Pliocene Age Research Articles

CHARACTERISTICS OF GAS SHALE IN DAKEBO FORMATION, AT WAGHETE AREA - PAPUA PROVINCE

Dakebo Formation is found in Akimeugah Basin. The formation is interpreted as Pliocene in age and it is sedimented on alluvial fan and flood plain environment, composed by conglomerate, sandstone, sandy shale, mudstone and lignite. In megascopic view, samples of rock in this area are blackish gray. Among shale beds there are thin sandstones and limestones layers as well as remains ofbrownish to blackish plants. The organic geochemistry and maceral analyses indicate that samples of rock contain organic material with fair to very good classification as source rocks, and consist of vitrinite and liptinite macerals. The presence of vitrinite maceral is ‘rare to major’ and liptinite is ‘rare to common’. Based on the TOC analysis, abundance of the organic material is about 3.11% to 12.62% with type II and type III kerogen. T value is about 401ºC to 431ºC and Rv is 0.28% to 0.31% indicated that organic material is immature. Kerogen type II has prone to produce oil and type III has prone to produce gas.

Occurrence of greigite in the Pliocene sediments of Lake Qinghai, China, and its paleoenvironmental and paleomagnetic implications

AbstractLake Qinghai in North China is the largest interior plateau lake in Central Asia and is climatically sensitive. An almost continuous 626 m long sediment core was drilled in an infilled part of the southern lake basin of Lake Qinghai. The magnetic susceptibility record reveals the presence of two distinct peaks within an interval of fine‐grained lacustrine sediments of Lower Pliocene age. We selected a depth interval of approximately 40 m spanning the magnetic susceptibility peaks for detailed rock magnetic and geochemical analyses in order to identify the magnetic mineralogy responsible and to assess its possible paleoenvironmental and paleomagnetic implications. Rock magnetic, X‐ray diffraction analysis, scanning electron microscopy (SEM), and energy dispersive analysis of X‐ray (EDAX) analyses reveal that the main magnetic carrier is greigite (Fe3S4). The greigite is of early diagenetic origin and formed in an inerval of high lake level and inferred relatively warm, humid climate. The greigite‐enriched zones are separated by an interval of relatively high total sulfur and organic carbon content, and we infer that in the adjacent greigite‐bearing zones, the lower concentrations of sulfur and organic carbon, and high levels of reactive iron, arrested the process of pyritization resulting in the preservation of the greigite on a time scale of several million years. The greigite zones contain narrow intervals of normally magnetized sediments which may be previously unrecognized cryptochrons within the Gilbert Chron, or alternatively they may reflect the continued formation of greigite long after the age of deposition of the surrounding sediment matrix.

Two new Tertiarius (Bacillariophyta, Coscinodiscophyceae) species from Mariovo Neogene Basin, Macedonia

The morphology, biostratigraphy and ecology of two new species, Tertiarius jurijlii and Tertiarius mariovensis are presented. The valve morphological variation and ultrastructure are described by light and scanning electron microscopy. Tertiarius juriljii is distinguished by the presence of hyaline area on the valve face; central area comprised of areolae arranged in single short or long radial rows; presence of small to large granules on the interstriae; and valve face fultoportulae arranged in radial rows around the valve center. Comparatively, in Tertiarius mariovensis the hyaline area around the central area is missing, and the taxon is characterized by tri- to biseriate striae in the central part of the valve face becoming uniseriate towards the valve centre and stalked rimoportula positioned between two costae inside the alveolar opening. Both species are found in nonmarine sediments of Pliocene age from Mariovo Basin, Macedonia.

