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1.
Sediment vibracores and surface samples were collected from the mixed carbonate/siliciclastic inner shelf of west–central Florida in an effort to determine the three-dimensional facies architecture and Holocene geologic development of the coastal barrier-island and adjacent shallow marine environments. The unconsolidated sediment veneer is thin (generally <3 m), with a patchy distribution. Nine facies are identified representing Miocene platform deposits (limestone gravel and blue–green clay facies), Pleistocene restricted marine deposits (lime mud facies), and Holocene back-barrier (organic muddy sand, olive-gray mud, and muddy sand facies) and open marine (well-sorted quartz sand, shelly sand, and black sand facies) deposits. Holocene back-barrier facies are separated from overlying open marine facies by a ravinement surface formed during the late Holocene rise in sea level. Facies associations are naturally divided into four discrete types. The pattern of distribution and ages of facies suggest that barrier islands developed approximately 8200 yr BP and in excess of 20 km seaward of the present coastline in the north, and more recently and nearer to their present position in the south. No barrier-island development prior to approximately 8200 yr BP is indicated. Initiation of barrier-island development is most likely due to a slowing in the Holocene sea-level rise ca. 8000 yr BP, coupled with the intersection of the coast with quartz sand deposits formed during Pleistocene sea-level highstands. This study is an example of a mixed carbonate/siliciclastic shallow marine depositional system that is tightly constrained in both time and sea-level position. It provides a useful analog for the study of other, similar depositional systems in both the modern and ancient rock record.  相似文献   

2.
The sedimentary record of 130 km of microtidal (0.9 m tidal range) high wave energy (1.5 m average wave height) barrier island shoreline of the Cape Lookout cuspate foreland has been evaluated through examination of 3136 m of subsurface samples from closely spaced drill holes. Holocene sedimentation and coastal evolution has been a function of five major depositional processes: (1) eustatic sea-level rise and barrier-shoreline transgression; (2) lateral tidal inlet migration and reworking of barrier island deposits; (3) shoreface sedimentation and local barrier progradation; (4) storm washover deposition with infilling of shallow lagoons; and (5) flood-tidal delta sedimentation in back-barrier environments.

Twenty-five radiocarbon dates of subsurface peat and shell material from the Cape Lookout area are the basis for a late Holocene sea-level curve. From 9000 to 4000 B.P. eustatic sea level rose rapidly, resulting in landward migration of both barrier limbs of the cuspate foreland. A decline in the rate of sea-level rise since 4000 B.P. resulted in relative shoreline stabilization and deposition of contrasting coastal sedimentary sequences. The higher energy, storm-dominated northeast barrier limb (Core and Portsmouth Banks) has migrated landward producing a transgressive sequence of coarse-grained, horizontally bedded washover sands overlying burrowed to laminated back-barrier and lagoonal silty sands. Locally, ephemeral tidal inlets have reworked the transgressive barrier sequence depositing fining-upward spit platform and channel-fill sequences of cross-bedded, pebble gravel to fine sand and shell. Shoreface sedimentation along a portion of the lower energy, northwest barrier limb (Bogue Banks) has resulted in shoreline progradation and deposition of a coarsening-up sequence of burrowed to cross-bedded and laminated, fine-grained shoreface and foreshore sands. In contrast, the adjacent barrier island (Shackleford Banks) consists almost totally of inlet-fill sediments deposited by lateral tidal inlet migration. Holocene sediments in the shallow lagoons behind the barriers are 5–8 m thick fining-up sequences of interbedded burrowed, rooted and laminated flood-tidal delta, salt marsh, and washover sands, silts and clays.

While barrier island sequences are generally 10 m in thickness, inlet-fill sequences may be as much as 25 m thick and comprise an average of 35% of the Holocene sedimentary deposits. Tidal inlet-fill, back-barrier (including flood-tidal delta) and shoreface deposits are the most highly preservable facies in the wave-dominated barrier-shoreline setting. In the Cape Lookout cuspate foreland, these three facies account for over 80% of the sedimentary deposits preserved beneath the barriers. Foreshore, spit platform and overwash facies account for the remaining 20%.  相似文献   


