西秦岭礼县新生代钾霞橄黄长岩系中的含钛透辉石

对西秦岭礼县新生代钾霞橄黄长岩系中的基质相含钛透辉石进行了矿物化学研究，根据透辉石中Ti和Al的含量划分出低Ti—透辉石和高Ti—铝透辉石两种基本类型，它们作为同源岩浆演化结晶的产物，结晶顺序前者先于后者。火山岩系的透辉石[Ca(Mg，Fe)Si2O6]结晶过程中广泛存在着CaTiAl2O6(钛辉石)分子替代，晚期熔体富Ti、Al贫Si、Mg。百草山岩筒是演化岩浆结晶的产物，熔体向富Ti、Al、Fe^3 、Na，贫Mg、Si趋势演化；在透辉石成分上表现为CaTiAl2O6和NaFe^3 Si2O6(锥辉石)端元分子对Ca(Mg，Fe)Si2O6的替代。本地区基质相透辉石与世界上典型地区的钾霞橄黄长岩系的透辉石具有不同程度的可比性，反映了这种特殊的岩浆熔体成分在一定程度上控制着透辉石的结晶过程和阳离子在矿物晶格中的占位。     

甘肃金川Ⅱ号岩体辉石化学特征及其地质意义

金川Ⅱ号岩体主要由二辉橄榄岩和硫化物橄榄岩构成,单斜辉石和斜方辉石为岩相中主要造岩矿物,单斜辉石含量一般高于斜方辉石.矿物间的结构关系表明主要造岩矿物的结晶顺序为:橄榄石-斜方辉石-单斜辉石-斜长石.单斜辉石的TiO2,Al2O3,Cr2O3和Na2O质量分数依次为:0.29%～1.26%、3.17%～3.59%、0.86%～1.14%、0.29%～0.57%,斜方辉石的TiO2,Al2O3,Cr2O3和Na2O质量分数普遍低于单斜辉石,依次为:0.16%～0.40%、1.85%～2.38%、0.48%～0.68%、0.03%～0.10%.元素间的相关关系显示辉石的类质同像置换方式为:M1Fe2 2 Si=M1Ti 2IV Al,M1Fe2 Si=M1Fe3 IVAl,Fe3 和Ti进入矿物晶格置换Fe2 来平衡Al置换Si产生的正电价差.两种辉石较低的TiO2,Al2O3和Na2O质量分数显示出母岩浆为拉斑玄武岩浆的特征.二辉石温度计和单辉石温度计算表明斜方辉石的结晶温度下限和单斜辉石结晶温度上限大致在1146℃～1166℃之间,单斜辉石的结晶一直持续到1032℃或者更低.金川Ⅱ号岩体单斜辉石演化明显表现出向透辉石端员偏离,暗示岩浆在结晶分异过程中,可能与富钙质围岩发生了同化混染作用.     

河北矾山杂岩体中单斜辉石的研究

河北矾山杂岩体属于二氧化硅不饱和的超钾质碱性-过碱性岩浆系列,由单斜辉石岩、辉石正长岩和碱长正长岩等不同类型岩石组成。各类型岩石主要组成矿物为单斜辉石、黑云母、石榴石和正长石。本文利用电子探针对单斜辉石进行了详细研究,发现所有单斜辉石属于高钙透辉石,随着岩浆的演化,主要表现为Fe²⁺对Mg²⁺的替代关系,结晶趋势为透辉石→钙铁辉石,这揭示矾山杂岩体岩浆体系的特点是高温、中等大小的氧逸度、贫硅、富碱（尤其是钾）。辉石中的Al^IV含量取决于岩浆的硅饱和度,硅越不饱和,Al^IV含量越高;Al^VI含量则与体系中的Al含量呈正相关关系。由Al对Si的替代引起的电荷不平衡主要由八面体位置的Fe³⁺来补偿,其次为少量的Ti⁴⁺和更少量的Al³⁺。体系中的Ti含量与体系的温度呈正相关关系,而Na含量则与辉石中的Ti和Fe³⁺含量成正相关关系。不同类型岩石中单斜辉石从核部到边部随着Mg^#的降低,Al、Ti含量呈现不同的演化趋势,这是因为它们于岩浆演化的不同阶段开始结晶,经历了不同的岩浆演化史。碱性岩中高钙辉石的出现和成分环带的普遍发育是由岩浆的贫硅富钾特征决定的。单斜辉石的成分不仅受控于结晶时的温度、压力条件,也受控于岩浆的总成分及其变异。     

