Geochemistry of eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey

Analytical data for Sr, Rb, Cs, Ba, Pb, rare earth elements, Y, Th, U, Zr, Hf, Sn, Nb, Mo, Ni, Co, V, Cr, Sc, Cu and major elements are reported for eocene volcanic rocks cropping out in the Kastamonu area, Pontic chain of Northern Turkey. SiO₂% versus K₂O% relationship shows that the analyzed samples belong to two major groups: the basaltic andesitic and the andesitic ones. High-K basaltic andesites and low-K andesites occur too. Although emplaced on continental type basement (the North Anatolian Crystalline Swell), the Pontic eocene volcanics show elemental abundances closely comparable with typical island arc calc-alkaline suites, e.g. low SiO₂% range, low to moderate K₂O% and large cations (Cs, Rb, Sr, Ba, Pb) contents and REE patterns with fractionated light and almost flat heavy REE patterns. REE and highly charged cations (Th, U, Hf, Sn, Zr) are slightly higher than typical calc-alkaline values. Ferromagnesian elements show variable values. Within the basaltic andesite group the increase of K%, large cations, REE, La/Yb ratio and high valency cations and the decrease of ferromagnesian element abundances with increasing SiO₂% content indicate that the rock types making up this group developed by crystalliquid fractionation of olivine and clinopyroxene from a basic parent magma. Trace element concentration suggest that the andesite group was not derived by crystal-liquid fractionation processes from the basaltic andesites, but could represent a distinct group of rocks derived from a different parent magma.     

青藏高原北羌塘新生代高钾钙碱岩系火山岩角闪石类型有痕量元素地球化学

利用电子探针和激光探针剥蚀系统（LA－ICP－MS）对北羌塘新第三纪高钾钙碱岩系英安岩中角闪石的主元素和微量、角闪石强烈富集Sc、Ti、V、Cr、Co、Ni等不相容亲铁元素，而相对亏损Th、U、Pb、Rb等强不相容的大离子亲石元素。稀土元素丰度高，且无Eu异常，批示北羌塘这套高钾钙碱岩系火山岩可能是青藏高原加厚的相当于榴辉岩相物质组成的下部陆壳脱水熔融的产物。     

内蒙古扎兰屯地区白音高老组火山岩地球化学、年代学及其地质意义

扎兰屯西南部白音高老组火山岩的岩相学鉴定为流纹岩组,少量英安岩.LA-ICPMS锆石U-Pb定年显示,流纹岩形成于125~129 Ma的早白垩世.岩石地球化学研究表明,火山岩高硅、富碱,为过铝质高钾钙碱性系列;稀土丰度较高（∑REE=128.35×10^-6~169.26×10^-6）,轻重稀土分馏明显（（La/Yb）_N=12.17~16.42）,弱负Eu异常（δEu=0.43~0.70）;大离子亲石元素（LILE）Rb、Th、K等相对富集,出现Ba的亏损,高场强元素（HFSE）Sr、P、Ti强烈亏损,Nb、Ta相对亏损,与A型花岗岩特征相似.Rb/Sr=0.58~2.06,Ti/Y=6.50~17.98,Ti/Zr=7.49~40.87,基性相容组分Cr、Co、Ni含量较低,Mg^#较低,具有壳源岩浆特征.综合考虑扎兰屯白音高老组火山岩的上述特征并结合他人研究成果,认为扎兰屯地区的这套火山岩源于地壳的部分熔融,形成于非造山板内伸展环境.     