3.
《Marine Geology》2006,225(1-4):63-84
This paper examines the role of peat compaction as a driving mechanism behind the widespread inundation of a late Holocene coastal wetland in southeast England, UK. Detailed stratigraphic and dating evidence (lithology, grain size, foraminifera, pollen and radiocarbon dates) from a sample site in Romney Marsh documents the gradual inundation of a coastal wetland after 1263–1085 cal. yr BP (c. 700–850 AD) and the establishment of a saltmarsh. Shortly thereafter there was a rapid increase in water depth that was associated with the deposition of nearly 4 m of laminated intertidal mudflat and tidal channel sediments, prior to site reclamation from the sea by AD 1460. Grain-size data and statistical analysis of sand and mud laminae thicknesses suggest the laminated sediments accumulated rapidly (c. 0.2 m per year) as heterolithic tidal rhythmites. Rapid compaction of the thick peat bed that underlies the study site provided the accommodation space for their deposition. This process began with the gradual tidal inundation of the site, but accelerated following the widening of a breach in a coastal barrier in the 13th century. Compaction lowered the peat surface by at least 3 m and was associated with widespread landscape change. The study demonstrates the powerful influence that compaction had on the evolution of the late Holocene landscape at this site and, we believe, at many other coastal lowlands in northwest Europe. This process is likely to have been a key driving mechanism behind rapid late Holocene coastal change, far exceeding the longer-term effects of either eustatic change or crustal uplift/subsidence.  相似文献   

4.
On the rocky coasts of the northwestern Mediterranean basin, biogenic littoral rims built by the coralline rhodophyte Lithophyllum lichenoides develop, whose remains may be preserved for millennia when submerged in a rising sea environment. These remains can be used as biological indicators of recent sea-level variations. Our survey of the continental coasts of Var and Bouches du Rhône, west of Marseilles (southern France) and of northern Corsica shows that relative sea level rose about 1.6 m in the study area during the last 4500 years without exceeding the present datum. The rate of sea-level rise was 0.4 mm per year between 4500 and 1500 yr B.P. and slowed down to 0.2 mm per year from 1500 yr B.P. to present time. There are also morphological indications of an acceleration of the rate of sea-level rise during the last century, supporting the evidence of tide gauges. Regions at the periphery of the above zone (Alpes Maritimes, Italian border zone, and the French and Spanish Catalonia regions) were also surveyed, but a weaker development of Lithophyllum rims and bad preservation of algal remains led to unconvincing dates which could also be linked to regional tectonic trends.  相似文献   

5.
Graham G. Shorten   《Marine Geology》1993,110(3-4):275-302
A deposit of post-glacial organo-calcareous silt 25–40 m thick blankets the floor of Suva Harbour and its marginal inlets, including Draunibota Bay, on the southeast coast of Viti Levu, Fiji. This deposit is notable for its involvement in a large number of foundation failures in the area. The organo-calcareous silt is the latest sedimentary infill over a late Pleistocene erosional surface which is dissected characteristically down to around 50 m below current mean sea level at the harbour margins, and to at least 90 m at the seaward end of the study area. The gross distribution of Pleistocene and Holocene sedimentary units is strongly influenced by Pliocene graben formation in the Mio-Pliocene bedrock. The silt deposit forms part of a transgressive and highstand systems tract related to the latest glacio-eustatic sea-level rise, and includes a series of lobate delta deposits currently prograding at the mouths of streams entering the harbour. The silt was deposited in a lagoonal/estuarine environment of restricted circulation in a marginal/back-barrier reef situation and received a variety of marine carbonate and terrigenous sediment contributions, as well as organic substances from both autochthonous and allochthonous sources. Undisturbed sampling indicates the silt to be homogeneous, non-layered and thoroughly bioturbated, but a distinct layering with a spacing in the order of 1–5 m, probably related to periodic influxes of terrigenous material, is obvious on continuous seismic profiles. Acoustic turbidity due to biogenic gas in thick accumulations over palaeo-channels may well represent zones of high pore fluid pressure, and indicate lower effective soil strength. There is also evidence that the passage of the overpressured gas front results in hydraulic fracturing and consequent degassing of the silt. The silt deposit displays a slight upward coarsening in response to shoaling conditions, accompanied by an upward increase in both organic carbon and calcium carbonate proportions, and a decreasing terrigenous contribution. The increase in organic carbon is closely mirrored by increased diagenetic development of bacterially-deposited agglomerates of iron sulfide crystals in the pore spaces. The resulting pore-space microstructure appears to exert a direct control on the in-situ void ratio, and hence directly affects the consolidation and strength characteristics of the sediment. Radiocarbon dates from the silt deposit indicate a consistent rate of deposition in the Draunibota palaeo-channel of 4.3 m/1000 yr since the marine transgressive front passed the site some 9600 yr B.P. The dates extend the reliable local sea-level data for southeast Viti Levu back some further 4000 years, and support an earlier contention that sea level reached its current position here at around 4000–4500 yr B.P., about 2000 years later than on the coast of southeast Australia. Water depth at the Cement Works Bridge site reached a maximum of 20 m some 5000 yr B.P. and, subsequently, has gradually shoaled to its present position just below mean sea level.  相似文献   

