黄土高原一个连续的晚新生代剖面及其划分与对比

陕西旬邑地区一个地层厚约 2 30 m的晚新生代剖面 ,全为土状堆积。岩性划分、古地磁测年、古生物研究及其他一些手段的分析测定表明 ,该剖面记录了距今 6 .8Ma到现代的沉积 ,其中第四系厚 141.2 m,全为黄土—古土壤沉积序列 ;新近系厚约 90 m,全为红土沉积 ,底部不整合面之上有 6— 7m红土层被覆盖 ,无法取样 ,其上实测厚度83.4m,将每层红土层及紧接其下的钙质结核层称为一个成土—成壤组合 ,新近系约含 80个明显的成土—成壤组合。 N/Q岩性界线在剖面深度的 141.2 m处 ,但古地磁 M/G界线在相当于剖面深度的 137.6 m处 ,即 L43 顶界之上0 .4m处 ,古地磁极性的转移滞后于岩性的变化。多层生物化石的发现对各段地层时代的确定及古气候环境的分析起了积极的作用     

Laboratory organic matter maturation at high pressures: heat-up effect on vitrinite reflectance

A laboratory study was conducted to assess the effect of heat-up to high diagenetic to low metamorphic temperatures on vitrinite reflectance (VR) at high pressures using the same heat-up processes, apparatus and starting material as those employed in prior experimental studies on huminite/vitrinite maturation. ??Heat-up?? is the isobaric increase in temperature of an organic matter maturation experiment from room temperature to the desired run temperature T ^ehu (T ^ehu ?=?temperature at the end of heat-up). The experiments were performed on xylite of swamp cypress and used a heating rate of 50?°C/min. These confined system maturation experiments were carried out at 10?kbar and involved temperatures T ^ehu ranging from 175 to 450?°C. Additional experiments were conducted at pressures of 5, 20 and 25?kbar to evaluate the influence of pressure on the effect of heat-up on VR. At 10?kbar, results of this study show that heat-up does not influence VR for T ^ehu ?< ~270?°C. This absence of maturation is viewed as the result of an activation time delaying vitrinite maturation at these diagenetic to very low metamorphic temperatures. For T ^ehu ?> ~270?°C, heat-up has a significant effect on VR at 10?kbar: VR greatly increases with T ^ehu during the short heat-up event. This effect of heat-up on VR points out the rapid kinetics of the initial VR increase. Increasing pressure reduces VR increase gained during heat-up. Obviously, pressure retards the initial VR increase and thus controls organic matter maturation. In addition to temperature, the formulation of VR evolution rate equation must consider pressure, activation time and VR gained during heat-up.     

河南省泥石流危险度分区

在分析历史资料和防治现状的基础上引入城市重要性作为判别准则之一,以18个地级市为研究对象利用层次分析法对河南省泥石流危险度分区。依据泥石流危险度权重的不同将河南省分为5个区间,其中危险度大的城市1个,危险度中等的城市3个,危险度小的城市6个,危险度极小城市2个,无危险度城市6个。以期为河南省泥石流灾害的防治提供有益的参考。     

地球排气作用——建立整体地球科学的一条统纲

通过研究发现 ,现在可以用地球排气作用作为一条统纲 ,把原来分散的地球科学各个分支学科和谐地串联成为一个整体地球科学巨系统。地球排气的实质是幔汁 (HACONS超临界态流体 )从深部自发向上、向外的辐射排放 ,结果形成了地球内外的 5个气圈和气体地球动力学 ,幔汁上涌后通过碱交代作用产生蚀变和岩浆并促使原来为固体的上地幔、地壳发生溃变 ,在地球的 3个基本动力 ,即重力、地球自转变速、圈层旋转差速和天体 (主要是月球 )潮汐力联合作用的大前提下诱发出大地构造运动、地球演化和自然灾害。没有幔汁活动就没有壳幔运动。笔者初步认为 ,对现有流行的众多理论和结论都需要重新加以怀疑和再审鉴。否则 ,地球科学难以向前发展。我们今后不仅需要单科的或局域的岩石学家、地球化学家、大地构造学家、气象学家、海洋学家等 ,另外还需要有一大批整体地球科学家。     

