High-resolution sedimentary record of lead in the coastal mud of the East China Sea in the past one hundred and fifty years

In the East China Sea （ECS）, there are some mud areas, including the south coastal mud area, the north coastal mud area, and the mud area to the southwest of Cheju Island. X-ray fluorescence （XRF） techniques and Thermal Ionization Mass Spectrometry （TIMS） were used to study the high-resolution sedimentary record of Pb concentrations and Pb stable isotopic compositions in the past one hundred and fifty years in the coastal mud of the ECS. Pb concentrations of a ^210Pb dating S5 core in the study area have increased rapidly since 1980, and reached the maximal value with 65.08 μg/g in 2000, corresponding to the fast economic development of China since the implementation of the ＂Reform and Open Policy＂ in 1978; ^206Pb/^207Pb ratios generally had stabilized at 1.195 from 1860 to 1966, and decreased gradually from 1966 to 2000, indicating that the anthropogenic source Pb contribution to the ECS has increased gradually since 1966, especially since 1980. Pb concentrations decreased distinctly from 2000 to 2003 and ^206Pb/^207Pb ratios increased from 2001 to 2003, corresponding closely to the ban of lead gasoline from 2000 in China. From 1950 to 2003, there occurred four distinct decrease events of ^206Pb/^207Pb, possibly responding to the Changjiang River （Yangtze River） catastrophic floods in 1998, 1991, 1981 and 1954; from 1860 to 1966, there were two decrease periods of ^206Pb/^207Pb, which may respond to the catastrophic floods of Changjiang River in 1931 and 1935, and 1870. As a result of the erosion and drowning by the catastrophic floods, the anthropogenic lead accumulated in soil and water environments over a long period of time was brought into the Changjiang River, then part of them was finally transported into the ECS, which leads to changes in Pb stable isotopic composition.     

Early Jurassic rift structures associated with the Soapaga and Boyacá faults of the Eastern Cordillera, Colombia: Sedimentological inferences and regional implications

The NW-trending Bucaramanga fault links, at its southern termination, with the Soapaga and Boyacá faults, which by their NW trend define an ample horsetail structure. As a result of their Neogene reactivation as reverse faults, they bound fault-related anticlines that expose the sedimentary fill of two Early Jurassic rift basins. These sediments exhibit the wedge-like geometry of rift fills related to west-facing normal faults. Their structural setting was controlled further by segmentation of the bounding faults at approximately 10 km intervals, in which each segment is separated by a transverse basement high. Isopach contours and different facies associations suggest these transverse anticlines may have separated depocenters of their adjacent subbasins, which were shaped by a slightly different subsidence history and thereby decoupled. The basin fill of the relatively narrow basin associated with the Soapaga fault is dominated by fanglomeratic successions organized in two coarsening-upward cycles. In the larger basin linked to the Boyacá fault, the sedimentary fill consists of two coarsening-upward sequences that, when fully developed, vary from floodplain to alluvial fan deposits. These Early Jurassic rift fills temporally constrain the evolution of the Bucaramanga fault, which accommodated right-lateral displacement during the early Mesozoic rift event.     

The origin of the Pedra Furada sandstone tubular structures (South of Lisbon, Portugal)

The Pedra Furada is a 12 m wide, 18 m high outcrop feature showing hundreds of ferruginised sandy tubes and looking in part like a giant organ. In this paper the origin of the tubes is explained on the basis of geochemical, petrographic and microscopic (optical and electronic) analytical data. The tubes are considered to represent vertical escape channels for overpressured water, exhibiting inward decreasing grain size due to water velocity gradients inside the escape channels. The ferruginisation is due to iron oxides associated with colloidal/clayey fine sediments and to goethite formed from solution. The overpressure of water may be due to seismically fluidised beds below the Pedra Furada outcrop or to artesian water ascent. In both cases, fault rupturing may have played a major role in the focussing of the ascending flow.     

Crustal structure across the Grand Banks–Newfoundland Basin Continental Margin – II. Results from a seismic reflection profile

New multichannel seismic reflection data were collected over a 565 km transect covering the non-volcanic rifted margin of the central eastern Grand Banks and the Newfoundland Basin in the northwestern Atlantic. Three major crustal zones are interpreted from west to east over the seaward 350 km of the profile: (1) continental crust; (2) transitional basement and (3) oceanic crust. Continental crust thins over a wide zone (∼160 km) by forming a large rift basin (Carson Basin) and seaward fault block, together with a series of smaller fault blocks eastwards beneath the Salar and Newfoundland basins. Analysis of selected previous reflection profiles (Lithoprobe 85-4, 85-2 and Conrad NB-1) indicates that prominent landward-dipping reflections observed under the continental slope are a regional phenomenon. They define the landward edge of a deep serpentinized mantle layer, which underlies both extended continental crust and transitional basement. The 80-km-wide transitional basement is defined landwards by a basement high that may consist of serpentinized peridotite and seawards by a pair of basement highs of unknown crustal origin. Flat and unreflective transitional basement most likely is exhumed, serpentinized mantle, although our results do not exclude the possibility of anomalously thinned oceanic crust. A Moho reflection below interpreted oceanic crust is first observed landwards of magnetic anomaly M4, 230 km from the shelf break. Extrapolation of ages from chron M0 to the edge of interpreted oceanic crust suggests that the onset of seafloor spreading was ∼138 Ma (Valanginian) in the south (southern Newfoundland Basin) to ∼125 Ma (Barremian–Aptian boundary) in the north (Flemish Cap), comparable to those proposed for the conjugate margins.     

