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1.
通过2002年7月沿鹿同头珊瑚礁坪断面方向，在原生滨珊瑚(Porites)礁表面进行系统采样，并进行^14C测年和年代校正，初步划分出全新世以来珊瑚礁演化的5个阶段：珊瑚礁繁盛期(7300-6000cal．aBP)、珊瑚礁发育停滞期Ⅰ(6000-4800cal．aBP)、珊瑚礁发展期(4800-3000cal．aBP)、珊瑚礁发育停滞期Ⅱ(3000-1000cal．aBP)和现代珊瑚礁发育期(1000cal．aBP以来)。鹿回头珊瑚礁在7300-6000cal．aBP处于发育的繁盛期，已基本上形成了现代珊瑚礁的地貌格局。后来不同时期珊瑚礁是在此时期形成的礁塘或礁坑等低洼地中形成，并存鹿同头半岛两侧向外发展，现代珊瑚礁则发育于全新世珊瑚礁的外礁坪或礁前斜坡带。 相似文献
2.
海南岛鹿回头珊瑚礁与全新世高海平面 总被引：4，自引：2，他引：2
通过实地考察和资料分析,海南岛南部全新世以来以沉降活动为主要特征,鹿回头珊瑚礁能够反映全新世以来的海平面变化,鹿回头岸礁礁坪面上的原生珊瑚礁是全新世高海平面时期的产物.全新世以来南海北部至少存在过4期相对高海平面阶段：7 300～6 000、4 800～4 700、4 300～4 200和3 100～2 900 cal.aBP.其中7 300～6 000 aBP是整个全新世最高海平面时期,也是鹿回头珊瑚礁发育的繁盛期,基本形成了现代珊瑚礁的地貌格局,后来不同时期发育的珊瑚礁是在此时期形成的礁塘或礁坑等低洼地中形成,并在鹿回头半岛两侧向外发展,现代珊瑚礁则发育于全新世珊瑚礁的外礁坪和礁前斜坡带.另外,鹿回头珊瑚礁反映的南海北部全新世高海平面时间与南海其他地区高海平面时间可以衔接或对应,说明南海地区全新世高海平面具有全球背景,至少在南海是一致的,且与气候变暖紧密相联. 相似文献
3.
通过实地考察和资料分析,海南岛南部全新世以来以沉降活动为主要特征,鹿回头珊瑚礁能够反映全新世以来的海平面变化,鹿回头岸礁礁坪面上的原生珊瑚礁是全新世高海平面时期的产物。全新世以来南海北部至少存在过 4 期相对高海平面阶段:7300~6000、4800~4700、4300~4200和3100~2900cal.aBP。其中 7300~6000aBP 是整个全新世最高海平面时期,也是鹿回头珊瑚礁发育的繁盛期,基本形成了现代珊瑚礁的地貌格局,后来不同时期发育的珊瑚礁是在此时期形成的礁塘或礁坑等低洼地中形成,并在鹿回头半岛两侧向外发展,现代珊瑚礁则发育于全新世珊瑚礁的外礁坪和礁前斜坡带。另外,鹿回头珊瑚礁反映的南海北部全新世高海平面时间与南海其他地区高海平面时间可以衔接或对应,说明南海地区全新世高海平面具有全球背景,至少在南海是一致的,且与气候变暖紧密相联。 相似文献
4.
尕海地区晚冰期以来沉积记录的气候环境演变 总被引：3，自引：0，他引：3
通过对尕海沉积物烧失量和碳酸盐含量以及岩性变化分析,重建了尕海地区晚冰期以来的气候环境演变。结果显示:烧失量及碳酸盐含量指标可以较好地反映晚冰期以来的气候变化,晚冰期的阿勒罗德暖期和新仙女木事件有较好的反映。全新世则可划分为早全新世的不稳定期,年代为11150-8240 cal.aBP,中全新世较为暖湿期,年代为8240-3200 cal.aBP,晚全新世干冷期,年代为3200 cal.aBP至今。并发现1550-1440 cal.aBP存在一暖湿事件。 相似文献
5.
雷州半岛珊瑚礁生物地貌带与全新世多期相对高海平面 总被引：20，自引：5，他引：20
通过多次野外调查，将灯楼角珊瑚礁分为8个生物地貌带；礁前斜坡活珊瑚林带，外礁坪大块滨珊瑚礁岩带，中礁坪块状珊瑚混合带，中礁坪块状珊瑚-角孔珊瑚混合带，内礁坪角孔瑚瑚带，沙坪台-海滩，沙堤和洼地，它们是海平面和气候环境变化的产物，以珊瑚礁及其生物地貌带作为高海平面的标志，根据13个表层珊瑚礁样品的TIMS铀系年代和1个^14C年代，指出全新世以来至少存在过5期相对高海平面（7.2-6.7,约5.8,5.0-4.2,2.8-2.0，约1.5cal.kaBP)，每一期中还存在低海平面的波动，其中6.7-7.2kaBP是整个全新世最高海平面时期，在这个时间段已经基本形成了现代珊瑚礁的地貌格局，这个时间段以后形成的珊瑚礁是在6.7-7.2kaBP形成的珊瑚礁礁坪的礁塘或礁坑等低洼地中形成的，迄今为止，没有再出现过高出6.7-7.2kaBP时期的海平面。 相似文献
6.
