Pliocene Marls Research Articles

Investigating the impact of urban development on the activation of a paleolandslide. A case study from Pissouri, Cyprus

The present study investigates the reactivation of a paleolandslide due to the expansion of a community in an area covered by plastic Pliocene marls in the southwestern part of Cyprus. The landslide, which takes place in an area with gently sloping ground and relatively shallow water table, affects more than 100 residential buildings. In the context of the study, building damages and ground surface ruptures were mapped through field work campaigns. Remote sensing data from InSAR (Interferometric Synthetic Aperture Radar) analysis were evaluated in conjunction with available geological, geotechnical and hydrogeological data. Subsequently, the landslide was backanalyzed using the finite element method to examine possible failure mechanism scenarios and shed light on the influence of potential triggering factors. The results indicate that the paleolandslide has been almost fully reactivated, with the main cause of the reactivation being the rising of the phreatic water table due to long-term discharges of wastewater through the absorption pits of the residential developments. The water table rise was further amplified by rainwater infiltration during rainy years. According to the backanalysis results, the slip surface follows the bedding planes of weak marl horizons with residual friction angle of the order of 10°.

New insights on the latest Messinian-to-Piacenzian stratigraphic series from the Dahra Massif (Lower Chelif Basin, Algeria): Lago Mare, reflooding and bio-events

Geological investigations carried out on the Dahra Massif have revealed sedimentary changes and bioevents characterizing the post-gypsum detrital sediments (from Messinian to Piacenzian), which are followed by the Trubi equivalent Pliocene marls or white marly limestones. Structured into two superimposed steps, the late Messinian deposits yielded two successive ostracod assemblages. They indicate a brackish environment for the lower and a fairly open shallow brackish environment for the second. Based on their ostracod content, assemblage 1 (Cyprideis, Loxoconcha muelleri) corresponds to the Lago Mare biofacies 1 of the Apennine foredeep, which is correlated with the Lago Mare 1 episode dated between 5.64 and 5.60 Ma. Assemblage 2 (Loxocorniculina djafarovi) is referred to the Lago Mare biofacies 2 described in the same region. It is correlated with the Lago Mare 3 episode, dated between 5.46 and 5.33 Ma. Moreover, the stratigraphic succession is marked by a major discontinuity indicated by a hardground, separating step 1 from step 2 and corresponding to the ostracod assemblages 1 and 2, respectively. This discontinuity is considered here to be equivalent to the Messinian Erosional Surface, already evidenced in the region and widely known around the Mediterranean Basin. These late Messinian deposits and their ostracod assemblage 2, notably the detrital sedimentation with Ceratolithus acutus, Globorotalia margaritae, Reticulofenestra cisnerosii document a marine incursion into the Lower Chelif Basin, corresponding to the latest Messinian marine reflooding of the Mediterranean Basin, that happened before the earliest Zanclean R. cisnerosii occurrence. Finally, the bioevents evidenced in the Dahra Massif, reinforce the evidence of the late Messinian Lago Mare 3 episode, and support the ante-Zanclean age of the marine reflooding of the Mediterranean. The overlying deposits are marked by coral constructions (cf. Cladocora cf. caespitosa, Dendrophyllia sp) never described before and covering the entire early Zanclean, testifying the existence, at that time, of warm enough conditions, which may correspond to the marine isotopic stage TG5.

Swelling and collapse behavior of expansive marl and its implications in foundation engineering

Expansive soils increase their volume upon wetting, but under high vertical stresses may exhibit collapse, with the latter aspect being rather overlooked in foundation engineering. Oedometer swelling/collapse tests on expansive Pliocene marls of various calcium carbonate content and plasticity index sampled from Nicosia, Cyprus, indicate that, unlike the free swelling strain, the swelling pressure is rather insensitive to the initial degree of saturation. Consequently, significant collapse strains upon wetting are not unlikely to occur in practical situations. The paper discusses the implications of this behavior in the case of shallow foundations and proposes methods of analysis. Under certain conditions, foundation design based on settlement calculations that use as input the fully saturated soil properties may be unconservative and supported structures may be exposed to severe risk of damage. For the design of mat foundations, stepwise distributions of the equivalent modulus of subgrade reaction across the mat as a function of the average bearing pressure are proposed based on the results of coupled finite element simulations. These distributions allow prediction of the peak bending moments produced at the end of the wet and dry seasons due to ground swelling and shrinkage, respectively, for the climatic conditions of Cyprus.

