岭南东江流域晚更新世哺乳动物化石的新发现

近年在南岭以南的广东东江流域河源地区东源县上莞镇的碧寿洞中发现较丰富的古哺乳动物牙齿化石。经鉴定为6个目5属5种,称之为碧寿动物群。根据碧寿动物群指示的古生态、化石层位、热释光测试结果和生物地层对比初步认为,该动物群与西江流域的罗沙岩动物群一样,都属于晚更新世时期的大熊猫—剑齿象动物群,生活在MIS5a时的间冰期,但罗沙岩动物群的时代略早,为(79.0±15)kaBP,而碧寿动物群则存在于末次冰期/末次间冰期之交的MIS5a之末叶。此动物群为广东东江流域历年首现,代表了当时的热带北缘森林草原的自然环境。     

A sedimentary facies model for stepped,fluvial tufa systems in the Iberian Range (Spain): the Quaternary Piedra and Mesa valleys

Stratigraphic and sedimentological analyses of the Quaternary tufa and associated deposits in the Piedra and Mesa river valleys allowed a number of stages of their sedimentary evolution to be characterized, and a depositional sedimentary model for this north‐central sector of the Iberian Range (Spain) to be established. The proposed sedimentary facies model may explain tufa arrangements in other medium to high gradient, stepped, fluvial tufa systems with narrow transverse profiles occurring in temperate, semi‐arid areas, in both recent and past scenarios. There are several tufa deposits within the Piedra and Mesa river valleys that, over a maximum thickness of about 90 m, record one or more stages of tufa deposition produced following the fluvial incision of the bedrock or previous tufa deposits. Each depositional stage begins with coarse detrital sedimentation. Six fundamental, vertical sequences of tufa facies with small amounts of detrital material reveal the sedimentary processes that occurred in different fluvial environments: channel areas with: (i) free‐flowing water; (ii) barrages and/or cascades; and (iii) dammed water and palustrine floodplains. The proposed sedimentary model involves narrow, stepped, fluvial valleys in which tufa cascades were common. Alternating intervals of bryophyte and stromatolite facies commonly formed at some cascades. Many of these represented barrage‐cascade structures that consisted of phytoclast rudstones, thick phytoherms of mosses and associated stromatolites, and curtain‐shaped phytoherms of stems. Upstream of these structures, dammed areas with bioclastic sands and silts developed and palustrine vegetation grew. The channel stretches between barrages and/or cascades were loci for extensive stromatolite growth in fast flowing water. The palustrine floodplain was home to pools and drainage channels. The model also explains the growth of some barrages in the River Piedra that surpassed the height of the divide, with the diffluence of the main channel into a secondary course forming other tufa deposits in the area. The distribution and abundance of certain types of tufa facies in fluvial basins may be an indicator of differences in their gradients. The facies studied in this work suggest that the gradient of the ancient River Piedra was steeper than that of the ancient River Mesa. Assuming similar scenarios for climate and hydrology, the depositional settings mentioned above and their dimensions would have been determined mainly by the gradient and width of the associated river valleys. This sedimentary model may also be useful for inferring variations in other river basin slopes, as well as accounting for the presence of tufas in areas that normally have no permanent water input.     

大兴安岭北段宝兴沟金矿床成矿流体特征及矿床成因

宝兴沟金矿床是大兴安岭北部上黑龙江成矿带内大型金矿床之一,矿体主要产于下侏罗统二十二站组砂岩与早白垩世石英闪长岩、闪长玢岩内外接触带内,其热液成矿作用可划分为：黄铁矿±毒砂-石英（Ⅰ）、多金属硫化物-石英（Ⅱ）及少硫化物-碳酸盐（Ⅲ）3个阶段。流体包裹体岩相学研究表明：Ⅰ阶段矿石主要发育气液两相（LV）、少量含CO₂三相包裹体（H_CO2）及富气相包裹体（FV）;Ⅱ阶段矿石中主要发育LV及少量H_CO2包裹体;Ⅲ阶段矿石中只发育LV包裹体。测温结果显示：Ⅰ、Ⅱ阶段包裹体总体均一温度峰值集中于225.00~300.00℃,盐度（w（NaCl））为2.00%~10.00%;Ⅲ阶段均一温度峰值集中于175.00~225.00℃,盐度为4.00%~8.00%;成矿流体为简单的含CO₂中低温、低盐度的NaCl-H₂O热液体系,总体具有从成矿早期到晚期均一温度、盐度逐渐降低的特征。氢、氧同位素分析结果显示,Ⅰ、Ⅱ阶段成矿流体δD_SMOW为-131.00‰~-108.00‰、δ¹⁸O_SMOW为1.00‰~4.00‰,Ⅲ阶段δD_SMOW为-108.00‰、δ¹⁸O_SMOW为-1.89‰,表明早期以岩浆水为主,晚期逐渐演化为与大气降水混合热液。矿石中黄铁矿（毒砂）δ³⁴S_V-CDT为1.50‰~4.20‰,显示其物质来源以深源岩浆为主。综合分析认为,区内金成矿作用与早白垩世（石英）闪长岩、闪长玢岩侵入活动有直接关系,矿床属中低温岩浆热液成因类型。     

