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The Maizuru Terrane in the Inner Zone of Southwest Japan consists of weakly metamorphosed ophiolitic complexes and Permian and Triassic strata. The Permian Maizuru Group is 1500–3000 m thick and consists mainly of mudstone, sandstone, and alternating beds of sandstone and mudstone. It is subdivided into lower, middle, and upper formations, and is overlain with angular unconformity by the Lower–Middle Triassic Yakuno Group. The Maizuru Group is characterised by the occurrence of the Capitanian Lepidolina kumaensis fauna in conglomerates of the middle and upper formations, and the Wuchiapingian Codonofusiella– Colaniella and Changhsingian Palaeofusulina– Colaniella faunas in lenticular limestones and conglomerates of the upper formation. Pre-Capitanian foraminifera are contained in limestone clasts of conglomerates of the upper formation and the basal part of the Yakuno Group. Examination on the stratigraphy, lithology, foraminiferal fauna, and Late Palaeozoic to Mesozoic tectonics in and around the Maizuru Terrane leads to the following conclusions. Capitanian and Lopingian limestone blocks and clasts were originally deposited on the continental shelf, and were subsequently redeposited on the deeper continental slope. Almost all of the pre-Capitanian limestone clasts were derived from the Akiyoshi Seamount accreted by the early Late Permian, except for those containing Verella prolixa and Pseudostaffella praegorski which were reworked from the shallow continental shelf. The Maizuru Terrane originated on the active continental margin located close to South China during Permian–Triassic time, but the depositional environment of the Permian and Triassic strata rapidly changed from deeper continental slope to shallow continental shelf.

Lithofacies distribution and petrography and intracontinental deformation in the North China block (NCB) and the South China block (SCB) show an active continental margin flanked by the eastern NCB, and a passive continental margin was present along the west side of the SCB, both margins initially trending N-NE. The Tanlu fault possibly initiated as part of the subduction zone during Paleozoic time along the eastern margin on the NCB. The NCB and the SCB were divided along the eastern–southern North China margin by the Qinling–Dabie–Tanlu–Sulu–Imjingang–Yanji zone from southwest to northeast. These two continental blocks made contact first in the northeast during late Early Permian time, finally in the southeast at Late Triassic time, and the clockwise collision probably lasted to Middle Jurassic time. The eastern suture, the Yanji–Imjingang–Sulu–Tanlu zone, was dominated by contractional deformation. The southern suture, the Qinling–Dabie zone, was a transpression belt dominated by right-lateral strike-slip.

A careful examination of the geochemical data set for SE China granulite xenoliths in Cenozoic basalts shows differences between the magmatic and cumulate granulite xenoliths, but no distinction between the Nushan and the other South China magmatic granulite xenoliths. Nushan granulite xenoliths with Archean Nd model ages were most likely derived from the Archean basement of the Yangtze craton itself and overprinted by a Paleoproterozoic to Mesoproterozoic tectonothermal event that occurred in the South China block, including the northern margin of the Yangtze craton. The granulate xenoliths therefore cannot be used to distinguish the North China and South China lower crust. Further, the discovery of the UHP eclogite xenoliths west of the Tanlu fault zone, along with recent paleomagnetic, seismic profiling, and other geochemical studies, favors a deep-seated, Tibetan-type, continental subduction of the Yangtze craton beneath North China along the Tanlu belt.

