四川龙门山南段青衣江河流阶地形成时代及其构造地貌意义     

王继龙  吴中海  张克旗  孙玉军  周游 《地质通报》2018,37(6):996-1005

地表调查发现,横穿龙门山南段的青衣江具有上游以发育深切峡谷为主,而中下游段阶地发育较完整的特点。采用光释光测年方法对现今青衣江低阶地进行年代学测试分析,获得了低阶地的形成年代,并结合对前人资料的对比和对青衣江河流阶地已有年代学数据的分析,基本确定青衣江中下游地区的T1~T7阶地主要形成于距今7.7~9.0ka,40~50ka,75~85ka,129ka,149ka,270~300ka,740ka。结合地表调查结果进一步推断,现今青衣江主河道在中更新世及之前已经存在。因此,现今的青衣江究竟是因断块整体倾斜式改道还是后期河流袭夺而形成需进一步研究。另外,据青衣江低阶地地貌面的年龄数据估算,龙门山南段青衣江流域不同段落的晚第四纪河流下切速率不同,中更新世以来,芦山至大岗顶段的河流下切速率明显较大,很可能是芦山地震发震构造(盲逆断层)在晚第四纪期间存在持续活动的地貌响应。  相似文献   

Spatiotemporal distribution of sea-island prehistoric dune sites,Holocene sea levels,and aeolian sand activities in Fujian Province,China     

JIN Jianhui  LING Zhiyong  LI Zhizhong  ZUO Xinxin  FAN Xuechun  HUANG Yunming  WANG Xiaoyang  WEI Changfu  REN Yongqing  QIU Junjie 《地理学报(英文版)》2022,32(6):1157-1176

The lower reaches of the Minjiang River and its adjacent areas were among the most active prehistoric archaeological areas in Fujian Province. The accumulation types of Neolithic archaeological strata are roughly divided into dune sites and dune/shell mound sites. The sites can also be roughly divided into estuarine, coastal, and sea-island sites based on their geomorphic features. The cultural development of these prehistoric sites is of great significance for understanding the migration and spread of Austronesian civilization. Based on luminescence dating of typical Neolithic sites on Haitan Island, their quartz-OSL (optically stimulated luminecesence) burial ages were determined. Synthesizing previously published results, the temporospatial distribution characteristics of the sea-island sites on Haitan Island are discussed, and the relationship between Neolithic human activities and regional geomorphic processes is analyzed. The results show that: (1) the spatial and temporal distribution of the Haitan Island Neolithic sites are closely related to small-scale geomorphic features and are controlled by mesoscale geomorphic processes. The sites were mainly distributed in the foothills of two high hills along an NNE-SSW trend. With an increase in altitude, the features were distributed as “single site (I) - superimposed site - single site (II)” and appear successively. Single type sites (I) mainly appeared at low sea level, whereas single type sites (II) mainly appeared at high sea level. Superimposed sites were not subject to sea level changes. The relative elevation of the superimposed sites in the study area indicates the optimal residential area for human activities in the region. The single site with an elevation lower than the optimal residential area was mainly restricted by the lowest residential area, whereas the single site at a higher elevation than the optimal residential area was mainly affected by livelihood patterns. (2) High sea level caused by the “backwater effect” in low latitude areas in the southern hemisphere, and coastal aeolian sand activity influenced by sea level fluctuations in the middle Holocene correspond well with human activities recorded in the cultural stratigraphy of sea-island type sites. The altitude of coastal aeolian sand accumulation can be used as an indirect index to estimate the age of coastal dunes.  相似文献   

滇西怒江河谷潞江段泥石流灾害时空发育特征     

杨艳  张绪教  叶培盛  高万里 《中国区域地质》2012,(2):343-350

通过对怒江河谷潞江段21条泥石流重点沟道堆积物的沉积特征、形成基本条件的野外调查,结合室内泥石流沟汇水面积、纵比降的数理统计,运用光释光（OSL）测年技术对洪积物的年龄进行测定,揭示了研究区泥石流的发育具有明显的区域性和分期性。结果表明以潞江为界,泥石流从西岸向东岸迁移;东岸泥石流的发育存在南北差异,具有从北向南发展的趋势而且期次明显,两岸泥石流发育分为3期。  相似文献   