Tindaria kretensis n. sp., a new deep water protobranch (Bivalvia) from the Early Pliocene of Crete (Southern Greece)

Tindaria kretensis n. sp., a minute deep-water protobranch, is described from Early Pliocene marls cropping out in the Voutes section, northern Crete Island. This is one of the few fossil records of Tindaria from the Mediterranean area, the first well documented for the Neogene. Tindaria is an almost cosmopolitan deep-water genus, absent from the modern Mediterranean. Its occurrence in the Early Pliocene is in agreement with what is known about the past psychrospheric conditions in the Mediterranean.

Late Quaternary beach deposits and archaeological relicts on the coasts of Cyprus, and the possible implications of sea-level changes and tectonics on the early populations

Abstract Late Pleistocene beach deposits in 22 selected sites around Cyprus demonstrate the vertical changes in the Earth's crust in that island over the last 125 ka. The beach/shallow-marine deposits were observed on the abraded coastal cliffs at 3–22 m above the present sea-level. They overlie Pliocene marls, and some of them contain the Senegalese marine gastropods Persististrombus latus , Bursa granularis and Conus ermineus that no longer live in the Mediterranean. These are index fossils for the Marine Isotope Stage (MIS) 5e in the Mediterranean and, as such, suggest an uplift of up to 15.5 m over about the last 125 ka: that is a maximal rate of 0.12 mm a −1 . These findings are in accordance with Holocene beachrocks, abrasion platforms, wave notches and Roman/Byzantine fish tanks that retained their elevations, and thus enable the reconstruction of the coast encountered by the early colonizers. While the maximal uplift since the early Holocene has been minor and did not exceed 1.2–1.5 m, the sea-level changes have reached 40–50 m. The transition between the impermeable Pliocene marls and the porous Late Pleistocene deposits above them is the origin of freshwater springs and associated vegetation. The early colonizers seemed to recognize the potential of that essential permanent source of water and excavated wells, the earliest wells known so far. The locations of the Early Neolithic settlements (Mylouthkia and Akanthou) adjacent to visible water springs along the coastal cliffs may not be incidental. Not surprisingly, recent wells dug in the coastal Pleistocene deposits rely on the very same hydrological setting. Supplementary material: Appendices 1–4, which include tables and diagrams showing the vertical changes (m) and rates of vertical changes (mm ka −1 ), assuming that MIS5e isotope stage deposits are 122 ka old and are at elevation of 7.2 m asl, or 116 ka at 6.5 m, are available at http://www.geolsoc.org.uk/SUP18830 .

An Integrated Methodological Approach for Source-Clay Determination of Ancient Ceramics: The Case of Aegina Island, Greece

AbstractA new model is proposed for analysis of the source clays used to create ceramics, based on geographic, petrographic, mineralogical, mineral-chemistry, and geochemical criteria. The development of this model became feasible after the discovery of a Pliocene volcanic clay horizon on NWAegina Island, Greece. The volcanic clay contains smectite, mixed-layer chlorite-smectite, biotite, and palygorskite and has greater feldspar content than the underlying Pliocene marls, which contain R0 mixed-layer illitesmectite, mica, dolomite, serpentine, talc and gypsum, and, in some places, palygorskite. The two units have distinct geochemical characteristics. In general the Pliocene volcanic clay is richer in SiO2, Al3O3, and Fe2O3 and poorer in Na2O, MgO, and P2O2 than the Pliocene marls. The Nb, Zr, Hf, Th, and rare earth element (REE) contents are also significantly greater in the Pliocene volcanic clay and comparable to those of the dacitic rocks of the island, reflecting the volcanic origin of the clay.The proposed model was used to identify the source-clay materials that were used for the production of ceramics on the island of Aegina (Aeginetan Ware). All five criteria should be considered in any provenance study. The use of individual criteria on their own can lead to ambiguous conclusions. In the present study the geochemical criterion was particularly helpful. It provided robust evidence for the nature of the source clay. The Pliocene volcanic clay horizon and the underlying Pliocene marls are the candidate raw materials for Aeginetan Ware. Although the Pliocene marls have been invoked as raw materials for Greek Bronze Age (~3000–1100 BC) Aeginetan ceramics and are used as raw materials by modern Aeginetan ceramists, the geochemical characteristics of a large set of Bronze Age Greek Aeginetan sherds with fine and coarse fabrics coincide with those of the Pliocene volcanic clay. This comparative and cumulative evidence suggests that the Pliocene volcanic clay was the main source clay for ancient Aeginetan ceramics, regardless of the fabric (coarse or fine) and that admixture of different sources might not be necessary for fine-grained ceramics.