Lithospheric subduction prior to the assembly of the South China and North China blocks is traditionally considered to be directed northward. However, some critical geological and geochemical data cannot be reconciled with this northward subduction. This paper presents new lines of evidence against the traditional models and proposes a new and revolutionary tectonic model to explain the distribution and exhumation of high pressure (HP)-ultrahigh pressure (UHP) metamorphic rocks of the Dabie-Sulu Belt. We emphasize the following: 1) The Triassic tectonic environment of the southern margin of the North China Block was passive, not active, based on the stratigraphy; 2) In the southern margin of the North China Block no arc magmatism was recorded. 3) Many Paleoproterozoic slices of Jiaobei affinity of the Jiao-Liao-Ji Belt in the North China Block were located in the Triassic Sulu Orogen. 4) Many 1.85Ga metamorphic zircons are preserved in the Dabie-Sulu high pressure-ultra-high pressure (HP-UHP) metamorphic rocks. 5) The geometric asymmetry of many structural patterns in the HP-UHP slices indicates top-to-the northwest thrusting during the exhumation of HP-UHP slices. 6) Blueschists occur in the south of the UHP eclogite slices. 7) In the eastern segment of the North Qinling Orogen, no components with an affinity of the South China Block have been found. Along the Shangdan Suture of the Qinling Orogen has been recorded an apparent northward subduction. We consider that the suture is just a lateral subduction zone rather than a major collisional zone. Along the Shangdan Suture, the rarity of I-type plutonism can be attributed to a transform-type continental margin. The Bureya-Jiamusi-Khanka Block has an affinity to the South China Block based on its similarity regarding the Paleozoic history of deformation and Triassic blueschist metamorphic facies metamorphism. The Bureya-Jiamusi-Khanka Block could be the northern extension of the Dabie-Sulu Belt, and this gigantic belt could be interpreted as an orocline related to the southeastward subduction of the North China Block beneath the Greater South China Block.

东亚大陆内存在华北、扬子、华夏、韩国京畿和岭南、日本飞弹、布列亚—佳木斯—兴凯等诸多地块/微地块,多数地块之间从太古宙到中生代都存在复杂的洋-陆格局和聚散过程。研究东亚大陆各个地块/微地块的属性和关系及其拼合过程对东亚大陆演化规律及古大陆重建具有重要意义,但对其认识迄今仍存在争议。因此,本文综合岩石学、地层学、古生物等方面的资料证据,对东亚各个地块之间的地层、古生物特征进行对比,进而探讨东亚大陆各地块/微地块的亲缘性,以期厘定各地块间的拼合时序与方式。结果表明,除华北地块外,华南、韩国、西南日本、布列亚—佳木斯—兴凯等地块/微地块都具有亲冈瓦纳的特征,它们早古生代可能为统一的板块,本文称为大华南地块。印支期随着华北地块向SE朝大华南地块揳入,造成大华南地块西侧构造旋转和弯曲,形成类似印度板块揳入欧亚板块所导致的喜马拉雅山型弯山构造。

敦化-密山断裂带是郯庐断裂北段的重要分支之一,其大规模左行走滑发生的时限以及平移距离一直存在较大争议。本文系统地总结了松嫩-张广才岭地块东缘、佳木斯地块以及兴凯地块之上古生代-中生代火成岩的锆石U-Pb年代学资料,结合其空间分布特征,对敦化-密山断裂带的平移时限及距离提供了制约。研究表明,松嫩-张广才岭地块东缘与兴凯地块在古生代-中生代期间具有类似的岩浆活动历史,两个地块之上该时期的岩浆作用可以划分为8个主要期次:中-晚寒武世(ca.500~516Ma)、早奥陶世(ca.480~486Ma)、晚奥陶世(ca.450~456Ma)、中志留世(ca.426~430Ma)、早二叠世(ca.285~292Ma)、晚二叠世(ca.255~260Ma)、晚三叠世(ca.202~210Ma)和早侏罗世(ca.185~186Ma)。相比之下,佳木斯地块中的古生代-中生代早期岩浆事件则集中在晚寒武世(~492Ma)、晚泥盆世(~388Ma)、早二叠世(~288Ma)、晚二叠世(~259Ma)和早侏罗世(~176Ma),而晚奥陶世-志留纪和晚三叠世的岩浆活动在佳木斯地块未见报道。早白垩世晚期(ca.105~110Ma)和晚白垩世(ca.90~94Ma)的岩浆活动在三个地块均存在。上述结果表明兴凯地块东缘与松嫩-张广才岭地块东缘在早古生代经历了共同的地质演化历史,而中生代早期,兴凯地块西缘与松嫩-张广才岭地块东缘经历了同样的岩浆作用历史。上述结果暗示,敦化-密山断裂可能经历了至少两次平移,分别发生在中-晚二叠世-早三叠世和中-晚侏罗世-早白垩世,推测其总的平移距离约400km。结合研究区中生代期间的构造演化历史,敦化-密山断裂中生代的左行平移应与中-晚侏罗世-早白垩世期间古太平洋板块(Izanagi板块)的斜向俯冲相联系。

