Early Devensian (MIS 5d–5b) occupation at Dartford,southeast England

A deeply buried horizon containing mint‐condition flint artefacts was discovered in 2006 during archaeological investigations in advance of major roadworks near Dartford, Kent, in southeast England. The context of the artefacts and the freshness of their condition suggest this horizon represents a buried occupation surface. Optically stimulated luminescence dating places this horizon in the period Marine Isotope Stage 5d–5b, early in the British Devensian glaciation. This paper describes details of the artefacts, their context and dates, and outlines how this apparent occupation fits in with the wider pattern of Neanderthal settlement in Britain and northwest Europe in the later Pleistocene. Copyright © 2010 John Wiley & Sons, Ltd.     

Stratigraphy and tectonic evolution of the Kazdağı Massif (NW Anatolia) based on field studies and radiometric ages

The Kazda?? Massif was previously considered as the metamorphic basement of the Sakarya Zone, a microcontinental fragment in NW Anatolia. Our new field mapping, geochemical investigations, and radiometric dating lead to a re-evaluation of previous suggested models of the massif. The Kazda?? metamorphic succession is subdivided into two major units separated by a pronounced unconformity. The lower unit (the Tozlu metaophiolite) is a typical oceanic crust assemblage consisting of ultramafic rocks and cumulate gabbros. It is unconformably overlain by a thick platform sequence of the upper group (the Sar?k?z unit). The basement ophiolites and overlying platform strata were subjected to a single stage of high-temperature metamorphism under progressive compression during the Alpine orogeny, accompanied by migmatitic metagranite emplacement. Radiometric age data obtained from the Kazda?? metamorphic succession reveal a wide range of ages. Metagranites of the Kazda?? metamorphic succession define a U–Pb discordia upper intercept age of ca. 230 Ma and a lower intercept age of 24.8 ± 4.6 Ma. This younger age agrees with ²⁰⁷Pb/²⁰⁶Pb single-zircon evaporation ages of 28.2 ± 4.1 to 26 ± 5.6 Ma. Moreover, a lower intercept age of 28 ± 10 Ma from a leucocratic metagranite supports the Alpine ages of the massif within error limits. Reconnaissance detrital zircon ages constrain a wide range of possible transport and deposition ages of the metasediments in the Sar?k?z unit from ca. 120 to 420 Ma. Following high-temperature metamorphism and metagranite emplacement, the Kazda?? sequence was internally imbricated by Alpine compression, and the lowermost Tozlu ophiolite thrust southward onto the Sar?k?z unit. Field mapping, internal stratigraphy, and new radiometric age data show that the Sar?k?z unit is the metamorphic equivalent of the Mesozoic platform succession of the Sakarya Zone. The underlying metaophiolites are remnants of the Palaeo tethys Ocean, which closed during the early Alpine orogeny. After strong deformation attending nappe emplacement, the unmetamorphosed Miocene Evciler and Kavlaklar granites intruded the tectonic packages of the Kazda?? Massif. During Pleistocene time, the Kazda?? Massif was elevated by EW trending high-angle normal faults dipping to Edremit Gulf, and attained its present structural and topographic position. Tectonic imbrication, erosion and younger E–W-trending faulting were the main cause of the exhumation of the massif.     

Qiarbahete Sanukitoids and adakitic rocks in NW Tianshan: age and geochemical constraints on their petrogenesis and tectonic settings

The Qiarbahete complex in NW China consists of gabbroic diorite, granodiorite, and late-stage quartz diorite porphyry veins. Zircon sensitive high-resolution ion microprobe (SHRIMP) U–Pb analyses show that the gabbroic diorite and granodiorite formed at 368 ± 5.2 Ma and 354 ± 4.1 Ma, respectively, indicating that the complex was emplaced in the Late Devonian–Early Carboniferous. The gabbroic diorites, characteristic of Sanukitoids, exhibit high Mg^# (62 average), MgO (6.84% average), Cr (195 ppm average), and Ni (61.4 ppm average) contents. The rocks show moderately fractionated rare earth element (REEs) patterns and weak negative Eu anomalies (δEu: 0.83–0.89), enrichment of large ion lithophile elements (LILEs), and depletion of high field strength elements (HFSEs), with low ?_Nd(t) values (1.46–1.73). The gabbroic diorites originated from partial melting of a hydrous mantle wedge followed by assimilation of crust during ascent. The granodiorites show a geochemical affinity with adakitic rocks, e.g. SiO₂ (64.95–67.87%) > 56%, Al₂O₃ (15.88–16.56%) > 15%, MgO (1.79–2.31%) < 3%, Sr (315–375 ppm) > 300 ppm, and Yb (1.84–2.06 ppm). They are enriched in light rare earth elements (LREEs) and LILEs and depleted in HFSEs, with weak negative Eu anomalies (δEu: 0.78–0.87). The granodiorites were mainly derived by the partial melting of a subducted oceanic slab, followed by subsequent melt–mantle interaction and crustal rocks contamination. All these indicate that the Qiarbahete complex was emplaced in a continental arc setting attending the southward subduction of the Junggar Ocean during the Late Devonian–early Carboniferous, generating the lateral accretion of continental crust in NW Tianshan.     

