Fourier Analysis Applied to Mimomys (Arvicolidae, Rodentia, Mammalia) First Lower Molars – Biochronological Implications

Fourier analysis was used in this study to help a specific determination of some Mimomys (Arvicolidae, Rodentia, Mammalia) species. Several Pliocene and Pleistocene Central and Western European Mimomys species first lower molar contours have been decomposed by Complex Discrete Fourier Transform. Inter- and intra-specific comparisons have been performed on the harmonics obtained from the decomposition and some problematic specimens have been classified.     

青海唐古拉地区侏罗纪非海相双壳动物群及其古环境分析

唐古拉山温泉以东约80km的冬曲一带产出丰富的侏罗纪非海相双壳类化石,中侏罗统雀莫错组顶部的紫红色细粒岩屑砂岩产Qiyangia,Yunnanopharus,Unio 3属3种,其中有新种Yunnanopharus substratus.这一动物群与过去在本区发现的中侏罗统“Cuneopsis”-Eolamprotula-Protomya动物群面貌明显不同,过去一直认为Yunnanopharus是晚三叠世的属,而Qiyangia则主要产于下侏罗统,根据地层层序及上、下层位产出的海相双壳类和腕足类化石时代分析,冬曲剖面的Qiyangia-Yunnanopharus动物群时代无疑为中侏罗世巴通期,扎窝茸组产非海相双壳类“Cuneopsis”,Yunnanopharus,Plicatunio,Nipponaia(Eonipponaia),Cyotrigonioides,Danlengicon-cha,Nakamuranaia等7属9种,其中包括新种Yunnanoconcha(?)ovalis,Danlengiconha tanggu-laensis,Cyotrigonioides(?)ellipticus和Nipponaia(Eonipponaia)?bifurcata,基于下伏海相地层中双壳类和腕足类化石的佐证,它们的时代最有可能是在晚侏罗世基末里期至早白垩世期间,据化石围岩的粒度分析以及埋藏学研究表明,这些类三角蚌类主要生活于水体安静、有机质含量丰富的淤泥质基底,繁盛于近海三角洲平原上的湖沼环境,同时,由于海退初期尚有可能受到海水短暂侵漫的影响,造成它们生存环境的咸化     

楚科奇海与加拿大海盆表层沉积物表观特征及其环境指示

通过对中国首次和第二次北极科学考察采集的表层沉积物的观察，根据沉积物的颜色和气味、砾石分布、底栖生物及贝壳分布特征的分析，探讨了该海区表层沉积物表观特征变化与有机质输入、沉积物的氧化还原状态的关系、底栖生物分布范围、冰筏碎屑的分布区域及与海流的关系，指出在研究区软体动物生长的北界位于73．5°N，比浮游动物的北界约低2个纬度。冰筏碎屑的北界可作为融冰水的北界或永久冰区的南界，位置在77°24′N附近。通过对沉积物表观特征的综合分析，结合研究区的海流特征，指出研究区的海流分布对沉积物分布有重要影响，尤其是两股不同性质的海流相遇，对西南部与东部两个区域的沉积物组成及性质具有较强的控制作用。     

Integrated Radiolaria,benthic foraminifera and conodont biochronology of the pelagic Permian blocks/tectonic slices and geochemistry of associated volcanic rocks from the Mersin Mélange,southern Turkey: Implications for the Permian evolution of the northern Neotethys

Blocks and tectonic slices within the Mersin Mélange (southern Turkey), which are of Northern Neotethyan origin (Izmir–Ankara–Erzincan Ocean (IAE)), were studied in detail by using radiolarian, conodont, and foraminiferal assemblages on six different stratigraphic sections with well‐preserved Permian succesions. The basal part of the Permian sequence, composed of alternating chert and mudstone with basic volcanics, is assigned to the late Asselian (Early Permian) based on radiolarians. The next basaltic interval in the sequence is dated as Kungurian. The highly alkaline basic volcanics in the sequence are extremely enriched, similar to kimberlitic/lamprophyric magmas generated at continental intraplate settings. Trace element systematics suggest that these lavas were generated in a continental margin involving a metasomatized subcontinental lithospheric mantle source (SCLM). The middle part of the Permian sequences, dated by benthic foraminifera and conodont assemblages, includes detrital limestones with chert interlayers and neptunian dykes of middle Wordian to earliest Wuchiapingian age. Higher in the sequence, detrital limestones are overlain by alternating chert and mudstone with intermittent microbrecciated beds of early Wuchiapingian to middle Changhsingian (Late Permian) age based on the radiolarians. A large negative shift at the base of the Lopingian at the upper part of section is correlated to negative shifts at the Guadalupian/Lopingian boundary associated with the end‐Guadalupian mass extinction event. All these findings indicate that a continental rift system associated with a possible mantle plume existed during the late Early to Late Permian period. This event was responsible for the rupturing of the northern Gondwanan margin related to the opening of the IAE Ocean. When the deep basinal features of the Early Permian volcano‐sedimentary sequence are considered, the proto IAE oceanic crust formed possibly before the end of the Permian. This, in turn, suggests that the opening of the IAE Ocean dates back to as early as the Permian.     