The main aim of igneous petrology is to develop a complete specification of the magma/igneous rock system. This paper is a sequel to an earlier essay ( Middlemost, 1991) on the classification of igneous rocks and magmas. It explores the ways and means of developing a single, consistent method of naming all igneous materials. All modal classifications are fettered by problems arising from heteromorphism, extremes in grain size, and the presence of glass. Only chemical parameters can provide a reliable and straightforward method of classifying all the common igneous rocks and their magmas. This is undoubtedly true of glassy rocks and magmas. The potential of the TAS diagram in this new and enlarged role is evaluated, resulting in a modification of some boundaries recommended for the volcanic rocks. A new comprehensive chemical classification of the plutonic rocks is introduced. To keep it and the volcanic classification in tandem, several new terms are proposed. They include gabbroic diorite as a plutonic equivalent of basaltic andesite and peridotgabbro as a plutonic equivalent of picrobasalt. Peridotite is defined as the plutonic equivalent of picrite and by taking the idea of equivalence a step further, it is defined as a peridotgabbroic or gabbroic rock that contains more than 18% MgO and less than 2% total alkalis. The picrobasaltic and basaltic rocks that contained more than 18% MgO and more than 2% (Na O + K O) are called alkalic picrites. Their plutonic equivalents are named alkalic peridotites. A benefit of this new chemical classification of plutonic rocks is that it enables one to avoid the awkward term ultramafic. A single classification that links magmas, plutonic and volcanic rocks should be appreciated by all geochemists and petrologists who amass, and manipulate, large geochemical databases but are unwilling, or unable, to carry out quantitative modal analyses. This classification also enables geoscientists to focus on magma the most important concept in igneous petrology.

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. SiO 2 % versus K 2 O% 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 SiO 2 % range, low to moderate K 2 O% 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 SiO 2 % 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.

苏州Ａ－型花岗岩岩体有三个侵入阶段，随着岩浆由早阶段向晚阶段演化，斜长石和钾长石中的Ｅｕ含量逐渐降低，由强正Ｅｕ异常逐渐转变成强负Ｅｕ异常，并且与全岩的Ｅｕ亏损呈正消长关系，研究表明，晚期岩体中斜长石和钾长石的负Ｅｕ异常主要由于它们是晚期结晶分异的产物，且结晶时的氧逸度较低。

内蒙古黄岗锡铁矿是大兴安岭南段成矿带中的一个重要矿床。LA-ICP-MS锆石U-Pb测年结果表明,黄岗岩体中的钾长花岗岩和花岗斑岩分别形成于136.7±1.1Ma和136.8±0.57Ma,属早白垩世的产物。黄岗花岗岩体SiO₂含量较高(66.81%~77.39%),Al₂O₃含量低(11.33%~14.54%),显著贫镁,ALK较高(5.65%~10.67%),K₂O/Na₂O值在0.32~10.53,平均为2.78。稀土配分曲线呈右倾轻稀土富集型,铕强烈亏损,<em>δ</em>Eu值为0.03~0.20。富集高场强元素Zr、Hf和大离子亲石元素Rb、U、Th,而元素P、Ti、Ba、Sr明显亏损,具有与洋岛玄武岩相似的Y/Nb等元素比值(>1.2)。上述特征与典型的A1型板内非造山花岗岩一致,其成因可能为在岩石圈伸展环境下,幔源岩浆的底侵促使上覆的先存地壳发生部分熔融形成花岗质岩浆,岩浆源区与壳幔混熔作用有关。

Geochemical data suggest that the rocks are highly fractionated I-type granites. Fractionation of biotite and feldspars was the principal process of magmatic differentiation and responsible for major element variation. Rb, Sr and Ba concentrations were controlled by feldspar separation, whereas REE elements were fractionated by accessory minerals, such as apatite, allanite and monazite.

