Middle Miocene Age Research Articles

Structure and morphology of the Red Sea, from the mid-ocean ridge to the ocean-continent boundary

The diversity and complexity of existing models on the structure of the Red Sea is the result of a mobile sedimentary cover that not only hides most of the basement and oceanic structures but also hamper the geophysical signals. In this study, we combined published with new unpublished geophysical data to propose a revised interpretation of the structure of the lithosphere between the Hanish Islands (ca. 13.5°N) and the Dead Sea Fracture Zone (ca. 27.5°N). The recognition of allochthonous salt and overburden allows to propose a structural model with simple geometries that are consistent with the present-day kinematic constraints (GPS velocities and Euler Poles) and with the rules of plate's motion on a sphere (Euler Theorem).We mapped a continuous Mid Ocean Ridge segment parallel to the main rift orientation in the southern Red Sea that becomes highly discontinuous and more oblique towards the north as it gets closer to the Euler Pole. These segments all point towards the Euler pole and are consistently offset to the right by transform faults in the central and northern Red Sea cumulating an offset of 400 km. The transform faults are accommodating seafloor spreading in the Red Sea and cluster in three main fracture zones: (1) the Ikwan Fracture Zone near the Ikwan (or Brother) Islands, (2) the Zabargad Fracture Zone in the vicinity of the Zabargad Island and (3) the Jeddah Fracture Zone offshore the Jeddah/Port Sudan area (central Red Sea). Based on a new seismic reflection dataset and published data we propose an interpretation of the Ocean Continent Transition (OCT) in the Red Sea. We bring new evidence (magnetic lineaments, distance of the OCT to the ridge, basin stratigraphy) to support a Middle Miocene (ca. 14 Ma) age for the initiation of seafloor spreading throughout the Red Sea, and we discuss this event with the initiation of strike-slip motion in the Aqaba-Dead Sea transform zone. Finally, compiling all available data and literature, we propose a regionally coherent geodynamic reconstruction using two different poles of rotation for the rifting and seafloor spreading phases.

Middle Miocene paleoenvironmental change and paleoelevation of the Lunpola Basin, Central Tibet

The Tibetan region underwent diachronous differential rises during the Cenozoic era. Its elevation history is critical for understanding the processes of mountain building, and for evaluating its climatic effects on atmospheric circulations. However, knowledge of paleoenvironment and paleoelevation in different geological domains of the Tibetan Plateau is still limited. Here we provide chronology of lacustrine deposits of the Upper Dingqing Formation in the Lunpola Basin in Central Tibet, which yields a middle Miocene age (15–12 Ma). Both stable isotope and palynological records indicate a climatic transition at ∼13.8 Ma marked by a change towards a cooler and drier climate after the Middle Miocene Climate Transition driven by global climatic cooling. Pollen and spore assemblages suggest that the vegetation was dominated by mixed coniferous–broadleaved forest with some grasslands. New palynological elevation reconstructions constrained by the co-existence approach yield a maximum paleo-elevation of 3100–3600 m (average 3350 m) of the Lunpola Basin, which was consistent with a maximum elevation of 3400 m based on floating-leaf plants. Our new data do not support previous views that the Lunpola Basin achieved its current elevation as early as the late Eocene or early Oligocene, but instead we suggest there has been a rise of up to 1200 m since 12 million years ago. Our results bring new light on both the paleoenvironmental reconstructions and the paleo-elevation estimates of the Lunpola Basin, Central Tibet.

MIDDLE MIOCENE VOLCANISM IN THE ČITAKLIJA LOCALITY OF VARDAR ZONE, NORTH MACEDONIA

This paper presents the results of the investigations of volcanic rocks of Middle Miocene age in the central parts of the Varadar zone for the first time. The volcanic rocks that appear in the Čitakliјa locality, according to their petrological and mineralogical characteristics, represent basic igneous rocks and they are transitional rocks between phonotephrites and high potassium shoshonites. The geochemical distribution of trace elements and elements from the group of rare earths (REE), as well as isotopes of 87Sr/86Sr (0.708348) and isotope values of 143Nd/144Nd (0.512319) indicate the fact that the magmatic sources of these rocks can be located in the border region between the upper mantle and the lower part of the continental crust.