New species of dinoflagellate cysts from the Bou Regreg Core: a Miocene-Pliocene boundary section on the Atlantic Coast of Morocco

The Bou Regreg borehole section is situated a few kilometers north of Rabat, in northwestern Morocco, at the western end of the Rifian Corridor. The Bou Regreg core penetrates 185 m of Late Miocene to Pliocene marls (chrones 7 to Gilbert). Palynological study of 180 samples from the core revealed extremely abundant and diverse dinocyst assemblages. In contrast, spore and pollen assemblages were sparse. The purpose of this paper is to document one new genus and seven new species of dinocysts, including: Capisocysta wallii Warny et Wrenn, gen. et sp. nov., Hystrichosphaeropsis somphosa Warny et Wrenn, sp. nov., Impletospheridum acropora Warny et Wrenn, sp. nov., Operculodinium floridium Warny et Wrenn, sp. nov., O. oriensum sp. nov., Spiniferites falcipedius Warny et Wrenn, sp. nov. and Barssidinium olymposa Warny et Wrenn, sp. nov. The occurrence of some of these taxa in correlative sections (in the Gulf of Mexico, in the Caribbean Sea etc.) suggest that they are biostratigraphically useful for correlation (Warny and Wrenn, 1996).

The Dead Sea Rift: lateral displacement and downfaulting phases

A sinistral strike slip of 105 km along the Dead Sea Rift is confirmed by the continuity in the restored trend of Eocene sedimentary belts. Yet, the similar characteristics on either side of the Rift between the Upper Miocene conglomerates, mudstones and lithographic limestones (particularly the Kefar Gil'adi Fm.) and the Pliocene marls, oolitic limestones and basalts (e.g., Bira Fm., Gesher Fm., Cover Basalt) raise doubts as to whether a major lateral slip occurred after the end of the Upper Miocene or even during that epoch. The master fault along which motion took place runs through the middle of the Jordan Valley, on the western side of the Hula Valley, through the Metulla saddle and the Ayoun Valley, and merges with the Yammunneh Fault. Major phases mainly of downfaulting occurred: (1) during the Middle and at the beginning of the Upper Miocene (Hordos Fm. and post Hordos); (2) subsequent to deposition during the Upper Miocene and Pliocene; and (3) towards the end of the Lower Pleistocene (post Ubediye and Mishmar HaYarden fms.), when tilting and folding within the Rift marked the last significant stage of its formation.

The enigmatic Messinian-Pliocene section of Cuevas del Almanzora (Vera Basin, SE Spain) revisited—erosional features and strontium isotope ages