吉林省东部延边和龙地区中生代闪长岩的锆石LA-ICP-MSU-Pb年龄为173~175Ma。岩石的SiO2含量为53.28%~58.02%,TiO2含为0.99%~1.08%,MgO和TFe2O3含量分别为1.96%~6.45%和6.59%~9.64%,Mg#值为37~59,Na2O含量为3.37%~4.88%,K2O含量为0.94%~2.30%,Na2O/K2O为1.70~4.16,Al2O3含量为15.87%~18.93%,相对富钠高铝,并且具有钠质钙碱性系列向高钾钙碱性系列过渡的趋势,稀土元素球粒陨石标准化曲线显示其具有富含轻稀土元素(LREE)、贫重稀土元素(HREE)以及无Eu负异常的特点。岩石富集大离子亲石元素(Rb,Th,Ba),明显亏损Nb,Ta,Zr,Hf和Ti等高场强元素(HFSE)。闪长岩的原始岩浆起源于受俯冲流体交代地幔楔的部分熔融,岩浆在上升过程中未受到明显的地壳混染。该期闪长岩形成于与古太平洋板块俯冲相关联的活动大陆边缘环境。

在云南个旧地区发育大量与成矿时空密切相关的侵入岩。个旧东区的老厂-卡房花岗质岩体为一隐伏的花岗岩体，侵入于三叠纪个旧组灰岩和碳酸盐地层中，岩性主要为中细粒黑云母花岗岩，是个旧地区与成矿关系最为密切的花岗岩体之一。岩石的ACNK值大多在1.0以上，属于高钾钙碱性系列岩石；U、Th含量较高，应归属于HHP花岗岩；岩石类型属于S型花岗岩，但经历了高度的分异和演化；n(Rb)/n(Sn)- n(Rb)/n(Ba)与n(CaO)/n(Na2O)-n(Al2O3)/n(TiO2)图解均暗示岩石的源区性质为由粘土岩所派生的岩浆。锆石LA-ICP-MS定年结果表明，老厂-卡房岩体形成于85±0.85Ma，相当于晚白垩世。根据区域地质和花岗岩的地球化学特征，暗示个旧地区燕山晚期处于伸展构造背景。

大兴安岭中南段主要铜矿类型为斑岩-热液脉型,其成矿与燕山早期浅定位中酸性侵入体有成因联系.成矿时代集中于180Ma～160Ma,与中生代早期岩石圈伸展背景下幔源岩浆底侵-同熔-分异作用有关,由于其形成于区域大规模火山喷发之前,深部岩浆来不及进行彻底分异,对铜的大规模成矿不利.因此,寻找大型以上规模的铜矿床必须综合考虑岩浆条件和矿源层两个主要因素.本区大规模岩浆作用晚期(燕山晚期)形成的紫金山式铜矿应是寻找大型铜矿的重要目标.

The genesis of Indo-Sinian granitic plutons with peraluminous and potassium-rich affinities from Hunan Province, China has been investigated by numerical modeling using the numerical code FLAC. On the basis of the regional geological evolution in South China, we employed a realistic numerical model in an attempt to unravel the influences of basaltic underplating and tectonic crustal thickening on the crustal anatexis. Heat production derived from basaltic underplating (e.g. ca. 220 Ma gabbro xenoliths) can result in dehydration melting of fluid-bearing minerals in crustal rocks such as gneisses and metapelites, but its effect is limited in a relatively short time span (5-15 Ma) and on a small scale. Accordingly, it is very difficult for basaltic underplating to generate the large-scale Indo-Sinian granitic bathliths unless voluminous mafic magmas had been underplated at the lower/middle crust during this period. Alternatively, crustal thickening induced by tectonic compression can also lead to geothermal elevation, during which the temperature at the boundary between lower and middle crusts can be up to or greater than 700 C, triggering dehydration melting of muscovite in gneiss and metapelite. The proportion of melts from muscovite-induced dehydration melting is close to critical melt percentage ( 20%) once the thickening factor reaches 1.3. These melts can be effectively transferred to the crust-level magma chamber and form large-scale granitic batholiths. In combination with the Indo-Sinian convergent tectonic setting in South China as well as sparse outcrops of contemporary mafic igneous rocks, we consider that tectonic crustal thickening is likely to be the predominant factor controlling the formation of the Indo-Sinian peraluminous and potassium-rich granitoids in Hunan Province.

