Provenance of Holocene beach sand in the Western Iberian margin: the use of the Kolmogorov–Smirnov test for the deciphering of sediment recycling in a modern coastal system

Detrital zircons from Holocene beach sand and igneous zircons from the Cretaceous syenite forming Cape Sines (Western Iberian margin) were dated using laser ablation – inductively coupled plasma – mass spectrometry. The U–Pb ages obtained were used for comparison with previous radiometric data from Carboniferous greywacke, Pliocene–Pleistocene sand and Cretaceous syenite forming the sea cliff at Cape Sines and the contiguous coast. New U–Pb dating of igneous morphologically simple and complex zircons from the syenite of the Sines pluton suggests that the history of zircon crystallization was more extensive (ca 87 to 74 Ma), in contrast to the findings of previous geochronology studies (ca 76 to 74 Ma). The U–Pb ages obtained in Holocene sand revealed a wide interval, ranging from the Cretaceous to the Archean, with predominance of Cretaceous (37%), Palaeozoic (35%) and Neoproterozoic (19%) detrital‐zircon ages. The paucity of round to sub‐rounded grains seems to indicate a short transportation history for most of the Cretaceous zircons (ca 95 to 73 Ma) which are more abundant in the beach sand that was sampled south of Cape Sines. Comparative analysis using the Kolmogorov–Smirnov statistical method, analysing sub‐populations separately, suggests that the zircon populations of the Carboniferous and Cretaceous rocks forming the sea cliff were reproduced faithfully in Quaternary sand, indicating sediment recycling. The similarity of the pre‐Cretaceous ages (>ca 280 Ma) of detrital zircons found in Holocene sand, as compared with Carboniferous greywacke and Pliocene–Pleistocene sand, provides support for the hypothesis that detritus was reworked into the beach from older sedimentary rocks exposed along the sea cliff. The largest percentage of Cretaceous zircons (<ca 95 Ma) found in Holocene sand, as compared with Pliocene–Pleistocene sand (secondary recycled source), suggests that the Sines pluton was the one of the primary sources that became progressively more exposed to erosion during Quaternary uplift. This work highlights the application of the Kolmogorov–Smirnov method in comparison of zircon age populations used to identify provenance and sediment recycling in modern and ancient detrital sedimentary sequences.     

全球地面降水月值历史数据集研制

全球降水历史数据是开展气候、水循环等研究的基础。收集整理全球12个数据源降水历史月值资料,通过站号、站名甄别不同数据源中相同台站,对344个通过相关系数、一致率、均值t检验、方差F检验的台站多源资料进行拼接,尽可能多地融合各套数据产品优势,最终形成全球降水历史月值数据集(CMA Global PrecipitationV1.0, CGP)。数据集重点解决当前国际数据产品在东亚地区站点稀少、同时应用多套数据应用门槛较高等问题。数据集收录3.1万个台站共计1.87×107组月降水记录, 4152个台站序列长度达百年。与美国大气海洋局(NOAA)的全球降水数据集(GHCN-M V2.0)对比,CGP新增1万个站点、0.5×107组有效观测记录和1030条百年序列,其中141条百年序列通过多源整合技术获取。CGP的站点和数据量优势主要体现在东亚、东欧、西伯利亚等站点稀疏地区。基于CGP分析的全球降水时空特征与国际同类产品的结果较一致。新增的数据虽然没有改变全球降水分布的总体特征,但对区域性的百年降水变化检测有一定影响。基于CGP的全球降水百年序列结果显示,20世纪前半叶全球降水量偏小,近20年是1900年以来全球降水量最大的时期,各纬度带、各个国家或地区的降水长期变化趋势呈现显著的差异。      

冬季东亚高空副热带急流和温带急流协同变化与中国南方地区降水的关系

利用NCEP/NCAR再分析数据和中国台站降水资料研究冬季东亚高空副热带急流和温带急流协同变化特征及其与中国南方地区降水的关系,发现冬季东亚高原急流与温带急流同期反向协同变化特征最为显著。即高原急流增强,同时温带急流减弱(SW型)和高原急流减弱,同时温带急流增强(WS型)。当高原急流增强(减弱)而温带急流减弱(增强)时,中国南方地区降水显著增加(减少)。合成分析表明,不同急流协同变化型态下冷暖空气活动特征存在较大差异,高原急流与温带急流的反向协同变化可以真实反映与冬季中国南方地区降水相关联的冷暖空气活动特征,进而导致不同降水形态的产生。     