Palynology of the Middle Miocene—Pliocene Novo Remanso Formation, Central Amazonia, Brazil

In order to reassess and amend previously published palynological data drawn from the Novo Remanso Formation, central Amazonia, we revisited the organic-rich samples from their work using systematic and quantitative biostratigraphic analyses, with possible implications in the biodiversity and paleoecological studies of Late Neogene deposits of Amazonia. In the study area, the Novo Remanso Formation is characterized by sandstones and mudstones deposited in a meandering river environment. The palynological assemblage comprises 46 morphotypes, including 21 species of pollen and 25 species of spores. Polypodiisporites usmensis, Retitrescolpites? irregularis and Mauritiidites franciscoi var. franciscoi, typical of lowland freshwater forests and shallow water lakes dominate the assemblage. Also, lower frequencies of Grimsdalea magnaclavata co-occur with Psilatricolporites crassoexinatus, Proteacidites triangulatus, Bombacacidites simpliciriloensis, Pteridaceoisporis gemmatus and Cingulatisporites laevigatus. Based on quantitative biostratigraphic techniques, the Novo Remanso Formation Is assigned a middle Miocene—Pliocene age In our study area. The presence of Elaterosporites klaszii (Albian-Cenomanian) In the Novo Remanso deposits strongly indicates Cretaceous rocks in the source-area, whereas absence of Andine palynomorphs may be indicative of a nearby source area for the deposits during the deposition of the Novo Remanso Formation.

Tectonostratigraphic and structural imprints from balanced sections across the north-western Zagros fold-thrust belt, Kurdistan region, NE Iraq

The giant oil and gas fields discovered in the north-western segment of the Zagros fold-thrust belt in the Kurdistan region (NE Iraq) became targets for oil companies and academics around the world. This work deals with tectonostratigraphic and cross-sectional balancing across several structural domains and a stratigraphic framework that measures and analyzes supersequences from the Early Jurassic to the Late Pliocene in age. The structural complexity passes through different tectonic zones, starting from an imbricated zone, then a high folded thrust zone and terminating at the boundary with a low folded thrust zone. Accordingly, three major cross sections have been constructed based on a new ratified geological map and a stratigraphic column of exposed sequences, oil wells data which are integrated with the few available valuable seismic profiles. The total shortening measured in the tertiary rocks ranges between 4.55 and 6 % and 15.3 and 20.7 % in the Cretaceous sequence, while in the Jurassic interval, it is between around 12.9 and 20.8 %. The measured partial shortening percentages of the Bazian–Sagrma–Qaradagh, Pira Magroon, Surdash and Azmar anticlines range from 9.8 to 12.5 %, 47.3 to 73.2 %, 29 to 41.3 % and 20.9 to 60.5 %, respectively. The Kometan Formation (M. Turonian to Santonian) in the B–B cross section can be adopted as the best measure for shortening in this area, and this is equal to 20.7 %. The partial shortening percentages obtained from the Bazian–Sagrma–Qaradagh anticlines range from 9.8 to 12.5 %; these increase in the Pira Magroon anticline, from 47.3.8 to 73.2 %, and for the Surdash anticline, they are from 29 to 41.3 % and the Azmar anticlinorium from 20.9 to 60.5 %. The total shortening values are, in general, low and attributed to the influence of thick-skinned tectonics during extensional tectonic phases that changed to thin-skinned tectonics during Oligocene and Miocene times, as well as being due to variations in their decollement nature, while the partial shortening values of the cross sections studied mostly coincide with those in the Iranian Zagros segment.

Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands.

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

Paleoenvironmental Implications from Biomarker Investigations on the Pliocene Lower Sajau Lignite Seam in Kasai Area, Berau Basin, Northeast Kalimantan, Indonesia

Pliocene age lignites from Lower Sajau seam, from borehole in Berau Basin, Northeast Kalimantan, Indonesia were investigated with respect to organic geochemistry by HPLC, GC and GC/MS. The analysis was conducted to drilling sequence of Kasai Coal Field, Berau Basin which has been applied to identify organic sources and maturity of organic matter. The result of normalized yields of the soluble organic matter (SOM) data indicates saturated and aromatic proportion of hydrocarbon are very low (under 10%), this was reflecting that lignite coal is still in immature stage. Moreover, biomarker hydrocarbon such as diterpenoids was not found from the sample that indicates absence of gymnosperm precursor in the paleo-peat. In contrast, there was great abundance of terpenoid biomarkers including lupane and oleanane showing domination of angiosperms indicate that angiosperm was dominated vegetation source. There also hopanoid biomarkers explaining acidic depositional environment in coal formation and microbes-affected conditions in peat formation process. Ratio of Tm/Ts shows paleomire where ratios value of Tm/Ts is in range of oxide condition.

