Tephrochronology and tephrostratigraphy of two Pleistocene continental fossiliferous successions from central Italy

The stratigraphical context of two Middle Pleistocene fossiliferous palaeosols from Central Italy (Abruzzo and Tuscany) have been studied. Small mammals and molluscs occur in both palaeosols, which are covered by tephra layers that were analysed using an interdisciplinary approach. Application of fission‐track dating to apatites separated from the Case Picconetto tephra (Pescara, Abruzzo), yielded an age of 0.48 ± 0.04 Ma, indistinguishable from those previously determined for the Campani Quarry (Lower Valdarno, Tuscany) (0.46 ± 0.05 Ma and 0.48 ± 0.05 Ma). Geochemical and petrographic investigations indicate that these tephra originated from different volcanoes, the Alban Hills Volcanic Complex and the Vico Volcano (Latium) respectively. Small mammal and mollusc assemblages indicate different palaeoclimatic and palaeoenvironmental conditions for the Case Picconetto and Campani Quarry palaeosols. Warm and humid conditions can be inferred for the Campani Quarry site, whereas open and cold conditions can be inferred for Case Picconetto. On the basis of faunal data, fission‐track dates and attribution of tephra to specific volcanic eruptions, we suggest a correlation of these faunas with marine oxygen isotope stage 14 (Case Picconetto) and with marine oxygen isotope stage 11 (Campani Quarry), respectively. Copyright © 2003 John Wiley & Sons, Ltd.     

The middle pleistocene deposits of Waverley Wood Pit,Warwickshire, England

A complex of channels underlying the Baginton-Lillington Gravel (Baginton Formation) at Waverley Wood Quarry, Warwickshire is described. Fossil pollen and plant macrofossils, Coleoptera, Ostracoda, Mollusca and Mammalia are described from the channel-fill deposits. Consideration of all the evidence allows the identification of four separate stages of channel fill which largely occurred under a cool temperate climate. At the top of Channel 2 evidence for a cold, continental climatic episode can be recognised, suggesting that the whole complex was deposited under a fluctuating climate at the end of a temperate stage. At two levels in the channels human artefacts were recovered confirming the presence of Palaeolithic people in Warwickshire during the deposition of the sediments. Amino-acid geochronology suggests an age within the ‘Cromerian Complex’ Stage for the channels. The small vertebrate and molluscan faunas indicate that the deposits are no older than the latter part of the ‘Cromerian Complex’ Stage of East Anglia. The regional stratigraphic significance of the Waverley Wood succession is outlined.     

Biostratigraphic and isotopic record of the Cenomanian–Turonian deposits in the Ohaba-Ponor section (SW Haţeg, Romania)

The middle Cenomanian–lower Turonian deposits of Ohaba-Ponor section (Southern Carpathians) were studied from biostratigraphic and isotopic points of view. Both the qualitative and semiquantitative nannofloral analyses, as well as the stable isotope (δ¹³C and δ¹⁸O) data support significant palaeoenvironmental changes in the investigated interval. Two δ¹³C positive excursions were recognized: (1) an excursion up to 1.8‰ (PDB) within the middle/late Cenomanian boundary; (2) an excursion up to 2.2‰ (PDB) in the Cenomanian/Turonian boundary interval. The oldest δ¹³C positive excursion recorded (placed within the Acanthoceras jukes-brownei/Eucalycoceras pentagonum Ammonite Zone boundary interval, and in the NC11 Calcareous Nannofossil Zone respectively) could be assigned to the middle Cenomanian Event II (MCEII). During the above-mentioned event, significant increase in abundance of Watznaueria barnesae, followed by successive blooms of Biscutum constans and Eprolithus floralis, were observed. The youngest δ¹³C positive excursion was identified in the Cenomanian/Turonian boundary interval (in the NC12 and lower part of the NC13 Calcareous Nannofossil Zones). Even the amplitude of this δ¹³C positive excursion is lower in the Ohaba-Ponor section, as generally reported, this may represent the regional record of the OAE2. The successive peaks of the nannofossils Biscutum constans, Zeugrhabdotus erectus and Eprolithus floralis indicate episodes of cooler surface water and high fertility, which preceded and lasted the Cenomanian/Turonian boundary event. Additionally, fluctuations of δ¹⁸O values between −2 and −6‰ suggest also cooler conditions within the Cenomanian/Turonian boundary interval.     

Far beyond the Gulf: the implications of warfare for Asian labour migration

The implications of the Gulf War are assessed for the countries in Asia that send labor migrants to the Middle East. "This paper seeks to examine the effects of...the loss of remittances (and related issues, including return migration), primarily in terms of the long-term implications of the War for the future of contract labour migration in the Asian region...."     

A pronounced dry event recorded around 4.2 ka in brine sediments from the northern Red Sea

Partly laminated sediments were sampled from the brine-filled, anoxic Shaban Deep basin in the northern Red Sea. At about 4200 cal yr BP more than two millennia of anoxic sedimentation is replaced by a sub-oxic facies strongly suggesting the episodic absence of the brine. At the same time stable oxygen isotopes from surface dwelling foraminifera show a sharp increase (within less than 100 yr) pointing to a strong positive salinity anomaly at the sea surface. This major evaporation event significantly enhanced the renewal of deep water and the subsequent ventilation of the small Shaban Deep basin. The timing and strength of the reconstructed environmental changes around 4200 cal yr BP suggest that this event is the regional expression of a major drought event, which is widely observed in the neighboring regions, and which strongly affected Middle East agricultural civilizations.     