江南造山带西段新元古代构造演化——来自湘西怀化辉绿岩中辉石、黑云母成分的启示

关于江南造山带的新元古代构造演化背景素有地幔柱—裂谷模型、岛弧模型及板块—裂谷模型之争,其争论的焦点在于扬子与华夏板块碰撞的具体时间,以及聚合后裂解的动力学环境。笔者等选取江南造山带西段湘西怀化地区～788 Ma辉绿岩中的单斜辉石和黑云母为研究对象,采用电子探针和激光剥蚀—等离子体质谱仪对其化学成分进行了精确测定,以期进一步约束该地区的成岩构造背景。怀化辉绿岩中的单斜辉石可分为普通辉石和透辉石两种,根据单斜辉石的n(Ca)/n(Al)值(3.48～7.15)和高w(Ti)/w(Eu)值(>1500)的特征,笔者等判断江南造山带西段的新元古代地幔可能遭受了硅酸盐熔体和俯冲流体的多重交代作用。单斜辉石温压计的估算结果表明,普通辉石的结晶温度为1080～1112℃,结晶压力0.3～0.6 GPa,对应的深度为9.1～20.8 km;而透辉石的结晶温度为1237～1274℃,结晶压力1.0～1.32 GPa,对应的深度为31.8～42.6 km。综合单斜辉石和黑云母的微量元素特征(单斜辉石的Al、Ti、Ca、Na等元素和黑云母的Mg、Fe等元素)、岩浆系列和构造环境判别图解,表明该区的亚...     

西秦岭礼县地区新生代钾霞橄黄长岩系地球化学特征及地质意义

西秦岭礼县地区新生代钾霞橄黄长岩系具有贫SiO2、Al2O3，富MgO、CaO、TiO2及K2O Na2O的特征，矿物组合中除橄榄石、透辉石外，普遍含有霞石／钾霞石、黄长石／白榴石和钛金云母等矿物。火山岩系的Sr、Nd示踪同位家和微量元素特征显示其与洋岛玄武岩(OIB)的地球化学体制相似，源区具有由软流圈流体交代导致的EMI型地幔端员成分。根据尖晶石相二辉橄榄岩地幔包体温、压条件估算，结合区域地球物理资料和区域大地构造环境以及火山岩的形成时代推断，钾霞橄黄长岩系的形成机制与本地区新生代岩石困伸展作用密切相关，原始岩浆源于＞92km的岩石圈底部热边界层的低度部分熔融。     