西北西部夏季干湿年的水汽输送特征

利用1961—2007年NCEP/NCAR逐月再分析资料和中国地面气候资料国际交换站数据集台站降水距平百分率资料,分析了西北西部干、湿年夏季的水汽输送差异。结果表明,北疆偏湿润年,在对流层中、低层有一支源于阿拉伯海的异常水汽输送通道,它向西北方向流经波斯湾后折向东北方向流入北疆,这是热带海洋水汽输送进入北疆的最短路径。南疆—河西走廊西部偏湿润年,异常水汽通道主要是位于对流层中、低层的一支源于北方的水汽输送带,它作反气旋式运动后以偏东气流的形式流入河西走廊西部及南疆,由于该水汽输送源自北方,水汽含量小,这可能是造成该地域极度干旱的直接原因之一;另一支更弱的异常水汽通道位于对流层高层,它源自阿拉伯海,流经印度半岛后折向北,越过青藏高原后进入南疆。     

Esterases activities and lipid peroxidation levels in muscle tissue of the shanny Lipophrys pholis along several sites from the Portuguese Coast

This study is part of a project aiming to validate the use of the intertidal shanny Lipophorys pholis as a sentinel species in pollution monitoring in NW European marine ecosystems. To this end, a characterisation of acethylcholin (AChE), butyrylcholin (BChE) and propionylcholin (PrChE) esterases in L. pholis muscle was performed and the results indicated that AChE was predominant. Furthermore, the use of eserine sulphate and BW284c51 (0.64–800 μM), and iso-OMPA (0.08–16 mM), confirmed the measurement of true cholinesterases (ChEs) as well as the presence of pseudocholinesterases. The field application of these markers to L. pholis, sampled in seven locations along the Portuguese coast, revealed that fish were likely to be affected by neurotoxic compounds. This was indicated by the significant depletion of AChE (p < 0.05) in animals collected at urban and industrialised sites, compared with those from reference locations. The inclusion of a marker of effect, measured as lipid peroxidation levels in muscle tissue, also revealed the existence of site differences. Overall, the study further validates the utility of L. pholis in pollution monitoring studies.     

Marsh benthic Foraminifera response to estuarine hydrological balance driven by climate variability over the last 2000 yr (Minho estuary,NW Portugal)

A high-resolution study of a marsh sedimentary sequence from the Minho estuary provides a new palaeoenvironmental reconstruction from NW Iberian based on geological proxies supported by historical and instrumental climatic records. A low-salinity tidal flat, dominated by Trochamminita salsa, Haplophragmoides spp. and Cribrostomoides spp., prevailed from AD 140–1360 (Roman Warm Period, Dark Ages, Medieval Climatic Anomaly). This sheltered environment was affected by high hydrodynamic episodes, marked by the increase in silt/clay ratio, decrease of organic matter, and poor and weakly preserved foraminiferal assemblages, suggesting enhanced river runoff. The establishment of low marsh began at AD 1380. This low-salinity environment, marked by colder and wet conditions, persisted from AD 1410–1770 (Little Ice Age), when foraminiferal density increased significantly. Haplophragmoides manilaensis and Trochamminita salsa mark the transition from low to high marsh at AD 1730. Since AD 1780 the abundances of salt marsh species (Jadammina macrescens, Trochammina inflata) increased, accompanied by a decrease in foraminiferal density, reflecting climate instability, when droughts alternate with severe floods. SW Europe marsh foraminifera respond to the hydrological balance, controlled by climatic variability modes (e.g., NAO) and solar activity, thus contributing to the understanding of NE Atlantic climate dynamics.     