Evolution of Calc-alkaline Magmas in Continental Arc Volcanoes: Evidence from Alicudi, Aeolian Arc (Southern Tyrrhenian Sea, Italy)

Major, trace element, and Sr isotopic data are reported forvolcanic rocks from the island of Alicudi, Aeolian Arc, SouthernTyrrhenian Sea. The island is constructed of basalt, basalticandesite to high-K andesite lavas, and pyroclastites, whichshow a continuum in the variation of many major and trace elements.Total iron, MgO, CaO, Ni, Co, Sc, and Cr decrease with increasingsilica, whereas incompatible elements Rb, Ba, Th, and LREE displaythe opposite tendency. Very significant positive correlationsare defined by incompatible elements on interelemental variationdiagrams. Sr isotopic ratios vary from 0–70352 to 0–70410.Overall, basalts (0–70352–O-70410) and basalticandesltes (0–70356–0–70409) are enriched in⁸⁷Sr compared with high-K andesites (O–70352–O–70367),which display the lowest Sr isotopic ratios within the entireAeolian archipelago. Overall negative relationships exist between⁸⁷Sr/⁸⁶Sr and several incompatible trace element abundancesand ratios, such as Th, U, LREE, Zr, La/Yb, and Th/Hf. Otherelemental ratios such as La/Rb, Ba/Rb, and Sr/Rb show more complexbehaviour, even though negative correlations with Sr isotopicratios are observed in the basalts. The observed compositional variations are best explained interms of a model in which primitive calc-alkaline magmas evolvedby crystal-liquid fractionation to give a series of variouslydifferentiated liquids, which underwent different degrees ofinteraction with crustal material. The more mafic and hotterbasaltic liquids appear to have assimilated higher amounts ofmetamorphic wall rocks than did the cooler late erupted andesiticmagmas. This process produced significant variations of Sr isotopicratios, Rb, Cs, Rb/Sr ratios, and LILE/Rb ratios in mafic magmas,but had only minor effects on the abundances and ratios of otherincompatible elements such as Th, LREE, La/Yb, and Th/Hf. When compared with mafic rocks from other Aeolian islands, theAlicudi basalts are more primitive geochemically and isotopically.Going eastward, there is a decrease in Ni and Cr abundances,mg-number and Nd isotopic ratios which parallels an increaseof Sr isotopic ratios in basaltic rocks along the arc. Thesecompositional variations are typical of volcanic series whichhave undergone interaction with upper-crustal material, andsuggest that this process may have contributed significantlyto the regional geochemical and isotopic trends observed inthe Aeolian arc.     

Late Ordovician island‐arc volcanic rocks,northern Capertee Zone,Lachlan Fold Belt,New South Wales

The Cape Hoskins volcanoes form part of the Quaternary volcanic island arc that extends from Rabaul in the east to the Schouten Islands in the west, and they overlie the northerly dipping New Britain Benioff Zone. The products of the volcanoes range in composition from basalt to rhyolite, and are normative in quartz and hypersthene. They contain phenocrysts of plagioclase and subordinate augite, hypersthene, and in most samples iron‐titanium oxides; some samples also contain olivine or quartz or both, and some pumice contains hornblende and, rarely, biotite.

Chemical analyses of 29 volcanic rocks are presented; 22 were also analysed for 17 minor elements — Rb, Ba, Sr, Pb, Zn, Cu, Zr, Y, Ni, Co, Sc, Cr, V, Ga, B, U, and Th.

Chemically the rocks have many of the characteristics of the ‘island arc tholeiitic series’, but do not show a pronounced relative enrichment in iron and appear to be relatively enriched in Sr. Compared with volcanic rocks from the northern part of the Willaumez Peninsula, they are lower in K (but not Na), Ti, Rb, Ba, Zr, Pb, Th, Ni, and probably also V, Cu, and Zn: these differences are attributed to the greater depth of the Benioff Zone beneath the Willaumez Peninsula. The more basic of the Cape Hoskins rocks are similar in most respects to lavas of comparable composition from Ulawun volcano to the east.     

