Holocene Marine Deposits Research Articles

Mid-Holocene marine faunas from the Bangkok Clay deposits in Nakhon Nayok, the Central Plain of Thailand.

Based on several field investigations, many molluscan shells and chondrichthyan teeth, together with other invertebrate and actinopterygian remains were found from the marine Bangkok Clay deposits in Ongkharak, Nakhon Nayok, at a depth of ~ 5-7 m below the topsoil surface. Animal macrofossils recovered from these Holocene marine deposits were identified and their chronological context was investigated in order to reconstruct the paleoenvironments of the area at that time. The majority of marine fossils recovered from the site consist of molluscs, with a total of 63 species identified. Other invertebrate species include a stony coral, a mud lobster, barnacles, and a sea urchin. The vertebrates are represented by fish remains, including carcharhinid shark teeth from at least nine species, stingray and trichiurid teeth, and one sciaenid otolith. The molluscan fauna indicates that the paleoenvironments of the area corresponded to intertidal to sublittoral zones, where some areas were mangrove forests and intertidal mudflats. The fish fauna is dominated by the river shark Glyphis, indicating freshwater influences and possibly occasional brackish conditions. The carbon-14 analysis of mollusc and charcoal remains shows that deposition of the marine sediment sequence began during the mid-Holocene, spanning approximately from 8,800 to 5,300 cal yr BP. This study provides in-depth insights into the diversity of fishes, marine molluscs, and other invertebrates from the Bangkok Clay deposits, supporting the existence of a marine transgression onto the Lower Central Plain of Thailand during the mid-Holocene.

Holocene marine deposits in the Bohai Sea: Depocenters, sediment sources, and oceanic and tectonic influences

The Bohai Sea is a semi-enclosed shallow shelf sea that has undergone a unique sediment source-to-sink process in the past. Despite this, our knowledge about the sediment budget, existence of depocenters and the factors controlling depocenter formation during the Holocene remains limited. This paper aims to address these gaps by estimating the Holocene marine deposit thickness and sediment budget in the Bohai Sea using high-resolution subbottom profiles. The results reveal that the mean thickness of Holocene marine deposits is approximately 7.8 m and a maximum thickness of 28 m was found in Jinzhou Bay. The Highstand System Tracts (HST) have a mean thickness of approximately 5.4 m and a maximum thickness of 25 m observed in the Jinzhou Bay. On the other hand, the Transgressive System Tracts (TST) have a mean thickness of approximately 2.5 m and a maximum thickness of 7 m in the north of the Laizhou Bay. The total accumulation in the Bohai Sea is estimated to be ∼713.97 × 109 tons, consisting of 489.28 × 109 tons from the HST and 224.69 × 109 tons from the TST. Three deposit centers were identified and estimated to be approximately 299 × 109 tons, accounting for approximately 42 % of the total Bohai Sea sediments. The development of Holocene marine deposit centers was mainly influenced by the Tanlu Fault zone and water circulations. Based on preliminary estimates, it is suggested that roughly half of the sediments dispersed from the estuaries are preserved on the Bohai Sea shelf since the maximum flooding (∼7000 cal yr BP). This research provides valuable insights for the post-glacial sedimentary and geomorphic evolution of the Bohai Sea.

