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福建长乐全新世地层划分与对比的探讨 总被引：4，自引：0，他引：4
本文从研究长乐汪田钻孔剖面入手,结合岩相、岩性、微体古生物、孢子花粉、~14C同位素等资料,对我省沿海全新世地层三分,即晚、中、早全新世.而且就有关的一些问题进行了讨论;1、全新世海侵与海退;2、中全新世存在一次海退沉积间断;3、全新世海侵究竟有几次;4、全新世海侵时,海水最大深度为何时;5、全新世的海平面是否比现在更高. 相似文献
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本文回顾和总结了不同纬度带大河三角洲全新世相对海平面曲线的特征及影响因素.以相近纬度带的长江、尼罗河与密西西比河三角洲为例,剖析了全新世中期无“高于现代平均海平面”的“壅水”现象,认为直布罗陀海峡、加勒比海岛屿和白令海峡对北极圈南下融水进入地中海、墨西哥湾和西太平洋起到了限制作用.大量的研究还表明,距今约7ka时尼罗河三角洲相对海平面低于现今约14m,而此时密西西比河三角洲相对海平面约为-10m,长江三角洲仅约为-5m;随后,它们的差距逐渐减小,反映了沉降作用对相对海平面变化的影响.论文提出一种利用全新世三角洲沉积层序、结合相对海平面曲线来判断区域沉降差异的方法;总结了三角洲古地形对海平面上升的响应模式,以及利用三角洲新石器遗址“最低居住面”重塑全新世相对海平面变化的路径.这些均为三角洲地区全新世海平面变化与地貌环境演化的相关研究提供了新的前景. 相似文献
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揭示晚全新世以来的海平面变化过程对于理解海平面所处的现状和变化的趋势等具有重要意义。构造活动相对稳定的雷州半岛珊瑚礁区蕴藏着丰富的海平面变化信息,文中对该区晚全新世发育的海滩沉积序列研究表明,距今约1.7～1.2Cal.kaBP(14C年代为2.1～1.7kaBP)期间总体上是一个海平面持续上升的时期,其中在距今约1.5Cal.kaBP时海平面有过短暂的下降波动,约1.2Cal.kaBP时的海平面比现在的至少高128cm;之后海平面开始下降,至今海岸线后退了约210m,形成现代海滩-沙堤地貌体系。结合本区珊瑚礁记录的全新世其他时段海平面的变化特征,本文认为全新世海平面与气候变化一样,也存在千年、百年、年代际尺度的波动特征。 相似文献
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广东全新世海平面重建与冰川均衡调整模型结果的比较 总被引：2，自引：0，他引：2
中国广东沿岸作为一个冰川均衡调整(GIA)“远场”地区,按照水动型均衡理论,应存在全新世中期高海平面.本文通过海平面标志物重建了广东古海平面的历史,结果显示出在粤东、粤西与珠江三角洲的海平面历史存在明显的差异.若将海平面历史与GIA模型结果对比,可以看出广东沿岸在全新世以来具有微小的区域性地壳沉降.这种大区域的沉降可归因于华南陆块向南延伸所引起.此外,粤西雷州半岛因新构造运动,于全新世早中期有轻微抬升.珠江三角洲盆地则因断裂构造沉降和沉积物压实作用,重建的中全新世海平面明显低于GIA结果. 相似文献
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根据中国沿海全新世海进海退时代的一致性及对渤海沿岸平原、苏北平原和长江三角洲平原的牡蝠礁、贝壳堤底板和海侵层项板等古海面标志物的高程、年代及其与古海面关系的分析对比，消除了地壳运动的影响。本文认为中国沿海全新世中期5000-7000aBp存在着+ 2~+3m的高海平面，它是当时全球温暖气侯通过海水温度—体积效应造成的全球平均海平面变化(eustatic change )的反映;同时区域大地水准面的垂直变化和水平移动对海平面的影响值得深人研究;此外大陆径流量，沿海降水量季及风环流的变化也可能对沿海海平面产生过一定影响。 相似文献
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东海残留沉积区舟山ＱＺ５０４孔未发现上海地区普遍存在的全新世暗绿色硬粘土层。但通过对该孔微体古生物组合特征的分析与对比，划分了全新世与更新世的更线，反映了气候的变化，证实了滚流对本区的影响。 相似文献
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杭州湾钱塘江两岸全新世以来的古植被及古气候研究 总被引：1，自引：0，他引：1
根据杭州市三个钻孔的孢粉资料对杭州市地区全新世以来的植被和古气候演变进行讨论。这三个钻孔分别位于钱塘江两岸的三盈村(HZ1)、新街三星(HZ2)和下沙镇市场(HZ3),笔者对其进行了孢粉样分析和地层年代学研究。研究结果表明,该区自晚更新世晚期以来的植被演化可以划分为4个阶段:第一阶段为针叶林,气候温凉较湿,海平面低于现今海平面;第二阶段为针叶林或针阔叶混交林,气候温和较湿,海平面接近现今海平面;第三阶段为针阔叶混交林,枫香、榆花粉明显增多,气候温暖较湿,出现高海面;第四阶段为针叶林,气候暖和较湿,海平面接近现今位置。其中第一阶段为末次冰期,第二、三、四阶段为全新世。根据第三阶段的孢粉组合特征、岩性特征以及微体化石可知,全新世中期的气候比较适宜,气候温暖湿润。 相似文献
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全新世时期的环境和气候变化是全球气候模拟、预测中不可或缺的资料.对苏拉威西海西北部MD98-2178孔(3.6200°N,118.7000°E,水深1 984 m)全新世的样品进行孢粉分析和浮游有孔虫氧稳定同位素测试,重建全新世苏拉威西海周边地区植被演化和气候变化图景.根据孢粉记录得到:在全新世早期至7 ka BP时,各孢粉组合浓度剧烈下降,指示海平面处于上升阶段;在7~4 ka BP时,各孢粉组合浓度都处于低谷,体现为高海平面期;在4 ka BP之后,孢粉记录则显示海平面有小幅的下降.在全新世中期,即5~4 ka BP,热带高山雨林花粉含量明显上升,表明是温度低值期.蕨类孢子记录显示降雨量在全新世早期是持续增加的,但在全新世中期之后,降雨量有所减少,这与陆地孢粉记录和印尼石笋记录的结果相似,体现全新世该地区降雨量受海陆格局和太阳活动共同影响. 相似文献
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收集和整理上海地区各类古海面标志的地质意义及~(14)C测年资料,建立了上海地区全新世海面变化曲线。并结合上海地区地层建造、微古化石、孢粉及古人类遗址的发掘资料,探讨了上海地区全新世的环境演化,及环境变化对古人类活动的影响。 相似文献
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Anthony C. Massey W. Roland Gehrels Dan J. Charman Glenn A. Milne W. Richard Peltier Kurt Lambeck Katherine A. Selby 《第四纪科学杂志》2008,23(5):415-433
