钙镁硅酸盐系列结晶釉的研究——氧硅比对析晶种属的影响

针对K2O－Na2O-CaO-MgO-Al2O3-SiO2系统，选定CaO/MgO值近于1和0．5，配制釉式中碱性组分、氧化铝含量确定的两组结晶釉，研究氧硅比对矿物种属的影响。结果显示：CaO/MgO≈1时，O／Si值近于3．1时析出钙镁黄长石，在3左右同时出现黄长石和透辉石，小于3为透辉石，继续减小开始产生少量硅灰石；CaO/MgO≈0．5时，O／Si值大于3．1时同时形成钙镁黄长石和透辉石，近于3时仅出现透辉石。     

胶东莱西—平度一带麻粒岩相岩石的变质作用特征

胶东的麻粒岩主要分布在莱西、平度、昌邑、安丘一带。特征的矿物组合为Opx+Cpx+Hb+Pl±Q±Sca。斜方辉石的出现及其与角闪石共生,表明Hb+Q=Opx+Cpx+Pl+H_2O的反应未进行彻底,处于角闪岩相与麻粒岩相的过渡相,即角闪麻粒岩亚相。采用Opx-Cpx、Opx-Hb、Cpx-Hb、Fib-Pl及铁-钛氧化物等矿物地质温压计确定,本区主期变质作用的温度为720—810℃,压力为0.5GP_a,fo_2为10~(-19.5),则地热梯度为41—46℃/km,属“低温”低压麻粒岩相。     

德兴含铜埃达克质斑岩的地球化学特征、成因及地质意义

德兴斑岩铜矿位于扬子地块江南隆起带东缘,含矿斑岩类型为花岗闪长斑岩。岩石主矿物组合为斜长石(中长石、更长石)+石英+钾长石+角闪石+黑云母,常见副矿物为磁铁矿、磷灰石、榍石、钛铁矿和锆石。斑岩主量元素具有高硅(SiO2=63.59%)、高铝(Al2O3=15.54%)、低镁(MgO=2.2%)的特征,岩石富钾贫钠(K2O=3.06%;Na2O=3.67%),高K2O/Na2O(0.89)比;ALK=6.66%,A/CNK=1.086,σ=2.18,A.R=2.07,显示岩石为弱过铝质高钾钙碱性系列;稀土元素特征表现为轻稀土富集(121.81×10-6),重稀土亏损(8.8×10-6),具有较大的LREE/HREE比值(13.93);微量元素表现为富集大离子亲石元素LILE(Rb、Ba、La、Sr)和亏损高场强元素HFSE(Nb、Ta、Y),具低Y(11.21×10-6)和Yb(1.23×10-6)含量特征,有较高Sr/Y(57.29)、La/Yb(28.93)比值,具较高的87Sr/86Sr比值(0.7040),弱的负Eu异常(δEu=0.91),以及负εNd值等特征,表明德兴花岗闪长斑岩为"C"型高钾钙碱性埃达克岩,埃达克岩浆来源于活动陆缘加厚下地壳的部分熔融。     

江苏省首次找到锂皂石粘土岩

汉克托石—Hetorite;Гекторит,是一种不含铝而含锂、镁的、其层间阳离子钠可被钙交换的含水硅酸盐矿物。它的分子式:(Ca_(0.5)Na)×(H_2O)_4{Mg_(3-x)Lix[Si_4O_(10)](OH),F},X≈0.33,或者写成{Si_8(Mg_(4.95),Li_(1.05))O_(20)(OH)_4}Mg_(1.05)~+·H_2O,其中Mg~+几乎经常是Na~+。晶体结构为三八面体型,归属于蒙脱石—蛭石族中的蛭石亚族成员。该矿物首先发现于美国加利福尼亚州的汉克托,故而得名汉克托石。     

西藏措勤尼雄矿田滚纠铁矿磁铁矿元素地球化学特征及对成矿作用的制约

尼雄矿田滚纠铁矿地处拉萨地块隆格尔-工布江达岩浆弧,是冈底斯成矿带中生代铁铜多金属成矿作用的典型代表。在详细的野外地质调查和室内研究基础上,分析了滚纠铁矿床磁铁矿的成因矿物学特征。电子探针测试和ICP-MS分析表明,磁铁矿主量元素具有富SiO_2,贫TiO_2、V_2O_5的特征;微量元素Ba、Ti相对亏损,Cs、U相对富集,Eu、Lu、Tb、Ho、Tm强烈亏损。磁铁矿的Ti-(V+Cr)和(Ti+V)-(Al+Mn)协变图显示氧逸度、温度对矿物元素含量有明显制约作用,同时w(TiO_2)与w(CaO+MgO)、w(Na_2O+K_2O)表现出明显正相关关系,指示矽卡岩系统中流体-岩石相互作用是磁铁矿地球化学元素变化的主要控制因素。通过研究矿床中矿物生成顺序和磁铁矿中Ti、V元素特征并结合前人流体包裹体测温资料,认为矿区铁矿化阶段为高氧逸度的中高温环境,初步限定磁铁矿成矿温度为300～450℃。矿物的w(Ni)均值为8.98×10~(-6),Ni/Co比值1(变化范围0.15～0.59),Ti/V比值为6.71～25.52,从矿物化学角度进一步印证滚纠铁矿的成矿物质来源于矿区中酸性岩浆流体系统。TiO_2-Al_2O_3-(MgO+MnO)和(Ca+Al+Mn)-(Ti+V)等成因判别图解在矿区具有良好适用性,说明磁铁矿是矽卡岩矿床成矿过程的重要指示矿物。     