Mid and Late Holocene sea level variations in the Canary Islands

The eastern coast of Fuerteventura (Canary Islands, Spain) hosts the most complete and representative emergent Holocene marine deposits in the middle latitudes (27°N to 30°N) of the eastern Atlantic Ocean. The deposits consist of berms of gravel and foreshore sands which form beach rocks comprising >62 bed sets, with each bed set containing dozens of individual laminations suggesting a cyclical cause as, for example, the orbital movement of the Earth. Calibrated radiocarbon ages place a group of older Holocene highstands of Fuerteventura at around the Mid-Late Holocene boundary (around 4.2 kyr B.P.), and another group of more recent highstands in the Dark Age Period (around 1.4 kyr B.P.) of the Northern Hemisphere. They have been recorded at 4 m and 3.5 m apmsl respectively. The present-day tidal amplitude is around 3 m. Assuming a similar value for the Holocene, the corresponding relative sea level rises were around 2.5 m and 2 m apmsl respectively. Moreover, terrestrial deposits intercalated between the marine deposits indicate a lowering of the sea level at ca. 3 kyr B.P. When the sea levels reached their highstands during these two periods, the sea surface temperatures (SST) at the southern tip of the cold Canary Current were, respectively, 0.5 and 1.5 °C colder than the present-day SST (21.23 °C). The fossil fauna content confirms that these highstands occurred in cold conditions. In contrast, the present SST reaches the range of temperatures of the Holocene Optimum in the area.Fuerteventura has been vertically stable since the last interglacial period, and the sedimentology of the deposits precludes an origin from tsunamis or storms. This island is in a far-field region in terms of glacial isostatic adjustment (GIA) processes. Here, we suggest that the deposits may be related to GIA and ice mass losses effects in the Southern Hemisphere.

Holocene tephra from the Chukchi-Alaskan margin, Arctic Ocean: Implications for sediment chronostratigraphy and volcanic history

Developing chronologies for sediments in the Arctic Ocean and its continental margins is an important but challenging task. Tephrochronology is a promising tool for independent age control for Arctic marine sediments and here we present the results of a cryptotephra study of a Holocene sedimentary record from the Chukchi Sea. Volcanic glass shards were identified and quantified in sediment core HLY0501-01 and geochemically characterized with single-shard electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This enabled us to reveal a continuous presence of glass shards with identifiable chemical compositions throughout the core. The major input of glasses into the sediments is geochemically fingerprinted to the ∼3.6 ka Aniakchak caldera II eruption (Alaska), which provides an important chronostratigraphic constraint for Holocene marine deposits in the Chukchi-Alaskan region and, potentially, farther away in the western Arctic Ocean. New findings of the Aniakchak II tephra permit a reevaluation of the eruption size and highlight the importance of this tephra as a hemispheric late Holocene marker. Other identified glasses likely originate from the late Pleistocene Dawson and Old Crow tephras while some cannot be correlated to certain eruptions. These are present in most of the analyzed samples, and form a continuous low-concentration background throughout the investigated record. A large proportion of these glasses are likely to have been reworked and brought to the depositional site by currents or other transportation agents, such as sea ice. Overall, our results demonstrate the potential for tephrochronology for improving and developing chronologies for Arctic Ocean marine records, however, at some sites reworking and redistribution of tephra may have a strong impact on the record of primary tephra deposition.

Groundwater salinity influenced by Holocene seawater trapped in incised valleys in the Red River delta plain

Brackish to salty waters have been found in inland areas of delta aquifers. Geophysical data and modelling suggest that salty groundwater in the Red River delta originates from trapped seawater contained in underlying Holocene marine deposits.

Bioeroded boulders in Holocene marine deposits of the Bahía Blanca Estuary: palaeoenvironmental considerations and provenance

On the north shore of the Bahia Blanca estuary, Buenos Aires, Argentina, sand shell ridges composed by a high proportion of boulders of sedimentary origin are present. Many of these clasts show significant signals of bieorosion. The procedence of this material is linked to the extensive abrasion platforms present to the east of the estuary (coasts of Pehuén Co). Two ichnofacies were established: Trypanites ichnofacies comprising Gastrochaenolites, Maeandropolydora, Trypanites, Gnathichnus and Radulichnus, typical of hard substrates and Skolithos ichnofacies represented by Ophiomorpha galleries developed in soft substrates. Both characterize a shallow coastal environment. During the Holocene transgression, coastal substrates were affected by the advancing sea and eroded fragments were transported by littoral drift into the estuary. Finally, storm events deposited material with signs of bioerosion in the littoral ridges. Today, many of these boulders, which exhibit gradations in size into the estuary, are in transit across the beaches by east-west littoral drift.