The northernmost Eurasian Miocene beavers: Euroxenomys (Castoridae, Mammalia) from Olkhon Island, Lake Baikal (Eastern Siberia)

The castorid dental material described in this paper derives from Miocene, fossiliferous deposits of the Baikal rift valley, exposed at Tagay Bay on Olkhon Island in the Lake Baikal, in eastern Siberia. It consists of maxillary fragments and isolated upper and lower teeth of the small trogontheriine beaver Euroxenomys minutus (von Meyer, 1838). It is the first record of the species in Asia and at the same time the northernmost occurrence of Eurasian Miocene beavers. The magnetostratigraphic correlation of the Tagay -1 section, indicates a late Burdigalian, Early/early Middle Miocene age of ~16.5 to ~16.3 Ma that corresponds to the Mammalian Neogene zone MN4/5. The presence of E. minutus in Tagay is an indicator for an Orleanian European-Siberian bioprovince during the Mid-Miocene Climate Optimum, and for a continuous belt of humid, warm-temperate to subtropical forests, stretching from Europe to Siberia, and probably further to East and South-Eastern Asia. In Eurasia, beaver remains are an indicator of permanent water bodies, which is in agreement with the palaeoenvironment of the Tagay locality.

Coal deposition in the Barito Basin (Southeast Borneo): The Eocene Tanjung Formation compared to the Miocene Warukin Formation

Coal seams of Late Eocene (Tanjung Formation) and middle Miocene age (Warukin Formation) are present in the Barito Basin of Borneo. The seams are laterally continuous and can be traced over at least 20 km. The thickness of three Eocene seams in the TAJ Pit–1D mine ranges from 1.4 to 3.4 m. These seams (from base to top: D, C, B) were studied to reconstruct their peat–forming environment and to compare the characteristics of Eocene and Miocene coals. The comparison reveals differences in peat types, flora and climate. The study is based on 38 Eocene coal and six non–coal samples, each representing a stratigraphic interval of 0.2 m. The samples were analyzed for ash yield, carbon and sulphur contents, and maceral composition. Organic geochemical parameters (incl. biomarkers) were obtained on every second coal sample to obtain information on the peat-forming vegetation and its diagenetic alteration.The Eocene seams were deposited in rheotrophic mires with palm/fern–dominated vegetation. Transitions to local ombrotrophic mires cannot be excluded. Very low to low sulphur contents (max. 0.9 wt%) speak against a marine influence, despite a general coastal plain setting. Upward increasing sulphur contents in the lower seam D and the upper seam B are interpreted to reflect transgression, which ended peat accumulation. The seam C formed in a rheotrohpic seam with a relatively high water level. This favored the accumulation of aquatic plants.Miocene coals from the Warukin Formation in the Barito Basin were studied recently in a companion paper. The comparison of Eocene and Miocene coals shows major differences, which include: Miocene coals are significantly thicker (up to 50 m) and display a cyclic structure. Miocene coals accumulated in ombrotrophic mires dominated by more decay resistant angiosperm trees (and subordinate gymnosperms). Therefore, preserved plant tissues are more abundant in Miocene coals. In addition, Miocene coals contain a significantly higher amount of root–derived macerals (suberinite). Leaf–derived macerals (cutinite, fluorinite) and resinite are ubiquitous in Miocene coals, but even slightly more abundant in Eocene coals. At least part of the resinite in Miocene coals, but not in Eocene coals, is derived from dammar resin produced by Dipterocarpaceae. Fungal activity, recorded by high funginite percentages, was high in low-ash ombrotrophic and high-ash rheotrophic mires both in Eocene and Miocene times.