Depositional environment and age of some key Late Pliocene to Early Quaternary deposits on the underfilled Cedrino paleovalley (Orosei): Insight into the Neogene geodynamic evolution of Sardinia

In order to better constrain the relationship between tectonics and sedimentation of the Eastern Sardinian Margin, from the Messinian to the present day (METYSS project), a lithostratigraphic study was carried out on the Late Neogene deposits along the Cedrino Valley (eastern Sardinia). The late Neogene evolution is documented from sedimentological and tectonic analysis, biostratigraphic dating, and by mapping and logging stratigraphic sections. Previous authors have differentiated an early Pliocene marine formation from an older continental formation, possibly Miocene, the entire system being covered by late Pliocene to Quaternary lava flows. Preliminary biostratigraphic data suggest the absence of the lowermost Pliocene, based on the absence of Globorotalia margaritae and the presence of Globorotalia puncticulata, implying a sediment age between 3.81 and 2.41 Ma. At the foot of the Fiuli cliff, some mud clasts include a coccolith microflora, Tortonian in age, suggesting reworking. The Pliocene marine deposits consist of a single filling sequence instead of a succession of superimposed sequences as we would expect during this period of time; the occurrences of terms rarely respect the usual transgressive-regressive succession. Contrasting bathymetric environments (fore-shore, pro-delta, shelf or upper slope) can be abruptly superimposed on top of the other, along few meter thick intervals. A rapidly flooded term is observed in several sites and indicates a spatial variability over only a few kilometers distance. Some deep water deposits are in the middle of the infilling Pliocene sequence, whereas shallower water deposits can be repeated along a vertical section, or even interrupted by emersion. These marked differences can express syn-, or possibly post-sedimentation tectonic uplifts. The 10–25° bed dips originated through local tectonic uplift. At Fiuli, the geometry of the bedding planes is indicative of tilting toward the west, in a direction opposite to the one observed at Onifai. These Pliocene series form a wide syncline with an approximately NNE–SSW axis. This morpho-structural behavior appears to be largely atypical of this East-Sardinian coastal area.

Polygonal feeder tubes filled with hydroclasts: a new volcanic lithofacies marking shoreline subaerial–submarine transition

This paper describes for the first time a new lithofacies that formed in the passage zone during the construction of pahoehoe lava-fed deltas in the north and NE coastal areas of Gran Canaria (Canary Islands, Atlantic Ocean). These lava-fed deltas, which are Pliocene in age, present similar lithofacies associations to those previously described in the literature, except for two distinct features: low abundance of hyaloclastites and a new lithofacies in the passage zone. This new lithofacies, which we propose to name ‘polygonal feeder tubes filled with hydroclasts’, comprises metre-scale lava feeder tubes with decimetre-scale coherent poorly vesicular and aphanitic rinds of polygonal morphology, filled with closely packed hydroclasts generated in situ . It represents the first stage in the interaction between seawater and thick lava flows entering the sea under the influence of a tidal regime, thus marking sea level. This lithofacies should be easily recognizable in ancient successions, and thus represents a useful marker of palaeoshorelines. Supplementary material: Sample preparation and sample geochemistry are available at http://www.geolsoc.org.uk/SUP18785 .

