晚更新世南黄海西部陆架的古长江三角洲

晚更新世气候的冷暖交替引起全球海平面的下降与上升,在南黄海地层中,最直接的体现就是海陆交互式沉积层。利用最新的高分辨率浅地层剖面资料,对南黄海西部近海陆架晚更新世以来的地震地层进行了详细划分,探讨了晚更新世两个海进层序中古三角洲的划分及其地震相特征,认为晚更新世南黄海古三角洲可分为4个较大的期次。根据沉积物特征分析判断4期古三角洲均为古长江形成,各期三角洲相互叠置,范围、厚度及扩建方向均有不同,各期古长江三角洲与海平面变化有很好的对应关系。     

Time scale effect and uncertainty in reconstruction of paleo‐hydrology

Tree‐ring‐based reconstructions of paleo‐hydrology have proved useful for better understanding the irregularities and extent of past climate changes, and therefore, for more effective water resources management. Despite considerable advances in the field, there still exist challenges that introduce significant uncertainties into paleo‐reconstructions. This study outlines these challenges and address them by developing two themes: (1) the effect of temporal scaling on the strength of the relationship between the hydrologic variables, streamflow in this study, and tree growth rates and (2) the reconstruction uncertainty of streamflow due to the dissimilarity or inconsistency in the pool of tree‐ring chronologies (predictors in reconstruction) in a basin. Based on the insight gained, a methodology is developed to move beyond only relying on the annual hydrology‐growth correlations, and to utilize additional information embedded in the annual time series at longer time scales (e.g. multi‐year to decadal time scales). This methodology also generates an ensemble of streamflow reconstructions to formally account for uncertainty in the pool of chronology sites. The major headwater tributaries of the Saskatchewan River Basin, the main source of surface water in the Canadian Prairie Provinces, are used as the case study. It is shown that the developed methodology explains the variance of streamflows to a larger extent than the conventional approach and better preserves the persistence and variability of streamflows across time scales (Hurst‐type behaviour). The resulting ensemble of paleo‐hydrologic time series is able to more credibly pinpoint the timing and extent of past dry and wet periods and provides a dynamic range of uncertainty in reconstruction. This range varies with time over the course of the reconstruction period, indicating that the utility of tree‐ring chronologies for paleo‐reconstruction differs for different time periods over the past several centuries in the history of the region. The proposed ensemble approach provides a credible range of multiple‐century‐long water availability scenarios that can be used for vulnerability assessment of the existing water infrastructure and improving water resources management. Copyright © 2015 John Wiley & Sons, Ltd.     

Mineralization,Geochemistry and Zircon U‐Pb Ages of the Paodaoling Porphyry Gold Deposit in the Guichi Region,Lower Yangtze Metallogenic Belt,Eastern China

The newly discovered Paodaoling porphyry Au deposit from the Guichi region, Lower Yangtze River Metallogenic Belt(LYRB), contains 35 tons of Au at an average grade of ~1.7 g/t. It is a porphyry ‘Au-only' deposit, as revealed by current exploration in the depths, mostly above-400 m, which is quite uncommon among coeval porphyry mineralization along the LYRB. Additionally, there are also Cu-Au bearing porphyries and barren alkaline granitoids in the Paodaoling district. Zircon LA-ICP-MS U-Pb dating of the Cu-Au-bearing porphyries yield an age of 141–140 Ma, falling within the main magmatic stage of the LYRB, whereas the barren granites give an age of 125–120 Ma, coeval with the regional Atype granites. The Cu-Au-bearing porphyries are LILE-, LREE-enriched and HFSE-depleted, typical of arc magmatic affinities. The barren granites are HFSE-enriched, with lower LREE/HREE ratios and pronounced negative Eu anomalies. The Cu-Au-bearing porphyries in the Paodaoling district have high oxygen fugacities and high water content. Pyrite sulfur isotopes of the Paodaoling gold deposit indicate a magmatic-sedimentary mixed source for the ore-forming fluids. Based on the alteration and poly-metal zonation of the deepest exploration drill hole from the Paodaoling Au deposit, we propose that Cu ore bodies could lie at depth beneath the current Au ore bodies. The magmatism and associated Cu-Au mineralization of the Paodaoling district are likely to have formed in a subduction setting, during slab rollback of the paleo-Pacific plate.     