6.
Controlled by the NE-and NW-trending faults the Hanjiang Delta formed in the Early Quaternary received deposits in the Middle Quaternary, continued to develop since the Holocene, and subsided at a velocity of 1 mm/yr. About 2000-3000 years BP the Hanjiang Delta began to uplift and became a land. Its formation and development are controlled by faulting. Early and late developments are controlled by the NE-and NW-trending fractures, respectively, indicating the rebirth and Intense activity of the latter.  相似文献   

7.
Z. Shi 《Geo-Marine Letters》1993,13(3):182-188
Rates of saltmarsh accretion were determined for the Dyfi Estuary, central Cardigan Bay, Wales, using marker layers and X-ray radiographic laminae counts. A three-month study revealed the amount of sediment that had accumulated, totalling 2.5 mm, equivalent to 10.0 mm/yr. The saltmarsh sediment accretion rate estimated by laminae counts is 11.5 mm/yr. These data, compared with previous published data, indicate that the rate of sediment accretion has decreased since the 1920s. This is cautiously proposed as suggesting that the upward trend of relative sea level in the Dyfi Estuary may have been decreasing over the last 80 years.  相似文献   

8.
Based on preliminary results of sedimentological and organic geochemical investigations, distinct changes in the composition of siliciclastic and biogenic components occured in sediments from the East Greenland Continental Slope and Shelf and Scoresby Sund during the latest Pleistocene to Holocene times. These changes probably reflect the (? early/) late Weichselian glacial to Holocene interglacial transition, i.e., the decay of continental ice masses and sea-ice cover, causing major changes in supply of terrigenous matter and surface-water productivity. Flux rates of coarse-grained ice-rafted debris (IRD) distinctly decreased on the continental slope/shelf during the deglaciation interval. During the last 10,000 years, major amounts of IRD were trapped in the Scoresby Sund system. In comparison to modern interglacial conditions, surface-water productivity was significantly lower during the last glacial.  相似文献   

9.
对深圳湾北岸新民钻孔岩心沉积物中铁、钒元素、矿物鉴定的伊利石以及生物指标贝类介壳揭示的环境特征资料进行了分析,研究初步表明,该钻孔岩心沉积物理深12．12～10．91m层段的杂色花斑粘土中存有晚更新世晚期至早全新世气候波动的记录。钒元素和伊利石分析也得到了相应的证实。所记录的短期降温和升温事件可能表明,在第四纪末次冰期-冰消期中,气候曾强烈波动,并逐渐由晚冰期向冰后期过渡。这对研究晚武木冰期最低海面时期以来,海面回升及晚更新世晚期／早全新世的古环境方气候影响提供有价值的资料。  相似文献   

