡、杨村样品主体为高岭石,足洞样品中发育大量埃洛石,而石排样品中高岭石与埃洛石比例相当。电感耦合等离子体质谱分析表明稀土元素在粘土矿物中大量富集,其稀土元素配分不仅受到原岩的影响,而且受到粘土矿物本身性质的影响。Ce元素在足洞和石排样品的粘土矿物中表现出正异常,而在其他样品粘土矿物中表现为负异常,可能与其中发育的埃洛石密切相关。Ce元素可能以方铈矿胶膜的形式包裹在针状埃洛石中,和/或以离子形式被选择性吸附于埃洛石表面。     

Chemical composition of platinum-group minerals from the Bor-Uryakh massif (Maimecha-Kotui Province,Russia)

This contribution firstly presents particularities of mineral chemistry of platinum-group elements (PGE) mineralization from placer deposits linked to the Bor-Uryakh massif of the Maimecha-Kotui Province, northern part of the Siberian Craton. The chemical composition of PGE mineralization has been studied by electron microprobe analysis. At Bor-Uryakh, main platinum-group minerals (PGM) comprise Os-Ir and Pt-Fe alloys represented by individual crystals, and polyphase PGM assemblages. The majority (e.g., 12 out of 19) of the Os-rich nuggets are iridian osmium, with subordinate amounts of native osmium (Os) and chengdeite (Ir₃Fe). Pt-Fe alloys have a stoichiometric composition close to Pt₂Fe. According to the nomen-clature by L. Cabri and C. Feather [1975] these minerals correspond to ferroan platinum. Based on geological position and geochemical features of investigated PGE mineralization the particular rock sources have been established. This study has demonstrated the similarity of chemical characteristics of Os-Ir and Pt-Fe alloys of the Bor-Uryakh massif to those of PGM from the Guli massif (Maimecha-Kotui Province), platiniferous zoned-type ultramafic massifs (e.g., Kondyor, Inagli and Chad) of the Aldan Province and Platinum belt of the Urals (Nizhny Tagil, Kytlym, etc.).     

湖南香花铺钨矿床含钙矿物的稀土元素地球化学

香花铺矿床是湘南地区唯一的萤石-白钨矿型矿床。本文利用高精度LA-ICP-MS对该矿白钨矿和方解石中的稀土元素进行了原位分析。结果表明,该矿的白钨矿表现为LREE富集和正Eu异常特征,方解石则具有LREE富集型和相对平坦型两种稀土配分模式,且均呈现负Eu异常特征。该矿属于与岩浆活动有关的热液矿床,成矿流体在还原环境下的运移过程中,首先结晶出白钨矿和LREE富集型方解石,而后沉淀形成了具有相对平坦型REE模式的方解石。此外,稀土元素在该区矿物中的分布存在明显的不均一现象,在不同微区REE的含量、配分模式以及分异程度等均可能存在差异,其原因除了结晶过程中水动力学条件的变化,还可能与矿物结晶后颗粒外表层受流体作用的改造有关。     

Age and evolution of the Grenville Province in eastern Labrador from U-Pb systematics in accessory minerals

U-Pb isotope analysis of zircon, titanite, monazite and rutile extracted from 15 different Grenville Province rocks in eastern Labrador reveals: 1) major crust formation through magmatism between 1,710 and 1,630 Ma ago; no evidence of older crustal material was found. 2) Pegmatite and gabbro intrusions between 1,500 and 1,400 Ma ago, probably related to incomplete rifting of the earlier formed crust. 3) Granite and syenite plutonism, presumably anorogenic, circa 1,300 Ma ago. 4) High grade metamorphism and anatexis during the Grenvillian Orogeny, causing Pb-loss in primary zircon and new growth of zircon, titanite and monazite at circa 1,030 Ma ago in the south (Lake Melville and Mealy Mountains terranes) and circa 970 Ma ago in the north (Groswater Bay Terrane and Trans-Labrador Batholith); geochronological distinction of these large-scale crustal segments substantiates their juxtaposition along deeply rooted, intracontinental ductile thrust zones during Grenvillian Orogeny. 5) Late Grenvillian growth of rutile in gabbros circa 925 Ma ago.