Abstract A complex of crustally derived leucogranitic sills emplaced into sillimanite-grade psammites in the upper Langtang Valley of northern Nepal forms part of the Miocene High Himalayan granite association. A series of post-tectonic, subvertical leucogranitic dykes intrude the underlying migmatites, providing possible feeders to the main granite sills. The leucogranite is peraluminous and alkali-rich, and can be subdivided into a muscovite–biotite and a tourmaline–muscovite facies. Phase relations suggest that the tourmaline leucogranites crystallized from a water-undersaturated magma of minimum-melt composition at pressures around 3–4 kbar. Potential metasedimentary protoliths include a substantial anatectic migmatite complex and a lower-grade mica schist sequence. Isotopic constraints preclude the migmatites as a source of the granitic melts, whereas trace-element modelling of LILEs (Rb, Sr, and Ba), together with the Nd and Sr isotopic signatures of potential protoliths, strongly suggest that the tourmaline-bearing leucogranites have been generated by fluid-absent partial melting of the muscovite-rich schists. However, REE and HFSE distributions cannot be reconciled with equilibrium melting from such a source. Systematic covariations between Rb, Sr, and Ba can be explained by variations in protolith mineralogy and P – T –a H 2 O . Tourmaline leucogranites with high Rb/Sr ratios represent low-fraction-melts (F{small tilde} 12%) efficiently extracted from their protoliths under conditions of low water activity, whereas the heterogeneous two-mica granites may result from melting under somewhat higher a H 2 O conditions. The segregation of low-degree melts from source was probably by deformation-enhanced intergranular flow and magma fracturing, with the mechanisms of migration and emplacement controlled by variations in the uppercrustal stress regime during late–orogenic extensional collapse of the thickened crust.

Strongly peraluminous (SP) granites have formed as a result of post-collisional processes in various orogens. In `high-pressure' collisions such as the European Alps and Himalayas, post-collisional exhumation of overthickened crust (>50 km), heated by radiogenic decay of K, U and Th during syn-collisional thickening, produced small- to moderate-volume, cool (<875°C) SP granite melts with high Al O /TiO ratios. In `high-temperature' collisions such as the Hercynides and Lachlan Fold Belt (LFB), there was less syn-collisional crustal thickening (≤50 km). Crustal anatexis was related to post-collisional lithospheric delamination and upwelling of hot asthenosphere, forming large-volume, hot (≥875°C) SP granite melts with low Al O /TiO ratios. Both clay-rich, plagioclase-poor (<5%) pelitic rocks and clay-poor, plagioclase-rich (>25%) psammitic rocks have been partially melted in high-pressure and high-temperature collisional orogens, with the pelite-derived SP granites tending to have lower CaO/Na O ratios (<0.3) than their psammite-derived counterparts. The predominance of pelite-derived SP granites in the Himalayas and psammite-derived SP granites in the LFB suggests that mature continental platforms made up more of the accreted crust in the Himalayan collision than in the LFB.

豆乍山花岗岩主要由中细粒二云 母二长花岗岩构成,是桂东北苗儿山复式花岗岩体中段的一个重要产铀的岩体。单颗粒锆石 SHRIMP U-Pb 年龄为228±11Ma,属于印支期岩浆活动产物。地球化学特征显示该花岗岩以过铝、富硅、富碱和低 CaO/Na_2O 比值为特征,微量元素主要富集 Rb、Th、U 和 Ta,亏损 Sr、Ba 和 Ti。稀土总量30.24×10~(-6)～139.18×10~(-6),轻稀土轻微富集(LREE/HREE=4.00～6.35,(La /Yb)_N=3.24～6.74),Eu 亏损明显(δEu=0.14～0.19)。结合其它相关地质资料,表明豆乍山花岗岩是壳源型花岗岩,是在印支运动晚期地壳伸展—减薄的构造背景下,成分为 泥质的变质岩通过低程度部分熔融方式而形成。