中国东部夏季暴雨的年代际跃变及其大尺度环流背景

本文利用1960~2011年中国东部地面测站的逐日降水资料和JRA-55再分析资料探讨了夏季暴雨分布的年代际跃变及其相关联的大尺度环流异常特征。基于暴雨频数和占比(夏季暴雨占比是指5~8月暴雨降水量对总降水量的贡献百分比)的分析结果表明:中国东部夏季暴雨分布在20世纪70年代末和90年代初经历两次反相的经向"三极子"跃变。中国东部夏季暴雨的年代际演变过程可分为三个时段:1960~1979年为华南和华北暴雨偏多、江淮流域暴雨偏少的经向"三极子"分布;1980~1991年为南方和华北暴雨偏少、江淮流域暴雨偏多的经向三极子"分布;1992~2011年为南方暴雨显著偏多、华北暴雨持续偏少,逐渐形成经向"偶极子"分布,并导致近十多年我国夏季"南涝北旱"的整体格局。1970年代末(1990年代初)跃变相关联的大尺度环流异常配置:东亚夏季风的减弱(增强),西太平洋副高的增强西伸但南撤(北抬),南亚高压的减弱南缩(增强东扩),以及蒙古高原中低层的气旋式(反气旋式)环流异常。与此同时,低层局地环流也发生调整:华北和黄淮地区以及华南和江南地区均为反气旋式(气旋式)环流异常,而江淮流域和四川盆地受控于风场切变式辐合(辐散)异常;涡度场发生相应变化,南北方大部分地区的负(正)涡度异常不(有)利于低涡的发展,而江淮流域和四川盆地的正(负)涡度异常有(不)利于低涡的发展,进而引发江南和华南暴雨减少(增加)、江淮流域和四川盆地暴雨增加(减少)、黄淮和华北暴雨减少(增加)的经向"三极子"跃变。     

A note on “Origin of components in Chilean thermal waters” by

Risacher et al. (2011) have presented voluminous data on thermal waters of Chile that is quite appreciable; however, their work still falls short on several counts. The most notable shortcoming of the work is the presentation and treatment of data. The interpretations are based on questionable premises (viz., extent of seawater intrusion) and considerations (viz., using average chemical composition of rock types for geochemical modeling, considering volcanic rocks as the only rock type in contact with the geothermal fluids) and assumptions not always substantiated by facts (with proper references) could have been corroborated. Use of Cl/Br ratio for discrimination purpose is unconvincing, considering the uncertainty in the measurement of low (<1 mg/L) Br concentration.     

延边开山屯花岗闪长岩-石英闪长岩体年代学、地球化学特征及对古太平洋板块俯冲作用时限的制约

近年来古太平洋构造域的构造演化备受学者关注。本文报道的延边开山屯地区花岗闪长岩-石英闪长岩体LAICP-MS U-Pb年龄表明其形成时间为早侏罗世早期(198±1Ma),所采样品可根据Zr/Hf值分为高Zr/Hf值组花岗闪长岩和低Zr/Hf值组石英闪长岩。高Zr/Hf值组花岗闪长岩起源深度浅,富集Rb、Th、U、K等大离子亲石元素(LILEs),贫Nb、Ta、Ti等高场强元素(HFSEs),具壳源岩浆的特点。低Zr/Hf值组为壳源岩浆与来自深部的亏损地幔岩浆混合而成,岩石亏损Nb、Ta、Zr、Hf、Ti等高场强元素,具有典型的弧型岩浆地球化学特征。岩体中存在细粒闪长质包体,镜下可见针柱状磷灰石。开山屯岩体属钙碱性系列岩石,结合前人资料,认为其与该地区同时代火成岩组成北-东向分布的早侏罗世活动大陆边缘型火成岩带,而位于该带西侧的小兴安岭-张广才岭地区存在同时代弧后拉张带,两者构成典型的大陆弧与弧后拉张带模型,共同揭示了早侏罗世早期古太平洋板块对东北地区的俯冲作用。     