The Cuevas del Almanzora section was, in the late seventies, the focus of a discussion because of alleged continuous marine Messinian to Pliocene sedimentation. However, a discontinuity has been shown to exist in the shape of laminated strata including the late Messinian brackish/ lacustrine “Lago Mare” biofacies. More recently, Benson and Rakic-El Bied (1991) concluded that the section is still one of the best biostratigraphic successions for the western Mediterranean in which to document terminal Miocene events, but that it entirely has an early Messinian age (i.e. it antedates deposition of the main evaporites). This paper presents strontium isotope ages indicating that the “classic” threefold division in an earlier marine Messinian, a “Lago Mare”, and a Pliocene interval (sensu Geerlings et al., 1980; Cita et al., 1980) should be maintained. Moreover, the Sr isotopic composition of the euryhaline Cyprideis ostracodes from the “Lago Mare” laminites is similar to those from central Mediterranean basins. This stresses the importance of late Messinian water exchange between the Vera Basin and the then enclosed Mediterranean. It thus refutes the opinion of Benson and Rakic-El Bied (1991) that this interval is a local facies, of no particular stratigraphic importance. A time gap of up to ∼0.8 Ma between the youngest marine strata of the Messinian and the overlying Pliocene provides a maximum timing for the duration of the Messinian salinity crisis during which very little net sedimentation occurred, compared to coeval deposits in, for example, the nearby Nijar and Sorbas basins. In the Cuevas section an inconspicuous, and hitherto overlooked, erosional gap has been observed. This separates the “Lago Mare” marls from the Pliocene marls. More field observations have been made and are discussed in the light of existing interpretations, in order to demonstrate the importance of more widespread erosion in the Vera Basin. Gypsum-containing mass-flow deposits, filling up a late Messinian palaeorelief in the Garrucha area, are shown to be derived from the basin. These probably continue offshore as feeder channels related to a late Messinian sea-level fall. A holistic approach of a key section, thereby not overlooking the regional geology, is a necessary step to be made before far-reaching claims can be made about its interregional significance.

The Messinian event on the margin of the Mediterranean Sea in the Nice area, southern France

Seismic reflection profiles have been used to map the Messinian erosion surface and associated basin-margin deposits on the continental margin off Nice. A palaeovalley extends seaward from the incised Var palaeovalley mapped on land. The lower part of this valley is filled by an acoustically incoherent unit with a flat top and steep slope into the basin: this unit is interpreted as a coarse-grained deltaic deposit that accumulated synchronously with the upper Messinian evaporites in a ponded lake basin. Two submersible dives on strategic outcrops supported the interpretation of the seismic profiles. We examined and sampled outcrops of probably early Tertiary sandstones underlying the Messinian erosion surface and of a fining-up, predominantly conglomeratic sequence that fills Messinian channels on the continental slope and probably overlies the deltaic deposits. These conglomerates pass up into Early Pliocene marls and have turbidite sedimentary structures. These are prodeltaic deposits formed during the transgression at the end of the Messinian. Based on seismic facies mapping, sampling and submersible observations, a palaeogeographic reconstruction of the area is proposed. A basal erosion surface, including the Var palaeovalley, represents extreme dessication of the western Mediterranean and was followed by accumulation of the main Messinian salt. Following this, a lake was ponded in the Ligurian Basin, with accumulation of evaporites and shales. A Gilbert-type delta prograded into the basin from the Var palaeovalley. Relative sea (lake)-level lowering is estimated to be about 1200 m at this time. There has been little faulting on the margin since the Early Pliocene transgression, but there is estimated to have been about 800 m of flexural subsidence due to both thermal subsidence and water loading.

Geomorphological observations concerning the evolution of the Basin of Athens

Tectonism is an important element in the determination of the present landscape of Greece. It has shaped and is shaping the numerous highlands and depressions and consequently settlement patterns of the country. One such area is the Greater Athens region, a triangular basin, opening to the sea in the southwest and surrounded by four mountain masses. The presence of an old planation surface on the surrounding mountains; of thick lateritic soils in the basin overlain by Miocene and Pliocene marls, marly limestones, sands and conglomerates; Pleistocene fluvio-torrential deposits; alluvial fans; and fluvial and marine terraces, enabled the authors to put together the Tertiary and Quaternary tectonic and geomorphic evolution of the Greater Athens area. The paleogeographic evolution goes back to a probable mountainous topography before the Miocene with near tropical climatic conditions. In the Early Miocene, the breaking up of the highland area and the formation of today's basin begins or has already begun. During the Late Miocene, a transgression of the sea occurs, particularly in the western half of the basin. This is followed by regression, erosion and Late Pliocene transgression. During the Neogene and Quaternary we have continuous fluvio-torrential deposition intercalating with marine sediments. In the Quaternary, the tectonic activity in the area slowly subsides and climate, particularly in the late Pleistocene and Holocene and eustatism, especially along the coastal zone, affect more readily the depositional and erosional regime and geomorphic processes.