Granites may be subdivided according to their intrusive settings into four main groups—ocean ridge granites (ORG), volcanic arc granites (VAG), within plate granites (WPG) and collision granites (COLG)—and the granites within each group may be further subdivided according to their precise settings and petrological characteristics. Using a data bank containing over 600 high quality trace element analyses of granites from known settings, it can be demonstrated using ORG-normalized geochemical patterns and element-SiO2 plots that most of these granite groups exhibit distinctive trace element characteristics. Discrimination of ORG, VAG, WPG and syn-COLG is most effective in Rb–Y–Nb and Rb–Yb–Ta space, particularly on projections of Y–Nb, Yb–Ta, Rb–(Y + Nb) and Rb–(Yb + Ta). Discrimination boundaries, though drawn empirically, can be shown by geochemical modelling to have a theoretical basis in the different petrogenetic histories of the various granite groups. Post-collision granites present the main problem of tectonic classification, since their characteristics depend on the thickness and composition of the lithosphere involved in the collision event and on the precise timing and location of magmatism. Provided they are coupled with a consideration of geological constraints, however, studies of trace element compositions in granites can clearly help in the elucidation of post-Archaean tectonic settings.

In the Lachlan Fold Belt of southeastern Australia, Upper Devonian A-type granite suites were emplaced after the Lower Devonian I-type granites of the Bega Batholith. Individual plutons of two A-type suites are homogeneous and the granites are characterized by late interstitial annite. Chemically they are distinguished from I-type granites with similar SiO 2 contents of the Bega Batholith, by higher abundances of large highly charged cations such as Nb, Ga, Y, and the REE and lower Al, Mg and Ca: high Ga/Al is diagnostic. These A-type suites are metaluminous, but peralkaline and peraluminous A-type granites also occur in Australia and elsewhere.Partial melting of felsic granulite is the preferred genetic model. This source rock is the residue remaining in the lower crust after production of a previous granite. High temperature, vapour-absent melting of the granulitic source generates a low viscosity, relatively anhydrous melt containing F and possibly Cl. The framework structure of this melt is considerably distorted by the presence of these dissolved halides allowing the large highly charged cations to form stable high co-ordination structures. The high concentration of Zr and probably other elements such as the REE in peralkaline or near peralkaline A-type melts is a result of the counter ion effect where excess alkali cations stabilize structures in the melt such as alkali-zircono-silicates. The melt structure determines the trace element composition of the granite.Separation of a fluid phase from an A-type magma results in destabilization of co-ordination complexes and in the formation of rare-metal deposits commonly associated with fluorite. At this stage the role of Cl in metal transport is considered more important than F.

<p>阿鲁科尔沁地区早白垩世侵入岩主要由中细粒花岗闪长岩、中细粒二长花岗岩、花岗斑岩组成，岩体总体具有富硅、富钠而相对贫钾的特征，属准铝质&mdash;弱过铝质的钙碱性系列。岩体中稀土元素总量较低，轻重稀土发生分馏，具有明显的Eu负异常，亏损高场强元素Nb、Ta、P、Ti，相对富Th、U、Zr、La和轻稀土元素，相对贫Sr，属I型花岗岩。岩体主体来源于壳源组分的部分熔融，形成于早白垩世的后碰撞伸展环境，为有利成矿构造演化阶段。岩体中，<em>w</em>（K）/<em>w</em>（Rb）比值、<em>w</em>（Rb）/<em>w</em>（Sr）比值、<em>w</em>（Fe₂O₃）/<em>w</em>（FeO）比值、分异指数DI较大，固结指数SI较小，属演化程度低、分异程度较高的氧化型磁铁矿系列花岗岩，其地球化学含矿性参数显示Mo、Cu、Pb-Zn金属成矿潜力依次降低，Au成矿潜力差。</p>

突泉协力地区晚侏罗—早白垩世的次火山岩主要由石英二长斑岩、花岗斑岩、闪长玢岩等组成.通过岩相学和地球化学分析,石英二长斑岩和闪长玢岩的里特曼指数δ介于2.55～3.84之间,为钙碱性岩系,铝饱和指数ACNK为1.00～1.18,为弱过铝质Ⅰ型花岗岩;稀土总量较低(∑REE为113.41×10-6～170.27×10-6),轻、重稀土分异较强(LaN/YbN为8.94～ 17.98),Eu具弱负异常,δCe为0.97～1.09,Ce异常不明显;Nb、Ta、P、Ti等相对亏损,Rb、Ba、K、Hf等相对富集,Nb/Ta比值(10.03～11.96,平均为10.87)小于16.2,岩浆来源于上地幔或下地壳,形成过程中同化混染了壳源物质.岩浆的形成与晚侏罗—早白垩世造山晚期华北板块北缘软流圈上隆过程中、在火山型被动陆缘处发生强烈的构造—岩浆改造有关,其岩石地球化学及含矿性参数显示,研究区具有寻找次火山岩—斑岩型Au、Ag、Cu矿的潜力.