10.
刘阿成  张杰  唐建忠 《海洋学报》2020,42(11):49-61
本文采用高分辨率单道浅地震剖面资料研究闽江口外海域的全新统沉积作用。研究区的全新统底面为MIS 2期侵蚀面，局部为古河道，深度一般在现海面下约30～60 m，最深约65 m；近岸浅，外海深，局部受古河道的下切影响呈条带状负地形。全新统由早全新世晚期以来的海相沉积层(U1)和早全新世河流湖沼相沉积层(U2)组成，前者包括滨浅海平行地震相和河口滨岸前积地震相，根据其反射波向陆上超和向海下超底界面，结合沉积物厚度分布特征，可以判断主要的沉积物来源和运移趋势。全新统沉积层厚度一般为10～20 m，最厚约38 m，位于古河道区，但是在马祖列岛和白犬列岛之间海区缺失。海相全新统沉积层的厚度为数米至20 m，最厚约25 m，位于研究区东南部(海坛岛东侧)。自全新世海侵以来，沉积物主要来源于3部分:台湾海峡来沙为研究区南部海区提供了沉积物；闽江悬沙扩散沉积物覆盖研究区北部海区，主要沿NE方向至外海，在河口向南呈舌状，现代沉积中心位于河口北部，厚度大于15 m；浙闽沿岸流来沙对研究区东北部海区的沉积物有影响。沉积环境划分为台湾海峡源沉积区、闽江源沉积区、东北部混合沉积区和马祖?白犬沉积缺失区，平均沉积速率分别约为0.8 mm/a、1.0 mm/a、1.1 mm/a和0 mm/a。马祖?白犬沉积缺失区主要因为沉积物受沿岛环流的控制。  相似文献   

11.
全新世以来硕项湖地区的海陆演变   总被引：4，自引：0，他引：4  
凌申 《海洋通报》2003,22(4):48-54
硕项湖古为淮北地区著名的大湖，全新世以来经历了“浅海—潟湖—湖泊—平原”的海陆演变过程。早全新世这里是一片浅海；中全新世发育为潟湖：晚全新世演变为一座淡水湖泊；清以后淤为平原。  相似文献   

12.
A small Holocene fan is forming where Queen Inlet, a hanging valley, enters West Arm fjord, Glacier Bay, Alaska. Queen fan formed in the last 80 years following retreat of the Little Ice Age glacier that filled Glacier Bay about 200 yr BP. It was built mainly by a turbidite system originating from Carroll Glacier delta, as the delta formed in the early 1900s at the head of Queen Inlet. The Late Holocene Queen fan is comparable to large Pleistocene fans that formed in the Gulf of Alaska and differs from trough-mouth fans formed by cooler climate glacier systems. Received: 7 January 1999 / Revision received: 3 June 1999  相似文献   

13.
The sequence-stratigraphic investigation by Very High-Resolution (VHR) seismic profiles allowed recognition of the detailed architecture of the late Pleistocene and Holocene succession of the Venice area. In this way deposits previously known by the analyses of scattered cores, mainly taken along the lagoon margin and the littoral strips, have been correlated at regional scale including the near offshore sector and the result has pointed out the lateral variability of the stratal architecture. Late Pleistocene deposits consist of an aggrading floodplain and fluvial channel fills accumulated during decreasing eustatic sea level, and they are coeval with offlapping forced regressive marine wedges in the Central Adriatic basin. The Holocene sequence is composed of three main seismic units separated by major stratal surfaces. Unit 1 (up to 9 m thick) is formed by channelized deposits separated by areas showing sub-horizontal and hummocky reflectors, and is bounded at the base by a surface that records prolonged conditions of subaerial exposure and at the top by a flatter surface resulting from erosion by marine processes. Deposits of Unit 1 are interpreted as estuarine and distributary channel fills, and back-barrier strata. Unit 2 is well distinguishable from Unit 1 only in the offshore area and at the barrier island bounding the Venice Lagoon, and is composed of a prograding marine wedge (up to 10 m thick) that interacts laterally with ebb tidal deltas. Unit 3 consists of a tidal channel complex and inlet deposits, which testify the evolution of the lagoon area. Tidal channels are entrenched in the lagoon mud flat (coeval with Units 1–2) and cut the Pleistocene–Holocene boundary in several places.Following current sequence-stratigraphic concepts, the Holocene sequence is composed of a paralic transgressive systems tract (TST) (Unit 1) overlying a sequence boundary (the Pleistocene–Holocene boundary) and overlain by a marine highstand systems tract (HST) (Unit 2) in seaward locations and by highstand lagoonal deposits landwards. TST and HST are separated by a downlap surface that is amalgamated with a wave ravinement surface in several places. Unit 3 is coeval with the upper part of Unit 2, and its development has been favoured by human interventions, which led to a transgression limited to the lagoon area.Local factors during the deposition, i.e. subsidence, sediment supply, physiography, and current/wave regimes, led to a significant lateral variability in the architecture of the Holocene sequence, as evidenced by the extreme thickness variation of the TST along both depositional strike and dip. The HST, instead, shows less pronounced strike variations in the stratal architecture. Also, present data clearly evidence that the human impact has a great relevance in influencing the late Holocene sedimentation.  相似文献   