小兴安岭西北部花岗质糜棱岩锆石LA-ICP-MSU-Pb年龄、岩石地球化学特征及地质意义

通过对位于小兴安岭西北部黑河-呼玛地区与元古宙变质岩系伴生出露的三处强变形的花岗质岩石的锆石U-Pb LA-ICP-MS测年和岩石学、岩石地球化学研究,确认样品岩性分别为花岗闪长质糜棱岩(样品1-3-4和1-5-1)、角砾状花岗闪长岩(样品1121和1211)和花岗质糜棱岩(样品1218),锆石U-Pb年龄为299.6±1.0Ma、300.8±1.1Ma和294.3±1.0 Ma,形成于晚石炭世末至早二叠世初,而非前人确定的元古宙或早石炭世,并初步认为岩石韧性变形作用发生时间介于184~170 Ma之间。三种花岗岩分别属于富硅、高铝、贫钾的过铝质钙碱性系列(I-3-4和1-5-1)、贫硅偏铝、高钙铁镁的偏铝质高钾钙碱性系列(1121和1211)和富硅钾、低钙镁铝的弱过铝质钾玄质系列(1218),稀土元素特征相似,富集轻稀土,相对亏损重稀土,具有明显或弱的Eu负异常,微量元素富集Rb、La、Th、U等大离子亲石元素,相对亏损Sr和高场强元素Nb、Ta、Zr、Hf,具有高分异Ⅰ型花岗岩和A型花岗岩的特征,在构造环境判别图R_1-E_2图上分别落在同碰撞造山、晚造山和造山后环境,在Nb-Y图落入火山弧-同碰撞环境和板内环境。结合区域资料,认为上述花岗岩是兴安地块与松嫩地块晚古生代碰撞造山的产物,记录了两块体间碰撞造山到造山后伸展作用。     

大兴安岭中段索伦地区玛尼吐组火山岩年代学、地球化学及其构造背景

索伦地区玛尼吐组火山岩岩相学鉴定为安山岩、粗安岩和英安岩,化学成分显示以玄武粗面安山岩、粗安岩为主,少量流纹岩。LA-ICPMS锆石U-Pb定年结果显示其形成于130~132 Ma之间的早白垩世。地球化学特点上主要属高钾钙碱性系列。稀土总量较高(95.19~198.38)×10~(-6),轻重稀土分馏较明显(LREE/HREE=6.38~10.59),弱的负铕异常(δEu=0.68~1.01),富集大离子亲石元素(K、Rb、Th)和轻稀土元素,亏损高场强元素(Nb、Ta、P、Ti)。微量元素具高Sr(多499×10~(-6))和低Yb(最大值为2.83×10~(-6)3.6×10~(-6))、Y(多29.9×10~(-6))和高Sr/Y和低Rb/Sr比值,显示了弧火山岩的特征。正的ε_(Hf)(t)值(7.3~13.7),锆石~(176)Hf/~(177)Hf平均值为0.282964,显示玛尼吐组安山质岩浆源区主要为岩石圈地幔和新增生下地壳的部分熔融,且岩浆形成的过程中受到了流体的改造作用。玛尼吐组火山岩形成于岛弧构造环境,该岛弧构造背景的产生可能与受古太平洋板块俯冲作用有关。     

Experimental investigation of limestone of the Faiyah Range area,United Arab Emirates

The paper presents results of a laboratory experimental program performed on limestone rock samples, using both physical and mechanical methods. The studied rocks (Simsima Formation, Upper Cretaceous) can be classified as highly ferruginous and highly fossilliferous limestone. The lower part of the Simsima Formation contains common fauna such as Orbittoids, rhodolithic and rudists, whereas the upper part of the limestone is interbedded with conglomerates. Detailed geological, petrographic in addition to physical and mechanical tests were carried out on some representative samples from the Faiyah area, aiming at getting a better understanding of the important properties of these rocks. It is shown that the uniaxial unconfined compressive stress is the controlling factor of classification of the Faiyah limestone.     