昌乐方山新生代玄武岩中深源捕虏岩与熔体的相互作用

昌乐方山新生代玄武岩中携带有大量深源捕虏岩,其岩石类型以二辉辉石岩、二辉橄榄岩为主,方辉橄榄岩、单斜辉石岩、单辉橄榄岩少见,未见纯橄岩。二辉辉石岩、二辉橄榄岩、方辉橄榄岩的矿物岩石、地球化学特征和平衡温度压力计算显示为地幔来源,采用地质温度压力计进行计算,获取三者都源于岩石圈地幔,形成的深度范围为41~66.7 km。根据单辉橄榄岩和单斜辉石岩的矿物化学分析,单斜辉石岩和单辉橄榄岩形成深度要低于前三者,且与前三者有密切成因联系。"熔体—岩石"反应在各类深源捕虏岩中广泛存在,除方辉橄榄岩样品不存在明显的"熔体—岩石"反应外,二辉辉石岩、单斜辉石岩、二辉橄榄岩中不同的矿物边缘与玄武质熔体接触部位有着不同类型的反应边和反应矿物出现:橄榄石边部发生(Mg,Fe)_2SiO_4(镁橄榄石)+熔体(原始岩浆)=(Mg,Fe)_2SiO_4(贵橄榄石)+熔体(演化岩浆)反应,使得边部富铁贫镁;单斜辉石与玄武质熔体反应,多具有粉红色反应边,具有富Ti、Al、Fe,贫Si、Mg,较玄武岩基质中单斜辉石斑晶更低Mg~#的特征。斜方辉石与玄武质熔体反应生成复杂的反应带,存在斜方辉石+熔体=橄榄石+SiO_2(熔体)+单斜辉石的反应,反应带内新生成的矿物由内向外具有明显趋向玄武质熔体成分的变化;尖晶石与玄武质熔体反应边缘具有富Fe、Ti,贫Mg、Al,以及更高的Cr~#,趋向于形成钛铁矿的变化特征。二辉橄榄岩中熔体囊和单辉橄榄岩中筛状单斜辉石以及粉红色的反应边都暗示了二者至少经历了两个期次的熔体作用。随着岩石圈地幔的演化,熔体的再富集作用使得难熔的方辉橄榄岩逐渐转变为相对富集的二辉橄榄岩,后期二辉橄榄岩又与玄武质熔体反应,生成更加富集的单辉橄榄岩,而方山方辉橄榄岩也受到了熔体的轻度改造,已不具有难熔古老岩石圈地幔岩石的显著特征,鲁西新生代玄武岩中深源捕虏体与熔体的反应广泛存在,熔体成分以玄武质为主,这可能是华北克拉通岩石圈置换的重要方式之一,导致古老岩石圈地幔的消失。     

峨眉山玄武岩的辉石研究

本文研究的峨眉山玄武岩的辉石均为单斜辉石。东川碱性火山岩中以透辉石为主,显示碱性岩系辉石的特征,但相对贫 LREE、Ti 等不相容元素,结晶时的 fO₂较高;攀枝花岩带主要是透辉石质普通辉石;其他剖面和地区多为普通辉石,且具拉斑质岩系富钙辉石的成分和演化特点。攀枝花带和西岩区辉石在化学成分上比较原始,而东岩区和中岩区辉石的成分演化程度相对较高。含 Ti 的“其他”阳离子对在各岩区（带）的辉石中均限重要,暗示它们的形成与火山弧环境无关。     

江南造山带西段新元古代构造演化——来自湘西怀化辉绿岩中辉石、黑云母成分的启示

关于江南造山带的新元古代构造演化背景素有地幔柱—裂谷模型、岛弧模型及板块—裂谷模型之争,其争论的焦点在于扬子与华夏板块碰撞的具体时间,以及聚合后裂解的动力学环境。本文选取江南造山带西段湘西怀化地区~788 Ma辉绿岩中的单斜辉石和黑云母为研究对象,采用电子探针和激光剥蚀—等离子体质谱仪对其化学成分进行了精确测定,以期进一步约束该地区的成岩构造背景。怀化辉绿岩中的单斜辉石可分为普通辉石和透辉石两种,根据单斜辉石的n(Ca)/ n(Al)值（3.48~7.15）和高w(Ti)/w(Eu)值（>1500）的特征,本文判断江南造山带西段的新元古代地幔可能遭受了硅酸盐熔体和俯冲流体的多重交代作用。单斜辉石温压计的估算结果表明,普通辉石的结晶温度为1080~1112 ℃,结晶压力0.3~0.6 GPa,对应的深度为9.1~20.8 km;而透辉石的结晶温度为1237~1274 ℃,结晶压力1.0~1.32 GPa,对应的深度为31.8~42.6 km。综合单斜辉石和黑云母的微量元素特征（单斜辉石的Al、Ti、Ca、Na等元素和黑云母的Mg、Fe等元素）、岩浆系列和构造环境判别图解,表明该区的亚碱性拉斑玄武质岩浆来自于上地幔顶部与地壳结合的部位,是软流圈地幔部分熔融产生的板内碱性玄武质岩岩浆上升到浅部发生结晶分异作用形成的。结合区域的构造演化特征,本文提出一种三阶段的改进板块—裂谷模型,用以描述江南造山带西部的新元古代构造背景。     