Fluvial terrace formation in the lower Awhea and Pahaoa River valleys, New Zealand: implications for tectonic and sea-level controls

Altitudes and ages of fluvial terraces along the lower Awhea and Pahaoa River valleys are compared with the altitudes and ages of Holocene marine deposits and terraces in the actively uplifting southern Hikurangi Margin, New Zealand. From these, we infer fluvial terrace formation processes and examine implications for controls on river behaviour and the likely mechanism of uplift. Both river valleys contain a prominent fill terrace (PgT) radiocarbon dated at 10,000–8000cal. y BP, which formed in response to the rapid estuary infilling during the late stage of post-glacial sea-level rise. Older and younger terraces are primarily degradation terraces, with the exception of the oldest terraces mapped, which are fill terraces inferred to date from the Last Glacial Coldest Period. These results show the Awhea and Pahaoa Rivers respond to a number of competing controls including climate, tectonics, sea-level and anthropogenic (land use) changes, gradient and valley width. The influence of tectonic uplift can be isolated and Holocene marine terraces, estuarine deposits and the PgT tread altitudes are used to constrain the single-event displacement and slip rate of the submarine Palliser-Kaiwhata Fault, of 2–5m and 2.5±1mm/y, respectively. The results also provide insight into likely future response of rivers such as the Awhea and Pahaoa to sea-level rise and tectonic uplift.

First hydroacoustic evidence of marine, active fluid vents in the Naples Bay continental shelf (Southern Italy)

We present the first results of a multidisciplinary research aimed at the detection and mapping of Active Fluid Vents (AFVs) at the seafloor of the Naples Bay, Italy. This segment of the Campania continental margin is characterised by severe Quaternary extension and intense volcanism at Ischia and Procida islands, the Campi Flegrei and Somma–Vesuvius volcanic complexes. High resolution hydroacoustic profilers were used to identify and localize fluid emission from the seafloor. ROV direct observation showed that each emission centre is generally composed by the coalescence of several emitting points. CTD probes showed that there are no significant gradients in temperature profiles. The results of this study include the detection and mapping of 54 fluid emission points all located in the −71/−158m depth range, and spatially distributed into four main clusters. Three of the described clusters are located along the margin of a complex, toe-shaped seafloor morphology southwest of the Somma–Vesuvius, representing the shallow expression of partly buried, coalesced depositional features (namely, two flank collapses and one pyroclastic flow) associated with the Late Pleistocene activity of the volcano. The fourth AFV cluster was detected at the morphological - high, located about 8km south of Naples (Banco della Montagna), represented by a field of volcaniclastic diapirs composed of massive pumiceous deposits originated from the Campi Flegrei intruding rising through the latest Quaternary–Holocene marine deposits. Our study suggests that the occurrence of AFV in this area could be genetically linked to the interaction between volcanic related seafloor morphologies and the main, NE striking faults present in the area, i.e. the Magnaghi-Sebeto line and the Vesuvian fault.

Late Pleistocene and Holocene uplift history of Cyprus: implications for active tectonics along the southern margin of the Anatolian microplate

Abstract The nature of the southern margin of the Anatolian microplate during the Neogene is complex, controversial and fundamental in understanding active plate-margin tectonics and natural hazards in the Eastern Mediterranean region. Our investigation provides new insights into the Late Pleistocene uplift history of Cyprus and the Troodos Ophiolite. We provide isotopic ( 14 C) and radiogenic (luminescence) dates of outcropping marine sediments in eastern Cyprus that identify periods of deposition during marine isotope stages (MIS) 3, 4, 5 and 6. Past sea-levels indicated by these deposits are c. 95±25 m higher in elevation than estimates of worldwide eustatic sea-level. An uplift rate of c. 1.8 mm/year and possibly as much as c. 4.1 mm/year in the past c. 26–40 ka is indicated. Holocene marine deposits also occur at elevations higher than those expected for past SL and suggest uplift rates of c. 1.2–2.1 mm/year. MIS-3 marine deposits that crop out in southern and western Cyprus indicate uniform island-wide uplift. We propose a model of tectonic wedging at a plate-bounding restraining bend as a mechanism for Late Pleistocene to Holocene uplift of Cyprus; uplift is accommodated by deformation and seismicity along the margins of the Troodos Ophiolite and re-activation of its low-angle, basal shear zone. Supplementary material: An expanded description of the procedures used in determining OSL ages for samples given in Table 2 is available at www.geolsoc.org.uk/SUP18533 .

