垭头铀矿床控矿沉积相及成因

垭头铀矿是湘西沅麻盆地白垩系红层中较为典型的沉积矿床,位于盆地东北缘,靠雪峰隆起,置于Z_b,(?)_(1x),地层之上。本文是在综合野外实践的基础上,研究矿床的沉积特点、控矿沉积相以及矿床成因。     

碳同位素与早元古代地层对比

本文首次较详细地研究了早元古代碳酸盐地层的碳同位素组成，样品采自华北早元古代标准地层单元──山西五台地区滹沱群，结果表明碳同位素组成随地质时代有明显的变化，并与地层层位有很好的对应关系。作者认为，碳同位素对于早元古代碳酸盐地层的对比是很有用的。     

辽宁西部早白垩世朝阳翼龙科 (Chaoyangopteridae)化石一新种

中国辽宁西部早白垩世翼龙类化石非常丰富,其上部的九佛堂组翼龙类组合以含有丰富的无齿的古神翼龙科、朝阳翼龙科等进步类型而与下部的义县组翼龙类组合相区别。本文描述了辽宁西部建昌盆地九佛堂组一新的大型翼龙类化石,其以上下颌无齿、吻端指数为3.7、前颌骨背支细长且封闭鼻眶前孔背缘、很大的鼻眶前孔后端超过上下颌关节位置、轭骨的上颌骨突基部宽大而应被归入朝阳翼龙科(Chaoyangopteridae)神州翼龙属(Shenzhoupterus)。其以较大的体形(翼展2.05 m)、平直的上下颌咬合面、轭骨的眶后骨突较泪骨突长且基部略宽、第4～7颈椎长度依次减小等特征,区别于朝阳神州翼龙(Shenzhoupterus chaoyangensis),而被命名为三亚神州翼龙(新种)(Shenzhoupterus sanyainus sp. nov.)。这是辽宁西部早白垩世翼展最大且不具牙齿的翼龙类属种,它的发现丰富了九佛堂组翼龙类组合内容,对认识朝阳翼龙科的骨骼形态与生态习性亦具有积极意义。     

Early Cambrian high pressure/low temperature metamorphism in the southeastern Tarim craton in response to circum-Gondwana cold subduction

The circum-Gondwana subduction initiated by the early Cambrian has been suggested to reflect the establishment of the modern plate tectonics. The metamorphic rocks with low thermobaric (T/P) ratios indicative of cold subduction in the present tectonic regime have not been well investigated. To better understand the circum-Gondwana subduction and to test its possible link with the emergence of the modern plate tectonics, this study focused on blueschist-facies metamorphic rocks in the Altyn Tagh of the southeastern Tarim craton. Mineral assemblage and chemistry, phase equilibrium modelling, and quartz-in-garnet Raman elastic geobarometry reveal that the zoisite blueschist and glaucophane (Gln)-bearing quartz schist in northern Altyn Tagh were metamorphosed to lawsonite to epidote blueschist-facies at 520–545 °C and 16–19 kbar. It reflects high-pressure (HP)/low temperature (LT) metamorphism with low T/P ratios of <300 °C/GPa and thermal gradients of <10 °C/km. These blueschist-facies metamorphic rocks underwent rapid decompression starting at P-T conditions of <495 °C and <9.6 kbar during exhumation. Ar-Ar geochronology records paragonite Ar-Ar plateau ages of 520–506 Ma for the zoisite blueschist samples and phengite Ar-Ar plateau ages of 522–516 Ma for the Gln-bearing quartz schist samples, suggesting that the peak HP/LT metamorphism occurred prior to ca. 522 Ma. Based on new results and available data from the major Gondwana blocks, cold subduction was suggested to profoundly operate along circum-Gondwana in the early Cambrian after the amalgamation of Gondwana. The extensive circum-Gondwana subduction represents the earliest global cold subduction in Earth’s history associated with the establishment of the modern plate tectonics, as directly recorded by the studied early Cambrian blueschist-facies metamorphic rocks and a dramatic drop in the mean T/P of metamorphism since the early Paleozoic.     

贵州册亨岩架黑苗湾组的发现及其地质意义

作者在册亨尾排金矿普查地质填图工作中,于岩架镇高苕一带发现晚三叠世卡尼早期地层.根据岩性特征,将其划为黑苗湾组.本文对该地黑苗湾组的出露与分布及岩石地层特征进行详细介绍,并讨论其地质意义.     