黄海南部小黄鱼洄游分布及种群结构特征

Monthly fishery survey data of the small yellow croaker Larimichthys polyactis in the southern Yellow Sea from2003 and 2013 were employed to evaluate the variation in the resource distribution and biological characteristics(especially body length and sex ratio) in the population on a decadal scale.The results indicated that the small yellow croaker migrated from the Shawai fishing ground to the Dasha fishing ground in spring and was mainly distributed in the central and western parts of the Dasha fishing ground in April and May.Larimichthys polyactis in the Dasha fishing ground migrated eastward to offshore wintering grounds in autumn and reached the central Dasha fishing ground in October and November.The small yellow croaker entered the western waters of the Shawai fishing ground in winter.A large number of age 0+ fish occurred in the Shawai and Jiangwai fishing grounds in October of 2003 and 2013.The body lengths of the spawning stock and wintering stock in 2013 were larger than those in 2003,and the monthly sex ratios(female to male) were significantly less than 1 in both years.The monthly distribution of this fish in the southern Yellow Sea was consistent with a previous finding that "the stock migrated between the wintering grounds in the west of Jeju Island and the Lüsi spawning grounds" but tended to move more northward,with the spawning grounds extending outward.In the past decade,body length variation experienced a decline after an increase,rather than a steady decrease.The sex ratio in the single-stick stow net showed a tendency to increase over the decade,but was either less than or more than 1 depending on the fishing gear;therefore,further studies should be conducted to determine the sex structure.     

杨林坳钨矿尾矿资源勘查及综合回收利用工艺浅析

通过对湖南省衡南县川口乡杨林坳钨矿尾矿库尾砂的勘查、试验分析、前期综合利用科研工作情况介绍,分析了今后综合回收尾矿中有价金属、非金属及充分消耗尾砂的工艺思路,以达到充分利用、消耗尾砂,提高循环经济利用率,大大降低尾砂对环境污染和尾矿库存在的隐患。     

苏里格大型致密砂岩气田储层结构与水平井提高采收率对策

在分析苏里格气田辫状河体系及储层结构特征的基础上,提出了剖面储量集中度的概念,建立了厚层块状型、垂向叠置泛连通型、分散局部连通型、分散孤立型4种砂体分布模式,探讨了不同储层结构下的水平井采出程度,提出了水平井提高采收率技术对策。研究结果表明,辫状河沉积体系复合有效砂体由于“阻流带”的存在,直井动用不完善,水平井能克服“阻流带”的影响,提高层内储量动用程度;但由于砂体多层状分散分布,水平井开发会导致纵向含气层系储量动用不充分,影响层间采出程度。对于剖面储量集中度高的厚层块状型、垂向叠置泛连通型储层,采用水平井整体开发,Ⅰ+Ⅱ类井比例达70%以上,可显著提高储量动用程度和采收率。对于剖面储量集中度低的分散局部连通型储层,采用直井井网开发后进行甜点式优选水平井井位加密部署,可提高采收率10%以上。     

Episodic crustal growth in the Tanzania Craton: evidence from Nd isotope compositions

The analysis of available Nd isotope data from the Tanzania Craton places important constraints on the crust-mantle separation ages, and events marking juvenile crustal addition and crustal recycling. Nd model ages date the oldest crust extraction to 3.16 Ga in the Tanzania Craton, although a rock record of such antiquity is yet to be found there. The most significant period of juvenile crustal addition as well as crustal recycling is 2.7–2.6 Ga. The Nd isotopes of mafic samples show that chemical heterogeneity existed in the mantle beneath the Tanzania Craton, with some samples originating from significantly depleted mantle, and most samples originating from the mixture of primitive mantle and depleted mantle. The Nd isotope section reveals significant differences in Nd isotopes between the north craton and central craton; compared to the north craton, the central craton yields a Nd model age that is approximately 100 Ma older, and its ε_Nd(t) values are more negative, indicating that the two parts of the craton have different mantle source regions. Different types of granitoids are distributed in the Tanzania Craton, such as high-K and low-Al granite, calc-alkaline granite, peraluminous granite and transitional types of tonalite-trondhjemite-granodiorites (TTGs). Most of the granitoids formed later than the mafic rocks in syn-collision and post-collision events.