Palinología y palinofacies de una secuencia marina del Holoceno medio-tardío: Albufera Lanushuaia, Canal Beagle, Tierra del Fuego, Argentina

PALYNOLOGY AND PALYNOFACIES OF A MIDDLE-LATE HOLOCENE MARINE SEQUENCE: ALBUFERA LANUSHUAIA, BEAGLE CHANNEL, TIERRA DEL FUEGO, ARGENTINA. Palynological analysis, with emphasis on palynofacial analysis was carried out on Holocene marine deposits located on the northern coast of the Beagle Channel, Argentina. This analysis allowed paleoenvironmental assessments and paleoclimatic inferences. A fossil section from Albufera Lanushuaia (54°52'04.4S-67°60'44.9O), located on the northern coast of the Beagle Channel was analyzed. The set of particulate organic matter indicate the proximity of the area of continental input to the marine environments, with distances and/or times of transport relatively short. The presence of pyrite suggests reducing conditions, probably associated with marginal-marine environments. At the Albufera Lanushuaia, from the ca. 5,800 years 14 C BP, palynological associations reveal the same pattern of regional vegetation with a closed forest of Nothofagus and an assemblage of Peridiniales dinocysts dominated by taxa that suggest marginal-marine environments, with low to moderate salinity and high nutrient concentrations in shallow marine waters, probably due to the contribution of freshwater due to surface runoff. For the past 3,000 years, a decrease in pollen records of Nothofagus and an increase in shrub and herb pollen with a limited occurrence of aquatic palynomorphs were observed. These reflects the development of a more open forest and adjacent areas of herbaceous and shrub with marginal-marine influence, associated to a regressive event.

Late Pleistocene and Holocene chitons (Mollusca, Polyplacophora) from Uruguay: Palaeobiogeography and palaeoenvironmental reconstruction in mid latitudes of the southwestern Atlantic

Here we present a revision of the fossil record of chitons (Mollusca, Polyplacophora) of Late Pleistocene and Holocene marine deposits of Uruguay and discuss their potential for palaeoenvironmental reconstruction. Chitons were recorded as isolated valves in bivalve- and gastropod-rich assemblages. They are represented by the species Chaetopleura angulata (Spengler), C. isabellei (d’Orbigny), C. asperrima (Gould) and Ischnochiton striolatus (Gray). The last two species are recorded for the first time as fossils not only in Uruguay but also in South America. Exclusively recorded for the Late Pleistocene is the warm water species I. striolatus, whose current southern range limit is located in Santa Catarina, Brazil. Higher temperatures than at present are inferred for the Uruguayan coast during the Late Pleistocene, probably driven by the southward influence of the warm Brazilian Current along the eastern margin of South America. Chitons from Holocene deposits show a wider geographic distribution along the Uruguayan coast in comparison to current distributions. They are recorded where an estuarine and eurihaline fauna lives today, which suggests the former existence of marine conditions. This is explained by the westward displacement of the marine front in the Uruguayan coast during the Holocene transgressive events. Chitons have proven to be useful palaeoenvironmental proxies for the reconstruction of salinity and temperature trends in the Uruguayan coast during the climatic oscillations of the Late Pleistocene and Holocene epochs. As such, their patterns of distribution are related to the recent physical evolution of the Southwestern Atlantic Ocean.

First Quaternary fossil record of Polyplacophorans from southern South America

A diverse assemblages of well-preserved polyplacophoran shell plates is present in Holocene marine deposits along the Beagle Channel, Tierra del Fuego (54°S). They represent the first fossil Quaternary report of polyplacophorans from southern South America. The taxa include Callochiton puniceus (Couthouy MS, Gould), Plaxiphora aurata (Spalowsky), Plaxiphora sp., Tonicia atrata (Sowerby), Tonicia calbucensis Plate, Tonicia chilensis (Frembly), and Tonicia lebruni de Rochebrune. The presence of these taxa in a transitory area between the Atlantic and the Pacific oceans suggests that, in the recent past, the Beagle Channel acted as a path that facilitated faunal dispersion between the two oceans. These records also show an apparent stability of these faunas over a period of several thousand years (from ca. 7500 years BP to present).