白银厂矿田早中寒武世火山岩地球化学及成因分析

白银厂矿田早中寒武世火山岩主要为玄武岩－碱性玄武岩－安山岩－玄武安山岩－玄武粗安岩－英安流纹岩－流纹岩。其中基性和中基性岩类为碱性系列和亚碱性系列,碱性玄武岩主要为钾质玄武岩系列。酸性岩类为钙碱性系列。岩石全碱含量平均为５．７６％,Ｋ２Ｏ／,Ｋ２Ｏ／Ｎａ２〈１,Ｆｅ２Ｏ／ＦｅＯ平殚为０．７４;ＴｉＯ２绝大部分样品含量小于１％（在酸性火山岩中含量较低：０．２％～０．８３％,平均为０．５３％;基性和中     

Fractionnement des éléments en trace Li,Rb, Ba,Sr dans les séries andésitiques et shoshonitiques du Pérou. Comparaison avec d'autres zones orogéniques

In the calc-alkaline rocks of Peru, the rubidium content and the K/Ba, Rb/Sr ratios increase, while the strontium content and the K/Rb, Ba/Rb ratios decrease according to the distance of the trench. It is suggested that theses variations are related to a fractionation of plagioclase and contamination with differential migration of mobile elements. A comparative study between andesites of various localities shows in Peru an enrichment in Rb, Sr and Ba and a disparition of the Rb-Ba correlation; this last observation looks characteristic of continental margin andesites. The shoshonitic rocks differ from the andesites by a high content of Sr and Ba. The genetic relationships between these two kinds of rocks are discussed. It appears that the shoshonites are originated from a different magmatic source.     

苏北东台坳陷古新统阜宁组三段微量、稀土元素地球化学特征及其地质意义

沉积岩的微量、稀土元素对沉积环境的水介质变化有着较高的敏感度,对于研究古环境、沉积物源性质和构造背景方面具有重要的意义。前人对于东台坳陷元素地球化学方面的研究相对薄弱,利用元素地球化学资料解释古环境和源区性质方面的研究尚属空白。本文以苏北东台坳陷古新统阜宁组三段20件泥岩样品为研究对象,对其进行微量、稀土元素测定,并分析其地球化学特征及所揭示的地质意义。结果表明:(1)Sr含量、Sr/Cu、Rb/Sr、La_n/Yb_n比值指示干热气候;Li、Sr、Ni、Ga微量元素含量和Sr/Ba比值均指示淡水—半咸水的水体环境,整体以淡水环境为主,偶有咸水注入盆地,局部为半咸水环境;而V/(V+Ni)、V/Cr、Ni/Co、U/Th、δCe指示氧化—弱还原的水体环境。(2)Co/Th—La/Sc、La/Th—Hf判别图解和稀土元素配分模式,表明阜宁组三段沉积岩应来自于上地壳的长英质物质。(3)La—Th—Sc、Th—Co—Zr/10和Th—Sc—Zr/10构造背景判别图解反映了大陆岛弧与活动大陆边缘的构造背景,且与Bhatia不同构造背景杂砂岩的微量、稀土元素特征值的对比分析结果一致。     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours.     

Carboniferous deposits in the basement of the southwestern West Siberian geosyneclise (Kurgan Region)

The ⁴⁰Ar/³⁹Ar age of volcanics from the sections of core boreholes in the northern Tyumen’-Kostanai trough (Kurgan Region) has been determined. The geologic structure of the northern part of the trough has been refined. The paleogeographic environments and geodynamic settings of formation of Carboniferous deposits have been established by sedimentological, petrological, and geochemical studies of the sections. In the Visean, marine environments with maximum basin depths were predominant. In the Kachar epoch (C1v3-s), the submarine relief of the basin became more complicated; blocks of older rocks appeared in the deposits. The geochemical indicator characteristics of the volcanics—contents of HFSE (Ti, Nb, Ta, Th, and Hf)—are close to those of andesitoids of island arcs and Andean-type active continental margins, as well as present-day andesites from the Kurile-Kamchatka zone. They are an order of magnitude lower than those in similar continental-rift volcanics, among which are volcanics of the Valer’yanovka zone (according to some researchers). The contents of Ni, Co, and V are similar to those in island-arc andesites, including rocks of the Kurile-Kamchatka zone. The Ba/Ta and Ba/La ratios and the proportions of Th, Hf, and Ta in andesitoids of the Valer’yanovka and Kachar Groups are close to the indicator characteristics of island-arc and active-continental-margin volcanics. The Kachar Group siliceous rocks are similar in the Rb/Zr-Nb, Fe-Nb, and Rb-(Y + Nb) correlations to rocks of mature island arcs and active continental margins. The incompatible-element and REE patterns for the Valer’yanovka and Kachar volcanics are typical of island-arc volcanics, including rocks from the Kurile-Kamchatka zone. The indicator geochemical features and petrology of the volcanics and the sedimentologic features of the deposits testify to their formation on an Andean-type active continental margin (western margin of the Kazakhstan paleocontinent) in the Early-Middle Carboniferous.     