Geology of the Brega area and the ichnofauna of the ‘Brega Sandstone Bed’ (Pliocene), Libya

The sandstone outcrops in the Brega Area Two are designated as ‘Brega Sandstone Bed’ on the basis of the lithological similarities and stratigraphy of the region surrounding Brega. The ‘Brega Sandstone Bed’ is considered to be equivalent to the lower part of the Member V of the Sahabi Formation of the Pliocene age. The thinly bedded greyish to greenish sandstone interbedded with gravel and pebble beds exposed at the ‘Sea cliff section’ represents the upper part of Member V of the Sahabi Formation. Outcrops of Pleistocene-cemented marine dunes belong to the Ajdabiya Formation and are seen as patches of marine dunes of various shapes, lengths and heights that run parallel to the modern day Mediterranean Sea coastline. The Holocene sediments around Brega include coastal and inland sand dunes and sand sheets mixed with millions of 'beach balls'. The ichnofaunal assemblage of the ‘Brega Sandstone Bed’ is dominated by various types of vertical, oblique and horizontal burrows that are branched and unbranched. They are dominated by ichnogenera Ophiomorpha and Skolithos. The ichnocoenose dominated by these two ichnogenera belong to the marine soft ground Skolithos ichnofacies. Lithology of the ‘Brega Sandstone Bed’ and its ichnocoenose indicate a shallow marine, intertidal to shallow subtidal, moderate to high energy depositional environments.

A Terrestrial Gastropod Community from the Early Pliocene (Neogene) of Mendoza, Argentina, with Description of a New Species ofRadiodiscusPilsbry and Ferriss, 1906 (Mollusca: Pulmonata: Charopidae)

Numerous fossil gastropods have been recorded in an edaphic level of the middle section of the the Aisol Formation (Mendoza Province, Argentina). This stratigraphic section bears an association of fossil mammals suggesting an early Pliocene age (possible Montehermosan SALMA). Up to four taxa of gastropods have been identified, belonging in Succinea Draparnaud (Succineidae), Gastrocopta Wollaston (Vertiginidae), Bostryx Troschel (Bulimulidae), and a new species of Radiodiscus Pilsbry and Ferriss (Charopidae). The fossil record of terrestrial pulmonate mollusks in Argentina is scarce and mainly restricted to the Quaternary. Thus, the record of these taxa is of paramount importance because it constitutes the oldest record of Gastrocopta and Succinea in Argentina, the first record of Bostryx in Mendoza Province, and the first record of the family Charopidae (Radiodiscus sanrafaelensis nov. sp.) in Pliocene deposits of Argentina.

Geologic history of the Neogene “Qena Lake” developed during the evolution of the Nile Valley: A sedimentological, mineralogical and geochemical approach

Siliciclastic and carbonate sediments were laid down in southern Wadi Qena and around the Qena Nile bend (Middle Egypt) in a lacustrine–alluvial environment which dominated a relatively wide lake, the “Qena Lake” that interrupted the Nile course during the Neogene time. These sediments are represented mainly by the oldest dominantly lacustrine chocolate brown mudstones of the Khuzam Formation that accumulated nearer to the center of that lake (now forming a 185m terrace above sea level), overlain by the dominantly lacustrine carbonates and marls of the Durri Formation which accumulated during semi-arid conditions, mainly nearer to the periphery of the lake (now forming 170, 180 and 185m terraces a.s.l. in the studied sections). The water level of the “Qena Lake” reached 240m. above sea level, as indicated by the maximum carbonate elevation reached in the region. Finally fanglomerates of the Higaza Formation with its chert and limestone conglomerates accumulated during torrential periods at higher elevations (forming 240, 300 and 400m terraces a.s.l.). These three formations accumulated in this particular area before and during the unroofing of the basement rocks of the Eastern Desert, west of the watershed. According to the known Early Miocene initial development of the Nile Valley, beside the occurrence of similar deposits of Oligocene age along the eastern side of the basement range, the earlier known Pliocene age given for these sediments in the Qena area is here questioned. It might belong to earlier Miocene?–Pliocene times.As the basement rocks of the Eastern Desert were still covered by Cretaceous–Paleogene sedimentary rocks while the Khuzam, Durri and Higaza Formations were accumulating in the Qena Lake region, it is believed, contrary to the belief of some authors, that the basement rocks of the Eastern Desert were not the source of these sediments. The carbonate petrographic study, beside the X-ray, and the11 major oxides and 22 trace elements analyses, all point to that the mudrock sediments of the oldest Neogene Khuzam and Durri Formations of the “Qena Lake” phase were carried out and entered the area of southern Wadi Qena and around the Qena Nile bend mainly from the south. The intermediate igneous rocks of southern Egypt and northern Sudan were the main source areas. Additional contributions had possibly come from the weathering of the non-marine to brackish Cretaceous (pre-Campanian) shales of southern Egypt.Accumulation of conglomerates with mixed igneous and sedimentary clasts followed (forming 7 terraces in Wadi Qena, ranging from 240m in the north to 140m a.s.l. in the south), constituting the newly introduced Late Pliocene formation; El Heita Formation. These conglomerates were mainly drained from the then exposed basement rocks of the middle parts of Wadi Qena, and cut through the older Neogene sediments. Later on, after the lake became connected to the northern parts of the Nile Valley, the lake water level was lowered to 180m a.s.l., and another lake with this lower level was formed (Isawiyya Lake). With the successive lowering of water level the younger well known Issawia, Qena, Abbassia and Dandara Formations accumulated successively; nearer to, and within, the present Nile Valley.