Holocene activity of the Scilla Fault, Southern Calabria: Insights from coastal morphological and structural investigations

Integration of on-land and offshore geomorphological and structural investigations coupled to extensive radiometric dating of co-seismically uplifted Holocene beaches allows characterization of the geometry, kinematics and seismotectonics of the Scilla Fault, which borders the eastern side of the Messina Strait in Calabria, Southern Italy. This region has been struck by destructive historical earthquakes, but knowledge of geologically-based source parameters for active faults is relatively poor, particularly for those running mostly offshore, as the Scilla Fault does. The ∼ 30 km-long normal fault may be divided into three segments of ∼ 10 km individual length, with the central and southern segments split in at least two strands. The central and northern segments are submerged, and in this area marine geophysical data indicate a youthful morphology and locally evidence for active faulting. The on-land strand of the western segment displaces marine terraces of the last interglacial (124 to 83 ka), but seismic reflection profiles suggest a full Quaternary activity. Structural data collected on bedrock faults exposed along the on-land segment provide evidence for normal slip and ∼ NW-SE extension, which is consistent with focal mechanisms of large earthquakes and GPS velocity fields in the region. Detailed mapping of raised Holocene marine deposits exposed at the coastline straddling of the northern and central segments supplies evidence for two co-seismic displacements at ∼ 1.9 and ∼ 3.5 ka, and a possible previous event at ∼ 5 ka. Co-seismic displacements show a consistent site value and pattern of along-strike variation, suggestive of characteristic-type behaviour for the fault. The ∼ 1.5–2.0 m average co-seismic slips during these events document M e ∼ 6.9–7.0 earthquakes with ∼ 1.6–1.7 ka recurrence time. Because hanging-wall subsidence cannot be included into slip magnitude computation, these slips reflect footwall uplift, and represent minimum average estimates. The palaeoseismological record based on the palaeo-shorelines suggests that the last rupture on the Scilla Fault during the February 6, 1783 M w = 5.9–6.3 earthquake was at the expected time but it may have not entirely released the loaded stress since the last great event at ∼ 1.9 ka. Comparison of the estimated co-seismic extension rate based on the Holocene shoreline record with available GPS velocities indicates that the Scilla Fault accounts for at least ∼ 15–20% of the contemporary geodetic extension across the Messina Strait.

Seismic stratigraphy of Late Quaternary deposits in the eastern Skagerrak

High-resolution seismic profiles from the Swedish west coast divide Quaternary deposits into six seismic sequences, containing 13 different seismic facies. Documentation of these sequences and facies and their stratigraphic and geographic variability is the first step in a basin-fill analysis to interpret depositional environments and major controlling processes. The deposits are attributed to one deglaciation cycle. The seismic sequences are: (I) bedrock, (II) coarse glacial deposits, (III) Weichselian glacimarine ice-proximal deposits, (IV) Weichselian glacimarine ice-distal deposits, (V) channel fill deposits and (VI) Holocene marine deposits. The major part of the sediment package is the Weichselian glacimarine ice-proximal deposits, deposited during the ice recession period, close to or adjacent to the retreating ice. Typical appearances for these deposits are conformably well-stratified deposits with high amplitude. The second largest sequence consists of Holocene marine deposits and these are mainly found in the southern part of the study area. They have typically a near-transparent seismic configuration with only weak parallel stratification. These two major sequences are separated by a regional nonconformity, creating a hiatus of at least 6000 years. The hiatus was formed when strong bottom currents related to the cyclonic under-water circulation in the Skagerrak started to influence the area. Later the conditions changed, reducing the erosional effect of the bottom currents, allowing new sedimentation in the southern part while the northern part is still exposed to erosion.

