南方更新世红土氧化物地球化学特征

江西、浙江和湖南等地更新世红土化学组成分析结果表明,各地各类红土的化学组成具有较好的一致性。以SiO2、Fe2O3和Al2O3为主,K2O、Na2O、CaO和MgO大量淋失,相对于上陆壳(UCC)平均组成富Ti、Fe和Al,贫K、Na、Ca和Mg。符合亚热带地区脱硅富铝或脱硅富铝铁的基本成土过程,总体形成于湿热环境。其烧失量(LOI)对红土脱硅富铝程度具有一定的指示意义,LOI越大,脱硅富铝程度越强。同一剖面从网纹红土至均质红土或从网纹红土至棕色黄色风化程度渐弱。然而,全岩样品的SiO2/Al2O3、SiO2/R2O3分子比在直接指示红土风化强度方面不够有效。白网纹与红色基质的物源一致,化学组成却存在一定分异。以UCC为背景的元素盈亏状态和以均质红土为背景的元素绝对迁移量特征一致表明,物质迁移,尤其是Fe迁移与网纹红土网纹化过程之间存在必然的联系。Fe迁出区形成白网纹,Fe加入区继承红土化特征。     

川西平原中更新世网纹红土主量元素地球化学特征

川西平原中更新世网纹红土地球化学分析结果表明,网纹红土的主量元素组成具有较好的一致性,以SiO2,Fe2O3 和
Al2O3 为主,三者含量之和平均值为90.92%;K2O,Na2O,CaO 和MgO 等易溶组分含量低,除K2O 含量略高于1% 外,其余氧化物均不足1%。相对于上陆壳（UCC）平均组成,主量元素富集TiO2,TFe2O3,贫Na2O,MgO,P2O5,K2O,MnO。样品中的Fe2O3,Al2O3,R2O3（Fe2O3+Al2O3）与SiO2 含量呈明显的负相关关系,表明该地区网纹红土符合亚热带地区脱硅富铝或脱硅富铝铁的成土过程,总体形成于湿热环境。通过化学蚀变指数（CIA）、风化淋溶系数（BA）和A-CN-K 图解等对比分析,该区中更新世网纹红土的化学风化强度与九江红土、宣城红土相近,认为该区网纹红土在湿热环境下遭受了强烈的化学风
化作用,同时也表明中更新世川西平原与长江中下游地区具有相似的古气候环境。     

赣北鄱阳湖地区土塘剖面第四纪红土地球化学特征及古气候意义

赣北鄱阳湖地区土塘剖面发育第四纪红土,自下而上可分为强网纹红土层、弱网纹红土层、微网纹红土层、均质红土层和下蜀黄土层。基于常量元素、粒度分析数据以及前人年代框架,初探土塘剖面化学风化特征及其古气候意义。(1)土塘剖面粒度组分均一,常量元素含量相近,风化淋溶强烈。(2)土塘剖面各地层间化学风化强度存在差异:下蜀黄土层为初期的去Na、Ca阶段;均质红土层为中期的去K阶段;微网纹红土层由去K阶段向去Si阶段过渡;网纹红土层已完全进入晚期去Si阶段。剖面常量元素的相对迁移能力为:Na₂O>MnO₂>CaO>P₂O₅>MgO>K₂O>SiO₂>Al₂O₃>TiO₂>Fe₂O₃。(3)中更新世以来赣北鄱阳湖地区气候总体上由暖湿趋于干冷,期间伴随多个明显的干湿旋回佐证强烈的淋溶与干湿交替作用是网纹红土发育的重要驱动因子。     

广东西樵山MIS5a网纹红土常量元素分布及其气候意义

广东西樵剖面厚约9.6m,其中该剖面的MIS5a网纹红土"XQ41"厚约33cm,位于该剖面719~751cm深度。对MIS 5a网纹红土按1cm间隔采集,总共获得32个样品的常量元素分析结果。研究表明,化学风化指标SiO2/Al2O3、CIA、ba和CIW的分布范围和平均值都显示其在物质组成上具有总体上均一的特征;SiO2-ba、SiO2-CIW和SiO2/Al2O3-CIA散点图上则分别以大部分、几乎全部和全部地聚集于现代热带红土(砖红土)散点的分布范围。据此提出,西樵网纹红土主要形成于热带气候影响下的生物气候带。有意义的是,与西樵网纹红土相同时代的西樵邻近区域的碧寿洞和罗沙岩哺乳动物化石群,都含有指示热带气候的物种。这进一步表明,热带生物气候带与发育成熟的网纹红土存在着逻辑上的因果关系。这一研究结果,为MIS5a全球变化与中国低纬区域环境响应提出了一个新的认识问题的材料,相应地也为轨道变化与冰期间冰期旋回学说增添了一个新的内容。     

