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1.
以54个浅层新钻孔和多个野外露头为研究对象,综合沉积物粒度、薄片、微体古生物、孢粉、14C测年及静力触探等资料,分析了鲁北平原晚第四纪的地层结构和沉积类型,总结了晚更新世晚期以来的沉积演化。研究表明,末次冰期盛冰期到冰后期,受地势、气候条件控制的黄河河道迁移和海水进退是影响地层结构和沉积特征的主要因素,南北地层结构差异明显,发育古河道、湖沼、黄土、三角洲、潮坪和滨浅海等沉积类型,其中古河道分布面积最广,自下而上可划分为三期。晚更新世晚期至早全新世早期,受干冷气候影响,发育第Ⅰ期古河道,小清河以南沉积黄土层;早全新世晚期至中全新世,气候转暖导致海平面升高,沿海地区形成海侵层和三角洲,内陆地区继承性发育第Ⅱ期古河道和湖沼沉积;中全新世末期或晚全新世以来,受黄河泛滥影响,沉积第Ⅲ期古河道和现代黄河三角洲。地层结构和沉积物分布的研究对于分析地下水位的变化规律,以及选择合适的地震激发层等均有重要的指导意义。 相似文献
2.
位于河北省西北部的阳原盆地在第四纪期间长期被泥河湾古湖所占据,堆积了巨厚的第四纪河湖相地层,其中夹有多层化学沉积。文中对广泛分布于盆地西端河湖相地层顶部的白色化学沉积进行了深入研究,通过野外调查和年代测试、电子显微镜扫描观察、X射线粉晶衍射、常量和微量元素分析,以及硅藻和介形类化石鉴定等一系列实验手段,确认北梁地区地层中的灰白色化学沉积主要由文石组成,其年龄大致在270 ka前后,属中更新世晚期,是在当时比较温干的气候环境下,湖泊逐渐萎缩、湖水不断咸化、文石类矿物大量析出的结果。该地区的泥河湾古湖于中更新世晚期消亡。本研究首次发现了中更新世晚期的化学沉积,在时代上明显区别于以前发现的晚更新世晚期化学沉积。该化学沉积的发现为探讨泥河湾古湖消亡过程和原因提供了直接的沉积学证据,对于重建我国北方中更新世晚期的古环境也具有重要的科学意义。 相似文献
3.
根据札达盆地香孜组河湖相地层剖面的接触关系、沉积旋回、沉积体系和岩相岩性特征,可将札达盆地下更新统香孜组河湖相地层划分为2个沉积相、3个岩段。香孜组一、二岩段为一套砾岩夹砂岩的粗碎屑岩,属典型的冲（洪）积扇沉积物;第三岩段为砾岩与砂岩互层,属冰水冰缘相沉积。ESR法和古地磁法测年结果表明,札达盆地香孜组河湖相地层的形成时代为早更新世早期（2．68—1．36Ma）。札达盆地为一同生断陷盆地,在后期重新复活的过程中,盆地只经历了冲积体系域和水进体系域。冲积体系域形成于札达盆地早更新世早期重新复活层序发育的早、中期,水进体系域形成于札达盆地早更新世早期重新复活层序发育的晚期。 相似文献
4.
东河塘油田位于塔北隆起西部,其周缘多个构造带均获得油气,是一个重要的富油气区带,泥盆系东河砂岩和侏罗系地层是两套最为重要的储集层。原油主要来自于中、上奥陶统海相烃源岩,晚海西期和晚喜山期是两个重要的充注期,其中早期形成的油气藏普遍遭受降解破坏,现今发现的正常原油以晚期注入为主。侏罗系还包括晚喜山期库车坳陷生成的陆相油气的注入,白垩系卡普沙良群之下的不整合面是重要的油气运移通道,与之相接触的层位均有机会捕获陆相油气。综合油气地球化学特征与及横向、纵向地质对比,东河砂岩深部的奥陶系、志留系可成为潜在的勘探目的层,而东河塘地区侏罗系陆相油气的存在,进一步拓宽了塔北隆起陆相油气的勘探领域。 相似文献
5.