扬子克拉通古元古代变质演化——来自黄陵穹窿石榴斜长角闪岩的证据

为探讨扬子克拉通古元古代变质作用特征及其形成的构造背景,对黄陵穹窿北部石榴斜长角闪岩开展了岩相学、地球化学和年代学研究。结果表明,石榴斜长角闪岩中主要矿物有石榴子石、斜长石、角闪石、单斜辉石、石英、钛铁矿等,其中保留有3个阶段的不同变质期次的矿物组合,进变质矿物组合为角闪石+斜长石+石英+钛铁矿,峰期矿物组合为石榴子石+角闪石+斜长石+单斜辉石+石英+钛铁矿,退变质矿物组合为石榴子石+角闪石+斜长石+石英+钛铁矿。石榴斜长角闪岩原岩为亚碱性玄武岩,属于拉斑系列,Mg^#较低,表明其原岩经历了一定程度的分异作用。使用传统地质温压计计算不同变质阶段的温压条件分别为：进变质阶段,t=596～625℃,p=0.70～0.82 GPa;峰期变质阶段,t≈760℃,p≈1.35 GPa;退变质阶段,t=692～738℃,p=0.68～0.74 GPa,并建立了一条顺时针的p-t轨迹,显示出先升温升压至峰期阶段,随后发生近等温减压的过程。这一p-t轨迹体现了汇聚板块边缘俯冲-碰撞的构造背景,对石榴斜长角闪岩中的锆石进行U-Pb定年,获得了2 008±11 Ma的谐和年龄,并结合该...     

福建李坊重晶石矿床形成环境及矿床成因

为了解福建李坊重晶石矿床成因和成矿物质来源,对重晶石单矿物的主量元素、稀土元素、微量元素和硫同位素进行了研究,研究结果显示:重晶石单矿物表现出富Al、Si、Fe的特征;ΣREE总量较低,富集轻稀土元素;δEu呈正异常,δCe呈负异常;微量元素富集Ba、Rb、Nb、Th、P等元素,亏损K、Zr等元素;各个中段δ34S均值大于32.6‰,且直方图中只显示一个主峰。重晶石单矿物成因判别图解、ΣREE-La/Yb图解,分别指示了重晶石单矿物形成于热水沉积区,成矿物质来源于沉积岩区;Si O2/Al2O3、MnO/TFe2O3、U/Th等比值指示了弱碱性—碱性的氧化环境;(La/Ce)N、Al/(Al+Fe)等比值指示大陆边缘环境。研究表明,李坊重晶石矿床形成于大陆边缘构造环境的热水沉积成矿作用,其Ba主要来源于沉积岩区,S主要来源于寒武纪海水,并且有较多陆源物质的输入。     

西天山高压脉及主岩的氧同位素研究——古俯冲带深部流体及俯冲特征的启示

位于中国南天山的西天山高压变质带代表了伊犁-中天山与塔里木两个板块间古生代南天山洋的古俯冲混杂岩带.高压变质带内广泛发育高压脉.为探讨古俯冲深部流体来源及运移特点及板块俯冲特征,对高压脉和主岩的全岩及主要的高压变质矿物的氧同位素进行了分析.高压脉的δ18O值变化于+8.28‰与+10.70‰之间,多数在+9.50‰±1范围内.基性变质岩的主岩与高压脉具相似的氧同位素组成,变化于+9.25‰～+10.10‰之间.高压脉和主岩的全岩δ18O值变化不大.高压脉与相邻主岩间、同一高压脉中间与边部间氧同位素组成的变化没有明显的规律,一般变化不大,对于大多数脉-主岩对,变化小于1‰.与全岩完全不同的是,单矿物氧同位素组成显示出很大的变化范围,石英、石榴石、绿辉石的δ18O值分别为+11.40‰～+15.20‰,+3.59‰～+11.60‰和+8.30‰～+13.05‰,多硅白云母和蓝闪石δ18O的变化较小,分别为+10.00‰～+11.10‰和+9.26‰～+9.94‰.榴辉质岩石中高压变质矿物间氧同位素分馏广泛不平衡.全岩氧同位素组成特征表明,俯冲带深部流体主体来自邻近主岩,外来流体对氧同位素贡献有限.单矿物氧同位素广泛不平衡特征可能指示古俯冲带俯冲板片的快速俯冲和折返以及部分外来流体的参与.     