对细碧—石英角斑岩系种属划分和命名的建议

为深化古海相火山岩的研究，新提出了细碧－石英角斑岩系的种属划分和命名方案，建议首先按岩石化学万分恢复原岩种属名称，然后结合细碧－石英角斑岩系的大类名称确定其种属名称：变质强质、原生矿物没有或罕见的岩石以原岩种属名称为字头，以大类名称为字尾变质较弱、原生矿物残晶常见的岩石以大类名称为字头，以原岩种属名称为字尾变质较。评述了该方案的适用性，介绍了在青海拉脊山古海相火山岩的研究中应用该方案所取得的较好效     

古氧相——一个新的沉积学研究领域

简要介绍了富氧相、贫氧相、厌氧相、外富氧相和这氧相的主要特征、成因及目前古氧相分析的主要途径，包括古生态学、遗迹学、有机相和沉积地球化学分析。根据国内外研究资料，结合笔者科研成果，综述了古氧相在今地球科学研究领域，如层序地层、岩相古地理编图、重要地质事件研究及地史恢复中的应用及其前景。     

冲绳海槽南部两万年来碳酸盐溶跃面的变迁

对冲绳海槽南部表层沉积和晚第四纪沉积柱状样中百余个样品进行了浮游及底栖有孔虫、翼足类等微体化石定量分析。通过表层沉积样品中底栖有孔虫占有孔虫全群比例、底栖有孔虫群中胶结质壳比例、浮游有孔虫碎壳率和浮游及底栖有孔虫丰度等多种标志的水深变化,确定冲绳海槽现代的碳酸盐溶跃面位于水深１５００～１６００ｍ处。进而,在高分辨率地层学基础上,检验这些指示溶解作用的标志和翼足类丰度等在柱状样中的变化,结果发现末次冰期冲绳海槽碳酸盐溶解作用显著减弱,碳酸盐溶跃面和文石补偿深度急剧变深;至冰后期碳酸盐溶解作用又急剧增强,溶跃面和文石补偿深度又变浅至与现代相当的位置。这些变化与南海等西太平洋其他海区的特征相一致。     

东特提斯二叠纪地层,古地理及矿产国际学术讨论会综述

概述了“东特提斯二叠纪生物地层、古地理和矿产资源国际学术讨论会（ＰＥＴ）”和“澳大利亚生物古地理国际学术讨论会（ＰＡＦＦ）”所涉及的主要内容及最新研究进展,简要评述了东特提斯地区联合古陆时期的古地理、古气候、古海洋研究现状,指出了我国在该方面存在的差距和今后研究值得注意的方向。     

武当山地区中上元古界及成岩构造环境的地球化学论证

通过对分布于武当山地区的中上元古界武当山群,耀岭河群的变火山岩、变沉积岩的岩石学、岩石化学,微量元素地球化学和稀土元素地球化学及有关图解的综合研究和应用,笔者认为武当山群的成岩环境为古岛弧,而耀岭河群的成岩环境为古陆缘裂谷。中晚元古代期间,武当山地区构造演化经历了从古岛弧向古陆缘裂谷转化的历程。     

四川盆地西缘早三叠世早期碳酸盐重力流沉积与环境

四川竹园坝?梨园里地区下三叠统飞仙关组地层中,碳酸盐砾屑沉积类型有:碎屑流和浊流;根据岩性组合可分三种组合层序:Ⅰ.碎屑流与半深水泥晶灰岩沉积组合层序;Ⅱ.碎屑流与浊流沉积组合层序;Ⅲ.复合层序?据重力流形成环境,计算了古斜坡坡度,测定了古流向,结合重力流形成及古构造?古地理演化,提出了区内碳酸盐重力流的演化及沉积模式?