夏季北黄海水体浊度分布特征的初步研究

应用2007月7月国家908专项北黄海区块水体调查获取的浊度资料,与同步获得的悬浮物质量浓度进行拟合分析,结果表明,中底层水的相关系数在0.94以上,表层相关度较差.根据调查海域浊度的水平大面分布及选取的6个典型断面的垂直分布,初步阐述了夏季北黄海水体浊度的分布特征——近岸高和底层高,山东半岛北部沿岸、成山角海域和老铁山水道以及庄河河口附近海域为高浊度区.夏季北黄海冷水团对水体浊度分布具有控制性影响:调查海域水体垂向层结稳定,北黄海冷水团海域中下层表现为高盐、低温、高密特征,水体浊度小,且浊度锋面的分布与温度较为相近.同时,夏季北黄海冷水团对悬浮物的分布起到了屏障作用——在山东半岛北部沿岸和辽东半岛南部沿岸阻止了近岸悬浮物的经向输送,而在山东半岛东部沿岸则阻止了近岸悬浮物的纬向输送.     

天山北坡经济带“组团”点轴城镇空间结构研究

以1990-2007年天山北坡城镇GDP、土地、人口、交通数据为资料,根据城镇空间分布“最近邻点指数”理论,空间相互作用和分形理论,分析了天山北坡城镇空间分布特征,构建了绿洲城镇相互作用强度判断模型,提出并论证了“组团”点-轴空间结构模式优越性。研究发现:①天山北坡经济带城镇人口规模和经济规模在空间结构呈现3个城镇高密集区,两个城镇稀疏区特征;②传统绿洲城镇空间结构下,城镇接受中心城市辐射差异很大,不利于城镇整体发展;③以“乌鲁木齐都市圈”为点的“组团”点-轴空间结构模式,有利于中心组团城镇对其他城镇的辐射;④以“５组团”为点的点-轴模式有利于组团之间的相互作用,有利于城镇发展;⑤天山北坡经济带向伊犁河谷延伸有利于中心组团城镇对其他组团城镇的辐射。     

Landslide susceptibility analysis with a heuristic approach in the Eastern Alps (Vorarlberg, Austria)

The aim of the study is landslide hazard assessment carried out on a working scale of 1:25 000. The study area within the Northern Calcareous Alps was geologically and geotechnically mapped in order to identify causes and mechanisms of active mass movements. The field surveys were digitised by a Geographical Information System and divided into data layers. The geological units were classified according to their geotechnical properties. All layers were converted into grids and spatially analysed together with a Digital Elevation Model. Comparing the layers with the inventory of active landslides, the prevailing factors leading to sliding movements were identified. Because of the complex tectonic setting and the small number of active landslides, a statistical method of hazard assessment was not applicable. Using the heuristic approach of an index method, the data layers of geotechnical class, bedding conditions, tectonic layouts, slope angles, slope orientations, vegetation and erosion were analysed. The susceptibility of each layer has been evaluated with help of bivariate statistics. The layers have been weighted with indices due to their importance iteratively and were combined into a landslide susceptibility map.     

Integration of reflection seismic and sediment grain-size data from Lake Khubsugul (Northern Mongolia): a reply to Prokopenko and Kendall

Prokopenko and Kendall (J Paleolimnol doi:, 2008) criticise the work presented in Fedotov et al. (J Paleolimnol 39:335–348, 2008), and instead propose an alternative interpretation for the grain-size evolution recorded in the KDP-01 core, retrieved from the central part of Lake Khubsugul. Their interpretation is based (i) on a seismic-stratigraphic re-interpretation of sparker seismic profile khub012 (which they copied from Fedotov et al. (EOS Trans 87:246–250, 2006)), (ii) on the presupposition that changes in lake level are the dominant control on facies distribution in Lake Khubsugul, and (iii) on the invalidation of our age-depth model. In this reply to their comment, we demonstrate that they interpreted seismic artefacts and geometries caused by changes in profile orientation as true stratigraphic features and that the lake-level reconstruction they derive from this interpretation is therefore incorrect. We also demonstrate that their grain-size predictions, which they consider to be predominantly driven by changes in lake level, are inconsistent with the measured sulphate concentration, which is a demonstrated proxy of lake level in Lake Khubsugul, and with the measured grain-size record. Finally, we point out that even if there would be a problem with the age-depth model, this problem would not affect the part of the sedimentary sequence discussed in Fedotov et al. (J Paleolimnol 39:335–348, 2008).     