Sedimentology,palaeoecology and geochronology of Last Interglacial deposits from Deeping St James,Lincolnshire, England

Pollen, plant macrofossil, molluscan and coleopteran data from organic muds below the low terrace of the River Welland at Deeping St James, Lincolnshire indicate deposition in the mixed oak forest phase of a Late Pleistocene interglacial. Coleopteran and molluscan data suggest summer temperatures up to 4°C warmer than at present in eastern England, and plant macrofossil material suggests a climate more continental than that of Britain in the Holocene. No direct analogue of this biota, however, exists currently in Europe. Biostratigraphical indications from the pollen coleoptera and Mollusca suggest an age in the Ipswichian Interglacial. Thermoluminescence dates between 120 ka and 75 ka and amino-acid ratios with a mean of 0.11 show that deposition of the sediments took place during Oxygen Isotope Stage 5. This accurate dating of a partial Ipswichian succession allows discussion of the ages of a number of other interglacial sites in eastern England of assumed Ipswichian age. Copyright © 1999 John Wiley & Sons, Ltd.     

中国非海相白垩纪腹足类组合序列和分布

中国白垩纪非海相腹足类可划分为4个组合:1)早白垩世凡兰吟期巴列姆期Probaicalia vitimensis-Ptychostylus-口盖化石Reesidella robusta组合;2)早白垩世阿普特期阿尔必期Bellamya clavilithiformis-Mesocoshliopa cretacea-Zaptychius costatus-Brotiopsis组合,由于环境的不同,这一组合可分为2个亚组合:Brotiopsis亚组合和Bellamya clavilithiformis-Mesocoshliopacretacea-Zaptychius costatus亚组合;3)晚白垩世科尼亚克期中马斯特里赫特晚期Mesolanistes nanxiongensis组合,由于产出的层位不同,这一组合又可分为2个亚组合,Mesolanistes ziziformis亚组合和Mesolanistes-nanxiongensis亚组合;4)晚白垩世马斯特里赫特期最晚期Palaeoancylusna nxiongensi组合。     

中国非海相白垩纪介形类化石组合

我国非海相白垩纪介形类化石可以划分为7个组合:1)分布于我国西北和西南地区欧特里沃期巴列姆期的Jingguella-Minheella-Pinnocypridea组合;2)分布于我国西北和西南地区巴列姆期的Cypridea-Latonia-Darwinula组合;3)阿普特期阿尔必期的Cypridea(Morinina)-Bisulcocypridea-Mongolocypris组合;4)分布于我国东北、中部及东部地区欧特里沃期巴列姆期的Cypridea-Mongolianella-Darwinula组合;5)分布于我国东北、中部及东部地区巴列姆期阿普特期的Cypridea(Cypridea)-Cypridea(Ulwellia)-Limnocypridea组合;6)塞诺曼期塞农期的Cypridea-Triangulicypris-Sunliavia-Lycopterocypris组合;7)坎潘期马斯特里赫特期的Talicypridea-Cypridea-Quadracypris-Candona组合。依据以上7个介形类化石组合,我国22个地区含介形类的73个地层单元(群/组)得到了对比。     