释光技术在水成沉积物测年中的应用进展   总被引：1，自引：0，他引：1  

赵秋月  魏明建  周锐  宋波  潘宝林  陈淑贞  赵晓红 《地质论评》2014,60(1):31-38

准确获得水成沉积物的年龄是第四纪年代学重要的前沿问题之一。随着释光技术的发展,水成沉积物释光测年在如下方面有新的进展：具体释光技术的选择、释光测量方法、测年矿物的种类、矿物的粒级和获得等效剂量的统计方法等。线性调整光释光技术能够提取光释光信号中衰退快的组分;单片再生法应用广泛;单颗粒技术在挑选沉积时晒退充分的颗粒方面具有一定的优势;水成沉积物中的石英比长石更易晒退;较多的实验表明水成沉积物中的粗颗粒比细颗粒更易晒退;获得等效剂量的统计模型很多,但尚无一种统计模型适用于所有样品。在此基础上探讨了水成沉积物释光测年在气候、构造运动、冰川进退历史和人类活动主导的土壤侵蚀量变化研究中的意义及今后的研究方向,为全面了解该领域的最新研究进展提供参考。  相似文献   

现代珠江三角洲地区QZK4孔第四纪沉积年代   总被引：2，自引：2，他引：0  

陈双喜  赵信文  黄长生  孙荣涛  曾敏  刘凤梅  陈雯  邵磊 《地质通报》2014,33(10):1629-1634

在地质环境变迁迅速的现代珠江三角洲地区,对于第四纪沉积的年代存在多种认识。结合南中国海的海平面变化记录,通过AMS14C和光释光测年发现,珠江三角洲腹地QZK4孔第四纪岩心底部最老年龄约为43.71ka BP。岩心记录的第四纪环境对南中国海海平面变化有着良好的响应:岩心下部陆相河流沉积和暴露风化层发育于末次冰期至早全新世的低海平面时期,上部滨海—河口湾沉积发育于早中全新世以来的高海平面时期。根据钻孔岩心的环境分析,推测现代珠江三角洲地区第四纪的底界可能较本钻孔记录的更老。  相似文献   

柴河铅锌矿碳酸盐矿物热发光标型及其意义     

刘成龙 《国土资源》1990,(3)

作者对柴河铅锌矿碳酸盐矿物热发光特征进行了系统研究。建立了含矿碳酸盐矿物的热发光标型。含矿碳酸盐矿物热发光具有发光强度显著衰减,发光中温峰消失或不明显,高温峰平缓,发光曲线呈钝型的特点。碳酸盐矿物热发光测定作为一种矿物学找矿方法,应用于中元古宙层控碳酸盐岩铅锌矿床的找矿实践中,不仅可以直接发现矿化和推断断裂构造,而且可以圈定热发光低强度区,从而缩小找矿靶区,为普查找矿提供依据。  相似文献   

北京平谷山前河流阶地发育序列、形成时代及地质意义     

王晓亮  赵元艺  赵希涛  陈军典  吴文彬 《地质论评》2024,70(1):2024010023-2024010023

河流阶地是研究河流演化、构造运动的良好载体, 虽然北京地区第四纪地质研究程度较高, 但北京东部地区对河流阶地的相关研究资料较少。本文以北京平谷燕山山前发育的泃河、黄松峪石河、将军关石河为研究对象, 通过野外地质调查、光释光测年技术（OSL）详细划分了上述河流阶地的发育序列, 在此基础上讨论了部分河流阶地的形成时代、阶地成因及河流阶地对燕山隆升的响应等地质问题, 认为泃河南岸发育有3级阶地, 北岸发育2级阶地;黄松峪石河最多发育有6级阶地;将军关石河发育有5级阶地。将军关石河至晚形成于中更新世晚期（161. 7±7. 7 ka BP）, 黄松峪石河至晚形成于晚更新世早期（121. 2±5. 4~100. 3±4. 1 ka BP）, 泃河至晚形成于晚更新世中期（79. 4±3. 3~70. 8±3. 4 ka BP）。泃河、黄松峪石河、将军关石河各级阶地的形成受到了古气候变化和燕山隆升的双重影响, 平谷地区燕山在中更新世晚期以来, 一直处于隆升的状态, 晚更新世早期时隆升速率达到最大, 可达0. 24~0. 34 mm/a, 晚更新世中期时隆升速率降低, 0. 18~0. 24 mm/a。以上成果对研究北京东部河流阶地发育特征、形成时代具有重要参考价值, 也为中更新世晚期以来燕山的隆升提供了新的证据。  相似文献   