塔河地区海西晚期火山岩地球化学特征及地质意义

通过岩心观察,塔河地区海西晚期先后发育基性火山岩和中酸性火山岩两大类。两类火山岩具有不同地球化学组成:基性火山岩K2O+Na2O=3.49%~4.25%,K2O/Na2O=0.18~0.381,为钠质系列玄武岩,富集大离子亲石元素K、Rb、Ba、Th和高场强元素Nb、Ta、Ti、Zr、P,δEu≈1,无明显亏损;中酸性火山岩表现为高场强元素Nb、Ta、Sr、P、Ti亏损,大离子亲石元素K、Rb、Ba、Th较为富集,稀土元素δEu=0.43~0.661,铕具明显负异常特征,K2O+Na2O=6.86%~8.82%,K2O/Na2O=1.25~1.591,为钾玄或高钾钙碱性系列英安岩。强不相容元素Th/Ta、Nb/U比值说明,玄武岩与英安岩成因没有明显亲缘性,玄武岩来源于地幔,英安岩来源于地壳。结合邻区火成岩对比分析,塔河地区发育的玄武岩、英安岩分别与塔中地区玄武岩和南天山分区花岗岩具有相同的地球化学特征,构造判别图解表明,玄武岩形成于板内主裂陷期,英安岩、花岗岩形成于板块边缘岛弧构造环境,作为特殊古构造位置,塔河地区先后发育的玄武岩、英安岩为板内主裂陷盆地边缘和弧火山边缘相互耦合的产物。     

豫西伊川地区中元古界兵马沟组泥质岩地球化学特征及其环境与物源示踪

华北克拉通南缘古-中元古代构造-沉积演化的俯冲说、裂解说之争由来已久,兵马沟组作为熊耳群形成后的第一套碎 屑沉积岩层,对解释上述过程有重要意义。该文通过对豫西伊川地区的兵马沟组泥质岩微量及稀土元素的地球化学特征分析, 探讨了其沉积环境、物源,进而揭示了其发育的大地构造背景。结果表明：（1）兵马沟组泥质岩稀土元素含量高,球粒陨石标准 化后轻重稀土分异明显,δEu负异常,δCe异常不明显,富集Rb、Th、La、Ce、Nd、Zr、Hf 等,较上地壳平均值富集Sc、V、Cr、Co、Ni、 Rb;（2）Ceanom指数、V/V + Ni反映了泥质岩沉积时的还原环境,Sr/Ba、B/Ga表明其为由陆相至海相的过渡型沉积;（3）Cr/Zr、Th/U 等元素比值关系反应其物源无深部物质加入,La/Yb-Ce、Co/Th-La/Sc图解表明物源为中酸性火山岩及少量稳定陆壳物质; （4）Th-Sc-Zr/10、Th-Co-Zr/10图解表明其物源主要来自大陆岛弧。综合上述分析结果,结合区域地质信息,可以得出中元古界 兵马沟组形成于大陆岛弧弧后盆地,熊耳群分布区为中元古代俯冲成因的大陆岛弧区。     

