塔里木盆地西北缘柯坪冲断带构造变形特征

柯坪冲断带位于塔里木盆地西北缘,是新生代南天山褶皱冲断系的一部分.本文根据野外实际考察和地震剖面解释,总结了该冲断带的构造变形特征.它是发育于古生界中且以中寒武统膏盐层为主滑脱面的薄皮构造,是内部结构相对简单的叠瓦状冲断,因更新世才定型而具暴露式冲断前锋,有断层传播褶皱发育但已遭强烈剥蚀,前展式冲断.上新世晚期的冲断曾控制了磨拉石盆地发育（西域组砾岩）,但该盆地已遭更新世的冲断推覆作用破坏.根据平衡剖面恢复,柯坪冲断带南部3排冲断层的总构造缩短量为29.1%-40.7%.     

The Manyas fault zone (southern Marmara region,NW Turkey): active tectonics and paleoseismology

The Manyas fault zone (MFZ) is a splay fault of the Yenice Gönen Fault, which is located on the southern branch of the North Anatolian Fault System. The MFZ is a 38 km long, WNW–ESE-trending and normal fault zone comprised of three en-echelon segments. On 6 October 1964, an earthquake (Ms = 6.9) occurred on the Salur segment. In this study, paleoseismic trench studies were performed along the Salur segment. Based on these paleoseismic trench studies, at least three earthquakes resulting in a surface rupture within the last 4000 years, including the 1964 earthquake have been identified and dated. The penultimate event can be correlated with the AD 1323 earthquake. There is no archaeological and/or historical record that can be associated with the oldest earthquake dated between BP 3800 ± 600 and BP 2300 ± 200 years. Additionally, the trench study performed to the north of the Salur segment demonstrates paleoliquefaction structures crossing each other. The surface deformation that occurred during the 1964 earthquake is determined primarily to be the consequence of liquefaction. According to the fault plane slip data, the MFZ is a purely normal fault demonstrating a listric geometry with a dip of 64°–74° to the NNE.     

喜马拉雅西北部逆冲带的地壳电性结构

印度板块北部地形起伏较大的喜马拉雅山地区由几个构造互异的地质单元组成,依地形高、低把喜马拉雅碰撞带分成低喜马拉雅和高喜马拉雅.为了研究与主要逆冲带（含主缝合带MCT和主边界带MBT）有关的地壳电性结构,沿Rohtangpass (海拔4000 m) 到Mandi (海拔400 m)剖面进行了MT探测.通过对16个测点观测资料的分析和考虑地形的二维反演,获得了沿剖面的二维电性结构.电性结构显示,在Chail和主逆冲边界带下方,东西走向的缝合带突然转向北.在下喜马拉雅的Rampur 区段的元古代基底为范围较大的高阻体,而浅部地壳被逆冲带分成向北倾的电导性块体和电阻性块体.Chail 逆冲带东侧低喜马拉雅Rampur 区段的推挤和它西侧的基底脊柱体导致主边界带及相关的逆冲带（Kangra 拐角）向北转弯,Kangra拐角处的应力可能是由于西侧基底脊柱体进入到Kangra 区引起的.     

Transposed high-pressure granulite fabrics (Cabo Ortegal, NW Spain): Implications on the scales of deformation localization

High-pressure granulite facies rocks of the Bacariza Formation (Cabo Ortegal, NW Spain) were syn-metamorphically deformed at the contacts with the bounding units (peridotite and eclogite massifs). This enabled the formation of meter-thick, spectacular shear zones with reworked and transposed foliations and lineations. The texturally stable mineral assemblage of the new fabrics records an intense, ductile deformation of the mineral aggregate at temperatures of 700–800 °C associated with amalgamation of eclogite, high-pressure granulitic rocks and ultramafic sheets in deep portions of a subduction channel. The lattice preferred orientation of the main constituent minerals (garnet, augite, amphibole, plagioclase, quartz and biotite) discloses the active deformation mechanisms at the scale of the mineral grains and the relationships with the deformation at larger scales. Overprinting relationships of the metamorphic assemblages demonstrates that partitioning and deformation localization occurred at different scales under similar high-grade conditions. Complete macroscopic transposition in the shear zones was complementary to meso and microscopic partitioning of deformation intensity and mechanisms between different lithological layers and mineral species.     