Dating and palaeoenvironmental reconstruction of the sediments around the Miocene/Pliocene boundary in Yermak Plateau ODP Hole 911A using marine palynology

The late Neogene evolution of the Arctic to Subarctic region is poorly understood due to few available records and poor age control. At the margin of the Arctic Ocean, Yermak Plateau Ocean Drilling Program (ODP) Hole 911A is strategically located for establishing a stratigraphic framework for the Arctic. Here we present dinoflagellate cyst and acritarch data from 24 stratigraphic levels in the lower part (474.26–505.64metresbelow the seafloor of ODP Hole 911A. The marine palynomorphs indicate a latest Miocene to earliest Pliocene age (between 5.8 and 5.0Ma) for the base of the hole based on the co-occurrence of the dinoflagellate cyst Barssidinium evangelineae and acritarch Lavradosphaera crista. Our age estimate can possibly be further refined to 5.0–5.33Ma based on the presence of Achomosphaera andalousiensis suttonensis, which apparently has a range restricted to the Pliocene. An age close to the Miocene/Pliocene boundary agrees with the planktonic foraminifer data. Together with recently available magnetostratigraphic data, the base of the hole is likely to be placed at ~5.2Ma. This new chronostratigraphy is a first step towards a better understanding of the late Neogene palaeoenvironment for the Yermak Plateau and also for the wider Arctic to the Subarctic region.The terrestrial and fresh water palynomorphs were most likely redistributed and/or displaced from the shelf towards deeper parts of the basin during contourite deposition under the influence of the West Spitsbergen Current. The in situ marine dinoflagellate cyst assemblage contains a mixture of cool water and thermophilic taxa, indicating sea-ice free, cool-temperate, and warmer than present conditions at the Yermak Plateau. Rivers were likely the source for the freshwater influence.Warmer than present conditions may have occurred due to northward warm water transport via the West Spitsbergen Current, but also the absence of sea-ice and consequent lower albedo could have played a role.

Epithermal Gold-Silver Deposits in Western Java, Indonesia: Gold-Silver Selenide-Telluride Mineralization

DOI: 10.17014/ijog.v1i2.180The gold-silver ores of western Java reflect a major metallogenic event during the Miocene-Pliocene and Pliocene ages. Mineralogically, the deposits can be divided into two types i.e. Se- and Te-type deposits with some different characteristic features. The objective of the present research is to summarize the mineralogical and geochemical characteristics of Se- and Te-type epithermal mineralization in western Java. Ore and alteration mineral assemblage, fluid inclusions, and radiogenic isotope studies were undertaken in some deposits in western Java combined with literature studies from previous authors. Ore mineralogy of some deposits from western Java such as Pongkor, Cibaliung, Cikidang, Cisungsang, Cirotan, Arinem, and Cineam shows slightly different characteristics as those are divided into Se- and Te-types deposits. The ore mineralogy of the westernmost of west Java region such as Pongkor, Cibaliung, Cikidang, Cisungsang, and Cirotan is characterized by the dominance of silver-arsenic-antimony sulfosalt with silver selenides and rarely tellurides over the argentite, while to the eastern part of West Java such as Arinem and Cineam deposits are dominated by silver-gold tellurides. The average formation temperatures measured from fluid inclusions of quartz associated with ore are in the range of 170 – 220°C with average salinity of less than 1 wt% NaClequiv for Se-type and 190 – 270°C with average salinity of ~2 wt% NaClequiv for Te-type.