Reanalysis LUSI Stratigraphic Based on Cutting of Banjarpanji#1 Well

The subsurface configuration or stratigraphy of the Sidoarjo Hot Mudflow (Lumpur Sidoarjo/LUSI) is used to see what formations are transported out and how the material properties can be known from the well log data of Banjarpanji#1 or BJP#1 well. There is something unusual about the BJP#1 log, namely the presence of solid volcanic sandstone at a depth of 6000-9297 ft where drilling ended. This abnormality was investigated by reanalyzing volcanic sandstone by reading the well log data which is drilling data during the exploration of the Banjarpanji-1 well by PT. Lapindo Brantas, Inc. which consists of rock logs as a result of predictions (prognosis) and facts found (actual) were then compared with the interpretation of the results of the investigation team with BP MIGAS 2006 which was then confirmed by petrographic and paleontological analysis. The unusual occurrence is the LUSI stratigraphic arrangement changes based on findings in volcanic sandstone sequences that were once considered part of the Kalibeng Formation of Plio-Pliestocene age, then changed to solid volcanic sandstone units of Middle Miocene age with a depositional environment in the outer neritic-upper bathyal.

Paleovegetation and paleoclimate inferences of the early late Sarmatian palynoflora from the Gleisdorf Fm. at Gratkorn, Styria, Austria

The Gleisdorf Formation (Fm.) deposits in the clay pit at Gratkorn, Styria, Austria, are dated to 12.2–12 Ma, and are of late Middle Miocene age (late Serravallian or Sarmatian). To reconstruct the paleovegetation and estimate the paleoclimate at this important vertebrate site, the palynoflora close to the boundary between the vertebrate-bearing layers of the Gratkorn Fm. and the overlying limnic clay deposits of the Gleisdorf Fm. was investigated. Using the single-grain method, 140 palynomorphs were identified. The palynoflora suggests that the paleovegetation was characterised by well-drained lowland and upland forests, riparian forest, and swamp forests. Depending on the dominating tree species, lowland and upland forests might have had closed or more open canopies. Open habitats included wet meadows and shrublands. In addition, conifers were present in the swampy lowlands and the forested uplands. The most prominent paleoclimatic signatures of the palynoflora indicate a fully humid warm temperate climate, with hot to warm summers and cool winters (Cfa-, Cfb-climate), and a seasonal climate with cool and drier winters and hot to warm and wetter summers (Cwa-, Cwb-climate). Our results align with existing studies bordering the Styrian Basin and support the presence of subtropical to warm-temperate vegetation around Gratkorn during the Sarmatian.

Miocene Stratigraphy of Abu-Jir Fault Zone, Al-Baghdadi Sub-Basin, Western Iraq.

Stratigraphy of Late Oligocene to Middle Miocene age, suggested the carbonates evaporate succession in the area between Heet and Haditha cities within Abu-Jir fault zone has distinguished as “Al-Baghdadi sub-basin” after Al-Baghdadi city. It has NW–SE trending align the western bank of the Euphrates. Al-Baghdadi sub-basin is a local basin, which forms a part of the western marginal of the large foreland Tertiary basin (Zagros Basin) that was created on the Arabian shelf as a result of the collide of Arabian and Eurasian plates. The impact of the Abu-Jir fault on the formations on both regions of the Euphrates has been determined by observing the changes in thickness and lithofacies of the Euphrates, Jeribe and Fat’ha formations. On the western side, the Euphrates and Fat’ha formations were deposited with a relatively a little thickness, with absence of the Jeribe Formation between them and the top of the Euphrates Formation is above sea level. On the eastern side of the Euphrates River, the three formations were deposited with large thickness as compared to the western side, and the top of the Euphrates Formation is below sea level. This is enough to indicate that the western side was uplifting locally due to the activity of the Abu-Jir Fault as a positive flower structure during Miocene, while the eastern side was subsiding. Abu-Jir fault zone behaves as the basin bounding fault that acted like a growth fault. There are also variations in lithofacies between outcrops within Al-Baghdadi sub-basin as revealed from lateral missing or thinning of some layers.