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.     

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.     

Comparison of horizontal and downward particle fluxes across canyons of the Gulf of Lions (NW Mediterranean): Meteorological and hydrodynamical forcing

In the framework of the European project Eurostrataform, an array of six near-bottom mooring lines was deployed in the heads of the major submarine canyons incising the continental slope of the Gulf of Lions (NW Mediterranean). All moorings were equipped with sediment traps, current meters and turbidity Optical Backscatters Sensors (OBS) situated at few meters above the bottom. Particulate mass fluxes were recorded weekly by the sediment traps between November 2003 and May 2004 and compared with horizontal export fluxes obtained from the turbidity and current meters.     

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.     

Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau,offshore NW Australia

Deep‐marine deposits provide a valuable archive of process interactions between sediment gravity flows, pelagic sedimentation and thermohaline bottom‐currents. Stratigraphic successions can also record plate‐scale tectonic processes (e.g. continental breakup and shortening) that impact long‐term ocean circulation patterns, including changes in climate and biodiversity. One such setting is the Exmouth Plateau, offshore NW Australia, which has been a relatively stable, fine‐grained carbonate‐dominated continental margin from the Late Cretaceous to Present. We combine extensive 2D (~40,000 km) and 3D (3,627 km²) seismic reflection data with lithologic and biostratigraphic information from wells to reconstruct the tectonic and oceanographic evolution of this margin. We identified three large‐scale seismic units (SUs): (a) SU‐1 (Late Cretaceous)—500 m‐thick, and characterised by NE‐SW‐trending, slope‐normal elongate depocentres (c. 200 km long and 70 km wide), with erosional surfaces at their bases and tops, which are interpreted as the result of contour‐parallel bottom‐currents, coeval with the onset of opening of the Southern Ocean; (b) SU‐2 (Palaeocene—Late Miocene)—800 m‐thick and characterised by: (a) very large (amplitude, c. 40 m and wavelength, c. 3 km), SW‐migrating, NW‐SE‐trending sediment waves, (b) large (4 km‐wide, 100 m‐deep), NE‐trending scours that flank the sediment waves and (c) NW‐trending, 4 km‐wide and 80 m‐deep turbidite channel, infilled by NE‐dipping reflectors, which together may reflect an intensification of NE‐flowing bottom currents during a relative sea‐level fall following the establishment of circumpolar‐ocean current around Antarctica; and (c) SU‐3 (Late Miocene—Present)—1,000 m‐thick and is dominated by large (up to 100 km³) mass‐transport complexes (MTCs) derived from the continental margin (to the east) and the Exmouth Plateau Arch (to the west), and accumulated mainly in the adjacent Kangaroo Syncline. This change in depositional style may be linked to tectonically‐induced seabed tilting and folding caused by collision and subduction along the northern margin of the Australian plate. Hence, the stratigraphic record of the Exmouth Plateau provides a rich archive of plate‐scale regional geological events occurring along the distant southern (2,000 km away) and northern (1,500 km away) margins of the Australian plate.     

DIFFERENCES BETWEEN DRY AND WET SUMMER IN THE VERTICAL MOTION ON NORTH SIDE OF QINGHAI-XIZANG PLATEAU AND THE THERMAL IMPACT OF PLATEAU*

To better analyse and understand the causes of Northwest China(NW China) arid climate formation,firstly the dry and wet standards were chosen and the yearly dry and wet grades on the north side of Qinghai-Xizang Plateau(hereafter NSQXP) in summers were classified utilizing the rainfall data of five stations over the area in June-August of 1952-1990.Then the differences between the vertical motion over the Qinghai-Xizang Plateau(QXP) and NSQXP in dry and wet summers were comparatively analyzed using the ECMWF's gridded data of June-August of 1979-1986.Finally the connection between the QXP surface thermal condition and the dry and wet summers on the NSQXP was discussed as well.The main results are the following:(1)the dry and wet standards taking the rainfall standard deviation as criterion are suitable for the arid climate area;(2)the QXP may be,to some extent responsible for the environment background of Middle Asia,NW China and North China arid climate areas;(3)there are the striking differences between the dominant vertical motion over the QXP and NSQXP in the dry and wet summers of NSQXP:(4)the QXP surface thermal condition is to a great extent,responsible for the year-to-year variation of NW China arid climate as well.