再论湖南板溪群及其大地构造环境

湖南板溪群具有成层有序，标志层稳定等属性，其微古植物在貌，古地磁特性等可与华北，扬子古陆前寒武纪地层类比；板溪群内的层状，似层状火山岩岩石学及地球化学组成，表明它们源于壳内，是陆内裂谷系不同幕次和不同构造部位的双模式火山岩；所获得的多种同位素年龄数据，表明湖南板溪群形成于９．５－８．０亿年。     

新疆塔城别斯托别苏长辉长岩的岩石学和锆石SHRIMP年代学研究

塔城市南约30km的别斯托别苏长辉长岩侵入石炭纪二长花岗岩中,二者的接触部位多被农田覆盖。二长花岗岩内部存在大量辉长岩、闪长岩、花岗闪长岩、石英闪长岩、石英斑岩等包体（但没有苏长辉长岩包体）。苏长辉长岩主要由透辉石-普通辉石、顽火辉石、基性斜长石（An：51 ~ 70）和少量钛铁矿-磁铁矿组成。从苏长辉长岩中分选出的锆石CL图像显示典型的扇形结构（锆石中存在辉石和斜长石包体）。对两个锆石样品进行的SHRIMP年代学研究得到平均年龄分别为：273.3 1.8Ma（MSWD = 1.18,n = 20）和272.5 2.8Ma（MSWD = 0.75,n = 12）。这两个年龄在误差范围内完全一致,表明别斯托别苏长辉长岩的形成时代为早二叠世晚期。在该苏长辉长岩与花岗岩接触带附近观察到的铜矿化现象为找矿勘探提供了方向。     

海南省抱板群研究的新进展

根据对抱板群的最新研究,自下而上建立两个岩石地层单位,即戈枕村组、峨文岭组。戈枕村组由片麻岩类变粒岩组成,厚度大于２３８１ｍ,具混合岩化。该组测得锆石一致曲线上交点年龄（１８２４±７７）Ｍａ,混合岩脉体Ｒｂ Ｓｒ等时线年龄（１６３７±３１）Ｍａ,推测形成于１６００～１８００Ｍａ之间,相当于长城纪早期。峨文岭组以各类片岩为主,其次是石英岩和变粒岩,无混合岩化作用。侵入该组的变质花岗岩体,测定３个锆石Ｕ Ｐｂ一致曲线年龄分别为（１４５６±６６）、１４４１、（１３６４±２５．６７）Ｍａ;另一件锆石蒸发法２０７Ｐｂ／２０６Ｐｂ峰值年龄为（１４０７±２０）Ｍａ。以上数据表明其形成年龄为１６００～１４００Ｍａ,相当于长城纪晚期     

树木年轮轮宽年表建立方法研究进展

树木年轮以其高分辨率、准确定年、样本广泛分布且可定量等优点,在全球变化特别是气候变化研究中广泛运用。去除以生长趋势为主的噪音,建立包含所需气候信息的轮宽年表是开展树木年轮气候学研究的关键。基于轮宽年表建立理论和树木径向生长概念模型,本文综述了轮宽年表建立过程中生长趋势拟合、指数化和均值化3个阶段的主要理论方法的研究进展;并详细介绍了最为关键的生长趋势拟合方法中,目前较为传统的曲线拟合类方法,和近20年来为克服曲线拟合类方法低频信息保留问题而受到关注和发展的区域曲线类方法;认为如何准确提取轮宽低频气候信息,将是树木年轮轮宽年表建立的主要发展趋势。     

冀北镇宁堡—赤城一带红旗营子杂岩变基性岩及其围岩锆石U-Pb年代学研究

红旗营子杂岩主要块体包括太古代火成岩(斜长角闪片麻岩、石英闪长岩-英云闪长岩-花岗闪长岩),晚古元古代或古生代变基性岩(退变榴辉岩和斜长角闪岩),晚古生代变表壳岩(石榴角闪黑云斜长片麻岩和蛇纹石化大理岩).本次研究的变基性岩(石榴斜长角闪岩)角闪岩相变质作用发生的时间为322.0 Ma-317.3 Ma,其围岩变表壳岩...     