受晚更新世以来海侵影响,渤海西南内陆第四系浅层经历了复杂的海陆交替演化。利用4口钻孔取芯井和88口静力触探井资料,采用现代测试技术和地层对比的方法对渤海西南内陆广饶地区第四系浅层进行沉积学综合研究。广饶地区地表以下30 m内,南部以风成黄土沉积为主,北部自上而下发育两期海相层,在研究区称为第一、第二海侵层,分别是10~4 ka B.P.的黄骅海侵层和40~28 ka B.P.的献县海侵层。黄土沉积于晚更新世玉木冰期,在研究区南部以17 m为界划分为大站组和羊栏河组(未见底)。晚更新世以来发生两期海侵事件(黄骅海侵、献县海侵),在海侵范围最大时到达广饶地区,先后对冰期沉积黄土层侵蚀改造,形成了“上超型海蚀黄土”的海侵演化模式。根据海侵与黄土沉积演化所对应的古气候变迁,将研究区晚更新世以来气候演变划分为6个期次:干冷期、温暖湿润期、干冷偏凉期、温暖期、潮湿湿润期和现代气候期,对应不同的沉积演化特征。 相似文献
6.
Archaic rock engravings are found widely across the arid interior of Australia and are thought to represent an early pan‐continental tradition. A late Pleistocene age is assumed because of extensive weathering, but attempts to test this by direct dating have been unsuccessful. We use AMS 14C dating of calcium oxalate skins covering archaic engravings at two rock shelter sites in Central Australia (Wanga East and Puritjarra), constrained by 14C dates of charcoal in sedimentary layers beneath the same engraved slabs, to show this rock art is mid‐Holocene in age. Despite a limited range of simple geometric designs and uniformity across the arid interior, this corpus of rock art is not associated with the initial peopling of the Australian desert, but is a later development reflecting the dynamics of established desert societies. © 2009 Wiley Periodicals, Inc. 相似文献
7.
为进一步厘清长江中游江汉—洞庭地区与黄广—九江地区更新统划分与对比,在区域地质调查基础上,识别出区内早更新世砾石层与上覆网纹红土之间的不整合关系,辅以年代学研究,开展了长江中游江汉—洞庭地区与黄广—九江地区第四系研究,建立了区域地层划分与对比格架。研究表明: 白沙井砾石层、阳逻砾石层、宜昌砾石层、九江砾石层等是区内短程河流的冲洪积相沉积,时代为早更新世晚期(Qp1),而上覆网纹红土则形成于中更新世(Qp2),二者之间为不整合接触,并以此为基础构建了区内第四纪更新世地层格架; 白沙井砾石层、阳逻砾石层、宜昌砾石层、九江砾石层与上覆网纹红土所代表的水动力条件和沉积环境的重大调整是长江三峡续接贯通的环境响应,暗示了长江上游“川峡二江”续接贯通的时限为早—中更新世之交。 相似文献
8.
The north–south-trending upper reaches of the Minjiang River run along the Longmen Shan–Min Shan fault zone, a zone of abrupt topographic change along the eastern margin of the Tibetan Plateau. Multiple levels of well-preserved soft-sediment deformation structures (seismites) occur in sediments deposited in paleo-dammed lakes in the upper part of the Minjiang River Valley. These deformation structures include liquefied convolute deformation, water-escape structures, flame structures, pseudonodules, ball-and-pillow structures, sedimentary dykes, mud lenses, and large-scale folds. Several kilometers from the barrier bar of the Diexi paleo-dammed lakes, seven deformed structural layers were identified at different heights in late Quaternary stratigraphic sequences near Shawan Village, Maoxian County. Analyses of the deformation structures, landforms, and the structural environment indicate that these deformation structures were caused by earthquakes, slumps, and landslides.OSL (optical stimulated luminescence) and 14C dating of soft-sediment layers from the Shawan site indicate that intense earthquakes occurred during the period 25–20 ka B.P. Therefore, accurate geological dating of deformed features in dammed lake deposits in high mountains and canyons enables the record of moderate- to large-magnitude earthquakes to be extended to the late Pleistocene–Holocene upon the eastern Tibetan Plateau. 相似文献
9.