Previous sea‐level studies suggest that southwest Britain has the fastest subsiding coastline in the United Kingdom, but tide‐gauge data, GPS and gravity measurements and geophysical models show little evidence of anomalous subsidence in this region. In this paper we present 15 new sea‐level index points from four coastal barrier systems in south Devon. Eight are from compaction‐free basal sediments and others were corrected for autocompaction. Our data suggest that relative sea level along the south Devon coastline has risen by 21 ± 4 m during the past 9000 years. Sea‐level rise slowed during the middle and late Holocene and a rise of 8 ± 1 m has occurred since ca. 7000 cal. yr BP. Anomalous ages for many rejected points are attributed to sediment reworking during barrier transgression. The relative sea‐level history during the early and middle Holocene shows a good fit with geophysical model predictions, but the geological and modelled data diverge in the later Holocene. Unlike the geophysical models, sea‐level index points cannot differentiate between late Holocene relative sea‐level histories of south Devon and southwest Cornwall. It is suggested that this discrepancy can be resolved by obtaining additional high‐quality sea‐level index points covering the past 4000 years. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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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
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
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Paula Garcia Carvalho do Amaral Paulo César Fonseca Giannini Florence Sylvestre Luiz Carlos Ruiz Pessenda 《第四纪科学杂志》2012,27(2):181-191
This paper provides a paleoenvironmental reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (δ13C, δ15N and C/N), microfossil (pollen and diatom) and grain‐size analysis from three shallow cores (～2.5 m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid‐Holocene than today, with a gradual and continuous lagoon–sea disconnection until the present. We add to the debate regarding relative sea‐level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi‐proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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CECILE BAETEMAN MARTYN WALLER PATRICK KIDEN 《Boreas: An International Journal of Quaternary Research》2011,40(4):557-572
Baeteman, C., Waller, M. & Kiden, P. 2011: Reconstructing middle to late Holocene sea‐level change: A methodological review with particular reference to ‘A new Holocene sea‐level curve for the southern North Sea’ presented by K.‐E. Behre. Boreas, 10.1111/j.1502‐3885.2011.00207.x. ISSN 0300‐9483. A number of disciplines are involved in the collection and interpretation of Holocene palaeoenvironmental data from coastal lowlands. For stratigraphic frameworks and the assessment of relative sea‐level (RSL) change, many non‐specialists rely on existing regional models. It is, however, important that they are aware of major developments in our understanding of the factors controlling coastal change and of the potential sources of error in sea‐level reconstructions. These issues are explored through a critical evaluation of a new sea‐level curve presented by Behre (2003, 2007) for the southern North Sea. In contrast to most sea‐level curves published from this region over the last 20 years, the curve shows strong fluctuations that are interpreted as representing vertical movements of sea level. We present a detailed examination of the data used by Behre. From