The Dir-Utror metavolcanic sequence,Kohistan arc terrane,northern Pakistan

The Dir-Utror volcanic series forms a NE–SW trending belt within the northwestern portion of the Kohistan island arc terrane in the western Himalayas of northern Pakistan. The Kohistan arc terrane comprises a diverse suite of volcanic, plutonic, and subordinate sedimentary rocks of late Mesozoic to Tertiary age, developed prior to and after suturing of the Indo-Pakistan and Asiatic continental blocks. The Dir-Utror volcanic series near Dir is dominated by basaltic-andesite and andesite, with subordinate basalt, high-MgO basalt, dacite, and rhyolite. Porphyritic textures are dominant, with less common aphyric and seriate textures. Plagioclase is the dominant phenocryst in mafic to intermediate rocks, K-feldspar and quartz phenocrysts predominate in the dacites and rhyolites. Chlorite, epidote, albite, and actinolite are the most common metamorphic phases; blue-green amphibole, andesine, muscovite, biotite, kaolinite, sericite, carbonate, and opaques are widespread but less abundant. Phase assemblages and chemistry suggest predominant greenschist facies metamorphism with epidote-amphibolite facies conditions attained locally.Whole rock major element compositions define a calc-alkaline trend: CaO, FeO, MgO, TiO₂, Al₂O₃, V, Cr, Ni, and Sc all decrease with increasing silica, whereas alkalis, Rb, Ba, and Y increase. MORB-normalized trace element concentrations show enrichment of the low-field strength incompatible elements (Ce, La, Ba, Rb, K) and deep negative Nb, P, and Ti anomalies—patterns typical of subduction related magmas. Mafic volcanic rocks plot in fields for calc-alkaline volcanics on trace element discrimination diagrams, showing that pre-existing oceanic crust is not preserved here. All rocks are LREE-enriched, with La=16–112×chondrite, La/Lu=2.6–9.8×chondrite, and Eu/Eu*=0.5–0.9. Dacites and rhyolites have the lowest La/Lu and Eu/Eu* ratios, reflecting the dominant role of plagioclase fractionation in their formation. Some andesites have La/Lu ratios which are too high to result from fractionation of the more mafic lavas; chondrite-normalized REE patterns for these andesites cross those of the basaltic andesites, indicating that these lavas cannot be related to a common parent.The high proportion of mafic lavas rules out older continental crust as the main source of the volcanic rocks. The scarcity of more evolved felsic volcanics (dacite, rhyolite) can be explained by the nature of the underlying crust, which consists of accreted intra-oceanic arc volcanic and plutonic rocks, and is mafic relative to normal continental margins. Andesites with high La, La/Lu, K₂O, and Rb may be crustal melts; we suggest that garnet-rich high-pressure granulites similar to those exposed in the Jijal complex may be restites formed during partial melting of the crust.     

青海治多多彩地区火山岩岩石特征

多彩地区处于西金乌兰-义敦晚三叠世岛弧带的东段,成矿区带位于三江成矿带的北西段,区内已发现了尕龙格玛铜多金属矿床和拉迪欧玛铜矿点.重点分析了与该区成矿关系密切的火山岩的岩石特征,初步恢复了该区火山岩的喷发环境和火山机构,并探讨了火山活动与成矿的关系.研究表明,本区火山岩主要为英安岩及英安质火山碎屑岩,其次为安山岩、安山质火山碎屑岩.火山岩微量元素具有富集亲石元素Rb、Sr、Th及亲铁元素Co、Ni,亲Cu元素Zr与参照值相近,V、Ba元素的含量高于地壳的丰度值,Sc、Cr等元素亏损的特征.中-酸性火山岩稀土总量较高,稀土配分曲线上普遍出现Eu负异常,总体特征与造山带火山岩相似,火山岩相为溢流相.本区海相火山喷发发生在浅海地带,火山岩构造环境总体属于岛弧环境.成矿作用主要与古火山机构和后期动力变质作用有关.     