Geothermobarometry in albite-garnet orthogneisses: A case study from the Gran Paradiso nappe (Western Alps)

The aim of this paper is to estimate syntectonic P-T conditions within albite- and garnet-bearing orthogneisses. These rocks are generally characterized by the assemblage quartz + albite + biotite + phengite + CaFe-garnet + epidote + titanite. Garnet contains up to 55 mole per cent of grossular. K-feldspar is a relict magmatic phase.

P-T conditions are estimated using several independent methods. First, it is shown that exchange reactions based on the Fe---Mg partitioning between garnet and biotite or garnet and phengite cannot be used to estimate temperatures in these rocks, due to the high grossular content of garnet. Second, maximum and minimum pressures are constrained, respectively, by the occurrence of albite instead of jadeite + quartz and by the assemblage phengite + biotite + quartz. Third, phase equilibria in albite- and garnet-bearing metagranites are modelled in the system K₂O---CaO---FeO---Al₂O₃---SiO₂---H₂O. Equilibrium curves are calculated for the observed phase compositions. Uncertainties in P-T estimates mainly result from the choice of appropriate non-ideal solution models for the garnet.

An application is developed for granites from the Gran Paradiso nappe (Western Alps). These granites show an heterogeneous deformation of Alpine age expressed by mylonitic shear zones cutting across weakly deformed domains. Estimated P-T conditions for the synkinematic assemblages are 10–16 kbar at 550±50°C.     

Petrography of Middle Jurassic to Early Cretaceous sandstones in the Kutch Basin,western India:Implications on provenance and basin evolution

This paper investigates the provenance of Middle Jurassic to Early Cretaceous sediments in the Kutch Basin, western India, on the basis of mineralogical investigations of sandstones composition(Quartz-Feldspar-Lithic(QFL)fragment), Zircon-Tourmaline-Rutile(ZTR) index, and mineral chemistry of heavy detrital minerals of the framework.The study also examines the compositional variation of the sandstone in relation to the evolution of the Kutch Basin, which originated as a rift basin during the Late Triassic and evolved into a passive margin basin by the end Cretaceous. This study analyzes sandstone samples of Jhumara, Jhuran and Bhuj Formations of Middle Jurassic,Upper Jurassic and Lower Cretaceous, respectively, in the Kutch Mainland. Sandstones record a compositional evolution from arkosic to subarkosic as the feldspar content decreases from 68% in the Jhumara Formation to 27%in the Bhuj Formation with intermediate values in the Jhuran Formation. The QFL modal composition indicates basement uplifted and transitional continental settings at source. Heavy mineral content of these sandstones reveals the occurrence of zircon, tourmaline, rutile, garnet, apatite, monazite and opaque minerals. Sub-rounded to well-rounded zircon grains indicate a polycyclic origin. ZTR indices for samples in Jhumara, Jhuran and Bhuj Formations are 25%, 30% and 50% respectively. Chemistry of opaque minerals reveals the occurrence of detrital varieties such as ilmenite, rutile, hematite/magnetite and pyrite, in a decreasing order of abundances. Chemistry of ilmenites in the Jhumara Formation reveals its derivation from dual felsic igneous and metabasic source, while those in Jhuran and Bhuj Formations indicate a metabasic derivation. Chemistry of garnet reveals predominantly Fe-rich(almandine) variety of metabasic origin. X-ray microscopic study provides the percentage of heavy minerals ranging from 3% to 5.26%. QFL detrital modes reflect the evolution of the basin from an active rift to a passive margin basin during the Mesozoic. Integration of results from QFL modal composition of the sandstones, heavy mineral analysis and mineral chemistry, suggests sediment supply from both northern and eastern highlands during the Middle Jurassic. The uplift along the Kutch Mainland Fault in the Early Cretaceous results in curtailment of sediment input from north.     

