桐庐杂岩体中共存的两种碱性长石研究

桐庐同熔型火山－侵入杂岩中出现两种碱性长石，一种为无色透明，另一种为微红色，本文利用X射线衍射仪，电子探针，透射电镜对其结构态，成分及出溶微结构进行了对比研究。结果表明，两者成分差别不大，而结构差别较大，无色透明的为透长石，出溶叶片发育；微红色的为正长石或低透长石，出溶结构不发育。而且随着冷却速率的变慢，无色透明碱性长石的Al/Si有序度增大，微红色碱性长石的有序度降低，分析后认为这种共存现象是岩浆混和造成的，从而为桐庐杂岩体的岩浆混合成因提供了有力的证据。     

碱性长石微结构特征与岩体冷却速率的关系

前人的研究(主要为实验研究)表明:岩体冷却速率越慢,隐纹长石出溶叶片周期越大。但笔者在研究中发现:如把不同地区的不同岩石按冷却速率的变化梯度排列起来,其隐纹长石出溶叶片周期变化为:熔结凝灰岩中300nm±,熔岩流中150nm±,较窄岩脉中100nm±,较宽岩脉中50nm±,火山颈相次火山岩中12nm±。可见随着冷却速率的变慢,碱性长石出溶叶片周期反而变小,这明显与前人的实验结果相矛盾。该结果可能由两个因素造成:一是以往的实验结果只是对由拐点分解形成的出溶叶片周期的研究,不适用于解释由非均匀成核及均匀成核形     

低温碱性溶液中微纹长石溶解性质研究

对微纹长石在碱性溶液中的溶解过程及表面特征变化规律进行实验研究，温度为60℃，实验溶液分别为NaOH(pH≈8)、Na2CO3，[ρ(Na^ )=26μg／mL]和NaCl溶液，利用X射线光电子能谱(XPS)和ICP-MS测定实验前后微纹长石的表面特征及实验溶液成分变化，结果表明，随着pH值升高，微纹长石的溶解性增强；微纹长石的溶解不是被单一反应模式所控制，而是在表面控制(surface-conrtolled)、扩散控制(diffusion-controlled)和次生物相形成三种过程交替进行的结果。碱性溶液中长石表面反应分三个步骤：H^ 与长石表面碱性阳离子交换反应；OH^-联合已进入长石架状结构内部空隙，具较大结合能的Al-O键逐步破裂，并生成铝的水解产物而溶出；表面形成富Si的络合物。     

碱性长石在次固相下的微组构重组织:碱性长石流体相互作用

辫状微纹长石通过粗化、微孔隙和亚颗粒的形成 ,最终发展为脉状微纹长石和条纹长石 ,粗化沿着不规则的前锋从晶体边缘往内部推移和扩展。亚颗粒和微孔隙的形成极大地提高了碱性长石的反应性和岩石的渗透性。通过沿着晶体边缘的拱状褶边、平行褶边以及褶头的过渡带往整个晶体内的推移和“繁殖” ,辫状微纹长石最终改造为脉状微纹长石和条纹长石。水从褶边向晶体内部的扩散促进了褶边的粗化以及过渡带的发展。流体长石相互作用机制包括 :体积扩散、管道扩散、溶解再沉淀。碱性长石流体的氧同位素交换机制主要是溶解再沉淀。碱性长石在次固相下的微组构重组织发生于约 4 75～ 4 0 0℃的温度下 ,区块性条纹长石的形成温度更低。碱性长石的微组构重组织导致放射成因氩的局部和部分丢失 ,从而给出年轻的表面年龄。     

碱性长石中Fe^3＋在四面体位置间交换动力学的EPR研究

在加热条件下,利用EPR方法研究了碱性长石中不同四面体位置间的Fe~(3+)、Al~(3+)交换。低温钠长石和透长石晶体分别在水热,1 kbar,500—900℃和干加热,1050℃条件下加热。在低温钠长石中,加热后Fe~(3+)线被加宽,当温度为800℃时,除T_1(o)位置外,没有出现其余四面体位置Fe~(3+)产生的谱线。透长石在1050℃加热1300h后,T_1和T_2线的相对强度发生了变化。实验表明,在碱性长石中不同四面体间Fe~(3+)、Ak~(3+)和Fe~(3+)、Si~(4+)交换与Al~(3+)、Si~(4+)交换比较,前者速度要缓慢得多。     