大兴安岭北端洛古河东花岗岩的地球化学、SHRIMP锆石U-Pb年龄和岩石成因

大兴安岭北端漠河县洛古河东岩体主要岩石类型为二长花岗斑岩、正长花岗斑岩和石英二长斑岩,内部可见闪长质微粒包体,属高钾钙碱性I型花岗岩。花岗岩的元素地球化学和锆石SHRIMP铀-铅年代学研究结果表明,洛古河东岩体形成于早白垩世,其花岗斑岩体的锆石SHRIMP铀-铅年龄为129.8±2.2Ma。花岗岩的SiO₂含量介于68.03%~74.32%之间,Al₂O₃含量介于13.06%~14.55%之间,Na₂O/ K₂O介于0.45~0.86之间,铝饱和指数为0.94~1.11,Mg^#指数介于18~42之间且多小于30。稀土元素总量为160.00×10^-6 ~ 235.15×10^-6,δEu介于0.31~0.52,(La/Yb)_N介于8.99~17.87,为轻稀土富集型。岩体Sr含量低,介于118×10^-6 ~ 268×10^-6之间,而Y含量高,介于16.9×10^-6~ 26.1×10^-6之间,Sr/Y比值低,介于5.62~13.81之间,属低锶高钇型岩石。在原始地幔标准化的微量元素蛛网图中,Rb、Th、U、K、Zr、Hf和轻稀土元素（如La、Ce、Nd和Sm等）富集,Ba、Sr、P和Ti等元素强烈亏损,Nb和Ta具有中等-弱亏损。主量、稀土和微量元素特征表明,岩石具后碰撞花岗岩类的地球化学特征,属后碰撞花岗岩。岩体ε_Nd (t)值介于-3.45~-2.64,平均-3.01;亏损地幔Nd模式年龄介于969~1131Ma之间,平均1018Ma;锶初始比值 (I_Sr)介于0.702486~0.707269之间,平均0.705434;钾长石²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb比值变化范围分别为18.5939~18.6721、15.6019~15.6058和38.4058~38.5249,平均值分别为18.6426、15.6035和38.4613;岩体中的钾长石氧同位素组成很低,δ¹⁸O (‰)值介于-8.1 ~ 4.1之间,多为负值,表明洛古河东岩体为低¹⁸O花岗岩。Nd、Sr、Pb和O同位素组成显示洛古河东岩体形成于含有较多幔源成分的源区物质的部分熔融作用,推测源区主要为Rodinia超大陆会聚过程中（中元古代—新元古代之交）形成的初生地壳。由于古亚洲洋和蒙古-鄂霍茨克洋分别于古生代末期和二叠纪—中侏罗世闭合,因此大兴安岭北端早白垩世花岗岩应该形成于中朝-蒙古大陆与西伯利亚大陆碰撞造山过程的后碰撞阶段。     

黑龙江省多宝山斑岩型铜(钼)矿床成矿流体特征及演化

黑龙江省多宝山斑岩铜(钼)矿床位于小兴安岭西北部,是中亚-兴蒙造山带北东段最大的斑岩型铜(钼)矿床,矿体产于加里东期花岗闪长岩和中奥陶世多宝山组安山岩、凝灰岩中。铜矿化与绢英岩化关系密切,而钼矿化主要产于钾硅化带中。矿区内脉体广泛发育,从早到晚依次为:石英+钾长石脉、早阶段石英+辉钼矿脉、晚阶段石英+辉钼矿脉、石英+黄铜矿+黄铁矿脉、石英+黄铁矿脉和方解石+石英脉。脉石英中广泛发育流体包裹体,包括气液两相水溶液包裹体(W型)、纯气相包裹体(G型)、含CO2三相包裹体(C型)及含子矿物多相包裹体(S型)。石英+钾长石脉中仅发育气液两相包裹体,均一温度峰值﹥550℃、盐度为16.2%～18.1%NaCleqv;早阶段石英+辉钼矿脉中发育大量气液两相包裹体和含子矿物多相包裹体,并见少量含CO2三相包裹体,均一温度集中在350～450℃、盐度变化于1.1%～﹥65.3%NaCleqv;晚阶段石英+辉钼矿脉体发育大量含CO2三相包裹体和含子矿物多相包裹体,另有少量气液两相包裹体,均一温度集中在270～350℃、盐度为0.8%～42.4%NaCleqv;石英+黄铜矿+黄铁矿脉中发育丰富的气液两相包裹体,见少量含子矿物多相包裹体、含CO2三相包裹体和纯气相包裹体,均一温度峰值在230～330℃、盐度为0.8%～42.4%NaCleqv;石英+黄铁矿脉和方解石+石英脉中仅发育气液两相包裹体,均一温度变化于110～200℃、盐度为3.9%～8.4%NaCleqv。成矿流体在古深度4.1km左右,温度在230～450℃之间、压力在10～41MPa之间,发生了强烈的流体沸腾作用,大量CO2等气体从流体中释放出来,黄铜矿、斑铜矿和辉钼矿等巨量沉淀下来,形成了铜(钼)矿体。成矿流体总体上属H2O-CO2-NaCl体系,多期次的流体沸腾作用是该矿床的主要成矿机制。     