Quartz luminescence sensitivity variation in the Chinese loess deposits: the potential role of wildfires     

Junjie Zhang  Sheng-Hua Li  Jimin Sun  Tongyan Lü  Xinying Zhou  Qingzhen Hao 《第四纪科学杂志》2023,38(1):49-60

The sensitivity of optically stimulated luminescence (OSL) of quartz grains has been applied to trace the provenances of sediments in various environments. Here, we studied the OSL sensitivity of quartz grains in four sections (Jingyuan, Huanxian, Xifeng and Luochuan) along a west–east transect on the Chinese Loess Plateau (CLP). The quartz OSL sensitivity in the palaeosol units is higher overall than that in the loess units, and it shows an increasing trend from the west CLP to the east CLP. In palaeosol units, it increases by a factor of ~20 along the west–east transect; while in loess units it increases by a smaller degree of 3–5. The change of provenances and the change of distances between the provenances and the loess sections cannot fully account for the large degree of sensitivity variation between the loess and palaeosol units in the central and eastern CLP. We propose that wildfires may have played an important role in enhancing the quartz OSL sensitivity in the palaeosol units in the central and eastern CLP. Quartz OSL sensitivity has the potential to be used as a proxy for palaeowildfires.  相似文献   

Chronology of the Paleolithic site of Xibaimaying in the Nihewan Basin,North China,inferred from optical dating of fine-grained quartz     

《Quaternary Geochronology》2022

The Paleolithic site of Xibaimaying (XBMY), once considered the youngest flake tool site within the Nihewan Basin, North China, is an ideal archive to study the chronological relationship between flake tool and microblade industries in the Nihewan Basin during the Upper Palaeolithic, but the previous ages obtained for the site remain controversial. From 2015 to 2019, three areas at two archaeological localities (XBMY-I and XBMY-II) of the site were excavated, and well-preserved fossils and flake tools were unearthed. In this study, a total of 26 samples were collected from the three areas for optically stimulated luminescence (OSL) dating using a single-aliquot regenerative-dose (SAR) protocol on fine-grained quartz. A shared ‘Standardized growth curve’ (SGC) for a section was constructed to reduce the time required for D_e estimation. The long-term weighted average water contents of the samples during their burial period were estimated based on the in-situ water contents of continuous samples from a nearby borehole. All the OSL ages were modelled via Bayesian statistics using the OxCal software, modifying the OSL ages with stratigraphic constraints in each section. The results show that the cultural layer bearing flake tool assemblages falls within the period of 122–36 ka, indicating that the flake tool industry of the Xibaimaying site is comparable to that of the Youfangbei (108–86 ka), Banjingzi (∼86 ka) and Xinmiaozhuang (75–63 ka) sites, rather than the youngest one in the Nihewan basin, which explains why the Xibaimaying site is characterized as pure flake tool culture without any ‘advanced’ trait. The OSL dating results also shed new light on the study of sedimentary processes in the Xibaimaying site area. The different deposition rates (0.01–1.61 mm/a) for the sediments at the three newly excavated areas imply complex geomorphologic processes in the site area.  相似文献   

燕山山地伊逊河下游河流阶地沉积物特征及古环境意义     

田钰琛  殷志强  张绪教  邵海  谷明旭  任伟  彭超 《地质论评》2022,68(1):111-121

河流沉积物蕴藏着其形成之时水动力条件及古气候变化等重要信息,因此研究河流相沉积物不仅可指示其沉积之时的水动力条件,还可对其反演的古气候进行一定的探索.伊逊河地处燕山东段,开展其下游河流相沉积物粒度、磁化率及形成年代的探讨,可为燕山山地河流相沉积物蕴藏的古环境意义研究提供参考.笔者等通过野外实地调查、光释光测年、粒度分析...  相似文献