河北唐山—卢龙地区寒武－奥陶系界线地层的牙形刺及其重要属种的演化

本文对唐山和卢龙地区寒武－奥陶系界线地层中的牙形刺再次进行研究，厘定了过去报道的一些重要属种，并对最具地层意义的Ｃｏｒｄｙｌｏｄｕｓ的几个种的演化进行了分析。指出了该属的两个进化系列，第一支进化系列是Ｅｏｃｏｎｏｄｏｎｔｕｓｎｏｔｃｈｐｅａｋｅｎｓｉｓ－Ｃｏｒｄｙｌｏｄｕｓｐｒｉｍｉｔｉｖｕｓ－Ｃ．ｐｒｏａｖｕｓ－Ｃ．ｃａｂｏｔｉ－Ｃ．ｉｎｔｅｒｍｅｄｉｕｓ－Ｃ．ａｎｇｕｌａｔｕｓ；而另一支则是Ｅｏｃｏｎｏｄｏｎｔｕｓｎｏｔｃｈｐｅａｋｅｎｓｉｓ－Ｃ．ｃａｂｏｔｉ－Ｃ．ｐｒｏｌｉｎｄｓｔｒｏｍｉ－Ｃ．ｌｉｎｄｓｔｒｏｍｉ－Ｃ．ｐｒｉｏｎ。本文对寒武－奥陶系界线的几个划分方案也进行了简单的讨论     

GEOLOGICAL MARKS OF A POSSIBLE EXTRATERRESTRIAL IMPACT EVENT ON THE BOUNDARY BETWEEN SINIAN/CAMBRIAN IN TIANMENSHAN IN WESTERN HUNAN

Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.     

Occurrence of the Indian genus Hemibos (Bovini, Bovidae, Mammalia) at the Early–Middle Pleistocene transition in Italy

The morphology of the horn-core structure and section shape of the Bos galerianus type specimen, as well as the general anatomy of the frontal and occipital areas of the skull, suggest that the skull is better attributed to the Indian genus Hemibos. This finding contributes to our understanding of faunal dispersal patterns into Europe at the Early–Middle Pleistocene transition.     

晚中更新世以来武威盆地沉积特征——基于WV3 钻孔的释光年代学研究

青藏高原东北缘河西走廊形成了一系列新生代盆地,是研究盆地沉积演化的重要区域。武威盆地位于河西走廊东部,盆地内沉积了较厚的新生代冲洪积地层。为了厘清武威盆地晚中更新世以来的沉积演化历史,笔者等在武威盆地石羊河中上游处钻取了长207 m的WV3 钻孔岩心,获得了上部17 m岩心的 19 个钾长石两步法 pIR200IR290 年龄和 2 个多步法 MET-pIRIR 年龄,结合粒度资料,重建了武威盆地石羊河流域中下游晚中更新世以来的光释光年代学框架和沉积历史。结果表明：两步法 pIR200IR290 和多步法MET-pIRIR年龄在误差范围内一致。220~128 ka时期,沉积速率最小,为 0.35 mm/ka,水动力条件较强,以侵蚀为主;128~108 ka (MIS 5d、MIS 5e) 时期沉积速率为 1.94 mm/ka,沉积物粒径由粗变细,表明此时水动力条件由强变弱;末次冰盛期到全新世早期 (19~9 ka) 沉积速率为2.78 mm/ka,沉积物粒径较细,表明此时水动力条件较弱,沉积速率最大,沉积为主。该地区新构造运动比较活跃,在末次间冰期至末次冰盛期期间存在逆冲活动。该研究对于揭示晚中更新世以来祁连山东北部石羊河流域沉积演化特征具有重要意义。     

鲁西寒武系凝块石特征及其形成机制的探讨

鲁西地区寒武纪地层分布广泛、出露连续,中寒武世张夏组和晚寒武世炒米店组均有凝块石产出。本文通过对该地区凝块石的野外观察和镜下鉴定,认为形成凝块石的微生物主要为附枝菌,其次是葛万菌、肾球菌和放射状菌,根据枝杈的直径大小、枝杈的细胞状分割结构及结晶程度等,附枝菌又可细分为:泥晶粗枝杈状、泥晶分段枝杈状、泥晶细枝杈状、微晶管状枝杈状和亮晶粗枝杈状。相应的群落也可划分为:泥晶树枝状、单个房室状、簇球状和亮晶树枝状。凝块石的凝块为附枝菌等蓝细菌钙化体和周围粘结的碳酸盐微粒所组成的团块,其按形态可分为:斑状、网状和树枝状。根据上述的研究,本文认为形成凝块石的理想过程可以分为4个阶段:蓝细菌的捕捉和粘结作用、蓝细菌自身钙化作用、碳酸盐的原地沉淀和沉积后作用。