this analysis it is clear that many of the data points used are unsuitable for high‐resolution (centimetre or decimetre) sea‐level reconstruction. This paper also gives an overview of possible sources of error with respect to the age and altitude of sea‐level index points and of changes in our understanding of the processes that underpin the interpretation of the organic and occupation levels used as index points. The constraints on the spatial scale over which sea‐level reconstructions can be applied (changes in palaeotidal range and crustal movements) are also considered. Finally, we discuss whether the large‐amplitude centennial‐scale sea‐level fluctuations proposed by Behre can be reconciled with the known mechanisms of sea‐level change and other recent high‐resolution studies from this region. We conclude that such fluctuations are highly unlikely to be real features of the sea‐level history of the southern North Sea. 相似文献
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Frihy Omran E. 《GeoJournal》1992,26(3):389-394
Carbon dating data of changes in seal level during the Holocene at the Nile delta coast provide eustatic depth-time curve
of the region. The curve reveals that sea level was approximately 41 meters below the present level around 8,500 years ago.
Trend analysis indicates that with melting of glaciers there was a rapid rise in sea level of about 3 mm/yr. The constructed
data points are found to be comparable with other curves in the Mediterranean and wold-wide regions. The general changes of
the data points are fairly correlated with the ancient shoreline indicators of morphological features (shelf terraces and
slopes, old dunes, sand accretion ridges) and sediments at continental shelf and its contiguous coastal zone that belong to
Holocene transgression. 相似文献
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The Okha Shell Limestone Member of Chaya Formation is the coarse grained, shell rich deposit commonly recognized as the beach
rocks. It has been age bracketed between Late Pleistocene and Holocene. Late Quaternary sea level changes have been studied
with beach rocks along the Saurashtra coastal region. The present study has been carried out in the Okhamandal area of the
Saurashtra peninsula especially on the Okha Shell Limestone Member as exposed at various locations along the coast from north
to south. Temporal and spatial correlations of the observations have revealed three events in the Okha Shell Limestone Member
of Chaya Formation that are correlated laterally. The events show depositional breaks represented by discontinuity surfaces,
the taphofacies varieties and ichnological variations. The present study in the context of available geochrnological data
of the region suggests a prominent depositional break representing low sea level stand (regression) during an Early Holocene
during the deposition of Okha Shell Limestone Member. 相似文献
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全新世以来山东半岛东北部沿岸的相对海面（基准面）变化控制了入海河流河谷内全新统的发育,并通过影响进入海岸带碎屑物质的类型与数量,深刻影响了海岸带全新统的发育。全新世早期（１０～６ｋａ Ｂ． Ｐ．）快速的相对海面上升导致河谷溯源堆积,河流输沙中的推移质均堆积于河谷中,仅有悬移质进入海岸带堆积,因而海岸全新统下部均为细粒的海湾、湖、沼泽相沉积。全新世中期（６～４ｋａ Ｂ．Ｐ．）时海面虽已相对稳定,但早期基准面上升导致的河谷堆积作用仍在进行,因而中全新统的粗碎屑海岸沉积均为源于基岩海岸侵蚀的含贝壳砂砾石。从全新世后期（４ｋａ Ｂ．Ｐ．以来）开始有较丰富的河流推移质输沙进入海岸带,但由于不同规模河流对相对海面变化的地貌响应有显著差别,不同河流对海岸全新统发育的影响各不相同。上述结论为精确地解释低序列、小尺度地层层序提供了理论依据 相似文献