14.
The study of past changes in sea level, and of historical and pre-historical coastal evolution, using coastal sediment stratigraphies is well-established over a range of geographic areas, in both seismic and aseismic settings. In the eastern Mediterranean, however, such studies are less common, and, notably, the use of sediment geochemistry, and its combination with lithostratigraphic studies to analyze palaeoenvironmental and palaeo-sea-level change, has not been explored to any significant extent, despite the fact that geochemical data have been successfully used elsewhere to aid in the identification of sea-level changes. Here, we use a combined geochemical, stratigraphic and microfossil approach to reconstruct late Holocene coastal evolution and sea-level change at two sites near Gythio in the southern Peloponnese, Greece. The sites show stratigraphic and geochemical evidence of the presence in Late Helladic times (ca. 1500 BC) of barrier-protected coastal lagoonal/wetland environments, which have gradually infilled over the last ca. 3500 yr. Archaeological remains and ceramic and charcoal-bearing horizons within the sediment sequences indicate Late Roman occupation of the area, although there is no sedimentary evidence of significant pre-Roman activity at the study sites. An apparent brackish wetland peat deposit at − 3.4 m (overlain by anoxic lagoonal clays) at Kamares (Kato Vathi) Bay shows a calibrated radiocarbon age of 1640–1440 BC, suggesting a relative sea-level rise of 0.8–1 mm/yr in this area over the past 3500 yr, in good agreement with previous archaeological and sea-level modelling studies. There is no evidence, based on the stratigraphic, microfossil or geochemical record, of sudden marine flooding events related to local or regional seismic activity, despite the presence of the area in a seismically active zone known to be subject to periodic earthquakes and tsunami. The data highlight the utility of combining geochemical and stratigraphic studies in the reconstruction of coastal evolution and the study of palaeo-sea-level changes, particularly in sequences (such as those described here) where microfossils are poorly preserved.  相似文献   

15.
Holocene deposits exhibit distinct, predictable and chronologically constrained facies patterns that are quite useful as appropriate modern analogs for interpreting the ancient record. In this study, we examined the sedimentary response of the Po Plain coastal system to short-term (millennial-scale) relative fluctuations of sea level through high-resolution sequence-stratigraphic analysis of the Holocene succession.Meters-thick parasequences form the building blocks of stratigraphic architecture. Above the Younger Dryas paleosol, a prominent stratigraphic marker that demarcates the transgressive surface, Early Holocene parasequences (#s 1–3) record alternating periods of rapid flooding and gradual shoaling, and are stacked in a retrogradational pattern that mostly reflects stepped, post-glacial eustatic rise. Conversely, Middle to Late Holocene parasequences (#s 4–8) record a complex, pattern of coastal progradation and delta upbuilding that took place following sea-level stabilization at highstand, starting at about 7 cal ky BP. The prominent transgressive surface at the base of parasequence 1 correlates with the period of rapid, global sea-level rise at the onset of the Holocene (MWP-1B), whereas flooding surfaces associated with parasequences 2 and 3 apparently reflect minor Early Holocene eustatic jumps reported in the literature. Changes in shoreline trajectory, parasequence architecture and lithofacies distribution during the following eustatic highstand had, instead, an overwhelming autogenic component, mostly driven by river avulsions, delta lobe switching, local subsidence and sediment compaction. We document a ∼1000-year delayed response of the coastal depositional system to marine incursion, farther inland from the maximum landward position of the shoreline. A dramatic reduction in sediment flux due to fluvial avulsion resulted in marine inundation in back-barrier position, whereas coastal progradation was simultaneously taking place basinwards.We demonstrate that the landward equivalents of marine flooding surfaces (parasequence boundaries) may be defined by brackish and freshwater fossil assemblages, and traced for tens of kilometers into the non-marine realm. This makes millennial-scale parasequences, whether auto- or allogenic in origin, much more powerful than systems tracts for mapping detailed extents and volumes of sediment bodies.The Holocene parasequences of the Po coastal plain, with strong age control and a detailed understanding of sea-level variation, may provide insight into the driving mechanisms and predictability of successions characterized by similar depositional styles, but with poor age constraint, resulting in more robust interpretations of the ancient record.  相似文献   

