宁夏隆德县泥石流形成条件分析

2013年,隆德县遭遇了50年一遇的强降雨,导致境内发生了17处泥石流.在野外详细调查的基础上,结合区域现有资料,从沟坡比降、物源和水源三个主要方面分析了隆德县泥石流的形成条件.结果表明:隆德县泥石流均分布于丘陵地貌区,坡度范围在20°～50°之间,相对高差在50～100m之间,为泥石流的发生提供了有利的地形地貌条件;流域内新近系(Ngn)桔红色砂质泥岩残坡积物,具有弱膨胀性,吸水后会发生一定程度的崩解软化,导致土体结构联结减弱、强度降低,构成了泥石流的物源;降雨是隆德县泥石流最主要的触发因素.通过实地调查与降雨数据分析,可知隆德县泥石流的形成主要受前期降雨的影响,属于前期降雨控制型泥石流.因此,可通过监测前期降雨,特别是间接前期降雨,对泥石流进行预警预报.     

REMARKS ON THE OIOCEROS SPECIES (BOVIDAE, ARTIODACTYLA, MAMMALIA) FROM THE NEOGENE OF CHINA

<正> The genus Oioceros was created by C. Gaillard (1902) based on the species Antilope rothii Wagner, 1857 from the Turolian of Pikermi, Greece. Its diagnosis is that 'Bovidae of small size with long slender muzzle; face bent down on basicranial axis either slightly or to a moderate extent; orbits with expanded orbital roof; horn-cores twisted counter-clockwise in a fairly close spiral of one or two revolutions, widely separate, tilted backward or fairly upright, divergent, with a cross-section almost circular or elliptical, keeled either anteriorly or posteriorly or both; dentition moderately hypsodont, premolar series rather long and slender, molars broad with ribs of medium strength.' (after Pilgrim and Hopwood, 1924, p. 24). Up to now, it has included approximately seventeen species from the Neogene of the Old World (twelve species in Asia, four in Europe and one in Africa).     

Dating the Northern African cercopithecid fossil record

The primitive cercopithecidProhylobates is known only from the (middle?) Orleanian sites of Moghara (Egypt) and Zelten (Libya). No cercopithecid is known from north Africa during the Astaracian and Vallesian periods.Macaca (or a closely allied form) appears in the (late?) Turolian of Sahabi (Libya) and Menacer (Algeria) where it is associated with colobines.Macaca persists into the Pliocene (Wadi Natrun, Egypt; Garaet Ichkeul; Ain Brimba) but apparently disappears before the end of this period, and is absent from north Africa until the middle Pleistocene (Ain Mefta).Theropithecus is known from a single tooth from the upper Pliocene of Ain Jourdel, and from several jaws from the middle Pleistocene of Ternifine (c. 0.7 m.y.) and Thomas Quarry III (c. 0.4 m.y.) in Algeria.     

从孢粉学论证东海盆地下第三系的存在

传统的地质学观点,将东海盆地与台湾海相地层相提并论,以至误解东海盆地只有上第三系沉积。而在东海海域龙井构造中首钻的龙井一井和次钻的东海一井下部地层中所获得的孢粉组合证明,东海盆地龙井构造史前的早第三纪时曾与苏北相连成陆,只是在晚渐新世一早中新世时才全面解体接受海侵,这一事实表明,其成盆历史大体与南海相仿。     

A revision of fossil Rhizomyid rodents from Northern India and their correlation to a Rhizomyid biochronology of Pakistan

Based on the biochronology of rhizomyid rodents of Northern Pakistan, fossil horizons in the Siwaliks of Northern India can be correlated to the late Neogene sequence of Pakistan with greater precision than previously possible. The indian Siwaliks do not include records of the most primitive Rhizomyidae, but rhizomyid faunas of India display strong affinity with those of Pakistan in the late Miocene. Pliocene differentiation of rhizomyid faunas in India and Pakistan may reflect ecological partitioning within the Indian subcontinent. Use of the term «Nagri for deposits at Haritalyangar suggests an erroneous equivalence in age to the Nagri stratotype in Pakistan.     