Detrital apatite fission track analyses of the Subei basin: implications for basin-range structure of the northern Tibetan Plateau

The northern Tibetan Plateau has evolved a unique basin-range structure characterized by alternating elongated mountain ranges and basins over a history of multiple tectonic and fault activities. The Subei basin recorded evolution of this basin-range structure. In this study, detailed detrital apatite fission track (AFT) thermochronological studies in conjunction with previously documented data reveal provenance of the Subei basin, important information about the Indo-Eurasia collision, and two Miocene uplift and exhumation events of the northern Tibetan Plateau. Detrital AFT analyses combined with sedimentary evidences demonstrate that the Danghenanshan Mountains is the major provenance of the Subei basin. In addition, very old age peaks indicate that part sediments in the Subei basin are recycling sediments. Age peak populations of 70–44 Ma and 61–45 Ma from the lower and upper Baiyanghe formations record the tectono-thermal response to the Indo-Eurasia collision. Combined detrital AFT thermochronology, magnetostratigraphy and petrography results demonstrate the middle Miocene uplift and exhumation event initiated 14–12 Ma in the Subei basin, which may resulted from the Miocene east-west extension of the Tibetan Plateau. Another stronger uplift and exhumation event occurred in the late Miocene resulted from strengthened tectonic movement and climate. A much younger AFT grain age, breccia of diluvial facies and boulders of root fan subfacies record the late Miocene unroofing in the Danghenanshan Mountains.     

New Early Cretaceous shrimp (Decapoda) from the Sidi Aïch Formation of the Northern Chotts Range,southern Tunisia: Taxonomy,biostratigraphy, and palaeoenvironmental implications

The fossil dendrobranchiate shrimp Macropenaeus was originally described from the Upper Cretaceous (Cenomanian) limestones of Hadjoula, northwest Lebanon. A new species, M. sidiaichensis sp. nov., was recovered from the Sidi Aïch Formation in the Northern Chotts Range, southern Tunisia. The Barremian occurrence of the genus in Tunisia suggests that Macropenaeus most likely originated in northern Africa and then migrated to Arabia in the Cenomanian. The association of the fossil shrimp with conchostracans, plant fragments, and fish indicates the interaction of freshwater and marine conditions that characterized the northern African margin as part of widespread coastal complex, paralic environments during the Barremian.     

大兴安岭北段富林矽卡岩铜矿床成因:印支期含矿岩浆源区特征、蚀变矿物学及勘查意义

新近发现的印支期富林矽卡岩铜矿床位于大兴安岭北段新林区新林镇东约90km。矿区发育与成矿直接相关的花岗岩和侵入花岗岩中的花岗斑岩,矿体主要赋存于花岗岩与古元古代兴安桥组大理岩和早奥陶世黄斑脊山组钙质粉砂岩接触带内。富林矿床矿化与矽卡岩密切相关,整个矿化过程可分为两期:矽卡岩期和石英-硫化物期,5个阶段:早期矽卡岩阶段、退化蚀变阶段、氧化物阶段、早期硫化物阶段和晚期硫化物阶段,其中铜矿化主要发生在早期硫化物阶段。硫化物主要包括黄铜矿和黄铁矿,并含少量闪锌矿、方铅矿、斑铜矿等。蚀变类型包括石榴子石-透辉石矽卡岩化、阳起石-透闪石矽卡岩化、绿帘石矽卡岩化、绿泥石化、绢云母-粘土化、钾长石化和局部角岩化。电子探针分析(EMPA)结果表明:矿区内的石榴子石属钙铝-钙铁榴石系列,主要为钙铁榴石,辉石为透辉石-钙铁辉石系列,以透辉石为主,闪石主要为透闪石、阳起石以及少量镁绿钙闪石和铁浅闪石,帘石为黝帘石-绿帘石系列。黑云母以镁铁黑云母和铁叶云母为主,绿泥石主要为密绿泥石和铁叶绿泥石,长石以正长石和钠长石为主。石榴子石成分剖面显示从核部到边部,石榴子石呈现出钙铝榴石和钙铁榴石交替变化的环带特征,且Fe~(3+)含量的逐渐升高暗示后期成矿流体氧逸度升高,结合黑云母Mg-Fe~(3+)-Fe~(2+)图解,说明富林矽卡岩型铜矿床形成于较强的氧化环境。锆石LA-ICP-MS U-Pb测年结果显示花岗岩形成于~253Ma,花岗斑岩形成于~244Ma,为大兴安岭地区一期新的成矿事件。锆石原位Hf同位素测试结果表明,花岗岩εHf(t)介于-1.60~2.23,花岗斑岩εHf(t)介于-3.53~1.90,二者均具有古老的两阶段模式年龄,结合前人对区域构造背景的研究,认为富林花岗质岩石可能来自于松辽地块和兴安地块后碰撞背景下俯冲板片断离软溜圈上涌导致古老下地壳的部分熔融并卷入少量地幔物质而形成的岩浆。花岗斑岩及与斑岩有关的脉状矿化和蚀变的出现暗示富林地区可能存在印支期的斑岩型矿床,此外结合石榴子石、辉石成分特征以及辉石Mn/Fe比值与世界矽卡岩矿床对比,指出富林矿区外围找矿应综合考虑铜、钼、铁、金、铅、锌等矿化组合。     

