Petrology and geochemistry of potassic rocks in the Gölcük area (Isparta, SW Turkey): genesis of enriched alkaline magmas

The Lower Pliocene volcanic rocks occurring in the Gölcük area of SW Turkey exhibit alkaline major element trends with a general potassic character. The development of volcanism can be divided into 2 major stages such as trachytic ancient lavas/domes and tephriphonolitic, trachyandesitic to trachytic Gölcük eruptions (ignimbrites, lava/dome extrusions, phreatomagmatic deposits, and finally, young domes). Volcanic rocks consist primarily of plagioclase, clinopyroxene (which ranges in composition from diopside to augite and are commonly zoned), biotite, and phlogopite. Amphibole phenocrysts are restricted to the pyroclastic deposits. Pseudoleucites are also seen only in the lava/dome extrusions. Oxides and apatites are common accessory phenocryst phases. As would be expected from their potassic–alkaline nature, the volcanic rocks of the Gölcük area contain high amounts of LILE (Ba, Sr, Rb and K), LREE, and Zr. Concentrations of compatible elements such as Cr, Ni and V are very low, possibly indicating fractionation of olivine and clinopyroxene. Correlation of SiO₂, Rb/Sr and MgO with ⁸⁷Sr/⁸⁶Sr (0.703506–0.704142) exhibit an increasing trend in the direction of crustal contamination. However, the isotopic compositions of Sr are not as high to indicate a high level of crustal contamination. Geochemical data are consistent with the derivation of Gölcük volcanic rocks from a metasomatized and/or enriched lithospheric mantle source during crustal extension in the area. This metasomatism was probably occurred by fluids released from the northward subduction between African and Eurasian plates during Tertiary, as the Gölcük volcanic rocks display features of island-arc magmas with having high Ba/Nb (>28) ratios, and Nb and Ti depletions. Lower Pliocene volcanism in the Gölcük was response to extensional tectonics.     

鄂尔多斯盆地塔巴庙地区上古生界砂岩储层"酸性+碱性"叠加溶蚀作用与储层质量主控因素

从岩石学薄片观察、埋藏史恢复、成岩流体包裹体检测、地层水化学特征和砂岩、粘土矿物成岩作用及储层性能评价等入手,对鄂尔多斯盆地塔巴庙地区上古生界下石盒子-山西组砂岩储层储集性能主控因素进行了初步探讨.研究成果认为:(1)工区下石盒子-山西组砂岩储层在早白垩世达到最大埋深(约4500m),强压实和高含量岩屑变形以及杂基充填粒间,使得砂岩原生粒间孔隙几乎完全丧失,储集空间主要为次生溶蚀孔隙,原生孔隙不发育;(2)碳酸盐胶结物和少量长石及岩屑在中等埋藏深度发生酸性溶蚀,而石英骨架颗粒和泥质、微晶石英杂基在深埋藏阶段发生碱性溶蚀,从而形成“酸性 碱性”叠加溶蚀次生孔隙带,成为控制工区目的层储层质量的主控因素;(3)粘土矿物演化剖面、地层水化学剖面和储层物性与储层岩屑、方解石、自生硅质和填隙物含量关系对比剖面,揭示大约在2670m附近存在一个重要的界面,在此界面之上为酸性溶蚀带,在此界面之下为先期酸性、后期叠加碱性溶蚀的深部次生孔隙带,其中在2670～2740m深度段为高孔高渗带,天然气沿此深度带优先充注.因此,这个带也是一个天然气高产带,在今后的勘探应给予高度重视.     

雅鲁藏布大峡谷地质成因

文中总结了雅鲁藏布大峡谷科学探险考察中获得投奔 石学和构造地质学认识与区域上已经取得的多学科成果,论述了牙鲁藏布大峡谷得以形成的根本原因是该地区深部存在着地幔上涌体,雅鲁藏布大峡谷和大另弯的形成是地幔上涌体作用于岩石圈和地表的效应。地幔上涌体的确认揭开了该地区的特有的生物学,气候特征等方面的奥秘,雅鲁藏布大峡谷及其周缘地区是大陆动力学研究,壳－幔动力学,地球系统中各圈层间耦合作用及大陆块体运动学研     

电渗析脱盐时威尔逊公式修正的新方法

本文列举了铝制品洗白碱性废水［１］、海水第二脱盐段①和人工配制ＮａＣｌ水溶液②三种水质，采用伏－安法测定权限电流密度后，用三步作图法，分别求出威尔逊修正式中的系数Ｋ，浓度指数ｍ和流速指数ｎ，建立了威尔逊修正公式的新模式：Ｉ_（ｌｉｍ_＝ＫＣ~ｍＣ~（ａ＋ｂｃ）本模式适用于组份复杂、浓度变化范围大的水溶液体系。用该模式计算的极限电流密度值与实验测定值之间的偏差在±１０％之内，具有很好的实用性。     

Form changes and bio-effect of cadmium in the alkaline soil operated by inorganic salts