Late Quaternary stratigraphy and morphogenesis in the Danish eastern North Sea and its relation to onshore geology

AbstractGeological structures and Late Quaternary stratigraphy of the shallow subsurface along the southernmost Danish North Sea coast have been investigated using seismic data and shallow boreholes. A large-scale glaciotectonic thrust complex has been mapped in an area of 15 km by 40 km in the Fanø Bugt area. The affected succession consists of Neogene and Quaternary sediments deformed down to a depth of 200 – 360 m. A kineto-stratigraphic correlation to onshore glaciotectonic deformation suggests that the deformation took place during a westward advance stage of the Late Saalian (Warthe) glaciation. The western limit of the glaciotectonic structures constitutes an N-S striking deformation front situated 35 km off the west coast. Based on the glacial stratigraphy outside the deformation front, it is suggested that the same ice advance that caused the glaciotectonic deformation, eroded the top of the thrust sheets, and subsequently deposited a lower unit of meltwater sediments and an upper heterogenous glacigenic unit. The upper glacigenic unit forms a bank about 30 km offshore. Between the bank and the shore, the surface of the Saalian glacial landscape forms a wide depression ca. 50 m below sea level. This basin has controlled deposition in the area since the late Saalian and is filled with sediments of late Saalian, Eemian, Weichselian and Holocene age. The base of the Holocene marine deposits is thus a flat erosional surface extending eastward several kilometres below the onshore coastal areas and the northern Wadden Sea. This surface was transgressed 8800 years ago. An inverted, in plan view T-shaped, Holocene sand accumulation approximately 25 km long, 30 km wide and 15 – 25 m thick is situated on top of this surface at Blåvands Huk. According to recent estimates by the Danish Coastal Protection Board some 2.5 million m3sediments are supplied annually to the system from the north. In the last 3000 years, 25 km of the west coast and the associated shoreface slope have prograded ca. 3 km towards the west forming a barrier spit complex. Large aeolian dunes and cover sands now conceal the spit complex. Extending twenty km west of Blåvands Huk is a highly dynamic bank, the Inner Horns Rev, with active sand-accumulation on the slopes. The Inner Horns Rev bank has grown ca. 3.5 km westward during the last 800 years. The deposits seem to be sourced by the coastal longshore sand transport from the north. The Outer Horns Rev was previously assumed to be a Saalian terminal moraine. However, this investigation reveals that it is also mainly a Holocene marine accumulation landform, but sourced from the west. Other sand accumulations, which are situated 20 – 30 km west of the coast, are probably sourced from both the south and the west.

Natural and anthropogenic patterns of covariance and spatial variability of minor and trace elements in agricultural topsoil

The aim of this study is to analyze the sources of variation in soil geochemical composition related to spatial scale and sampling procedure. Apart from an intrinsic interest, research was motivated by practical questions regarding sampling strategies for regional soil surveys. An unbalanced nested sampling design, based on single samples, was implemented at Walcheren/Zuid-Beveland, an agricultural area in the south-west of the Netherlands. This polder landscape consists of Holocene marine deposits. The samples were digested with aqua regia and analyzed by ICP-MS. The resulting data for 40 elements were examined through principal component analysis in combination with varimax rotation (PCA-V), unbalanced analysis of variance (UANOVA) and a fuzzy c-means clustering of the UANOVA results. The increase in noise when using single samples was further assessed through comparison with results of a previous study in the area based on composite samples. The three factors of the PCA-V are interpreted as being the results of natural, human, and geohydrological processes. The UANOVA analysis makes a different grouping into three spatial variance patterns. Two groups show a gradual increase of variance with distance and contain respectively clay/feldspar related elements and heavy rare earth related elements. The third group encompasses all anthropogenically and geohydrologically influenced elements with a larger part of the variance at small scales. In general regional variance predominates over local variance and the extra effort of compositing is of limited value for a regional survey. However, environmental priority metals like Cd, Cu, Pb, Sb, Sn and Zn, were found to have larger local variance components. For these elements, compositing is relatively more beneficial.