河北小寺沟铜钼矿埃达克岩: 年龄、地球化学特征及其地质意义

小寺沟斑岩型铜钼矿产于华北板块北缘,其主体岩体类型为英云闪长岩和二长花岗岩类,矿物组合为斜长石+角闪石+石英+钾长石±黑云母±辉石+不透明矿物,岩性为钙碱性Ⅰ型侵入岩.K-Ar法测得小寺沟岩体花岗斑岩年龄为(122.83±2.46)Ma.岩石主量元素具有高SiO2、Al2O3、Na2O、Mg#,低K2O、TiO2、MgO、CaO、P2O5特征.稀土元素具有负Eu异常不明显,低HREE和Y,轻、重稀土元素强烈分异特征.研究认为,小寺沟岩体与埃达克岩相似,其初始岩浆主要为加厚下地壳的部分熔融产物,即小寺沟埃达克岩为C型埃达克岩,其初始岩浆中可能还有部分地幔物质.小寺沟大型斑岩型铜钼矿的形成与埃达克岩的成矿专属性、华北板块北缘特殊构造环境密切相关.     

滇西哀牢山镇沅煌斑岩~(40)Ar-~(39)Ar年代学和地球化学特征

滇西镇沅煌斑岩呈岩脉状产出于金沙江-哀牢山富碱斑岩带南段。不同脉体的矿物组合特征相似,均为云煌岩。煌斑岩黑云母40Ar-39Ar坪年龄结果为35.69±0.40Ma和36.21±0.43Ma,与区域富碱斑岩年代一致。煌斑岩Si O2含量为43.26%~47.66%,K2O+Na2O含量为6.39%~8.22%,K2O/Na2O比值为3.68~5.55,属于碱性、高钾钙碱性系列。岩石富集大离子亲石元素(Rb、Ba、K、Sr)和轻稀土元素(LREE);相对亏损高场强元素(Nb、Ta、Ti、Zr)和重稀土元素(HREE);LREE/HREE为6.32~7.44,δEu为0.80~0.91;Nb/U值为1.15~2.18,接近俯冲带含水流体的Nb/U比值(Nb/U≈0.22)。La/Sm比值与La值具有弱的正相关趋势。岩石学和地球化学特征显示,哀牢山古特提斯洋壳俯冲交代作用形成的富集地幔,在新生代三江地区岩石圈地幔拆沉-软流圈上涌形成的伸展背景下经过部分熔融,上升侵位形成煌斑岩脉。     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

General contents of JOURNAL OF PALAEOGEOGRAPHY,2014

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Clay Mineralogical and Geochemical Studies of Detrital Rocks of the Upper Cretaceous Salt-bearing Strata,Simao Basin,SW China:Implication for Provenance and Source Weathering

正1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and     

Status of China’s Mineral Resources in 2013

正On 22nd April 2014,with the approach of the 45th World Earth Day,China’s Ministry of Land and resources issued the status of China’s mineral resources in 2013.The first task of the prospecting breakthrough strategy action implemented in the last five years has been completed,and China’s security capacity for mineral resources has been significantly improved.In the     

Thermodynamics of the Calcium-Containing Brine Systems

正There are more than 700 salt lakes with area of more than 1km2 on the Qinghai-Tibet Plateau of China.In recent years,an oilfield brine was also found in the Nanyishan Section of Qaidam Basin in the Qinghai-Tibet     

Mechanism of Salt Migration Driven by Tectonic Processes:Insights from Physical and Numerical Modeling

正1 Introduction Physical and numerical models are constructed to investigate the evolution and mechanism of salt migration driven by tectonic processes.In recent years,we have designed and ran series of models to simulate salt     

Palynological Assemblage Age and Palaeoenvironment of the Cretaceous Salt-bearing Strata in Laos and Yunnan,China

正The study of Cretaceous-Palaeogene salt-bearing strata of the Khorat Basin Laos and the Lanping-Simao Basin in Yunnan,China has an great significance not only in explaining the basin evolution and the genesis of potash     

Geological Characteristics of Potassium-Bearing Salt Layers in the Well Block Quele of the Kuqa Depression and their Significance

正Potash is one of the long-term scare deposits in China,and potash prospecting has long been listed as a key brainstorm project for our nation and geological prospecting units.There have been considerable studies in search for potash deposits in the Kuqa depression of the Tarim basin(Jackson et al.,1991;Gemmer et al.,2004;Vendeville,2005;Vendeville and Jackson,1992a,1992b),     

Integration of Resources and Technological Advantages,Creation sustainable Qinghai Potash Fertilizer Industry Base

正1 Introduction Qaidam Basin in Qinghai,including 43 salt lakes with multiple dominant mineral such as potassium,magnesium,lithium etc.,is the most intensive distribution of Saline