新疆西准噶尔地区两类蛇绿岩中橄榄岩的矿物学研究

两类蛇绿岩中变质橄榄岩的矿物表现出的共同特征是:从二辉橄榄岩→斜辉橄榄岩→斜辉辉橄岩→纯橄岩→铬铁矿石,其橄榄石、斜方辉石和单斜辉石的Mg/(Mg+Fe)(矿物牌号)依次升高,表现出富Mg贫Fe的演化趋势;铬尖晶石的Cr/(Cr+Al)亦同时升高,表现为富Cr贫Al的演化特征。 变质橄榄岩中的矿物均是原始上地幔岩部分熔融的残余物。在部分熔融过程中,橄榄石与铬尖晶石是生成相矿物,而斜方与单斜辉石则是消失相矿物,正是通过两种辉石的不断消失,岩石才从二辉橄榄岩依次转化为纯橄岩,并造成纯橄岩与铬铁矿的紧密伴生。在此过程中,矿物成分时刻都在变化,造岩矿物向富Mg贫Fe,金属矿物向富Cr贫Al方向调整,这与实际测定结果是一致的。     

莫来铁尖晶岩的发现和玄武岩浆的深部分异作用

莫来铁尖晶岩是首次发现的一种新型火山岩,由铁尖晶石、莫来石、铁板钛矿和火山玻璃组成,其平均化学成分相当于一个简化的SiO_2-FeO~*—Al_2O_3三元系。莫来铁尖晶岩浆是原始岩浆深部分异的结果。原始玄武岩浆在地幔深处分离结晶出富含硬玉分子的斜方辉石、单斜辉石,进化岩浆向富Al、Fe而贫Si的方向演化,最终产生莫来铁尖晶岩浆。后者喷出地表,冷凝结晶形成莫来铁尖晶岩。     

The Zoned Clinopyroxenes of the Shiant Isles Sill, Scotland

The zoned clinopyroxenes in samples from a near-vertical sectionthrough the main Shiant Isles sill have been studied using theelectron microprobe. In terms of Ca: Mg: Fe the over-all fractionationtrend is much greater than had been believed from bulk pyroxeneanalyses and is of a distinctive calcic augite-hedenbergitetype. In this respect it differs from both the augite-ferroaugiteand salite-aegirine trends generally regarded as typical oftholeiitic and alkaline basic magmas respectively, and it isproposed that this trend represents a third major type typicalof mildly alkaline basic magmas. The Al, Ti, and Na contentsof the pyroxenes are dependent on the degree of fractionationas represented by Mg/(Mg+Fe) and it is suggested that the Aland Ti contents are controlled by the Ti content of the liquidand the crystallization of titaniferous magnetite whereas theentry of Na into the pyroxene as aegirine is dependent on theactivity of Fe³⁺ in the liquid. To provide a basis for discussion of the crystallization ofthe zoned clinopyroxenes the existing petrogenetic hypothesesfor the Shiant Isles sill are reviewed and a new model proposedfor its emplacement and differentiation. It is concluded thatthe differences between the pyroxenes of the mildly alkalineShiant Isles sill and those of more strongly alkaline basicmagmas result from fundamental chemical differences in the magma.The lower Ca contents of the early pyroxenes are due to theslightly higher Si activity of the magma and the subsequenttrend towards hedenbergite rather than aegirine is due to crystallizationunder conditions of relatively lower oxygen fugacity, probablyas a result of lower initial H₂O content of the magma.     