小兴安岭平顶山一带早侏罗世花岗岩类年代学、地球化学特征及其地质意义

小兴安岭平顶山大地构造位于兴蒙造山带东段,隶属松嫩地块。本文对小兴安岭平顶山一带碱长花岗岩和正长花岗岩进行了锆石U-Pb年代学和岩石地球化学研究,以确定其形成时代、岩石成因及大地构造背景。结果显示：碱长花岗岩形成于（189±3） Ma,正长花岗岩形成于（191±3） Ma,同为早侏罗世岩浆事件演化的产物;岩石具有高硅（w（SiO₂）为75.00%~77.60%）、富碱（w（K₂O+Na₂O）为7.13%~9.00%）、贫镁（w（MgO）为0.05%~0.45%）、贫钙（w（CaO）为0.17%~1.10%）、低磷钛（w（P₂O₅）为0.01%~0.07%,w（TiO₂）为0.09%~0.23%）的特点,A/CNK值为0.94~1.17,属于准铝质-弱过铝质、高钾钙碱性系列岩石;亏损高场强元素Nb、P、Ti、Ta和大离子亲石元素Ba、Sr,Rb、K、Th、Hf等元素具有明显的正异常;稀土元素总量（w（ΣREE））为（38.76~297.13）×10^-6,稀土配分曲线显示为轻稀土略微富集、重稀土较为平坦缓向倾斜的右倾型,具明显的负Eu异常。锆石饱和温度值及地球化学特征等多种证据显示,岩石为高分异的I型花岗岩。结合小兴安岭区域构造演化特征分析,研究区早侏罗世花岗岩类为松嫩地块与佳木斯地块沿嘉荫—牡丹江缝合带碰撞拼合后伸展环境下的产物,岩浆起源于下地壳火成岩物质的部分熔融。     

大兴安岭红山子盆地火山岩系岩石地层对比

针对大兴安岭南部中生代火山岩系岩石地层单位存在的时间跨度大、不同岩石地层单位时代重叠的问题,选择红山 子盆地火山岩进行SHRIMP 锆石U-Pb 测年,并结合其它地区已有的锆石U-Pb 年龄数据和岩石组合特征对比火山岩系岩石 地层。红山子盆地2 个碱性流纹岩样品（HS505 和HS102）和1 个高钾钙碱性流纹岩样品（HS601）所含锆石均具有明显的 振荡环带,Th/U比值高,属典型的岩浆成因锆石。SHRIMP 锆石U-Pb 测年结果表明,样品HS601 的10 个分析点的206Pb/238U 年龄变化范围为150~160 Ma,加权平均值为（156.5±1.6）Ma,MSWD=1.11;样品HS102 的11 个分析点的206Pb/238U 年龄范 围为153~159 Ma,加权平均值为（154.7±1.7）Ma,MSWD=0.77;样品HS505 的14 个分析点的206Pb/238U 年龄变化范围为 151~160 Ma,加权平均值为（156.5±1.4）Ma,MSWD=1.16。可见,红山子盆地火山岩的年龄范围为157~155 Ma,属晚侏 罗世早期。红山子盆地火山岩以高钾钙碱性流纹岩- 碱性流纹岩组合为特征,与新民组的岩石组合特征基本一致,且层位 相当,应归入新民组。大兴安岭南部地区原划归满克头鄂博组和玛尼吐组、但地质时代属晚侏罗世的长英质火山岩组合应 改归新民组,修正后的新民组与冀北-辽西髫髻山组或蓝旗组和大兴安岭北部塔木兰沟组铁镁质火山岩组合的地质时代一 致,显示出中国东北部晚侏罗世火山岩组合具有南北分带性。