广东从化石岭碱性杂岩的岩石学特征及其地质意义

对广东从化石岭碱性杂岩体进行了１：１万地质调查和填图,并进行了详细的岩石力学研究。其结果表明：杂岩体由霞石角闪石正长岩、角闪石正长岩、墨云母正长岩等岩性组成,为Ａ－型花岗岩的分异结晶作用所形成,产于板内引张构造环境,与深大断裂有关。岩体本身已构成霞石正长岩矿床,具有较高的工业利用和经济价值。     

含霞石翡翠的成因研究

本文针对鲜有报道的含霞石翡翠,选择了若干具有代表性的样品进行了详细的岩相学、矿物化学、拉曼光谱和X射线粉晶衍射等方面的研究,并对其成因进行了深入探讨。本研究中的样品属于翡翠中的“飘蓝花”品种,为柱粒状结构,主要由硬玉、霞石、角闪石和少量的钡铝硅酸盐等组成。硬玉可分为两个世代,早期硬玉呈自形,发育规则的环带结构,反映了成岩流体的反复补给过程。早期自形的硬玉颗粒部分被后期细粒化的硬玉±角闪石取代,反映了后期流体事件的改造作用。根据产出和成分特征可将霞石分为两种：贫钾霞石和富钾霞石,其中贫钾霞石多沿自形的硬玉颗粒边界分布,而富钾霞石充填在自形的硬玉颗粒之间。根据结构特征可以推测,含霞石翡翠主要是从成岩流体中直接结晶形成的。矿物组成及其成分特征表明该成岩流体主要富集Na、Al、Si、K、Ba以及少量的Ca、Fe、Mg等元素,微量元素则相对富集LREE、HFSE和Sr等元素。结合样品中的矿物相关系和前人的研究结果,含霞石翡翠中硬玉的结晶压力和温度范围分别被限制在0.6～1.4GPa和300～450℃之间,其中霞石代表着母岩减压后流体活动的产物。     

Age and origin of a Palaeozoic nepheline syenite from northern Shanxi Province,China: U–Pb zircon age and whole-rock geochemical and Sr–Nd isotopic constraints

Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on a suite of Palaeozoic nepheline syenites from Zijinshan to characterize their ages and petrogenesis. Laser ablation inductively coupled plasma-mass spectrometry U–Pb zircon analyses yield consistent ages of 525.7 ± 2.8 million years for a sample (HYK01). These intrusive rocks belong to the foid syenite magma series in terms of K₂O?+?Na₂O contents (14.3–15.2 wt.%) and to the shoshonitic series based on their high K₂O contents (5.42–5.61 wt.%). The nepheline syenites are further characterized by high light rare earth element contents [(La/Yb) _N ?=?29.1–36.1]; show modest negative Eu anomalies (δEu?=?0.5–0.6) and positive anomalies in Rb, Th, U, Pb, Zr, and Hf; are depleted in Ba and high field strength elements (P and Ti). In addition, all the nepheline syenites in this study display relatively low radiogenic Sr (⁸⁷Sr/⁸⁶Sr) _i (0.7042–0.7043) and positive ?_Nd (t) (0.7–0.8). These results suggest that the nepheline syenites were derived from depleted continental crust. The parent magmas likely experienced fractional crystallization of plagioclase, Ti-bearing oxides (e.g. rutile, ilmenite, and titanite), apatite, and zircon during ascent, with negligible crustal contamination before final emplacement at a high crustal level.     

四川省南江县霞石矿地质特征及成因

南江霞石矿位于米仓山南缘,赋存于吕梁期第二期坪河超基性—碱性杂岩中,是钛铁霞辉岩一霓霞岩一磷霞岩系列的浅色单元。形成过程为偏铁质基性岩浆,在深部同化基底碳酸盐岩,使之脱硅,同时带入大量的Ca、Mg和部份Na、K的超基性碱性岩浆,上升时首先形成钛铁霞辉岩,随着暗色矿物大量析出,深部岩浆中Na2O、K2O、AlO3相对增加,相继上升侵入早期钛铁霞辉岩内,形成霓霞岩、磷霞岩,分异出霞石局部富集成矿。     

翡翠中共生矿物含量对翡翠定名的影响

目前翡翠市场上出现了越来越多含共生矿物的翡翠品种,给翡翠定名带来了一定的困难。针对这一问题,选取了具有代表性的原石样品进行了研究。研究方法包括实测样品的相对密度,X嘣线粉末衍射（XRD）物相量化分析,以及利用红外光谱观察共生矿物出现的机率。根据所含的共生矿物种类,翡翠可分为两类,一类为含钠长石的样品,另一类为含霞石和角闪石的样品。在反射光下,钠长石为透明玻璃状,而霞石呈磨砂玻璃状。基于上述鉴别特征,即可区分出钠长石和霞石。两类样品的相对密度都随共生矿物含量的增加逐渐降低,而理论密度值与实际测试密度值略有不同。结合上述研究结果以及岩石学命名规则,笔者探讨并提出了一套关于含共生矿物翡翠的命名规则。     