岩石中低量稀土和其他痕量元素的X-荧光光谱测定

用X-荧光光谱测定岩石中低量稀土元素的仪器参数和测定条件,文[1]已作过讨论。本文介绍样品分析所采用的基本校正,谱线重叠校正和背景处理方法,并将这些方法应用于其他少量和痕量元素的测定。基体的吸收校正岩石样品中最重的主元素是铁,镧系元素La～Er的La线和Ti,Sc,Cr,Mn,Fe,     

新疆阿舍勒盆地阿舍勒组火山岩锆石U-Pb测年及地球化学特征

新疆阿舍勒盆地中阿舍勒组火山岩主要为英安质、流纹质火山角砾岩,凝灰岩、沉凝灰岩等火山角砾岩及火山熔岩,顶部为玄武岩及碧玉岩、灰岩.玄武岩亏损Nb,Ta,Ti等高场强元素,富集Ba,Th,U,Sr等大离子亲石元素,具岛弧玄武岩特征;英安岩为钙碱性系列,富集Rb,Ba,Th,U等大离子亲石元素,Nb,P,Ti亏损十分明显,...     

K,Rb, Sr,Ba, U and Th geochemistry of the Lapland Granulites (Fennoscandia). LILE fractionation controlling factors

The LILE geochemical patterns of the three main lithological units (graywacke-shale metasedimentary sequence, tholeiitic metaigneous rocks and migmatitic rocks) of the Lapland Granulite belt are described. K, Ba, Sr and Th concentrations in metasediments are nearly similar to average continental crust, whereas Rb and U are unevenly impoverished. In particular graphitic metashales and calcsilicate rocks are not significantly depleted in uranium. Tholeiitic metaigneous rocks comprises metavolcanics which present K/Rb ratios similar to metasediments, and metaplutonics with LILE abundances close to those of the low-K-tholeiites. Migmatites show wide range in LILE content. Metatexites and diatexites have higher K, Rb, Th and U concentrations and similar K/Rb ratios with respect to equivalent unmobilized rocks. Potassic pegmatoïds are strongly enriched K, Rb, Ba and Th but moderately in Sr and U. Plagioclasic pegmatoids and ferromagnesian restites are rich in Sr and poor in other LIL elements.A comparative review of the LILE geochemistry between Lapland granulites and equivalent lithological units taken from non metamorphosed to high grade terrains suggest that fractionation processes are not systematic but controlled by original lithology and mineralogy, mineral — fluid equilibria during progressive (or retrogressive) metamorphism and mineral-melt-fluid equilibria during anatexis. Moreover, statistical analysis on K-Rb distribution patterns in these various rock types shows that there is no metamorphic trend characteristic of granulite facies terrains as previously suggested.Large Ion Lithophile Elements     

Mineralogical and chemical changes of soil and stream sediment formed by intense weathering of the Danburg granite, Georgia, U.S.A.

A series of soil and stream sediments developed during intense weathering on the metaluminous Danburg granite, northeastern Georgia, U.S.A., have been analyzed mineralogically and chemically. The concentrations of Ba, Na, Rb and Cs in the silt and coarser fractions are controlled mainly by feldspars and biotite. Hf is controlled by zircon, and the REE (rare-earth elements) and Th are largely controlled by sphene. Variations in feldspar, sphene and zircon may produce small variations in Eu/Sm and La/Lu ratios. Ferromagnesian minerals control Ta, Fe, Co, Sc and Cr concentrations.

The mineralogical and chemical composition of the Danburg granite is more closely reflected in the silt than in the sand or gravel fractions of stream sediments. In the silt, the contents of Rb, REE, Th, Ta, Fe, Co and Sc and the ratios of La/Sc, Th/Sc, La/Co, Th/Co, Eu/Sm and La/Lu are similar to those in the unweathered granite. In contrast, these element contents or ratios in the sands and gravels are 0.05−3× the concentration in the unweathered granite. Ta and Ba contents are an exception to the above. The Ta and Ba contents of the sands and gravels are similar to those of the granite.