Holocene Earth’s magnetic field variations recorded in marine sediments of the NW African continental margin

Holocene records documenting variations in direction and intensity of the geomagnetic field during the last about seven and a half millennia are presented for Northwest Africa. High resolution paleomagnetic analyses of two marine sediment sequences recovered from around 900 meter water depth on the upper continental slope off Cape Ghir (30°51′N, 10°16′W) were supplemented by magnetic measurements characterizing composition, concentration, grain size and coercivity of the magnetic mineral assemblage. Age control for the high sedimentation rate deposits (∼60 cm/kyr) was established by AMS radiocarbon dates. The natural remanent magnetization (NRM) is very predominantly carried by a fine grained, mostly single domain (titano-)magnetite fraction allowing the reliable definition of stable NRM inclinations and declinations from alternating field demagnetization and principal component analysis. Predictions of the Korte and Constable (2005) geomagnetic field model CALS7K.2 for the study area are in fair agreement with the Holocene directional records for the most parts, yet noticeable differences exist in some intervals. The magnetic mineral inventory of the sediments reveals various climate controlled variations, specifically in concentration and grain size. A very strong impact had the mid-Holocene environmental change from humid to arid conditions on the African continent which also clearly affects relative paleointensity (RPI) estimates based on different remanence normalizers. To overcome this problem the pseudo-Thellier RPI technique has been applied. The results represent the first Holocene record of Earth’s magnetic field intensity variations in the NW Africa region. It displays long term trends similar to those of model predictions, but also conspicuous millennium scale differences.     

Seasonal and event-controlled export of organic matter from the shelf towards the Gulf of Lions continental slope

To investigate the role of coastal canyons in the transfer of organic matter from the shelf to the slope and basin, we deployed sediment trap/current meter pairs at the head of five canyons in the Gulf of Lions (GoL) between November 2003 and May 2004. Analysis of organic carbon, biogenic silica, Corg isotopic composition, Corg/total nitrogen, chloropigments, and amino acids clearly shows the seasonal influence and effect of extreme meteorological events on the composition of collected particles. The sampling period was divided into three “scenarios”. The first corresponded to a large easterly storm and flood of the Rhone river during stratified water column conditions; the composition of material collected during this event was influenced by increased transfer of riverine and coastal particulate matter, with a lower Corg content. During the second “fall-winter” scenario, northern and northwestern winds blowing over the shelf caused cooling and homogenization of the shelf water column; particles collected at this time reflected the homogeneous source of particulate matter transported through canyons; particles sitting in the vicinity of canyon heads are most likely swept downslope by the general south-westward circulation. Organic tracers indicate a degraded origin for organic matter transported during this period. A third “spring” scenario corresponded to northern winds alternating with eastward windstorms that triggered and/or enhanced the cascading of dense waters accumulated on the bottom of the shelf due to previous cooling. These conditions occurred in conjunction with increased phytoplankton productivity in shelf surface waters. Organic matter advected mainly by dense shelf water cascading was fresher due to the transport of newly produced particles and a variable terrestrial fraction; this fraction depended on the proportion of resuspended material accumulated during previous high discharge periods that was involved in each transport pulse. The tight link shown between meteorological conditions and organic matter transport is important for continental margin geochemical studies as future changes in climatic conditions may lead to dramatic changes in carbon sequestration capability and in the ecosystems of deep margin environments.     

Life Cycle of Liocarcinus arcuatus (Brachyura: Portunidae) in the Ría de Arousa (Galicia, NW Spain): Role of Beach and Mussel Raft Culture Areas

Abstract. The population biology of the portunid crab Liocarcinus arcuatus is analyzed over a yearly cycle in beach zones and mussel raft culture areas in the Ria de Arousa.
The breeding cycle of this species has two annual peaks, which result in two annual cohorts that are recruited in different areas. The growth rate is higher in the group settled in spring than in autumn, and, especially, in the culture areas compared with the beach zones. There are movements from the beach zones to the raft polygons related to reproductive and feeding behavior as well as growth. The role of mussel culture in the dynamics of this species is discussed.     

Defining ecological indicators of trawling disturbance when everywhere that can be fished is fished: A Mediterranean case study

Selecting indicators of the response of the benthic community to fishing effort restrictions is important for testing the efficacy of management actions that seek to minimise ecosystem degradation. Components of epifaunal communities are sensitive to trawling, and concordant measurements of trawling effort can be used to establish a link between response and impact variables. Trawling effort on Mediterranean fishing grounds can be assessed, but the lack of data from communities inhabiting these areas makes establishing the response–impact relationship difficult. This study addresses this challenge by investigating benthic communities from the NW Mediterranean subjected to a gradient of fishing effort, and confirms that indicators based on functional components of epibenthos can be a useful tool to describe the response of communities to disturbance across habitat types.