雷州半岛南部地区晚第三纪沉积古环境演化

通过提取280号钻孔岩心中有孔虫组合的信息,对岩心中浮游和底栖两大类有孔虫的分布、底栖有孔虫的组合、特殊属种的生态及复合分异度、优势度进行分析计算,重塑了本区沉积相,为雷州半岛南部地区晚第三纪以来沉积古环境演化提供了研究资料。     

南海北部陆架晚第三纪δ~(13)C记录与古生产力——以珠江口盆地BY7-1-1和PY33-1-1井为例

南海珠江口盆地ＢＹ７－１－１及ＰＹ３３－１－１井晚第三纪浮游有孔虫的丰度、底栖有孔虫小泡虫超科中葡萄虫（Ｕｖｉｇｅｒｉｎａ）和小泡虫（Ｂｕｌｉｍｉｎａ）的相对丰度（Ｕ＋Ｂ含量）以及浮游有孔虫壳体的δ１３Ｃ记录表明，晚第三纪期间表层水生产力总体上呈增高趋势，其中早中新世为表层水生产力较低的时期，但由Ｎ４至Ｎ８带表现为递增趋势，中—晚中新世为高生产力时期，早上新世为又一个高生产力时期。其中中—晚中新世时期本区最可能处于非上升流的高生产力地区，而早上新世为受上升流影响的高生产力地区。     

芒林均质坝采用第三系与残坡积混合料研究

根据芒林水库工程地质条件,适宜利用当地材料修建均质土坝。本文通过芒林水库土料场地质勘察,推荐采用第四系与第三系混合料作为填坝材料,对地表第四系及下部第三系地层进行勘探、取样、分析后,认为第四系与第三系混合比例在1∶2范围内,技术指标能满足规范要求。为工程建设节省了征地,减少了工程投资。     

Formation of spinel-cordierite-feldspar-glass coronas after garnet in metapelitic xenoliths: reaction modelling and geodynamic implications

Spinel + cordierite + K‐feldspar + plagioclase + glass form coronas around garnet in metapelitic xenoliths at El Hoyazo and Mazarrón, two localities of the Neogene Volcanic Province (NVP) of SE Spain. The presence of fresh glass (quenched melt) in all phases shows that corona development occurred under partial melting conditions. Algebraic analysis of mass balance in the NCKFMASH system suggests the reaction Grt + Sil + Bt + Pl = Spl + Crd + Kfs + melt as the most plausible model for the development of coronas in the El Hoyazo sample, and indicates that biotite was required as reactant for the formation of cordierite. The P–T conditions for the formation of coronas are estimated at ～820 ± 50 °C, 4.5 ± 0.6 kbar at El Hoyazo, and ～820 ± 50 °C, 4.0 ± 0.4 kbar at Mazarrón. The El Hoyazo xenoliths record a complex P–T history, characterized by early melt production during heating and additional melting during decompression. A local cooling event characterized by minor retrograde reaction and melt crystallization preceded ascent and eruption. This study shows that detailed xenolith analysis may be used to track magma evolution in a chamber.     

Kinematics of the Southern Rhodope Core Complex (North Greece)

The Southern Rhodope Core Complex is a wide metamorphic dome exhumed in the northern Aegean as a result of large-scale extension from mid-Eocene to mid-Miocene times. Its roughly triangular shape is bordered on the SW by the Jurassic and Cretaceous metamorphic units of the Serbo-Macedonian in the Chalkidiki peninsula and on the N by the eclogite bearing gneisses of the Sideroneron massif. The main foliation of metamorphic rocks is flat lying up to 100 km core complex width. Most rocks display a stretching lineation trending NE–SW. The Kerdylion detachment zone located at the SW controlled the exhumation of the core complex from middle Eocene to mid-Oligocene. From late Oligocene to mid-Miocene exhumation is located inside the dome and is accompanied by the emplacement of the synkinematic plutons of Vrondou and Symvolon. Since late Miocene times, extensional basin sediments are deposited on top of the exhumed metamorphic and plutonic rocks and controlled by steep normal faults and flat-ramp-type structures. Evidence from Thassos Island is used to illustrate the sequence of deformation from stacking by thrusting of the metamorphic pile to ductile extension and finally to development of extensional Plio-Pleistocene sedimentary basin. Paleomagnetic data indicate that the core complex exhumation is controlled by a 30° dextral rotation of the Chalkidiki block. Extensional displacements are restored using a pole of rotation deduced from the curvature of stretching lineation trends at core complex scale. It is argued that the Rhodope Core Complex has recorded at least 120 km of extension in the North Aegean, since the last 40 My.