Structural and physiographic control on the Holocene marine sedimentation in the bay of Cadiz (SW Spain)

The Quaternary tectonic activity in the Gulf of Cadiz has considerably influenced the depositional regime and distribution of Holocene marine deposits. The aim of this work is to determine the nature of the recent sedimentary filling in the Bay of Cadiz sea bottom and adjacent continental shelf and to establish the main controlling factors on the Holocene marine sedimentation. The sedimentary record indicates siliciclastic sedimentation supplied from the continent, with alternating episodes of high and low sedimentation rates. The recent sedimentary evolution of this marine area was controlled by the Late Quaternary eustatic fluctuations. Bathymetric, geophysical and drilling data have been employed to prepare a detailed isopach map of the non-consolidated recent sedimentary cover. Thickness distribution shows significant variations related to the infilling of former fluvial palaeochannels incised during the Late Pleistocene lowstand, and highly controlled by the structural neotectonic trends of faults and joints: NNW-SSE, NNE-SSW and ENE-WSW. The general distribution of isopachs in this area is clearly influenced by these morphostructural lines, which controlled the sedimentary processes during the Holocene. These results are coherent with the main regional neotectonic structures previously described in the nearby continental area, and confirm their prolongation towards the marine domain.

Factors affecting trace element concentrations in soils developed on recent marine deposits from northern France

Total concentrations of 18 trace and 2 major elements (Al, Fe) as well as physico-chemical characteristics (texture, organic C, pH, CaCO 3, CEC) were measured in cultivated soil samples (fraction <2 mm) from 23 surface and 38 deeper horizons developed in recent marine deposits. Correlations between trace element contents and other soil parameters were compared in order to reveal those soil factors affecting the trace element distributions. Whatever the horizon type, Co, Cr, In, Ni and V are almost exclusively associated with the fine (<20 μm) mineral fraction and do not show a direct association with organic matter. Bismuth, Sn, Tl and Zn also show a close association with the fine mineral fraction of the deep horizons, but seem to be partly associated with organic matter in the ploughed horizons. In the deep horizons, the association of Cd, Cu and Pb with the fine mineral fraction is clearly less close, while these elements appear to be associated with organic matter in the ploughed horizons. The Mn content increases with that of the fine mineral fraction up to a certain point. Arsenic, Mo and Sb contents are poorly correlated with the fine solid phase of the deep horizons. The distribution of Hg does not appear to be associated with any specific soil component. The ploughed horizons are highly enriched with Pb, Cu, Cd, Hg and Se (+84% to +225%) and moderately enriched with Tl, Mn, Sb, Bi, Sn and Zn (+7% to +48%). There is no surface enrichment of As, Co, Cr, In, Mo, Ni and V. It is possible to model most of the trace element distributions with pedotransfer functions of the physico-chemical characteristics.

Late quaternary marine deposits of the Paraguana Peninsula, state of falcon, northwestern Venezuela: Preliminary geological observations and neotectonic implications

Abstract Four marine terraces are identified on Paraguana at +80 m, +40–50 m, +15–20 m and +6 m, skirting the ‘inselberg’ of cerro Santa Ana. Besides the Holocene marine deposits, patches of correlative sediments are only associated with the two youngest terraces within a narrow strip along the seashore because older Quaternary marine terraces are mainly erosional surfaces that truncate the uppermost limestone of the Pliocene Paraguana formation. Diverse marine deposits are observed between seashore and +5–6 m: sand barriers, mud flats, salt flats, stromatolites mats, coquinas and coral reefs in living position. Some of these facies are undoubtfully Holocene, but some others proved to be older than the 14 C dating limit. Therefore, the latter ones should be ascribed to isotope-stage 5, but further sampling and dating are required to confirm their chronology. It is worth mentioning that probable stage-5 facies of Paraguana are as high as its worldwide undeformed equivalents, implying a certain tectonic stability during late Pleistocene. However, the assumption of a stable Paraguana block has to be modified since the existence of staircased marine terraces implies a certain amount of uplift, even if it is rather slow (≤ 0.8 mm/year).

An Extant Whale Barnacle (Cirripedia, Coronulidae) From Holocene Deposits of Buenos Aires (Argentina)

Cetopirus complanatus is recorded for the first time in the southwestern Atlantic Ocean, viz., as a fossil. It was collected in holocene marine deposits along the coast of Buenos Aires. The species at present lives, attached to specimens of the Right Whale, usually in Subantarctic waters.