Four soluble inorganic salts were used to examine their influences upon cadmium forms in the alkaline soil and the contents of cadmium absorbed by plants. After KCl solution added in the soil, the contents of effective form of cadmium in the soil increased from 28% to 122%, carbonate form decreased from 2% to 47%, iron-manganese oxidation form increased from 20% to 150%. As to the organic combination form, when the KCl solution of lower concentration was added in the soils, the organic combination form contents of cadmium would decrease, while the KCl solution of higher concentration was added in the soils, the organic combination form contents of cadmium would increase. After CaCl2 solution was added in the soils, the contents of effective form of cadmium in the soils increased from 7% to 33%, the carbonate form contents of cadmium decreased from 10% to 60%, the contents of the iron-manganese oxidation form of cadmium increased from 5% to 90%, the organic combination form of cadmium increased from 5% to 73%. After KH2PO4 solution was added in the soils, the contents of effective form of cadmium in the soils decreased from 20% to 46%, the carbonate form contents of cadmium decreased from 14% to39%, the contents of the iron-manganese oxidation form of cadmium increased from14% to 95%, the organic combination form of cadmium increased from 5% to 65%. After K2CO3 solution was added in the soil, the effective form contents of cadmium decreased from 5% to 22%, the carbonate form contents of cadmium increased from 12% to 64%, the contents of organic combination form of cadmium in the soils were similar to those of the carbonate form, increasing by 3%-38%. The content variation of the iron-manganese oxidation form of cadmium was slight after K2CO3 solution was added in the soils.     

碱性模式氢化物发生-原子荧光光谱法测定多金属矿中的微量铋

建立了碱性模式氢化物发生-原子荧光光谱法测定多金属矿石中微量铋的分析方法,对仪器和实验条件进行了最佳化选择,讨论了共存离子的影响。方法经国家标准物质分析,测定值与标准值吻合,方法精密度(RSD,n=12)为2.97%,回收率为95%~104%。     

Geochemical and isotopic evidence for the age,orogenic setting and petrogenesis of the Nychum Volcanic association,North Queensland

Rb‐Sr and K‐Ar age determinations agree with palaeobotanical evidence in assigning an age of 270 Ma (Lower Permian) to the Nychum Volcanics, North Queensland. Geological and geochemical evidence (moderate ‐REE, La/Yb, Th, Zr/Y, Hf/Yb, Sc/Ni) indicate that the volcanics were erupted on a thin, active continental margin. Five magma groups are present: high‐alumina basalts, andesite‐dacites, acid rocks, tholeiitic andesites, and pitchstone with a high La/Yb ratio. The high‐alumina basalts and calc‐alkaline andesites have a parent‐daughter (source rock‐partial melt) relationship. The acid rocks share high HREE, Zr, Hf, Zn, Sc, Fe/Mg and low Al with, and may be fractionated from, the tholeiitic subduction‐zone andesites. Low‐pressure fractional crystallisation is evident in all five magma groups.     

富碱岩长石结构态及其地质意义

采用X射线衍射法研究了16个碱性岩和碱性花岗岩体长石的结构态,获得了122个数据,并对样品进行探针或化学分析。这些富碱岩都以碱性长石为主,有单斜、三斜钾长石,以及由它们和钠长石组成的条纹长石。钾长石分属各种结构态,钠长石有中、低钠长石,钾、钠长石在一些岩体中体现了由高→低结构态有序化演化进程。长右结构态与矿物温度计所获得的资料得到了很好的对照,表明了长石Si/Al有序程度主要受结晶温度的影响。     

黑龙江省五大连池、科洛、二克山火山群富钾火山岩中的浅色矿物

本区富钾火山岩中浅色矿物有碱性长石、白榴石和霞石。碱性长石主要为钠透长石、钙歪长石,少数为钙钠透长石和歪长石,其光性变化与长石的地质时代和长石内部的隐条纹结构有关。白榴石的成分及产出方式主要与岩石中的SiO_2含量有关,SiO_2不饱和程度大的白榴苦橄岩的白榴石贫SiO_2;而SiO_2不饱和程度低的白榴碧玄岩和白榴玄武岩中,白榴石富SiO_2而稍贫K_2O+Na_2O,仅见于过渡相,而中心相由于水压较高和近于平衡的结晶条件,白榴石不能晶出,或先晶出后又与熔体反应形成碱性长石。     

新疆北部花岗岩类的稀土特征

新疆北部的改造系列花岗岩演化由斜长花岗岩阶段、钾长花岗岩阶段至碱长花岗岩阶段,其稀土配分组成递降曲线簇.新疆北部的同熔型花岗岩类稀土配分基本为轻稀土富集型,具Eu负异常,有递增曲线簇和递降曲线簇两种情况.深源碱性系列轻重稀土比值大、Eu负异常一般不显著.文中还叙述了新疆北部的幔分异系列花岗岩类及一些古老花岗岩的稀土特征.