Pico- and Nanophytoplankton Dynamics in Two Coupled but Contrasting Coastal Bays in the NW Mediterranean Sea (France)

Due to its ecological context, the Toulon bay represents a site of scientific interest to study temporal plankton distribution, particularly pico- and nanophytoplankton dynamics. A monthly monitoring was performed during a two-year cycle (October 2013–December 2015) at two coupled sampling sites, referred to as Little and Large bays, which had different morphometric characteristics and human pressures. Flow cytometry analyses highlighted the fact that pico- and nanophytoplankton were more abundant in the eutrophic Little bay. Furthermore, it evidenced two community structures across the Toulon bays: at times, a co-dominance of picoeukaryotes, nanoeukaryotes, Synechococcus 1-like cells and Prochlorococcus-like cells was found, and at other times, a Synechococcus 1-like dominated community existed. The alternation of one structure or the other can be explained by a combined action of temperature regime, nutrient conditions and degree of contamination. This study showed that pico- and nanophytoplankton dynamics were mainly driven by temperature in both sites, as in other temperate Mediterranean regions. Thus, the community was mainly composed of picoeukaryotes and Prochlorococcus-like cells in the winter (<?15 °C), while it was dominated by Synechococcus 1-like cells in the summer (>?20 °C). Additionally, the multiple human stressors in the Little bay seemed to affect the increase in abundance of Synechococcus 1-like cells as they were preferentially observed in the Large bay.     

The mantled gneiss domes of Kuopio (Finland): Interfering diapirs

Finite strain data from the Kuopio mantled gneiss domes are described. Synclines located between two domes have flattening-type strains while those situated between more than two domes exhibit constrictional strains. Cleavage trajectory patterns show that cleavage tends to parallel the dome boundaries and encloses characteristic points termed “cleavage triple points”, at junctions of synclines. The stretching lineation is generally steeply plunging in a mean southwest direction. Folds range from inclined to reclined. Their asymmetry is apparently related to irregularities in the cover-basement boundary. Two shear components of the deformation have been deduced from available data. The major one is steeply plunging and is well exhibited by cleavage fans, steeply plunging lineations and finite-strain gradients. The second shear component is horizontal, as deduced from asymmetric folds and other small-scale structures, and is controlled by bosses and dimples in the cover-basement boundaries.The described structural features are explained in terms of interference between progressively inflating neighbouring diapirs. Furthermore, some of these features, such as cleavage triple points, flattening between two domes and constriction between three or more domes, and horizontal shear components controlled by cover-basement boundary irregularities, could be used as criteria of diapirism. A model of progressive dome interference is presented in which each dome inflates and interacts with neighbours. Such a model could possibly be applied to other orogenic situations with closely spaced diapirs, e.g., Archean greenstone belts or granite-rich orogenic belts.     

The first peak ground motion attenuation relationships for North of Vietnam

The first attenuation relationships of peak ground acceleration (PGA) and peak ground velocity (PGV) for northern Vietnam are obtained in this study. Ground motion data are collected by a portable broadband seismic network in northern Vietnam as a part of cooperation between the Institute of Geophysics, Vietnamese Academy of Science and Technology, Vietnam and Institute of Earth Sciences, Academia Sinica, Taiwan. The database comprises a total of 330 amplitude records by 14 broadband stations from 53 shallow earthquakes, which were occurred in and around northern Vietnam in the period between 01/2006 and 12/2009. These earthquakes are of local magnitudes between 1.6 and 4.6, focal depths less than 30 km, and epicentral distances less than 500 km. The new attenuation relationships for PGA and PGV are:

log₁₀(PGA)=-0.987+0.7521M_L-log₁₀(R)-0.00475R,