New data on the Miocene vertebrate assemblage of the Zaysan Basin (Central Asia) with implications for biostratigraphy, paleoecology, and paleobiogeography

ABSTRACT The Zaysan Basin in Central Asia has a long geological history, and it has therefore seen major climatic and evolutionary transformations. The Miocene fossil record of this locality is remarkably rich representing all groups of vertebrates. A revision of fish remains has been carried out and new records of fishes, reptiles, and mammals recovered from Miocene deposits of the Zaysan Basin have been described. The study of fossils has revealed the existence of a quite diverse vertebrate assemblage in the basin during the Miocene. Representatives of the Percidae and Amiinae, and the species †Leobergia zaissanica predominated among fishes, whereas reptiles were supposedly represented in the assemblage by pan-trionychid turtles and crocodiles. No amphibians have been revealed, while the only mammalian taxa in the studied sample is a fossorial rodent of the genus †Tachyoryctoides. In contrast to previous views regarding the Middle Miocene age of the Zaysan Formation, the analysis of fish and mammal remains recovered from this locality strongly suggests an Early Miocene age. Findings of bowfin remains in the Zaysan Basin confirm that this group had existed outside of North America beyond the Paleogene/Neogene transition, and, at the same time, these specimens are the last known occurrences of the taxa Amiidae, Amiiformes, and Halecomorphi outside of North America. Data also indicate the existence of a lacustrine ecosystem in the Zaysan Basin during the Miocene with a taxonomically rich vertebrate assemblage and diverse trophic relations being an important center of biodiversity in the Miocene of Central Asia.

Geophysical Investigation and Geochemical Study of Sediment along the Coastal Area in Kota Belud Sabah, Malaysia

This article discusses the geophysical investigation of sediment and the status of heavy metals pollution in the coastal sediment from Usukan Beach, Kota Belud Sabah Malaysia. Study area is located at the northwest coast of Sabah which is bounded by the South China Sea and made up of Crocker Formation which age from Late Eocene to Early Miocene, Wariu Formation with Middle Miocene age and Quaternary Alluvium. This study using geoelectrical method namely electrical resistivity (IR) and induced polarization (IP) to measure the thickness of sediment and the parent rock lithology respectively. Whereas the heavy metal contents were measured using the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP- OES). Three sets of subsurface cross-sections were conducted for the geophysical survey and covered the depth around 37 meters for all the survey line. The result of geophysical survey shows that the alluvium quaternary deposits in the low-lying flat area have a thickness up to 13 metres and overlie the mudstone dominated rock of the Crocker Formation. The geochemical analysis shows a decreasing ranking order of elemental concentrations Fe>Mn>Zn>Cu>Pb>Cr>As. The analyses show all elements are within the background values and acceptable standard limits of the Sediment Quality Guidelines (SQG) by USEPA for coastal sediments. The assessment of heavy metals revealed only minimal degree of pollution in the coastal sediments.

Facies Analysis Of The Late Eocene Deep-Marine Middle- To Outer-Fan Sequence Of The Crocker Formation In Tenom District, Sabah, Malaysia

The Crocker Formation, Late Eocene to Middle Miocene in age, was deposited in a deep-marine environment by a turbidity current. Most of the facies identified in the field are related to the sedimentary bed-form structures belonging to Bouma sequences. These prominently include unit divisions such as Ta referring to grading sand, Tb for parallel laminae, Tc for cross laminae, Td for mud laminae, and Te referring to hemipelagic mud. Five facies have adequately been identified using Bouma sequence implications, namely Facies 1 (F1: Ta-Tb layers), Facies 2 (F2: Ta-Te layers), Facies 3 (F3: Tb-Te layers), Facies 4 (F4: Tb / Tc-Te layers), and Facies 5 (F5: Td-Te layers). Based on the Crocker Formation facies analysis, three distinct groups of facies associations were recognised: Deep-Marine Channel-Lobe Association (Type A1), Deep-Marine Channel-Levee Association (Type A2), and Distal Lobe Association. These facies associations precisely revealed that the Crocker Formation's depositional environments were likely deposited in the middle-fan with associated outer-fan settings.