加积型网纹红土网纹化机制及形成环境

选取九江地区JL剖面网纹层段典型样品,针对红基质与白网纹的物质组成及理化性质展开异同分析,在此基础上探讨网纹红土形成环境。初步得到以下结论:1)红基质与白网纹的粒度组成、元素组成、风化特征基本一致,但铁元素有显著差异,"网纹"并非原生构造,不是岩性差异及差异风化的产物,而是同源物质经历化学风化过程中元素分馏的结果。2)地球化学分析、磁学分析和粘粒级矿物组成分析一致表明,白网纹与红基质在铁含量、铁氧化物形态、铁矿物类型方面存在明显差异。白网纹与红基质相比,全铁含量(4.30%)低于红基质(8.63%);Fe^3+/Fe^2+比值(40.66)低于红基质(90.95);游离铁量及游离度(7.01 g/kg,32.96%)低于红基质(76.21 g/kg,77.52%);铁活化度和晶胶率(25.31%,37.77%)高于红基质(8.77%,9.69%);赤铁矿和针铁矿含量极少,这充分表明白网纹局部存在明显的铁淋失。3)白网纹局部脱色机制主要受控于赤铁矿及其转化,红基质主导矿物为赤铁矿,并含有一定的磁赤铁矿和针铁矿,而白网纹则不含磁赤铁矿,赤铁矿含量也极少。此外高岭石含量也是影响色浅的因素之一,白网纹蛭石、高岭石含量(20.24%和45.08%)均略高于红基质(11.45%和41.82%)。4)赤铁矿的富集、局部铁迁移的特点,整体上指示高温、中强程度化学风化和季节性多水的环境。这在一定程度上暗示网纹红土形成时期气候高温多雨,且季节性反差增强。     

庐山北麓JL红土剖面粉砂粒级元素地球化学特征及其物源意义

加积型红土是中国南方第四纪环境变化研究的重要陆相载体,其沉积母质显示风成特性,后期经历较强的化学风化。为了明确加积型红土的物质来源,并减弱风化效应对其物源信息的影响,本文提取了庐山北麓JL红土剖面(厚18.46 m)部分样品的粉砂组分(4~63 μm),分析其元素地球化学特征,并通过元素比值及物源判别指数等方法讨论其蕴含的物源信息。结果显示:1)粉砂粒级化学组成中SiO2、Al2O3和Fe2O3三者的含量可达84.29%,K2O、Na2O、CaO和MgO四者含量仅1.30%,与全岩相比SiO2含量增高,Al2O3和Fe2O3含量明显降低,风化指数CIA值(74.02%)明显低于全岩样品(85.00%);微量元素中,粉砂粒级相对全岩Cu、Zn、Rb、Sr、Cr、La等含量降低,Y、Zr含量则略高。2)Na2O/Al2O3与K2O/Al2O3及Na2O/K2O与CIA的散点图中,粉砂粒级样点间的集聚程度明显降低,暗示风化效应在一定程度上被削弱。此外以洛川黄土和长江河漫滩沉积物为端元的物源指数计算表明,全岩样品消除粒级效应后的物源指数(PIw)与粉砂粒级物源指数(PIfs)吻合度较好,进一步验证了粉砂粒级地球化学特征在削弱风化效应方面的有效性。3)JL剖面上部黄棕色土的PIfs值为0.45,物源上更接近北方黄土,剖面中下部的网纹红土PIfs值为0.57,物源更接近长江沉积物。结合TiO2/Al2O3、Zr/Y、Hf/Ti等元素比值,JL剖面自下而上近源物质的贡献略有减少,远源物质的贡献则趋于增加,这可能意味着晚第四纪以来东亚冬季风不断增强的过程。     

江西赣县花岗岩型红土剖面常量元素地球化学特征

对赣县田村花岗岩红色风化壳剖面常量元素的迁移特征和化学风化强度的研究结果表明：（1）红土常量元素组成以 SiO2、Al2O3、Fe2O3为主,三者占总量的90%以上,其中又以SiO2的含量最高,K2O、CaO、Na2O与MgO等易溶组分的含量则 相对较低;（2）红土剖面风化过程中,常量元素的地球化学行为多表现为迁移淋失,迁移程度由剖面底部向上逐渐增强, 其中CaO与Na2O平均迁移量分别为97.34%、94.94%,属于强迁移元素;MgO、K2O和SiO2平均迁移量分别为52.50%、 39.89%、22.72%,属于易迁移元素,Fe元素表现为高度富集;（3）综合分析铝铁系数、化学蚀变指数和风化淋溶系数,指 示赣县花岗岩型红土在炎热、潮湿环境下遭受了强烈的化学风化作用,风化强度顶部向下渐弱。     