Morphotectonic evolution of connected intermontane basins from the southern Apennines, Italy: the legacy of the pre-existing structurally controlled landscape

The opening kinematics of several Pliocene to Quaternary tectonically controlled continental basins scattered along the axis of the southern Italian Apennines and their morphological features and evolution have been compared to define the behaviour of this particular interconnected negative morphostructure. In particular, three different but morphologically connected intermontane basins have been here investigated from a morphotectonic point of view (from the north: Auletta, Vallo di Diano, and Sanza basins). They are filled by more or less thick marine and/or continental sequences of sediments, Pliocene to Quaternary in age. Such basins are shaped by erosional land surfaces and fluvial dissection. The ages of the morphological de-activation of the terraced surfaces have been roughly defined on the basis of their morpho-stratigraphic relationships with Pliocene and Quaternary deposits, and better constrained by radiometric dating. The NNW–SSE-trending fault of the Alburni Mts, bordering the Auletta basin, indicates former left-lateral transtensional kinematics and later dip-slip kinematics, whereas the N140–150°-striking master fault bounding the Vallo di Diano basin is a normal fault. The Sanza basin can be assimilated to a morphostructural trough coinciding with a long-term transfer zone of the chain, in which a severe change in stress field, uplift rate, climate conditions, and relief production occurred during Pleistocene times. Such a complicated morphostructural setting may be interpreted as a function of the original orientation of the structural depressions, only partially coeval. In this sense, the Vallo di Diano basin should represent the structural low generated by pure extension during the Pleistocene, but probably already living as a Pliocene seaway, whereas both the Auletta and Sanza basins stand for two lateral branches with oblique kinematics, inherited from a pre-existing (i.e. Pliocene in age) set.

Petrographic study and its implication to the uniaxial strength of weathered volcanic rocks from tawau, sabah

This paper discussed the petrographic study and its effect to the uniaxial strength of weathered volcanic rocks from Tawau, Sabah, Malaysia. The volcanic rock consists of associated dacite, andesite and basalt rocks with the age of Pliocene to Quaternary. In this study the Murphy (1985) classification were used determine the weathering grade of volcanic rocks. The uniaxial strength value were used the Point Load Test and Uniaxial Compressive Strength test. The microstructures and identification of altered minerals were analysed using scanning electron microscope (SEM) and polarized microscope, respectively. The result of analysis indicated that the uniaxial strength of volcanic rocks decreased with the degree of weathering grades where the uniaxial strength decreased from 122.2 to 15.8 MPa for dacite, 143.4 to 10.1 MPa for basalt and 181.2 to 26.8 MPa for andesite. This result is due to the different percentages of quartz and feldspar minerals in the rock samples as well as formation of secondary minerals in weathered rocks. Microstructures study showed the appearance of micro fractures with narrow apertures in the minerals also influenced the uniaxial strength of the rocks.________________________________________GRAPHICAL ABSTRACT

Bočno razširjanje kot posebna oblika gibanja tal na območju Doline v občini Puconci

The paper presents a particular form of soil instability, which is rarely observed in Slovenia. This is a lateral spread of the soil, which appeared some years ago in the central part of Dolina area in the municipality of Puconci. The area is mainly build up from clay and sandy Sediments of the Pannonian Sea, predominantly Pliocene age. A significant damage of building has begun several years ago. According to data from research carried out, we suggest that the flat area is disintegrated into individual blocks, moving in different directions. These led to such extensive damage to buildings. Possible cause could be erosion of Dolinski stream at the eastern edge of the area or seismic survey (blasting, vibrations), which were carried out here about 20 years ago. Determination the exact cause of the formation of the soil lateral spread, its extent and dynamics, remain a challenge for the future.