Preliminary Study of Geology, Alteration and Ore Mineralisation at East Motoling Area, South Minahasa District, North Sulawesi, Indonesia

The East Motoling area is one of the prospect areas in the Minahasa region of North Sulawesi, which has indications of low sulfidation epithermal-type mineralization. The research was conducted as a preliminary study to determine the characteristics of geological conditions, alteration, and ore mineralization in the epithermal system. The research method is divided into two main parts, such as fieldwork including surface geological mapping (lithology, stratigraphy, geomorphology, structural geology, alteration and mineralization) and laboratory analysis methods including petrographic analysis. The stratigraphy of the study area consists of altered volcaniclastic breccia, altered lapilli tuff, altered tuff, limestone, welded lapilli tuff, and andesitic breccia. Volcaniclastic breccia, altered lapilli tuff, and altered tuff, member of the Volcanic Rock Formation which is Late – Middle Miocene age, are the host rock for ore mineralization and hydrotermal alteration process. There are 3 types of alterations that have developed, namely argillic (illite + quartz ± kaolinite), sericitic (sericite + illite ± chlorite), and propylitic (chlorite + epidote ± illite). The dextral slip fault with NW – SE trend present as a main control structure to formation of extention fracture/vein. The epithermal veins are relatively north-northeast – south-southwest, north-northwest – south-southeast, and northwest – southeast. The textures of the veins divided into 7 main groups, namely that is bladed-quartz, breccia, calcedony, colloform, comb, mold, and massive quartz. Ore mineralization is forms in the veins as pyrite and banded sulfide. Apart from that, the disseminated pyrite also limitedly found around the veins.

Biostratigraphy, Depositional and Diagenetic Processes in Carbonate Rocks from Southern Lebanon: Impact on Porosity and Permeability

AbstractCarbonate rocks contain prolific hydrocarbon reserves all over the world, particularly in the Middle East. For exploration and production strategies, it is essential to understand carbonate reservoirs in terms of their internal characteristics, depositional environment, relative age, diagenetic processes and impact on petrophysical properties. This study has been performed on exposed Cretaceous, Paleocene and Miocene marine carbonate sedimentary sequences in two localities (Maghdoucheh and Qennarit) near the city of Sidon (Southern Lebanon). It represents the first comprehensive study that takes into consideration the carbonate reservoir facies, diagenetic history and reservoir quality in the area. Rocks at Maghdoucheh are mainly dominated by limestone beds showing sedimentary structures and erosive bases alternating with microfossil‐rich silty marls, related to a shallowing upward sequence in a restricted marine platform environment. Shells of benthic foraminifera and mollusks dominate the fossil assemblage extracted from the studied rocks. The microfossil and nannofossil assemblage detected in the Maghdoucheh sections indicates a middle Miocene age. Rocks at Qennarit are composed of mudstone/wackestone limestone beds rich in planktonic foraminifera and nannofossils related to open marine conditions. Based on the nannofossil content, rocks from Qennarit 1 and 2 are Paleocene and Cretaceous in age, respectively. Four main types of microfacies have been identified, i.e. (1) microbioclastic peloidal calcisiltite, (2) pelagic lime mudstone and wackestone with planktonic microfossils, (3) grainstone/packstone with abundant foraminifera and (4) fenestral bindstones, mudstones and packstones with porostromate microstructures. The porosity‐permeability (poroperm) analysis of representative samples reveals moderate to good porosity but very low permeability. This is mainly due to the presence of large moldic pores that are isolated in nature. The diagenetic features are dominated by micritization and dissolution (both fabric selective and non‐fabric selective). Among all diagenetic features, dissolution in both localities contributes to porosity enhancement, while micritization, cementation, compaction and the filled fractures have negative impacts on permeability; hence the overall reservoir quality.

A new discovery of a Giraffokeryx skull and associated fossil assemblage of Ruminants from the Middle Miocene deposits of the Siwaliks

ABSTRACT A detailed taxonomic study of fossil ruminants from three localities of the Chinji Formation, Lower Siwaliks of the Siwalik Group, Pakistan has been carried out. These fossil sites; Dhok Bun Ameer Khatoon, Chinji type locality, and Lava have produced an important quantity of fossil fauna of the Middle Miocene age. Many new Ruminant samples have been collected including three different families Tragulidae, Giraffidae, and Bovidae. The 41 collected and described specimens belong to five species. Quantitatively, bovids and girafids provide evidence of small to medium size ruminants. The skull of Giraffokeryx punjabiensis has been reported for the first time from the locality Dhook Bun Ameer Khatoon. Giraffokeryx is the medium-sized member of the Giraffidae famed for its two pairs of horn cores. The litho-stratigraphic paleoenvironmental data of Chinji Formation (14.2–11.2 Mya) indicate that the Miocene climate of Pakistan was likely to be monsoonal and humid having extensive forest components and grasslands. Biogeographically, the Miocene fauna of Lower Siwaliks shows similarities with Eurasian and African Miocene sites. The composition of the fauna suggests a Middle Miocene age.