黄土高原定西鲁家沟黄土剖面15 ka以来的环境演变 总被引：1，自引：0，他引：1
根据鲁家沟黄土剖面粒度、磁化率、有机质和碳酸盐含量等气候代用指标的变化和14C测年结果,分析和讨论了定西地区近15 cal.kaBP以来气候演化的过程。结果表明15 cal.kaBP以来的气候变化可划分为4个阶段:(1)末次冰期晚期(14900~11200 cal.aBP),气候较为寒冷干旱;(2)全新世早期(11200~7560 cal.aBP),气候开始转暖转湿,但整体上较为寒冷;(3)全新世中期(7560~3600 cal.aBP),气候温暖湿润,夏季风强盛;(4)全新世晚期(3600~1200 cal.aBP),气候变得干旱,夏季风强烈减退,风尘堆积旺盛,形成了现代黄土和表土层。该区末次冰期晚期以来的环境变化是不稳定的,气候存在频繁次级波动。1500~1200 cal.aBP的晚全新世期间,有机质含量出现峰值,表明气候总体向干旱化发展的同时,叠加了人类活动的影响。 相似文献
7.
考古学发现江准东部已有十多处新石器文化遗址,形成了有区域特征的文化序列.分别为龙虬庄文化(7 000? 6 300～5 500 aBP)、大汶口文化(5 500～4 600 aBP)和龙山(岳石)文化(4 300～3 450 aBP).在中全新世适宜期,受气候、长江、淮河三角洲的发育和海面变化的共同作用,江淮东部约7 ... 相似文献
8.
南沙群岛永暑礁7个表层礁坪原生块状珊瑚的高精度TIMS U-Th和12个常规^14C测年结果表明，永暑礁表层礁坪形成于现代，与钻探研究结果吻合。全新世永暑礁系从约7300aBP开始，以现代礁坪面以下17m左右的晚更新世礁灰岩为基底连续发育至今，因此，与南海周边地区的珊瑚礁不同，南沙群岛珊瑚礁的表层块状珊瑚不能够提供全新世高海平面的证据。由于现代珊瑚礁的堆积速率大于地壳沉降速率，可能会形成更多的灰沙洲或灰沙岛。 相似文献
9.
兴凯湖沉积物磁化率和色度反映的28kaBP以来区域古气候环境演化 总被引：1，自引：0，他引：1
对兴凯湖长269 cm的沉积岩心的研究结果显示:沉积物的色度和磁化率特征可以较好地反映区域气候环境变化。沉积物明度分别与红度、磁化率、黏土和有机质含量之间及磁化率与黏土之间有很好的相关性;红度高值与明度低值对应暖湿气候环境,磁化率低值反映沉积物较粗的较低湖面,对应冷干气候。28480~26160 cal.aBP,湖区处于温湿气候时期;22880~18170 cal.aBP,岩心孢粉浓度很低,流域处于末次盛冰期疏桦林草原环境;18170~12650 cal.aBP处于Bφlling/Older Dryas/Allerφd暖期。岩心深度90~78 cm段,对应于新仙女木期;11500~4570 cal.aBP,进入全新世暖期,其中8000~5000 cal.aBP,本区处于全新世大暖期(气候适宜期);4570~1470 cal.aBP气候变为凉干;1470 cal.aBP以来,流域又变为暖湿气候环境,同时,人类活动逐渐增强造成水土流失加剧。 相似文献
10.
海南岛鹿回头珊瑚礁研究进展 总被引：5，自引：0，他引：5
前人在海南岛鹿回头珊瑚礁区所做的工作主要集中于以下三方面：(1)鹿回头珊瑚礁区地貌的粗略描述；(2)鹿回头珊瑚礁记录的古海平面研究：(3)鹿回头珊瑚礁记录的现代环境信息研究。通过野外实地考察，将鹿回头珊瑚礁分为8个生物地貌带：礁前斜坡活珊瑚带、礁缘砾石突起脊带、外礁坪带、中礁坪带、内礁坪带、海滩、沙堤、洼地，它们是全新世海平呵和气候环境变化的产物。关于本区珊瑚礁的研究，结合全球珊瑚礁与环境的研究来看，许多工作有待于展开和补充，大致可从以下4个方面进行深入研究：(1)珊瑚礁的生物地貌过程；(2)珊瑚及珊瑚礁的高分辨率环境记录；(3)珊瑚对海洋环境污染的记录：(4)珊瑚礁生态系统与社会、经济及人文系统的关系及其可持续发展。 相似文献
11.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
12.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
13.
The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
16.
The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance. 相似文献
17.
Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
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Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
20.
Shigehisa Nakamura 《Marine Geodesy》2001,24(1):27-33
This article concerns an interrelation between the sea levels and the western boundary flow near a tectonic boundary in a local zone in the Northwestern Pacific. In this zone, sea level variations at stations located on the coast facing the Pacific are studied to find the interrelation between variations of the Kurosio flow as an index of the distance of the flow axis off a specific coast. The result is discussed after data processing of the monthly means of the sea levels, and a notice is taken of variations caused by active crustal upheavals during a seismic event, a local earthquake. 相似文献