In the kaolinite-halloysite clays, the content of Na is depleted relative to the source. Rb, Cs, Ba, Hf and Ta are depleted or enriched in the clays relative to the source, while the REE, Th, Fe, Co, Sc and Cr are enriched. The Eu/Sm (Eu anomaly size) and La/Lu ratios, and the REE patterns of the clays are similar to those of the source.

Thus, the mineralogy and element contents of a siltstone developed from metaluminous, granitic sources during intense weathering would be expected to be more similar to the source rock than the sandstones and conglomerates. Claystones should contain similar REE patterns and Eu/Sm ratios as the source rock, but such fine-grained sediments might represent much larger areas of source rocks than the more locally derived sandstones or conglomerates.     

Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins

The graywackes of Paleozoic turbidite sequences of eastern Australia show a large variation in their trace element characteristics, which reflect distinct provenance types and tectonic settings for various suites. The tectonic settings recognised are oceanic island arc, continental island arc, active continental margin, and passive margins. Immobile trace elements, e.g. La, Ce, Nd, Th, Zr, Nb, Y, Sc and Co are very useful in tectonic setting discrimination. In general, there is a systematic increase in light rare earth elements (La, Ce, Nd), Th, Nb and the Ba/Sr, Rb/Sr, La/Y and Ni/Co ratios and a decrease in V, Sc and the Ba/Rb, K/Th and K/U ratios in graywackes from oceanic island arc to continental island arc to active continental margin to passive margin settings. On the basis of graywacke geochemistry, the optimum discrimination of the tectonic settings of sedimentary basins is achieved by La-Th, La-Th-Sc, Ti/Zr-La/Sc, La/Y-Sc/Cr, Th-Sc-Zr/10 and Th-Co-Zr/10 plots. The analysed oceanic island arc graywackes are characterised by extremely low abundances of La, Th, U, Zr, Nb; low Th/U and high La/Sc, La/Th, Ti/Zr, Zr/Th ratios. The studied graywackes of the continental island arc type setting are characterised by increased abundances of La, Th, U, Zr and Nb, and can be identified by the La-Th-Sc and La/Sc versus Ti/Zr plots. Active continental margin and passive margin graywackes are discriminated by the Th-Sc-Zr/10 and Th-Co-Zr/10 plots and associated parameters (e.g. Th/Zr, Th/Sc). The most important characteristic of the analysed passive margin type graywackes is the increased abundance of Zr, high Zr/Th and lower Ba, Rb, Sr and Ti/Zr ratio compared to the active continental margin graywackes.     

云南易门铜厂铜矿床碳酸盐矿物微量元素组成研究

易门铜厂矿床是云南易门铜矿带中的一个大-中型铜矿床,矿区存在早期沉积-成岩型和晚期热液脉状型2种铜矿类型。为深入阐明2种矿化类型的成矿作用特征,文章分别选取落雪组白云岩及层状矿石中的白云石和热液脉状矿石中的方解石,采用ICP-MS等方法,对其开展碳酸盐矿物的微量及稀土元素地球化学研究。研究结果显示：在微量元素组成方面,沉积-成岩型的白云石以富集Cu、Pb、Zn、Ba、Bi、Sb、Ga、Ag,亏损Mo、Cr、Ni、Co、V元素为特征,脉状方解石中则以亏损亲硫元素（Cu、Pb、Zn）和不相容元素（Ba、Be、Rb、Nb、Ta、Zr、Hf、Th、U等）,富集V、Co、Ni元素为特征;在稀土元素组成上,二者稀土元素总量均较低,具不同程度的Eu负异常和微弱的Ce正异常,但在稀土元素配分模式上,白云石为明显右倾的轻稀土元素富集模式,方解石则为轻稀土元素略富集,中稀土元素富集的缓右倾或平缓型配分模式。综合分析结果认为,2类脉石矿物是不同成矿系统的产物,白云石形成于正常浅海环境,为沉积-成岩成因,成矿物质的壳源特征明显。方解石为后期热液成因,有深源物质参与成矿。层状矿体与脉状矿体不具"同期+同源"的特征。