Early evidence of continental aridity and open-habitat grasslands in Europe as revealed by the Middle Miocene microflora of the Madrid Basin

In this study we present a new, extensive palaeobotanical and palaeoclimatic record from 85 microfloral assemblages of Middle Miocene (late Langhian–early Serravallian) age recovered from ten localities in the Madrid Basin. A large, shallow, slightly saline lacustrine system developed in the study area, promoting the occurrence of salt-tolerant plant communities on the lake margin. The regional landscape of the basin was characterised by grass-dominated, savannah-like vegetation under a warm (MAT: 13.8–18.8 °C) and semi-arid (MPwet: 151–71 mm, MPdry: 45–4 mm) climatic regime with marked seasonality of temperature and precipitation. These data re-open the debate on the origin of grasslands linked to dry conditions in Europe. Overall increased cooling and aridity through the Miocene led to the onset of grass-dominated habitats at the expense of forests, a process that in eastern Europe has been shown to occur from the Late Miocene. Our results, together with previous palaeobotanical and fossil mammal data from southern and central Spain, strongly indicate that open habitats were already prevalent in the Iberian Peninsula in the Middle Miocene, suggesting an earlier establishment here than in eastern Europe, possibly following a temporal pattern like the Anatolian Peninsula. The taxonomic diversity yielded by the samples from the Madrid Basin contributes to the understanding of the floristic composition of these early open habitats which were dominated by Poaceae, Amaranthaceae and Asteraceae with scattered shrubby and arboreal plants adapted to dry conditions such as Ricinus, Ephedra, Olea, Quercus, Acacia and Pinus. The age of the studied samples, coincident with the Middle Miocene Climatic Transition, indicates that this climatic episode marked an important step towards the establishment of open vegetation.

Tectono-stratigraphic evolution of the northeastern sector of the Ñirihuau basin, North Patagonian Andes, Argentina: Insights from sedimentology and geochronology data of the Ñirihuau Formation

An approximately 3500 m thick stratigraphic section was detailed surveyed in order to study the tectono-sedimentary evolution of the Ñirihuau Formation along the Arroyo Las Bayas, in the northern sector of the Ñirihuau basin, North Patagonian Andes. A total amount of 29 lithofacies were recognized and used to define facies, grouped into six facies associations (FA) that reflect different paleoenvironments: FA1 (Gray to brownish conglomerates), FA2 (Conglomerates and sandstones), FA3 (Tabular mudstones), FA4 (Brownish sandstones and conglomerates with large scale foresets), FA5 (White tuffaceous sandstones) and FA6 (Sandstones and conglomerates with mudstones). The lower section of the unit was interpreted as deposited in a medium to distal alluvial fan or an axial fluvial system developed in the most distal zone of an alluvial fan (FA1 and FA2). The middle section of the unit is characterized by a Gilbert-type delta developed between two lacustrine sequences (FA3 and FA4). In the upper section of the unit, higher energy deposits corresponding to fluvial systems are registered (FA5 and FA6). Deposits from synchronic volcanic events are recorded along the stratigraphic section. Also, a provenance analysis was carried out by using sedimentary petrography and U–Pb zircon geochronology data. The main identified sediment source corresponds to the contemporaneous Miocene volcanic arc. A secondary detrital provenance from older Cenozoic volcanic rocks of the El Maitén Volcanic Belt was also identified, as well as minor contributions from pre-Cenozoic igneous and metamorphic units. U–Pb geochronological data constrain deposition of the middle and upper sections of the Ñirihuau Formation in the Arroyo Las Bayas section to the middle to late Miocene, between 15 and 11.4 Ma (Langhian to Tortonian). Also, a possible middle Miocene age was discussed for the lower section. An integrated tectono-stratigraphic model was finally proposed, with contrasting extensional and synorogenic tectonic stages registered in the lower and upper sections of the Ñirihuau Formation, respectively.