吉尔嘎朗图凹陷宝饶洼槽下白垩统层序地层与沉积体系

运用高分辨率层序地层学原理和方法,通过对钻井和地震资料的综合分析,在二连盆地吉尔嘎朗图凹陷下白垩统中识别出1个超长期基准面旋回(二级层序)SSC1和5个长期基准面旋回(三级层序):LSC1,LSC2,LSC3,LSC4,LSC5,分析了各旋回的发育特征。识别出五种类型的沉积体系:滨浅湖近岸水下扇、较深水湖浊积扇、滨浅湖扇三角洲、滨浅湖辫状河三角洲和河流沉积体系,并在等时地层格架内分析了各基准面旋回的沉积体系构成和储层砂体的发育情况。综合分析生、诸、盖条件后认为,在垂向上,LSC3旋回为本区最有利的储集层段,在平面上,本区的油气勘探应主要寻找宝饶构造带辫状河三角洲前缘砂体,主要储层砂体类型为前缘分流水道砂和前缘席状砂。     

辽河盆地冷家油田沙河街组三段储层岩相古地理

辽河盆地在沙河街组三段早期水体较深,主要形成扇三角洲及盆底扇;沙三晚期水体较浅,发育湖泊砂体.依据沉积相分布规律,沙三早、中、晚3个时期可进一步分别划分出湖泊扩张和收缩阶段.盆地西部凹陷的冷家油田为东陡西缓的箕状洼陷.研究区内沙三段的古地理格局是决定相分布的关键因素,河流和湖泊能量相对强弱决定扇体沉积的规模.受相对湖平面变化的影响,纵向扇三角洲主要形成于湖泊扩张时期,并且有相带窄、过渡快、以粗碎屑沉积为主的特点.扇体沉积中主要发育前缘分流河道充填沉积,但位于河口前缘或侧缘的滩坝及前三角洲中的盆底扇局部也较发育.     

胜利油田车镇凹陷沙河街组二、三段沉积相

车镇凹陷古近系沙河街组三段上亚段-二段下亚段是较为典型的深断陷型三级层序.层序的发育主要受控于幕式断陷作用,可进一步划分出低位体系域、湖侵体系域和高位体系域.通过岩心观察、薄片镜下鉴定、粒度分析、古生物及遗迹化石分析,并综合利用测井曲线和地震相特征,认为该时期主要发育有扇三角洲、三角洲、近岸水下扇、湖底扇、滨浅湖滩坝等骨架砂体相,以及滨浅湖、半深湖-深湖等沉积相及其亚相.综合考虑物源特征、沉积环境、沉积体系平面展布以及生、储、盖组合关系,认为有利的沉积相带主要是三角洲、扇三角洲前缘、湖底扇、近岸水下扇的中扇和外扇以及滨浅湖中发育的滩坝和砂坝.     

河南省平顶山盐田盐矿床成矿特征探讨

以现有钻孔及区域资料为基础，对平顶山盐田盐矿床形成的构造条件和盐湖的沉积模式、沉积类型成矿物源进行了分析，为平顶山盐田的进一步勘查和开发提供了宝贵资料。     

Townsend's Hypothesis, Coherent Structures And Monin–Obukhov Similarity

Townsend's hypothesis states that turbulence near a wall can be divided into an activepart that transports momentum, and an inactive part that does not, and that these twokinds of turbulence do not interact. Active turbulence is generated by wind shear and has properties that scale on local parameters of the flow, while inactive turbulence isthe product of energetic processes remote from the surface and scales on outer-layerparameters. Both kinds of motion can be observed in the atmospheric surface layer, soMonin–Obukhov similarity theory, which is framed in terms of local parameters only,can apply only to active motions. If Townsend's hypothesis were wrong, so that activeand inactive motions do interact in some significant way, then transport processes nearthe ground would be sensitive to outer-layer parameters such as boundary-layer depth,and Monin–Obukhov theory would fail.Experimental results have shown that heat transport near the ground does depend onprocesses in the outer layer. We propose a mechanism for this whereby inactive motionsinitiate active, coherent ejection/sweep structures that carry much of the momentum andheat. We give evidence that the inactive motions take the form of streak patterns of fasterand slower air, and argue that these are induced by the pressure effects of large eddiespassing overhead. The streak pattern includes regions where faster streams of air overtakeand engulf slower-moving streaks. Transverse vortices form across the spines of the streaksat these places and some of them develop into horseshoe vortices. These horseshoe vorticesgrow rapidly and are rotated forward in the sheared flow so they soon contact the ground,squirting the air confined between the legs of the horseshoe vortex outwards as a forcefulejection. This model is consistent with a wide range of results from the field and laboratoryexperiments. Heat transport is significantly affected, so undermining the dimensionalassumptions of Monin–Obukhov similarity theory.     

狗头金成因新认识

依据金矿体中存在大块金金狗大头金与原生金矿体关系密切和表生条件下金的增生程度十分有限以及表生成因说无法解释的一系列疑点为基础，对狗头金的成因进行了探讨，指出存在于表生环境中的狗头金是原生块金在表生条件下经改造并发生有限增生的结果，狗头金发育地区应存在或曾存在原生金矿体。