东准噶尔地区石炭纪巴塔玛依内山组火山岩分布广泛,规模巨大。对 其岩石学、元素地球化学及同位素地球化学研究表明：1)该套火山岩岩石类型复杂,具玄武岩-安山岩-英安岩-流纹岩组合特征,属高钾钙碱性火山岩系,并富 集大离子亲石元素(Sr、K、Rb、Ba、Th)和轻稀土元素,亏损高场强元素(Nb、Ta、Ti)和重稀土元素,87Sr/86Sr和143Nd /144Nd初始值分别为0.70385~0.71312,0.152378~0.512998,εNd(t)多介于3.0~6.2之间,显示了与俯冲消 减作用相关的不成熟弧后盆地火山岩地球化学特征。2)火山岩物质来源以亏损地幔源为主,并混有少量主体由古生代残余洋壳、岛弧体系组成的年轻下地壳物质。 其中,基性熔岩以亏损地幔源为主,并在岩浆源区与少量新生地壳物质发生了近乎完全的壳-幔岩浆混合和Sm-Nd同位素体系均一化,其形成很可能与俯冲沉积 物和(或)俯冲洋壳变质脱水产生的流体引起上覆地幔楔物质的部分熔融有关；而酸性熔岩与基性熔岩存在明显的不同,酸性熔岩是少量幔源岩浆经强烈结晶分异和 经历较多壳源物质混染的结果。3)玄武岩全岩 Sm-Nd等时线年龄为319.7±5.9 Ma,与区域地质构造背景和已有化石证据基本一致,代表了火山岩的形成时代。综合研究表明,东准噶尔地区320 Ma左右依旧存在古亚洲洋的俯冲消减作用,准噶尔古洋盆最终闭合时间应介于320~311 Ma之间。在此过程中,火山岩浆作用强烈,蕴含成矿物质丰富,东准噶尔地区找矿前景值得期待。

The average chemical compositions of the continental crust and the oceanic crust (represented by MORB), normalized to primitive mantle values and plotted as functions of the apparent bulk partition coefficient of each element, form surprisingly simple, complementary concentration patterns. In the continental crust, the maximum concentrations are on the order of 50 to 100 times the primitive-mantle values, and these are attained by the most highly incompatible elements Cs, Rb, Ba, and Th. In the average oceanic crust, the maximum concentrations are only about 10 times the primitive mantle values, and they are attained by the moderately incompatible elements Na, Ti, Zr, Hf, Y and the intermediate to heavy REE. This relationship is explained by a simple, two-stage model of extracting first continental and then oceanic crust from the initially primitive mantle. This model reproduces the characteristic concentration maximum in MORB. It yields quantitative constraints about the effective aggregate melt fractions extracted during both stages. These amount to about 1.5% for the continental crust and about 8 10% for the oceanic crust. The comparatively low degrees of melting inferred for average MORB are consistent with the correlation of Na 2O concentration with depth of extrusion [1], and with the normalized concentrations of Ca, Sc, and Al ( 3) in MORB, which are much lower than those of Zr, Hf, and the HREE ( 10). Ca, Al and Sc are compatible with clinopyroxene and are preferentially retained in the residual mantle by this mineral. This is possible only if the aggregate melt fraction is low enough for the clinopyroxene not to be consumed. A sequence of increasing compatibility of lithophile elements may be defined in two independent ways: (1) the order of decreasing normalized concentrations in the continental crust; or (2) by concentration correlations in oceanic basalts. The results are surprisingly similar except for Nb, Ta, and Pb, which yield inconsistent bulk partition coefficients as well as anomalous concentrations and standard deviations. The anomalies can be explained if Nb and Ta have relatively large partition coefficients during continental crust production and smaller coefficients during oceanic crust production. In contrast, Pb has a very small coefficient during continental crust production and a larger coefficient during oceanic crust production. This is the reason why these elements are useful in geochemical discrimination diagrams for distinguishing MORB and OIB on the one hand from island arc and most intracontinental volcanics on the other. The results are consistent with the crust-mantle differentiation model proposed previously [2]. Nb and Ta are preferentially retained and enriched in the residual mantle during formation of continental crust. After separation of the bulk of the continental crust, the residual portion of the mantle was rehomogenized, and the present-day internal heterogeneities between MORB and OIB sources were generated subsequently by processes involving only oceanic crust and mantle. During this second stage, Nb and Ta are highly incompatible, and their abundances are anomalously high in both OIB and MORB. The anomalous behavior of Pb causes the so-called ead paradox , namely the elevated U/Pb and Th/Pb ratios (inferred from Pb isotopes) in the present-day, depleted mantle, even though U and Th are more incompatible than Pb in oceanic basalts. This is explained if Pb is in fact more incompatible than U and Th during formation of the continental crust, and less incompatible than U and Th during formation of oceanic crust.