Geochronology, Petrology and Geochemistry of Xingdi No. 3 Mafic-Ultramafic Intrusions in the Northeastern Tarim Craton, NW China

The Xingdi mafic-ultramafic intrusions occur in the northeastern margin of the Tarim craton. The Xingdi No. 3 intrusion is the smallest of four intrusions, with an exposed area of 1.7 km~2, and the zircon U-Pb age of the intrusion is 752±4 Ma. The intrusion consists of gabbros, pyroxenites and peridotites, and exhibits a crystallization sequence of the main rock-forming minerals as olivine, orthopyroxene, clinopyroxene and plagioclase. Mineralization occurred at or near the boundaries of the intrusion between pyroxenites and peridotites, and appears as a layered or lenticular shape about 500 m long and 4–15 m wide. The primary sulfides have a relatively simple mineralogy dominated by pyrrhotite-pentlandite-chalcopyrite assemblages, which occur as droplet, star-like and graphic texture and locally sideronitic structures. Geochronological and geochemistry investigations suggest that the Xingdi mafic-ultramafic intrusions and coeval volcanic rock in the Kuluktag area of the Tarim craton formed in an intracontinental breakup environment. Based on the composition of the dominant rockforming minerals and covariant relationships of other oxides versus Mg O, the parental magma of the Xingdi No.3 intrusion belongs to high-Mg tholeiitic basaltic magmas with Mg O of 10.78 wt%. The Xingdi No.3 intrusive rocks are characterized by light REE enrichment relative to heavy REE, negative Nb-Ta anomalies, low ~(143)Nd/~(144)Nd ratios(from 0.511183 to 0.511793) and high initial ~(87)Sr/~(86)Sr ratios(from 0.7051 to 0.7113). The magma was derived from the enriched-lithospheric mantle and was contaminated during emplacement. According to rock assemblages, mineralization, olivine characteristics, geochemical characteristics and mass balance, there are better copper-nickel ore prospects in the Xingdi No.3 intrusion than in the other three intrusions in the area.     

地震反射剖面揭示的苏北盆地北缘构造特征及其演化

苏北盆地位于下扬子板块东北部鲁苏隆起的南侧,由于构造位置特殊,其构造演化比较复杂。利用高分辨率反射剖面资料,得到苏北盆地北缘清晰的地下结构和断裂形态。结果表明,整个剖面以大东凸起为对称轴,两侧箕状凹陷近似对称发育,涟南凹陷呈南深北浅的形态,涟北凹陷呈南浅北深的形态,该凹陷内正断层发育。这些研究成果为建立研究区的构造演化模式提供了重要的信息,推测自白垩纪末期以来,研究区在印度板块碰撞和太平洋板块碰撞影响下,拉张裂隙和挤压隆起2种作用交替进行,形成了对称箕状凹陷。     

冀北-辽西地区侏罗纪土城子组的时代归属

土城子组的时代归属存有分歧.目前主要有5种观点：①中侏罗世晚期-晚侏罗世早期;②晚侏罗世早期;③晚侏罗世;④晚侏罗世-早白垩世;⑤早白垩世.根据侏罗纪年代地层学的研究现状,综合生物地层、磁性地层及同位素年代学的资料,认为土城子组的时代应为中侏罗世晚期-晚侏罗世早期（Callovian-Oxfordian）.土城子组的同位素年龄在147~136 Ma之间.