中国东北、韩国东南和日本西南部早白垩世非海相与海相地层对比,非海相软体动物的生物年代学和古地理意义

根据非海相与海相,特别是共同的海相和非海相软体动物化石的对比,并结合放射性同位素测年,中国东北黑龙江东部和辽宁西部,韩国东南部庆尚盆地,日本西南部内带岐阜县北部牧户/庄川地区和外带四国德岛和物部地区早白垩世地层得到了对比,产自这些地层的非海相软体动物的时代也因此受到了约束。著名的中国东北含煤地层龙爪沟和鸡西群,盛产热河生物群/动物群的热河群的时代均为欧特里沃期/巴列姆期阿普特期,它们的上覆地层桦山群和孙家湾组为阿尔必期。韩国西南部新洞群和除金洞组以外的河阳群为阿普特期阿尔必期,不整合于新洞群之下的卯谷组主要为欧特里沃期。日本西南部内带的牧户/庄川地区的手取群和外带德岛和物部地区的物部川群均为欧特里沃期阿尔必期。Cuniopsis kihongi,Nakamuranaia leei,Koreanaia cheongi和Trigonioides(Wakinoa)tetoriensis的时代为欧特里沃期早巴列姆期。Viviparus onogoensis,Unio ogamigoensis,Myrene(Mesocorbicular)tetoriensis及Tetoria(Tetoria)yokoyami为欧特里沃期阿普特期。Arguniella cf.quadrata,A.cf.ventricosa,Sphaerium(Sphaerium)anderssoni,Probaicalia vitimensis和Pr.gerassimovi为欧特里沃期/巴列姆期阿普特期。Nakamuranaia chingshanensis,Plicatounio(Plicatounio)multiplicatus,Sphaerium(Sphaerium)coreanicum和Micromelania?katoensis为阿普特期阿尔必期。Nippononaia sinensis,Nip.tetoriensis,Nip.ryosekiana和Trigo-nioides(Wakinoa)wakinoensis是阿普特期的标志。Trigonioides(Trigonioides)quadratus,T.(T.)heilongjiangensis,Plicatounio(Plicatounio)naktongensis,Unio longus与Sphaerium(Sphaerium)chintaoense为晚阿普特期阿尔必期或阿尔必期的标志化石。我国东北、韩国东南和日本西南部非海相,特别是淡水软体动物接近的相似性表明这三地区在早白垩世时相连,并处于同一水系。但是,在欧特里沃期阿尔必期期间,这一陆块的东部,即频临古太平洋的日本西南部的外带因地势低而多被海水覆盖,在牧户/庄川和黑龙江东部存有遭受海侵的浅而窄的海湾,凡兰吟期,特别是欧特里沃期/巴列姆期之前,中国东北韩国东南部日本西南部陆块为受造山运动引起的隆起和沉降活动影响的高低不平的高原,经受了广泛而长期的剥蚀。多数含有包括熔岩和凝灰岩在内的火山岩,并与北东北北东方向的断裂带近于平行分布的非海相白垩纪盆地直至欧特里沃期/早巴列期(有些地区可能稍早(凡兰吟期))(134～126Ma),即华北克拉通破坏的高峰期(130～120Ma)才形成。这一现象表明,这些盆地受断裂,特别是伴随有强烈火山喷发和时而局部海侵的沿着古太平洋西北缘和郯庐断裂带的构造运动的控制。     

泰国、老挝南部和越南中部的非海相白垩纪双壳类生物地层学

泰国、老挝和越南白垩纪沉积全属非海相,它们广泛分布于泰国北部、东北部、西南部和南部,老挝北部、中部和南部,越南东北部、西北部、中部和南部。泰国南部的白垩纪地层分为Lam Thap,Sam Chom和Phun Phin组;其他地区,特别是西北部的呵叻高原地区的白垩系属呵叻群的Phra Wihan,Sao Khua,Phu Phan,Khok Kruat,Maha Sarakham及Phu Thok组。在老挝,万象盆地的白垩系由老挝呵叻群的NamSet,Phu Phanang,Ban Ang,Champa和Ban Thalat组与丰洪群的Thangon和Saysomboun组组成;沙湾拿吉(东兴)盆地的白垩系由南通(河)群的Nam Phouan,Nam Xot,Nam Noy和Nong Boua组组成。越南的白垩系在西北部分为Nam Na,Yen Chau,Van Chan和Ngoi Thia组,东北部为Ban Hang组,中部分为NhaTrang,Mu Gia和Dong Dzuong组,南部则为Phu Quoc组。三国白垩系的岩性普遍以红棕色至浅灰色砂岩、砾(岩质)砂岩、粉砂岩、泥岩和砾岩为主。泥岩中具有钙质结核和硅结砾岩,但盐和石膏仅见于Maha Sarakham,Saysomboun和Yen Chau组内。过去,这些白垩纪地层的生物地层没有经过详细研究。根据地层层序和化石对比,在泰国东北部呵叻高原和南部半岛地区及老挝南部沙湾拿吉(东兴)盆地中识别出了2个标记非海相白垩纪的类三角蚌类化石组合:阿普特期(但可上延至阿尔必期)的Trigonioides(Trigonioides)kobayashi-Plicatounio(Guangxiconcha)suzukii组合,阿普特阿尔必期(但主要为阿尔必期)的Trigonioides(Diversitrigonioides)diversicostatus-Pseudohyria subovalis组合。越南中部可能也产早白垩世阿普特阿尔必期的类三角蚌类双壳类Plisatouniosp.-Trigonioidessp.组合。通过双壳类组合,并结合包括孢粉和恐龙在内的其他化石的对比,泰国北部和南部、老挝南部和越南中部的非海相白垩纪地层得到了定年和对比,从而揭示了东南亚非海相白垩纪盆地的演化历史。