16.
通过对东印度洋钻孔CJ01-185的生物硅来探讨东印度洋古生产力的变化和古气候演化的响应。CJ01-185钻孔的生物硅含量在末次冰期最低，为0.86%；而到了全新世晚期生物硅含量达到1.89%。全新世晚期生物硅的堆积速率明显大于末次冰期。随着全新世海平面的快速上升，巽他海峡贯通，来自爪哇海的陆源物质输入到东印度洋，导致全新世的生物硅含量和生物硅的堆积速率增加。研究表明：巽他海峡贯通前，研究区的古生产力主要受东南季风变化和上升流的活动影响；而巽他海峡贯通后，古生产力很明显受到陆源物质输入的控制，东南季风变化和上升流的影响较弱。  相似文献   

17.
Accumulation rates of (marine) organic carbon and estimates of paleoproductivity from organic carbon data indicate distinct late Quaternary glacial/interglacial cycles at Ocean Drilling Program (ODP) Site 646. During the last 240,000 years, surface-water productivity was significantly higher in the northern Labrador Sea during interglacial than during glacial times (70 to 170 gC/m2/yr vs. 30 to 70 gC/m2/yr). The reduced glacial productivity is probably caused by a closed sea-ice cover dominating the northern Labrador Sea during glacial intervals.  相似文献   

18.
2008年在南日群岛东部海域用钻机采集长度为1 004 cm的岩芯样品,测试沉积物中总有机碳（TOC）含量、稳定碳同位素比值（δ13CTOC）、碳氮比值（C/N）、碳酸盐含量以及14C数据,分析其垂直剖面上的变化特征,阐明其沉积环境和古气候的指示意义.沉积物TOC含量变化范围为0.44%～0.74%,垂直剖面上总体显示出末次冰期和全新世中期TOC含量较高,全新世早期相对稳定,而全新世中后期TOC波动范围明显增大.C/N值在5.3～14.9之间变化,平均值为8.1;δ13CTOC值范围为-23.07‰～-21.04‰,表明沉积物中的有机质以海洋自生为主,同时混有部分陆源有机质.碳酸盐含量在3.3%～10.9%之间.TOC含量、C/N比值、δ13CTOC值在岩芯垂直剖面上具有很好的相关性.14C测年数据以及各要素测值在垂直剖面上的变化特征表明：自11 250 aBP以来该海域附近古气候有可能经历了以下4个演化阶段：①11 500～9 000 aBP期间气候寒冷、海平面下降,采样点可能为浅水区或潮间带;②9 000～8 000 aBP期间为升温期,气候由寒冷转向温暖;③8 000～4 300 aBP期间,为相对稳定的暖湿期,在后期气候出现小幅的波动;④4 300 aBP至今,气候进入明显的周期性波动期,暖湿和干冷气候多次交替变化;4 300～3 000 aBP期间为相对寒冷的时期;3 000～1 800 aBP期间为较稳定温暖期,1 800～1 000 aBP期间气温快速降低,标志着研究区进入一个新的寒冷阶段,但是自1 000 aBP以来,气候又再次出现转暖的趋势.  相似文献   

19.
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   

20.
Eric Olausson 《Marine Geology》1991,100(1-4):45-51
Two cores from the Bannock Basin in the eastern Mediterranean have been analysed for δ180 and the δ13C in planktonic foraminifera. One core (02-PC) was extracted from the anoxic brine, the other (08-GC) from a plateau east of the brine.

The absence of sapropelic muds in Core 08-GC from the two Holsteinian euxinic cycles, together with the presence of isotopic spikes, suggests that the plateau has risen during the last ca. 200,000 years by ca. 2.5 mm/yr.

The δ180 amplitude of Globigerinoides ruber in eastern Mediterranean cores is only ca. 0.5%. larger than for this species in North Atlantic cores. This suggests that the surface oxygen isotopic composition of both bodies of water followed each other fairly closely during the Late Pleistocene, except during the stagnant phases.  相似文献   


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