桐庐、黄山花岗岩类岩体中碱性长石的出溶和超微双晶

本文研究了桐庐和黄山两地不同成因花岗岩类岩体中碱性长石的出溶和超微双晶。结果表明,碱性长石的出溶和超微双晶同岩体的成岩温度、冷却速率以及岩体成因类型和碱性长石的化学成份有关,成岩期后的热作用对碱性长石的出溶和超微双晶产生改造和破坏。     

二长石地质温度计在估算乌拉山金矿碱性长石形成温度中的应用

内蒙古乌拉山金矿田内主要出露晚太古代乌拉山群区域变质岩和规模不一的花岗岩体以及不同时代、不同种类的脉状地质体。含金矿脉中主要矿物共生组合为碱性长石、石英、斜长石、碳酸盐矿物(方解石、白云石)和少量金属硫化物。矿床的显著特征为碱性长石交代作用强烈，碱性长石也广泛产于该地区其他各种类型的岩石中。本文采用电子显微探针分析了共生碱性长石和斜长石的化学成分，并采用三元二长石温度模型估计了碱性长石的平衡温度。结果表明，第一成矿阶段的碱性长石一石英含金矿脉中碱性长石的形成温度为353℃，第二成矿阶段石英含金矿脉中碱性长石的形成温度为281℃，矿脉碱性长石形成压力约为5kbar。这些结果与同类矿石中平衡共生的碳酸盐矿物和云母类矿物的地质温度计估计的形成温度以及共生石英中流体包裹体的均一温度非常一致。因此，乌拉山金矿床形成和富集的温度可估测为260～380℃，压力约为5kbar。此外，应用二长石温度计计算了本地区区域变质片麻岩和花岗岩中碱性长石的平衡温度，所得温度比采用共生铁铝榴石和黑云母温度计估计的温度要低约250℃。这表明共生的铁铝榴石和黑云母的平衡温度可能代表其寄主变质岩变质期温度及寄主花岗岩原生温度，而区域变质岩和花岗岩中的碱性长石在经历了随后多次热液作用后，可能重新平衡再生，这也与前人对乌拉山金矿的矿床地质和同位素研究的结果一致。     

黄玉与红柱石,白云母,碱性长石之间的矿物平衡及其岩石学意义

黄玉的形成条件是阐明含黄玉岩石成因的关键。为定量解释黄玉的岩石学成因意义，本文利用黄玉和与其共存的矿物及流体组分的热力学性质，计算了花岗岩－Ｈ２Ｏ－ＨＦ体系中有关反应的ｌｏｇａＨＦ－ｌｏｇａＫＦ，ｌｏｇａＨＦ－ｌｏｇａＡＮ，ｌｏｇａＨＦ－Ｔ图及Ｔ－Ｐ图。利用上述计算结果，本文解释了含黄玉花岗质岩石及其极端分异产物的形成条件和斑岩Ｍｏ、Ｓｎ矿床蚀变分带的形成机制。     

山东五莲碱性三元长石的微结构研究

笔者对产于山东五莲县七宝山辉石二长岩中的碱性长石进行了电子探针,Ｘ射线衍射,透射电子显微镜以及＾２９ＳｉＭＡＳＮＭＲ谱研究,确定五莲碱性三元长石（Ｏｒ５０．３,Ａｂ４４．３Ａｎ５．４）为钾长石和钠长石共格出溶连晶,其基体钾长石为单斜对称,在透射电子显微镜下未见其呈现任何微结构,而在钠长石中见到宽度为１０．４ｎｍ（钠长石的８ｂ０）的片晶相互形成周期钠长石律双晶,钠长石叶片的宽度平均为３９ｎｍ（ｎ＝４     

内蒙东七一山碱长花岗岩及其成矿作用

碱长花岗岩在国内外普遍以含多金属元素、特别是稀有金属矿化为特征,该类矿化岩体在我国多分部在华南褶皱系,而产出在内蒙西部的东七一山碱长花岗岩是我国北方地区少见的一个大型稀有金属矿化体,由于前人工作不多,对其认识较浅。本文在前人工作基础上,对其岩石学、成矿学及成岩、成矿机制等方面做了较多细致、深入的工作,表明该岩体是一个壳源岩浆直接分异演化而成的碱长花岗岩体,岩体除铷含量较高外,其中的铌－钽也有很高的利用价值,碱长花岗岩还是钨、锡、铍资源的源泉,同时派生出的大型萤石矿和文石－方解石矿产也有很高的经济价值,从而大大提高了对东七一山碱长花岗岩成岩、成矿实践和理论认识,这对在区域上扩大与这类岩体有关的找矿工作具有重要指导意义。     