Optically stimulated luminescence ages of the Hengyu site and their implications for anthropogenic activities in the Fuzhou Basin,South China

The chronologies of few Neolithic sites in the lower reaches of the Min River of China have been well investigated for the middle to late Holocene. In this study, the Hengyu Neolithic site in Fujian Province, South China, which has significant archaeological remains, was dated using blue‐stimulated optically stimulated luminescence (OSL) and accelerator mass spectrometry radiocarbon (AMS¹⁴C) techniques. The results, comprising nine OSL and three AMS¹⁴C ages through the Neolithic sequence, provide new evidence towards understanding the relationship between environmental evolution and human activities in the middle to late Holocene in the Fuzhou Basin and coastal areas of South China. The ages of the site deposits vary from 6.83 to 1.67 ka and can be divided into two main phases: the Keqiutou–Tanshishan culture period and the Bronze culture period. In contrast, the persistent periods of ancient human activities at the Hengyu site seem to correspond to regional sea‐level changes and the East Asian winter monsoon as a secondary factor, which can affect human activities through sea‐level impacts. The warm and high sea level conditions provided a liveable environment for the ancient humans of Fujian and even South China. The ages of two building column bases are linked to the early stage of the Han dynasty, suggesting a potentially favourable habitation environment; that is, ancient humans occupied and settled this area for the long term within this time period, which is consistent with sea‐level changes and palynology records. Copyright © 2019 John Wiley & Sons, Ltd.     

高分辨率古环境指示器--湖泊纹泥研究综述

作为高分辨率古环境指示器,湖泊纹泥在重建晚第四纪特别是近代全球环境变化中具有特殊的地位和意义。纹泥携带的各种季节信息反映了区域生物学、地球化学、沉积学对季节性驱动力的响应,而且纹泥本身可以提供反映沉积环境和气候变化的精确计年,近３０年来湖泊纹发展历史表明,纹泥的应用主要集中于以下三个方面：纹波计年、纹泥厚度变化和纹泥沉积物分析,其中纹 精确测年是一切应用的基础。可以看出,在古环境研究中,纹泥作为一     

Paleoenvironmental Record from Wuqi Paleolake in Northern Chinese Loess Plateau

正Jinding core(ZK04,36°47′35.36″N,108°19′05.24″E)is located in the northern area of Luohe river basin,northern Chinese loess plateau,lying to the southeast of Wuqi County about 20 km.The total depth of Core ZK04 is 92.20     

Determining soil erosion rates on semi‐arid watersheds using radioisotope‐derived sedimentation chronology

This study investigates erosion dynamics of the past 90 years in three small semi‐arid watersheds with histories of grazing and vegetation change. Activity of ¹³⁷Cs and excess ²¹⁰Pb from 18 cores collected from sedimentation ponds were measured using a gamma spectrometer. The sediment was dated using a constant rate of supply (CRS) model. This study represents the first time that reservoir sediment accumulation rates determined from fallout isotopes have been verified by direct volumetric measurements of aggradation based on topographic surveys. Measured sedimentation in the ponds ranged between 1.9 and 2.3 cm y^?1, representing average sediment delivery rates from the watersheds of between 0.6 and 2.0 t ha^?1 y^?1. These sediment delivery rates were in agreement with those established by other methods for similar catchments in the region. Past variations in sedimentation rates were identified and correlated with recorded history of anthropogenic disturbance. ¹³⁷Cs and ²¹⁰Pb methods are suitable for use in arid environments and can complement each other to increase reliability of erosion rate estimates. The abundance of stock ponds in southwestern USA presents an opportunity to quantify historic erosion and sediment transfer dynamics in areas that have not been well studied or instrumented. Published 2016. This article is a U.S. Government work and is in the public domain in the USA     

祁连山东段河流阶地的形成时代与机制探讨

第四纪期间祁连山东段发育了多级洪积台地与河流阶地,它们是研究区域构造活动与气候变化良好的载体。对该区主要河流阶地序列的野外考察,利用ESR、TL、IRSL以及¹⁴C等测年方法,研究表明,第四纪期间石羊河上游的各大支流普遍发育了5-6级阶地,其中南营村附近金塔河五级河流阶地的形成时代大致为1.24MaB.P.(T₅)、0.78MaB.P.(T₄)、0.14MaB.P.(T₃)、0.06MaB.P.(T₂)和0.01MaB.P.(T₁),完全可以与该区沙沟河、黄河兰州段以及长江三峡段的阶地序列相对比。从各级阶地砾石层的堆积时代以及阶地的沉积特征分析,我们认为,即使在构造活动区域,气候变化在河流地貌演化过程之中起着重要的控制作用。