为进一步厘清长江中游江汉—洞庭地区与黄广—九江地区更新统划分与对比,在区域地质调查基础上,识别出区内早更新世砾石层与上覆网纹红土之间的不整合关系,辅以年代学研究,开展了长江中游江汉—洞庭地区与黄广—九江地区第四系研究,建立了区域地层划分与对比格架。研究表明: 白沙井砾石层、阳逻砾石层、宜昌砾石层、九江砾石层等是区内短程河流的冲洪积相沉积,时代为早更新世晚期(Qp1),而上覆网纹红土则形成于中更新世(Qp2),二者之间为不整合接触,并以此为基础构建了区内第四纪更新世地层格架; 白沙井砾石层、阳逻砾石层、宜昌砾石层、九江砾石层与上覆网纹红土所代表的水动力条件和沉积环境的重大调整是长江三峡续接贯通的环境响应,暗示了长江上游“川峡二江”续接贯通的时限为早—中更新世之交。 相似文献
10.
南京直立人地点与北京周口店第一地点时代与环境辨析 总被引：4，自引：1，他引：3
北京周口店第一地点和南京直立人地点是我国重要的古人类化石地点。近年来,采用TIMS铀系测年等手段对这两个地点的年代重新进行了测定,将北京和南京直立人生存年代均前移了100ka以上。南京直立人的时代可能大于500ka,抑或580ka。北京直立人的时代介于距今400ka至650ka,抑或800ka。新的年代框架促进了两个地点地层与环境的研究。重点梳理两个地点的年代学、地层学等方面的研究进展与分歧,并对测年方法与结果、古生物与地层分析等方面的不确定性或多解性进行了讨论。尽管这两个地点在时代和环境研究方面仍存疑问,有些问题一时尚难澄清,但还是尝试提出了解决这些问题的部分途径和方法。 相似文献
11.
大荔人头骨化石产地地层的再研究 总被引：8，自引：0，他引：8
1978年发现大荔人头骨化石以来 ,都认为该化石是产自中更新世晚期的地层中 ,一些学者一直认为其年龄是 180～ 2 0 0 ka B.P.,也有个别研究者认为是 2 30 ka、大于 2 5 0 ka、30 8ka B.P.的。实际上 ,不仅对化石的年龄有不同数据 ,对化石产地地层也有不同的划分与对比。经再研究 ,该区晚新生代地层从上上新统直到全新统都有发育。沉积类型有湖相 ,河流相和风成黄土—古土壤沉积。人类化石层应是上中更新统的下部或下中更新统的上部 ,或更靠下。 相似文献
12.
The sediment record from the Piànico palaeolake in the southern Alps is continuously varved, spans more than 15 500 years, and represents a key archive for interglacial climate variability at seasonal resolution. The stratigraphic position of the Piànico Interglacial has been controversial in the past. The identification of two volcanic ash layers and their microscopic analysis provides distinct marker layers for tephrochronological dating of these interglacial deposits. In addition to micro‐facies analyses reconstructing depositional processes of both tephra layers within the lake environment, their mineralogical and geochemical composition has been determined through major‐element electron probe micro‐analysis on glass shards. Comparison with published tephra data traced the volcanic source regions of the Piànico tephras to the Campanian volcanic complex of Roccamonfina (Italy) and probably the Puy de Sancy volcano in the French Massif Central. Available dating of near‐vent deposits from the Roccamonfina volcano provides a robust tephrochronological anchor point at around 400 ka for the Piànico Interglacial. These deposits correlate with marine oxygen isotope stage (MIS) 11 and thus are younger than Early to Middle Pleistocene previously suggested by K/Ar dating and older than the last interglacial as inferred from macrofloral remains and the geological setting. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
13.