福建太姥山晶洞碱长花岗岩地貌特征

太姥山是东南沿海低山丘陵唯一的花岗岩峰丛-石蛋地貌,燕山晚期"A"型晶洞碱长花岗岩是太姥山造景岩石,北东东、北北西向断裂、裂隙及节理是控制山峰形态和规模的主要构造,风化剥蚀、降水侵蚀和重力崩塌是地貌形成的主要外动力作用,目前该地貌演化处于壮年早期阶段。其构造位置特殊、成景岩性独特,地貌类型丰富,是东南沿海晶洞花岗岩山岳地貌的典型代表和宝贵的地质遗迹。     

Micropores in plagioclase

Plagioclase feldspar is often surprisingly porous on a small scale. Pores range in size from less than 1 μm to about 40 μm, and occupy up to 2.3 % by volume. In general, the highest plagioclase porosities occur in rocks which would have had a comparatively “wet” history: normal granites and pegmatites. Rocks which were drier—gabbro, a diabase and an exceptionally dry granite—have much lower plagioclase porosities, as do two lowgrade metamorphic samples. It is suggested that the nearly equant pores represent sites of former fluid inclusions, while the planar cavities of cracklike cross-section may be partially annealed fractures formed early in the history of the rock.     

云南个旧卡房锡-铜矿床碱长花岗岩厘定及意义

卡房矿床位于个旧矿田东南部,矿区花岗岩为致矿岩体,以往对花岗岩的研究也较多,对花岗岩的定名为:黑云母花岗岩、黑云母二长花岗岩或者黑云母斜长花岗岩等等。通过对卡房花岗岩进行系统的岩矿鉴定和电子探针分析,发现长石为碱性长石(钾长石和钠长石),钠长石的An值均小于等于5。因此最终确定卡房岩体花岗岩为碱长花岗岩。而这种碱长花岗岩由富挥发分的岩浆形成,液态不混溶作用广泛发育于岩体顶部附近,是锡多金属矿富集成矿的主要分异方式,钠长石的An值可部分作为花岗岩成矿属性的评价标识之一。     

浙东南玉苍山-彭溪碱长花岗岩锆石U-Pb年龄学、岩石地球化学特征及其成因类型

玉苍山-彭溪岩体位于东部沿海花岗岩带北端,受古太平洋板块俯冲制约。笔者等以该岩体碱长花岗岩为研究对象,开展锆石U-Pb测年,获得其加权平均年龄为96.50±1.81Ma和98.27±0.39 Ma,表明该岩体为晚白垩世岩浆活动的产物。该岩体主要矿物组成为钾长石（60%～70%）、石英（25%～35%）,少量斜长石（＜5%）、黑云母（＜2%）等,呈中细粒花岗结构。该岩体地球化学特征上呈现高硅、富碱、低铝,镁、钙、磷、钛、铁等元素含量极低,Rb、K等大离子亲石元素和Th、U、Zr、Hf等高场强元素富集,亲铁元素Co、Ni、Cr、V等含量较低;K/Rb值低,Rb/Sr、Rb/B值高;稀土元素总量高,且轻稀土元素富集程度远大于重稀土元素,同时具有明显的铕负异常,分异指数高;反映了该岩体具有强烈的壳源特征,且形成时岩浆演化分异程度高,存在斜长石、磷灰石等矿物的分离结晶,属于过铝质高钾钙碱性花岗岩系列。认为该岩体属于A型花岗岩,为晚白垩世时期板内伸展构造环境下软流圈地幔上涌、部分地壳参与熔融形成的。     

Zonal Distribution of Variations in Structural State of Alkali Feldspar within the Rader Creek Pluton, Boulder Batholith, Montana