安徽金寨响洪甸碱性侵入岩年代学、岩石地球化学及其意义

金寨响洪甸碱性侵入岩体分布在大别造山带东北缘的北淮阳地区,侵位于上元古界青白口系佛子岭群中。主要岩石类型为正长岩（似斑状正长岩）、碱性正长岩和霞石正长岩。正长岩的主要矿物为碱性长石及少量黑云母、普通辉石、绿钙闪石;碱性正长岩包含钾长石、角闪石、辉石和少量黑云母;霞石正长岩主要由碱性长石、霞石及少量绿钙闪石、普通辉石、次透辉石等矿物组成。化学成分上均具有偏铝质、富碱、高钾、贫钛的特点。富集大离子亲石元素K、Rb、U、Nd和轻稀土元素La、Ce、Pr、Nd、Sm,亏损高场强元素Nb、Ta、P、Ti,轻、重稀土元素比值及La/Nb、Ba/Nb值较高,呈弱的负铕异常。根据高精度同位素年代学测试结果,响洪甸碱性侵入岩成岩期次分为2期：早期霞石正长岩,LA-ICP-MS锆石U-Pb年龄为（135.1±0.7） Ma;晚期正长岩,SHRIMP 锆石U-Pb年龄为（125.0±1） Ma和碱性正长岩,颗粒锆石U-Pb年龄为122.3 Ma。主体岩石似斑状正长岩的Hf同位素分析结果表明,其初始 ¹⁷⁶Hf/¹⁷⁷Hf 比值为0.282 243~0.282 404,ε_Hf（t）为-10.376~-16.602,结合该岩体的Sr-Nd同位素地球化学特征,推测响洪甸碱性侵入岩是富集地幔部分熔融的产物,其源区可能有部分陆壳物质的参与。其形成的构造背景为后碰撞的伸展环境。     

河南省霞石正长岩地质特征及其成矿作用

[摘 要] 河南省霞石正长岩分布比较广泛,主要出露于安阳九龙山、嵩县纸房-黄庄、方城宋坟-双山-塔山和桐柏松扒等地,形成时代介于晚元古代(晋宁期) 至中生代(燕山期) 之间。TAS 图解表明其主要岩石类型为正长岩和副长石正长岩,主量元素成分特征揭示其成分变异与结晶分异作用无明显关系。自宋坟-双山-塔山向北,由纸房-黄庄至九龙山,K2 O 含量先增大后减小,表明其下地壳厚度持续增生,在印支期达到最大值,于燕山期发生减薄。河南省霞石正长岩的成矿作用十分显著,非金属成矿作用主要为霞石、萤石、钾长石及磷矿,金属成矿作用主要为Au、Mo、Cu、Pb、Zn、Fe、Nb、Ta、REE 及放射性元素。河南省霞石正长岩及其相关正长杂岩体具有较大的成矿潜力,应作为进一步地质找矿的主要目标之一。     

Sillimanite group minerals: a new promising raw material for the Russian aluminum industry

The raw-material base of the Russian aluminum industry is considered. The raw materials include common (bauxites, nepheline syenites) and uncommon (nepheline ores, synnyrites, anorthosites, power-and-heating plant ashes, kaolines) types of ores. With regard to many criteria (reserves and quality of ores, technology of their processing, etc.), the problem of alumina deficit can be solved by mining sillimanite group minerals Al₂SiO₅ (wt.%: Al₂O₃ = 62.9, SiO₂ = 37.1), namely, andalusite, sillimanite, and kyanite. Their proved reserves converted to the final product (aluminum) exceed 400 mln tons. This will be enough for more than a hundred years provided that aluminum is produced in the present-day output (4 mln tons in 2008). Almost all deposits can be explored by strip mining, with application of the gravitation, flotation, and electromagnetic separation methods for ore dressing. The alumina content in concentrates reaches 60–62 wt.%. Only high-grade bauxites and the above concentration methods can ensure such a high yield of Al₂O₃. Sillimanite group minerals can be processed together with nepheline ores by sintering or be used for the direct electrothermal production of silumin and aluminum, excluding the alumina production stage. The latter method is the most promising in Russia.     

Permo-Triassic stage of alkaline magmatism in the Vitim plateau (western Transbaikalia)

We present results of geochronological (⁴⁰Ar-³⁹Ar, U-Pb SHRIMP-II, and LA-ICP-MS) and geochemical studies of alkaline rocks of the Amalat, Sirikta, Tsipa, Pravyi Uligli, and Verkhnii Uligli massifs in the Vitim plateau (western Transbaikalia). The formation of the alkaline rocks and the accompanying albitization are dated at 261-242 Ma. The isotope inhomogeneity (?_Nd(T) = + 8.4 to -1.7) of the alkaline rocks indicates the heterogeneous composition of the source of their material, having a depleted component, an enriched juvenile metasomatic fluid, and a crustal substrate.     

皖西霞石正长岩合成沸石分子筛及提钾的实验研究

合成沸石因具有优异的吸附及离子交换性能而备受关注。本实验以皖西地区霞石正长岩为主要原料 ,成功地合成了 13 X型沸石分子筛 ,母液经蒸发、分离 ,制得了白炭黑及碳酸钾 ,表明霞石正长岩具有巨大的潜在综合利用价值。合成沸石、白炭黑和碳酸钾的成分、结构及性能分析表明 ,3种产品均达到了国家或化工行业标准。基于此 ,对工艺技术可行性作了分析评价