Guzel Danukalova Anatoly Yakovlev Liliana Alimbekova Tatyana Yakovleva Evgenija Morozova Andrey Eremeev Pavel Kosintsev 《Quaternary International》2008,190(1):38
Numerous caves and terraces with late Late Pleistocene (Upper Neopleistocene according to the Russian stratigraphic scale)–Holocene deposits are located in the Lemeza River valley in the surroundings of the Atysh waterfall, the native reserve territory of the Bashkortostan Republic. Lemeza River runs in the southern part of the western slope of the Urals and belongs to the Belaya River valley system (Russian Federation). A summary of the biostratigraphical investigations between 1992 and 2007 in this area is given. Deposits of cave and fluvial origin are characterized in the framework of the regional stratigraphy. The results of mammalian investigations and radiocarbon dating provide the basis for the stratigraphical subdivision. Palynology, mollusca, fishes, amphibian and reptiles are used for the reconstruction the palaeoenvironments. The Southern Urals stratigraphic subdivisions are correlated with Western European (Weichselian-Holocene), Eastern European (Russia) (Leningrad–Ostashkov–Shuvalov) and Uralian (Nevyansk–Polar Urals–Gorbunovsky) stratigraphic schemes. 相似文献
14.
Robust date for the Bronze Age Avellino eruption (Somma-Vesuvius): 3945 ± 10 calBP (1995 ± 10 calBC)
Jan Sevink Manfred J. van Bergen Johannes van der Plicht Hendrik Feiken Carmela Anastasia Annika Huizinga 《Quaternary Science Reviews》2011,30(9-10):1035-1046
We found Bronze Age lake sediments from the Agro Pontino graben (Central Italy) to contain a thin (2–3 cm) continuous tephra layer composed of lithics, crystals and minor volcanic glass. Tephrochronological and compositional constraints strongly suggest that this layer represents the Avellino pumice eruption, which has also been identified in Central Italian lake cores. Its provenance is corroborated by electron-microprobe analyses performed on juvenile pumice grains, showing that the tephra layer is probably the distal equivalent of the EU2 event of the Avellino eruption. We used multiple 14C age estimations of two lacustrine sequences with intercalated tephra layer, from the western border zone (Migliara 44.5) and the centre of the former lake (Campo Inferiore), for in tandem dating of this eruption, employing the OxCal code, which yielded a robust age of 3945 ± 10 calBP (1995 ± 10 calBC). To date, this is the only study providing both a terminus post and terminus ante quem of this precision, also demonstrating the advantage of dating distal tephra layers in a clear stratigraphic context over proximal deposits in sequences with major stratigraphic hiatuses. Our new results underscore the importance of the Avellino tephra layer as a precise time marker for studies on the Early Bronze Age of Central Italy. 相似文献
15.
通过野外地质填图和系统取样,以岩石地层特征为基础,以新构造运动为背景,按照多重地层划分观点,本文首次对若尔盖盆地晚新近纪岩石地层的对比和划分做了深入的研究。对黄河干流、白河支流和黑河支流水系的河道堆积岩石的典型剖面的研究,表明更新-全新世的不同发展阶段具有不同的特征;相同时期不同水系的沉积物也不尽相同,反映出盆地晚新近纪地层的发育过程及空间上的差异。对冰川堆积终碛垄测年等研究反映出末次盛冰期和全新世中几次较强的寒冷事件,并划分出4套冰碛层。综合前人的古脊椎动物化石和14C、TL、OSL和ESR等同位素测年资料,将为进一步提出研究区晚新近纪年代地层的划分奠定基础。 相似文献
16.
《Quaternary Research》1991,35(1):103-115
Detailed morpho- and lithostratigraphic investigations, allied with radiometric dating, in the Voidomatis basin, Epirus, northwest Greece, have identified four Quaternary terraced alluvial fills that range from middle Pleistocene to historic in age. Major-periods of alluviation during the late Quaternary were associated with valley glaciation (ca. 26,000–20,000 yr B.P.) and subsequent deglaciation (ca. 20,000–15,000 yr B.P.) in the Pindus Mountains during Late Würmian times, and more recently linked to overgrazing sometime before the 11th century AD. The late Quaternary alluvial stratigraphy of the Voidomatis River is more complex than the “Older Fill” and “Younger Fill” model outlined previously, and it is suggested that these terms should no longer form the basis for defining alluvial stratigraphic units in the Mediterranean Basin. 相似文献
17.