The granodioritic Rader Creek pluton of the composite Boulderbatholith contains microperthitic alkali feldspar of bulk compositionOr₆₅ to Or₈₆ with a structurally variable potassic phase. Completecell parameters, 2V measurements, and bulk composition are givenfor 11 feldspar samples. The 131 and 131 reflections for theseand 58 additional samples show the following structural typesin the potassic phase: orthoclase only; orthoclase with subordinatemaximum or near-maximum microcline (obliquity = 0.75–1.00);orthoclase with subordinate intermediate microcline (obliquity= 0.64–0.71); and intermediate microcline (obliquity =0.56–0.77) with subordinate orthoclase. Within the plutondifferent feldspar structural types occur in zones whose boundariesare approximately parallel to contacts with younger intrusiverocks cutting the Rader Creek pluton but are, in places, nearlyperpendicular to zonation within the pluton defined by rockcomposition. In general, the orthoclase zone is closest to thecontact with younger intrusives; the intermediate microclinezone is the most distant. Bulk compositions of alkali feldsparare more potassic in the orthoclase zone than elsewhere. Thedata suggest a complex history for the alkali feldspar, involvingat least two stages: 1. Exsolution and partial inversion oforthoclase to intermediate microcline during cooling of theRader Creek pluton; 2. Transformation of the intermediate-microclineassemblage to orthoclase during reheating of the pluton at thetime of intrusion of younger plutons of the batholith. The transitionalstage in this transformation is characterized by orthoclaseco-existing with subordinate microcline, whose obliquity usuallyapproaches that of maximum microcline.     

Microcracks in ultrabasic rocks under uniaxial compressive stress

The initiation and propagation of microcracks under stress are highly dependent upon the mineralogical and textural characteristics of the various lithotypes. Detailed observation and quantification of microcracks before and after uniaxial compression test were conducted. A fresh olivine-rich harzburgite and a serpentinized dunite were analyzed, collected from the Pindos and Vourinos ophiolites (northern Greece) respectively, in order to compare their microcrack patterns. Quantitative analysis indicated that during uniaxial compression the intragranular microcracks, which are the dominating crack-type, are gradually transformed or organized into transgranular cracks. Some of the newly formed transgranular cracks may also be a result of the growth of existing grain-boundary cracks. The new intragranular microcracks in the olivine-rich harzburgite are oriented predominantly parallel to the compressive stress direction, while those in the serpentinized dunite show a scattered orientation presumably due to the mesh texture of this rock-type. The new transgranular cracks of both peridotites tend to be subparallel to the compressive stress direction, however, many of them show a random orientation due to the fact that they have been formed as a result of the propagation of grain-boundary cracks. The occurrence of the soft serpentine along fracture surfaces of olivine, when it is in assemblage with orthopyroxene, tends to absorb the applied stress hampering the development of microcracks in olivine. On the other hand in serpentinized peridotites, the microcracks are enhanced in olivine because it is surrounded by large amounts of the much softer and flexible serpentine. Microcracks are usually formed along the cleavage planes of orthopyroxene porphyroclasts, indicating that such crystallographic preferred orientations act as planes of weakness, controlling the direction of the crack paths. Cr-spinel grains likely comprise locations of initiation of microcracks due to their very hard nature and different mechanical behaviour relative to the surrounding silicate phases. Knowledge of the mineralogical and textural characteristics may assist in the prediction of potential development of failure surfaces of an ultrabasic rock in-service.     

Feldspar relations in a composite magma

The coming together of basic and acid magma in a volcanic plug is believed to have produced above-liquidus temperatures and effected temporary fusion of oligoclase phenocrysts in the acid component. Electron-probe analyses of the minerals show a high degree of feldspar ternary solid solution which is related to composition of the magma and possibly to the effect of superheating.     

钾长石分解反应热力学与过程评价

综述了添加各种助剂分解钾长石的研究进展。对不同体系中钾长石分解反应的G ibbs自由能和能耗计算,综合考虑一次性资源、能源消耗量和烧结过程的环境相容性、产品方案等因素,结果表明:只有以石灰石、碳酸钠为配料的工艺路线具有实际工业应用价值;而唯有以碳酸钠为配料时,钾长石原料烧结过程才具有一次性资源消耗量最少、能耗最低、温室气体CO2排放量最小、且可生产高附加值产品、实现完全清洁生产等优点。因此,选择以碳酸钠为配料分解钾长石的技术路线,具有良好的工业化应用前景。