Early Pliocene sedimentation in the Cretan region: Implications for the timing and amount of vertical motion along the south Hellenic Arc (Eastern Mediterranean)

A boxcore taken from the top of a seamount south of Crete, on the outer (south) side of the Hellenic Trench, contains allochtonous coarse clastics, consisting mainly of rock fragments of alpine basement, brecciated Early/Middle Pliocene marls and reworked older Neogene sediments. This mixture of lithologies is interpreted as an Early/Middle Pliocene mass-flow deposit, which can be correlated with similar deposits from adjoining on- and offshore areas. The wide distribution of these sediments may be related to a period of increased tectonic activity which caused substantial vertical movements in the south Hellenic Arc. It is concluded that at the time of the formation of the mass-flow deposits this part of the Hellenic Trench had not yet evolved.

Prélèvements systématiques et caractérisation des réflecteurs acoustiques: nouvelle étape dans la compréhension de la géologie de la Méditerranée occidentale

A sampling survey in the Ligurian Sea and north of the Balearic Islands (Mediterranean Sea) brought back samples containing the following elements: (1) lithified Quaternary crust and deep-lying corals; (2) Early Pliocene marls corresponding to reflector level M in some cases; (3) red sediments tentatively assimilated with the Messinian continental equivalent; (4) rocks coming from the basement; (5) volcanic rocks. For the first time, basalts with olivine were discovered in the Algero-Provencal Abyssal Plain. A volcano 500 m high was sampled by dredging north of Minorca.

Les madreporaires du Pliocene d'Orosei (Nuoro, Sardaigne)

Abstract Describes madrepores (including Caryophyllia charrieri n.sp. and Dendrophyllia oroseiensis n.sp.) from Pliocene marls of the Orosei area, on the east coast of Sardinia, Italy.

The Undercutting of Coral Reef Limestone on the Coasts of Some Islands in the Red Sea

'T^HE object of this note is to describe the undercut cliffs of coral reef limeX stone which form a striking feature of parts of the coasts of certain islands in the Red Sea, and which appear to be formed, not by wave action, but by a combination of solution of the limestone by sea-water and erosion by boring organisms. Since the old view of solution as a factor has been energetically combated in America in recent years, to the extent of a denial of its possibility, it is necessary to consider the case in some detail. The coral reefs of the Red Sea have been studied by Ehrenberg,* who spent in all nearly twelve months there, and by Crossland and others, who dealt with more restricted areas of it. They are also considered by Darwin,f who had not personally visited them. None of these authors were, however, directly con? cerned with the aspect considered here. The facts described in the present paper are based on a fortnight's examination of the Ashrafi and Jubal Islands at the mouth of the Gulf of Suez in February 1925, and four months' work during the winter of 1926-1927 on the Farsan Islands and Kamaran Island in the south-eastern part of the Red Sea. With the exception of a few (probably) basalt and sandy islands in the Farsan group, all the islands mentioned above consist almost entirely of raised Pleistocene reef limestone, and are fringed with growing corals. The Ashrafi Islands rise to a maximum of 30 feet above high-water mark, and are com? posed completely of coral reef. The Jubal, Farsan and Kamaran Islands are higher in places (the Farsan Islands reach a maximum of about 260 feet), and some exposures of the underlying Pliocene marls and marly limestones are found on many of them. The Pleistocene limestone, which forms most of the coasts of the islands, consists largely of shells and their casts, interstitial material (cemented calcareous sand), and corals. Most of the islands project above a submerged reef limestone platform. The depth of water covering this at high tide varies from sometimes only a few inches near the shore up to some 6 feet at the growing edge, but is usually from 1 to 3 feet. The platform is often surprisingly even, and slopes very gently seawards; the outer edge is well defined, the depth of water increasing rapidly from 1 to 15 or 20 fathoms. The width of the platform is very variable, but is rarely less than 100 yards, and in places reaches 1000. Much of the platform is laid bare in exceptionally low water. It is often covered with a thin layer of mud, with various organisms; but pebbles and sand are rarely present. For a considerable portion of their periphery, the islands are bounded by low marine erosion cliffs of raised reef limestone, J varying up to nearly the