庐山地区中更新世晚期地层最佳剖面——下岸角剖面 总被引：4，自引：0，他引：4
在庐山东南麓发现一难得的中更新世晚期地层剖面——下岸角剖面,剖面中该期地层是一套夹在两层网纹红土之间的砂、亚砂、亚粘土、淤泥层,绝对年龄为２００－１２６ｋａＢ．Ｐ．,与深海氧同位素阶段６相当,是研究庐山冰期时期环境的最佳剖面。下岸角剖面地层界限清楚,沉积连续,时间跨度大,含有多种气候指标,时代确切,时空可比性强,具备中国东部中更新世晚期地层层型剖面的候选条件。 相似文献
18.
Bruce J. MacFadden Michael J. Whitelaw Phil McFadden Thomas H. V. Rich 《Quaternary Research》1987,28(3)
Three to seven oriented paleomagnetic samples were collected from 16 sites in the Nelson Bay and Bridgewater formations at Portland, Victoria, which contains the recently discovered Nelson Bay local fauna (L.F.). The entire section has reversed polarity. These results, along with Globorotalia truncatulinoides within the section, and the presence of underlying middle Pliocene-dated basalts, indicate that the Portland section, and the included Nelson Bay L.F., was deposited within the late Matuyama Chron between 1.66 and 0.73 myr ago. This represents the first well-documented pre-14C Pleistocene mammalian fauna in Australia calibrated in direct stratigraphic context with absolute dating methods. In addition, the reversed polarity for the Bridgewater Formation confirms the previous hypothesis that the depositional history of this beach-sand deposit is time-transgressive across the Brunhes-Matuyama boundary. 相似文献
19.
Abstract Fourteen bone samples are analysed to test the usefulness of equivalent dose (ED) determinations by electron spin resonance (ESR) as a rapid method of determining relative age and making an estimate of absolute age. ED values are compared with eight aspartic acid dates and two C14 dates. The latter are dates on charcoal found in close association with bone at archaeological sites. For samples less than 25 000 years old an excellent correlation is obtained when ED values are compared with dates obtained by the other two methods. The relationship suggests that ED values can be converted to estimates of bone age by assuming a mean annual dose rate of 0.1 rad/yr. Age determinations provide little evidence to support earlier suggestions that elements of the Late Pleistocene megafauna survived until the end of the Pleistocene. Bone material at some sites in the‐Florentine Valley and near Montagu appears to be much older than had previously been believed. Only one site (Main Cave, Montagu) containing megafaunal elements appears to be terminal Pleistocene in age but the possibility of reworking of megafauna material from nearby older sites cannot be excluded. ESR dating has considerable potential as an exploratory dating tool but can only be applied to dense, unaltered bone samples. Attempts to analyse five samples from Kutikina Cave in Western Tasmania were unsuccessful because of post‐depositional contamination of the bone. 相似文献
20.
Sasiphan Khaweerat Marshall Weisler Jian‐xin Zhao Yue‐xing Feng Kefu Yu 《Geoarchaeology》2010,25(5):527-540
Archaeologists rely on the spatial and temporal distribution of artifacts and other site‐based materials to understand the stratigraphic integrity of the matrix in which remains are embedded. Although they are aware of taphonomic and site formation processes that can cause post‐depositional movement of objects, misinterpretation can occur. We used high‐precision 230Th dating of branch corals found throughout cultural layers of a coastal Hawaiian midden to identify the effects of post‐depositional disturbances to the archaeological record. Fifteen corals distributed in three cultural layers of a Mo'omomi bay site on west Moloka'i, Hawaiian Islands, were 230Th dated between A.D. 1513 and A.D. 1623. Even though the cultural layers appeared visually intact, the positions of the dated coral samples indicate stratigraphic mixing as there is no positive age–depth correlation. Consequently, all cultural layers should be considered one analytical unit for analysis of contents. This study is applicable to other Pacific archaeological sites, especially throughout Hawaii and East Polynesia generally, that have well‐preserved branch coral for 230Th dating. © 2010 Wiley Periodicals, Inc. 相似文献