Granitoid rock compositions from a range of tectonic environments are plotted on a multicationic diagram devised by de la Roche and his coworkers. This shows that there is a systematic change through an orogenic cycle which leads progressively to the ultimate development of alkaline magmas. Possible source materials and mechanisms of magma generation are considered from analysis of mineral compositional vectors. These suggest that most granitoid series result from a two-stage process. First, fractional crystallisation of clinopyroxene, olivine and calcic plagioclase from a basic source with tholeiitic affinities produces a magma of intermediate composition. This magma then undergoes periodic mixing with a felsic magma followed by in situ fractionation to generate individual intrusions within granitoid series.

通过中国东北地区浅成低温热液矿床的综合特征研究,将矿床的分布划分为德尔布干、呼玛、小兴安岭和吉东4个矿集区,根据其矿床地质、地球化学特征初步确定成矿流体主要来自大气降水,部分混有岩浆水;成矿物质主要来自赋矿围岩和成矿岩浆-流体系统;多数矿床形成于中低温、中浅成环境,个别矿床成矿温度高、深度大,显示了斑岩型或造山型与浅成低温溶液型成矿系统之间的连续性;厘定大规模成岩成矿时间为130Ma左右,构造环境是古亚洲洋闭合后陆陆碰撞过程的挤压-伸展转变体制,并以矿集区尺度的CMF模式解释了浅成低温热液矿床岩浆-流体系统的发育机制.

Abstract p>During crystallization of a granitic magma, copper is shown to prefer octahedral sites, be they in the melt or in crystalline phases. Burns and Fyfe (1964) showed that the Al2O3/(K2O + Na2O + CaO) ratio of the magma is proportional to the number of octahedral sites available in the melt. A relatively large alumina/alkali ratio will mean more octahedral sites in the melt, a higher retention of copper in the melt, and, thus, a greater likelihood of porphyry-type mineralization, as the copper will still be in the melt at the hydrothermal stage. A comparison of this alumina/alkali ratio for mineralized and barren intrusives in the southwestern U. S. porphyry belt and in the Caribbean indicates that this relationship holds true. Generally speaking, for Laramide intrusives, mineralized stocks have a normative corundum content 2.5 weight percent greater than that of barren intrusives. This result suggests that in composite intrusives the more aluminous ones are better targets for porphyry mineralization and that early formed ferromagnesian minerals from mineralized intrusives should be copper deficient compared to barren systems (Kesler et al., 1975a).</p

中国大兴安岭地区位于东西向古生代古亚洲构造成矿域与北北东向中新生代滨西太平洋构造成矿域强烈叠加、复合、转换的部位。从而使大兴安岭地区的成矿地质条件优越、成矿期次多、成矿强度大、矿床类型多样。近年来区内找矿工作有了新突破 ,对内生金属矿床区域成矿规律的认识也有了新的进展 ,文中试图作一个阶段性的总结。文章将大兴安岭地区对照其大地构造单元划分成 4个成矿带 ,总结了两期主要成矿期 (海西期和燕山期 ) ,归纳出两大主要成矿系列 ,并分别就最近几年的新成果进行了典型矿床的举例