皖南网纹红土的粒度分布特征及古环境意义

安徽宣城向阳剖面高分辨率粒度分析结果表明:1)网纹红土含有较高的胶结性很强的次生氧化铁,样品前处理时单颗粒的分散效果将会显著地影响粒度测试结果。向阳剖面不含>2mm的砾石,砂粒(>63μm)的含量也很低,粘粒(<2μm)和粗粉砂(10～50μm)明显富集;2)除底部外,向阳剖面粒度组成特征反映了明显的风成特性,但不能因此忽视其强风化特征的存在,尤其是剖面中、下部的网纹红土。应肯定向阳网纹红土的风成特性,但不能简单地称其为风积成因;3)向阳剖面磁化率值与粘粒和细颗粒含量无显著正相关性,说明磁化率值不能指示网纹红土的风化强度;4)向阳剖面粒度分布特征无法提供该剖面存在多个“沉积—成土”过程旋回的证据。向阳网纹红土更多地体现了其具有原始风成沉积和后期强烈风化的双重特性。     

昆明石林碳酸盐岩红色风化壳元素地球化学特征

以昆明石林两个典型红土剖面为研究对象,探讨了主量元素及稀土元素在化学风化作用下的迁移特征及分布规律,为进一步认识碳酸盐岩风化剖面的演化过程以及红土剖面的物质来源提供地球化学依据。两个红土剖面的研究结果显示:(1)SiO_2、Al_2O_3和Fe_2O_3~T是两个剖面红土样品的主要成分,三者占到总量的80%以上,其中又以SiO_2的含量最高;(2)化学蚀变指数CIA(90以上)较高,硅铝系数和硅铁铝系数较低,显示出两个红土剖面经历了较强的风化淋溶作用,体现出研究区亚热带高原气候,温暖湿润的化学风化环境;(3)两个剖面稀土元素含量较高,范围分别在211.51×10~(-6)~416.40×10~(-6)和290.67×10~(-6)~626.89×10~(-6)之间,其稀土配分曲线均具有Eu亏损的轻稀土显著富集型特征,两个剖面都表现出轻稀土元素间分异较大而重稀土元素间分异较小的特征,这主要与剖面风化成土过程中的三价氧化物的强烈固定作用有关,且KP剖面的轻稀土元素分异更明显;(4)两个剖面经历了相似的风化迁移过程,结合元素对Al_2O_3-TiO_2、Al_2O_3-Fe_2O_3~T、Y-Yb相关性分析以及SiO_2/Al_2O_3-Na_2O/Al_2O_3相关图解可以得出,KP和CH剖面是由于下伏基岩风化而来。     

第四纪网纹红土的类型与网纹化作用

第四纪网纹红土在中国南方红土发育区内广泛分布,具有特殊的结构,是第四纪红粘土的重要组成部分,按照质地网纹红土可分为均质类网纹红土和非均质类网纹红土。测试结果显示:（1）均质类网纹红土的粒度组成以粉砂（5～50 μm）和粘粒（<5 μm）为优势粒级,砂（>50 μm）含量很小,不足3%;粒度频率曲线多数呈单峰正偏形态,众数峰值位于5.5～6.5之间,部分呈双峰形态,两个峰值分别位于6和8附近;CIA值较高（84.31%～89.26%）,ba值较低（0.19～0.30）;稀土元素平均含量和分布模式与风尘沉积相似,87Sr/86Sr值与佳县上新世红粘土接近;εNd（0）介于-10.54～-12.66之间,表明物质源区基本稳定;均质类网纹红土的理化特征体现了风成沉积的特性和风化成土作用的显著影响,可称之为加积型网纹红土。（2）非均质类网纹红土发育自冲洪积相、坡积相沉积物或基岩风化壳红土,土体粉砂含量明显减少,多小于50%,砂含量大大增加,>50 μm和>250 μm粒级的离散系数较高,指示了显著的非均质特征;CIA值多数大于84%,化学元素和风化指标的离散系数多小于10%,显示其经历了较为强烈和稳定的风化作用。第四纪网纹红土的形成先后经历了风化成土过程和网纹化过程,南方红土区在网纹红土发育期内具有整体湿润的气候条件。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Late Wuchiapingian (Late Dzhulfian,early Late Permian) limestone olistolites within the Tertiary flysch of Glypia Unit (Mount Parnon,central–eastern Peloponnesus,Greece)

Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931.     

PALEONTOLOGY

正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.)     

GEOCHEMICAL EXPLORATION

正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.)     

MICROPALAEONTOLOGY

正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.)     

PETROLOGY

正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus.,     

ENVIRONMENTAL GEOLOGY

正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an     

PROSPECTING EXPLORATION

正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of