新疆磁海铁矿床中辉石的研究与单斜辉石分类定名的多元三角图解法

一、磁海矿区单斜辉石的研究在我国新疆磁海铁矿区的辉长岩、辉绿岩、闪长岩、辉石花岗岩、石榴石辉石岩及辉石岩等不同类型的岩石中,辉石广为发育。辉石主要属单斜辉石中的透辉石—钙铁辉石系列及普通辉石系列。     

Rhönite in undersaturated alkaline gabbroic rocks,Central Alborz,North Iran: petrography and mineral chemistry

The Kamarbon alkaline gabbroic intrusion crops out in Central Alborz, north Iran, along the northern margin of the Alpine-Himalayan belt. The gabbroic intrusion includes theralites at margins which replace with teschenites toward the center. In teschenitic rocks, the main minerals are diopside, clinopyroxene, and rhönite. In this research, the occurrence of rhönite is reported in Kamarbon teschenitic gabbros, and also its mineralogical properties, paragenesis, and source magma are investigated. Based on whole rock and microprobe analysis data, we try to clarify the formation of Kamarbon gabbro and the crystallization condition of rhönite. In teschenitic gabbros, rhönite reveals the composition (Na, Ca)_1.97(Ti, ^VIAl, Fe⁺³, Fe⁺², Mn, Mg)_5.99(Si, ^IVAl)_6.02O₂₀. On the basis of petrographical observations and mineral chemistry, we suggest that the teschenites were formed in distinctive lower pressures and temperatures than theralites, below 1.9 kbar and 1075 °C. Rhönite was crystallized (at the mentioned P-T condition) as a primary phase, in the late stage of crystallization at shallow depth corresponding with 6–10 km, in teschenites. Important factors of the rhönite crystallization in undersaturated magmas can be regardarded as Al and Ti enrichment and Si depletion; the same enrichment and depletion are also observed in the associated clinopyroxenes.     

赣东北地区早白垩世火山岩的岩石学及岩石化学特征

岩石学及岩石化学特征表明，赣东北地区早白垩世火山岩及次火山岩主要有：玄武岩、伊丁石化橄榄玄武岩、橄榄玄武粗安岩、粗面玄武岩、安粗岩、粗面英安岩、粗面岩、流纹岩、凝灰岩及花岗斑岩等，可划分为高钾钙碱性、橄榄安粗岩和碱性玄武岩3个系列。高钾钙碱性系列富Si、K，贫Mg、Fe、Ca、Al；橄榄安粗岩系列和碱性玄武岩系列富碱，尤其富K，富Al、Ti，贫Si。相比之下，橄榄安粗岩系列比碱性玄武岩系列更富K、Al、Ti、Si。本区复杂的火山岩很可能是晚中生代时期古太平洋巨大板块中Faralong、Izanagi、Kula等板块相对亚洲大陆走滑和斜向俯冲及在大陆内产生的NE－NNE向平移剪切－伸展拉张的结果。     

Crystal-chemistry of clinopyroxenes from potassic and ultrapotassic rocks in central Italy: implications on their genesis

The clinopyroxenes mentioned have been investigated by single crystal X-ray diffraction combined with electron microprobe analysis. The aim of this study was to characterize the crystal-chemical variations of clinopyroxenes in order to delineate the intracrystalline constraints which are characteristic of specific magmatic environments. Clinopyroxenes (cpx) crystallized from peralkaline ultrapotassic melt with kamafugitic and lamproitic affinities are characterized by high Si contents, which are insensitive to variations in silica abundance and silica saturation of the melt. The high Si occupancy in clinopyroxenes from kamafugitic magma is coupled to large M1 (i.e. Mg and Fe²⁺) and M2 (high Ca occupancy) sites, whereas in clinopyroxenes from magmas with lamproitic affinity, high Si content is combined with large M1 but small M2 sites. Clinopyroxenes from Romantype alkaline potassic and ultrapostassic rocks are characterized by an expanded tetrahedron (high ^IVA1 content) and small M1 site which is combined with small M2 polyhedron in clinopyroxenes from the potassic rocks and large M2 site in those from the ultrapotassic rocks.     