The late Tertiary landscapes of western Ireland

This paper reviews two regions where the landscape of western Ireland can be partially reconstructed at the close of the Tertiary Period. The preglacial landscape of central western Ireland appears to have been heavily forested with a diverse range of tree types and the bedrock denuded with extensive karstification on limestone and with areas of tors and weathering mantles on the granites. There is also evidence that other clastic and igneous rocks were extensively weathered. Both of the palaeosurfaces described here are believed to be Pliocene in age and are at or near the present land surface. The preservation of such palaeosurfaces is considered in the context of the Tertiary landscape evolution of Ireland.

China's Yangtze delta: Geochemical fingerprints reflecting river connection to the sea

This study investigates sediment source to sink relating the connection of the Yangtze River to the sea. A sediment borehole (PD) on the river coast, penetrating thick Quaternary sediments and thin sediments of late Pliocene age down to the bedrock, recorded a change in sediment provenance through time. Geochemical elements and magneto-stratigraphy help identify five zones. Zone I (the late Pliocene–the Early Pleistocene), characterized by Pb, Th, U, Ba, La, Ce, Nd, Hf, Y, Zr, Nb and Mn, indicates a local sediment provenance. This means that the study area was a localized sub-basin. Zone II (the Early Pleistocene–the mid-stage of the Early Pleistocene), with remarkable high Fe, K, As and Rb implies a new sediment provenance joining the sub-basin from the middle Yangtze reach after the opening of the Zhenjiang Gorge. Zone III (the mid-stage of Early Pleistocene–the Middle Pleistocene), featured by Ti, V, Cr, Sr, Sc, Cu, Co, Ni, Mg, Ca, Na and P suggests a further extension of sediment provenance to the upper Yangtze basin, where a large block of the E'mei basalt and carbonate occurs. This suggests that the Three Gorges valley linking the upper and middle Yangtze reaches had developed by that time. Zones IV and V (the Middle Pleistocene–the Holocene) have shown their geochemical similarity to Zone III. Discrimination ratio f(Cr, Th), f(La) and f(K, La), a new approach developed for tracing sediment provenance, confirms a basin-wide sediment source through Zones III–V. These together witness a progressive extension of the sediment provenance towards the upper Yangtze basin, corresponding to the long-term tilting effect of the Cenozoic Topographic Reversal of the eastern China continent. The timing of the Yangtze River running through into the East China Sea appears at ca. 1.0–1.2Ma (bottom of Zone III).

Neogene tectonics and fault-related folds in the Gulf of Hammamet area, Tunisian offshore

The western part of the Gulf of Hammamet area lies in the Pelagian Platform, eastward of the Atlas front. This region shows large changes in structural style compared to the Pelagian Platform.During the Neogene, the Gulf of Hammamet recorded the convergence of the Eurasia and Africa plates. During the Pliocene to early Quaternary, the area recorded an NW–SE shortening related to the Atlas contraction followed by an NNE–SSW extension linked to the Pantelleria-Malta graben opening.Subsurface geology of the Gulf of Hammamet area allows us to propose a tectonic sketch, where the Neogene deformation is characterized by (1) Cenozoic age detachment level that located in the Mio-Pliocene and Quaternary series; (2) the growth of fault-related folds (mainly fault-propagation folds) and (3) a total shortening of about 6km.The thin-skinned thrusting is late Miocene age and is synchronous to the Africa–Europe collision. During the upper Miocene (Tortonian), fault-propagation folds developed above inherited normal faults. The Pliocene age was tectonically calm period. Finally, post-Villafranchian contraction reactivated these structures.Despite the large number of hydrocarbon discoveries, the Gulf of Hammamet remains under-explored. This new interpretation of Neogene tectonic events and folding models could lead to a new play idea for the hydrocarbon prospectively in this proven oil province.