内蒙古科右中旗地区梅勒图组安山岩年代学特征及其地质意义

对内蒙古科右中旗地区梅勒图组安山岩锆石LA--ICP--MS U--Pb年代学、锆石Hf同位素和岩石地球化学测试分析结果表明,梅勒图组安山岩形成时代约为早白垩世中期(123~125 Ma)。锆石εHf(t)=(+5.84~+9.34),一阶段Hf模式年龄为412~553 Ma。岩石地球化学分析表明,安山岩K2O含量较高,SiO2含量和Mg#值中等,富集大离子亲石元素,高场强元素Nb、Ta、Ti等明显亏损。这些特征反映出梅勒图组安山岩的源区为新形成的富集地幔。结合地球化学特征和区域大地构造背景,研究区梅勒图组安山岩的形成可能与太平洋板块俯冲作用后的陆内伸展环境有关。     

Magmatic activity and its geological significance in Early Jurassic in Mangui area of Inner Mongolia

By investigating the U-Pb zircon isotope geochronology and petrogochemistry of the major magmatic rocks in Mangui area, the authors in this paper discussed the forming era, tectonic background and geological significance. A large amount of intrusive rocks and a small amount of medium-acid volcanic rocks in Early Jurassic were found in this area. U-Pb dating by LA-ICP-MS method shows that the ages are from (199±1)Ma to (184±1)Ma and the rock types can be divided into fine-medium-grained quartz diorite, medium-grained granodiorite, fine-medium-grained monzogranite, medium-fine-grained macrophenocryst monzogranite, rhyolite, dacite and andesite, which didn’t ouur in Neoprotezoic-Paleozoic period as previous researchers thought, revealing the tectonic and magmatic activities during the Early Mesozoic period. The geochemical results show that the rocks are Ⅰ-type magmatic rocks of subluminous-peraluminous high-K calc-alkaline series. The fractionation between light and heavy rare-erath elements((La/Yb)_N= 3.42~32.96) and the Eu depletion degree is not complied with the evaluation from basic to acidic. The large ion lithophile element Ba is relatively rich and Rb, Sr are relatively delicient. The high field strength elements Th and U are relatively rich and Nb, Ti, Y are relatively deficient. The magma origin and tectonic setting show that quartz diorite and medium-fine-grained macrophenocryst monzogranite come from crust-mantle mixed magma, while the medium-acid volcanic rocks, granodiorite and fine-medium-grained monzogranite are from the partial melting of crustal materials, whose formation is connected with the evolution of Mongol-Okhotsk Suture Zone. The geology and geochemistry of the Early Mesozoic magmatic rocks indicate that the middle part of Mongol-Okhotsk Ocean might begin subduction at the end of the middle Triassic and close the Early Jurassic. The peak collision might take place at the Early Jurassic, not in the Late Triassic as previous thought. The Mohe over-thrust nappe system might form in the remote effect of southward extrusion during the closing process of the eastem part of Mongol-Okhotsk Ocean. The middle and eastern Mongol-Okhotsk Ocean closing age is of great importance to reveal the basin-range tectonic formation during the Middle Jurassic to the Late Cretaceous in Northeast China.     

江西修水第四系网纹红土的地层学研究

根据大量野外观察和室内分析结果，较详细论述了江西修水地区第四系网纹红土的地貌地层、岩石地层、磁性地层和年代地层等方面的特征，并在此基础上，就有关网纹红土的形成时代、成因以及与黄土的对比等问题进行了讨论，提出１）网纹红土可分为强网纹化红土和弱网纹化红土两个岩性段，每个岩性段又由若干个密集网纹层与稀疏网纹层构成；网纹红土与下伏红色砾石层属同期产物；２）网纹红土中的密集网纹层的地质意义相当于北方黄土中的古土壤；３）网纹红土形成于早更新世末（约０．９ＭａＢ．Ｐ．）至晚更新世初（约０．１ＭａＢ．Ｐ．）；４）网纹红土发育于湿热气候条件下，地下水埋深浅，地表低洼、排水不畅的环境。     

Fukuititan nipponensis, A New Titanosauriform Sauropod from the Early Cretaceous Tetori Group of Fukui Prefecture,Japan

<正>A titanosauriform dinosaur:Fukuititan nipponensis gen.et sp.nov.is erected based on the incomplete skeleton.It is characterized by elongated asymmetric tooth crown with a weak or absent labial groove and without lingual concavity;stalk-like epipophysis of cervical vertebra;the transverse width of the proximal end of the humerus approximately 32%of the humerus length;metacarpal longer,approximately 48%of the radius and the distal end of the ischia slightly expanded.It represents the first relatively complete titanosauriform skeleton found from Japan.The discovery of Fukuititan indicates that the diversity and geographical distribution of Titanosauriformes are much higher than the previous thought.     

云南的早期脊椎动物化石研究

我国云南是世界上早期脊椎动物化石的重要产地,古生代中期的鱼类不仅门类齐全,而且大多出现时代早、地区性属种多,其中不少化石材料如今已成为探讨如脊椎动物起源、硬骨鱼类起源、四足动物起源等一系列生命史中重大课题的关键资料。主要对古生代中期云南早期脊椎动物化石的研究做一个系统、全面的回顾与总结,并在此基础上对未来有关研究的重点与方向进行了展望。在探索生物演化格局的同时,不仅要加强对演化机制、环境以及古地理背景的研究,而且更要强调多学科的交叉与融合,充分利用我国古生代中期丰富的鱼类化石资料,在早期脊椎动物系统演化、古地理与古气候等方面做出原创性的成果。