一种新的闪石共存对—铁闪石与铁韭闪石对

新近在我国山西省娄烦县尖山铁矿的角闪片岩中发现一种取向连生的镁铁质闪石与钙质闪石共存对。电子探针分析确定它们分别为铁闪石Ｋ０．００１（Ｎａ０．０２７Ｃａ０．０７３Ｍｎ０．０３１Ｆｅ＾２＋１．８０１）１．９３２（Ｆｅ＾２＋２．９４８Ｍｇ１．９６４Ｔｉ０．００２Ａｌ０．０８７）５Ｓｉ８．０６９Ｏ２２．１０（ＯＨ）２与铁韭闪石（Ｋ０．１３５Ｎａ０．４６１）０．５９６（Ｎａ０．０８８Ｃａ１．８５３Ｍｎ０．     

Compressibility and structure behaviour of maruyamaite (K-tourmaline) from the Kokchetav massif at high pressure up to 20 GPa

Mineralogy and Petrology - The structural behaviour of maruyamaite (K-dominant tourmaline) X(K0.54Na0.28Ca0.19)Y(Mg1.3Al1.17Fe0.39Ti0.14)Z(Al5Mg)[Si5.95Al0.05O18](BO3)3V,W[O1.69(OH)2.31] from the...     

苏鲁造山带东部荣成榴辉岩中蓝晶石及绿辉石的分解——一种可能的新成因解释

在麻粒岩相条件下，荣成含蓝晶石榴辉岩发生退变质，其中的绿辉石退变质成透辉石＋中长石组成的后成合晶，蓝晶石大部分被冠状体取代，基于详细探针分析结果的成分迁移估算显示，冠状体的形成需要从绿辉石的分解中获取CaO,MgO,FeO，绿辉石的分解包含两个反应：一个为绿辉石中的硬玉分子与石英结合形成钠长石；另一个发生在绿辉石内部各端员组分之间，后者不但形成后成合晶，而且为蓝晶石周围冠状体的形成提供CaO,MgO,FeO，蓝晶石的分解未能给后成合晶的形成提供SiO2，绿辉石与蓝晶石在分解时并冰形成一个封闭体系，它们均从周围环境中获取SiO2。     

Chemical and phase heterogeneity of Ti-Fe-Mn-silica microspherules in crushed ore samples

A Fe-Ti-Mn-silicate microspherule from the heavy mineral fraction of crushed geological samples from an underground mine (Kellyam gold deposit, Yakutia) was examined by transmission electron microscopy. The 400-μm microspherule has a complex chemical composition and contains the following elements (in order of decreasing content): O, Ti, Si, Mn, Fe, Al, Mg, Ca, and K. The material of the micro-spherule shows a polyphase structure and chemical heterogeneity with separation into amorphous oxide-silicate (SiO₂) and crystalline metallic (α-Ti + FeTi) constituents. The spherical shape and the character of internal heterogeneity suggest that the microspherule was formed owing to the rapid solidification of a melt droplet. The nanoscale heterogeneity of the microspherule is a consequence of a two-stage process. (1) Liquid immiscibility in the initial melt droplet before its solidification resulted in the incomplete spatial separation of Si + Al and Ti + Fe + Mn and appearance of SiO₂ globules with admixtures of Al, Ca, K, Mg, Ti, Fe, and Mn approximately 100 nm in size. (2) Chemical heterogeneity developed subsequently both within the globules and within the matrix at the stage of melt solidification or after the solidification. The second-stage chemical heterogeneity was manifested in (a) the separation of heavy minor element oxides (Ti, Fe, and Mn) from the light elements Si, Al, K, Ca, and Mg(?) within the globules and (b) the separation of the matrix material into crystalline metallic (α-Ti + FeTi) and amorphous oxide-silicate [SiO₂-MgO-Mn₃O₄(?)-Fe₂O₃(?)-TiO₂(?)] parts. The obtained results do not rule out the possibility of formation of such microspherules during drilling operations.