Metamorphic PT path, U-Pb zircon dating and tectonic implications of High-pressure Pelitic Granulites from the Kharta region, Southern Tibet, China

HP pelitic granulites associated with eclogites from the Kharta Gneiss are found in the Thongmön area, central Himalaya, which provides significant constraints for the tectonic evolution of the Himalayan orogeny. Three generations of garnets are identified in pelitic granulites (DR15P15). The first generation of garnet is core sections of euhedral to subhedral porphyroblasts (Grt-I core) followed by growth of Grt-I mantle during the heating stage. The third generation of garnet is represented by thin rims of Grt-I and small grains (Grt-II) in the matrix, which likely nucleated and grew in response to peritectic reaction during exhumation. Petrographic evidence and P–T pseudosection calculation reveal a four-stages metamorphic evolution: 1) a prograde metamorphic stage (M1) represented by Grt-I core and its mineral inclusions rutile, ilmenite and quartz with metamorphic conditions of 740–760 °C and 13–16 kbar; 2) a near isobaric heating stage with slightly decompression to HP granulite-facies (M2, 820–840 °C, 13–14 kbar) indicated by the composition of Grt-I mantle and the increase of Zr concentrations of rutile in it; 3) a heating decompression stage (M3) supported by a decrease in grossular content in the Grt-I rim and higher XAn in plagioclase, yielding T > 860 °C and P = 10–11 kbar in the sillimanite stability field; 4) a final decompression stage followed by cooling (M4, T ~ 800 °C and P = 6–8 kbar) indicated by biotite replacing sillimanite and lower Ti content in biotite in the matrix. Based on the zircon trace element geochemistry, zircon inclusions, and the REE partitioning between garnet and zircon, the metamorphic zircon rims with middle Miocene age (16–13 Ma) probably grew during Grt-I rim/Grt-II formation at granulite facies stage (M3). The P–T history of the pelitic granulites of the Kharta Gneiss indicates that they were subducted beneath the Asian plate and exhumed to middle-lower crustal depths prior to 14–13 Ma due to the activity of STDS.

First finding of a fossilized Cantharidae (Insecta: Coleoptera) from the Middle Miocene deposits in Romania

The extraordinary fossil sites of Vlădiceni (Iaşi, Romania) recently discovered, with lithostratigraphy of Middle Miocene age, have uncovered a rich fauna especially of fishes, molluscs, amphipods and insects. This includes also the first fossil specimen of family Cantharidae from both this geological formation and from Romania: Malthodes (Malthodes) vladiceniensis sp. nov., which is illustrated and described and compared with living and fossil species of the genus.

Detecting pigments from gypsum endoliths using Raman spectroscopy: From field prospection to laboratory studies

AbstractMicrobial colonisations of gypsum from different sites from Southern Sicily and Eastern Poland were investigated using laboratory‐based Raman microspectrometers and portable Raman spectrometric devices. Selected zones of microbial colonisations of few types of gypsum are described from the point of view of the presence of algae and cyanobacteria. Macrocrystalline gypsum layers in Sicily and Eastern Poland originate from Tertiary sedimentary series. In Southern Sicily gypsum outcrops from late Miocene age were investigated near Scala dei Turchi, Torre Salsa and Siculiana Marina. Polish Tertiary Middle Miocene age examples of gypsum colonisations of decimetre to metre long outcropping gypsum crystals were studied near Chotel Czerwony, Skorocice and Chwalowice. Common microbial pigments were detected: carotenoids were documented in majority of the samples (common Raman bands at around 1525, 1157 and 1004 cm−1), Raman spectra of other pigments were recorded in several zones using near infrared excitation (785 nm): chlorophyll (1326, 1285, 1188 and 745 cm−1), scytonemin (1593, 1552, 1438 and 1173 cm−1) and phycobiliproteins (1275 cm−1). Raman microspectrometric investigations of colonisations allow to gather detailed information about pigment distribution in micrometric zones of gypsum samples. Portable instrumentation permits also detection of carotenoids. Observed shifts of positions of Raman features of carotenoids between gypsum samples (and sites worldwide) and relative to reference values are discussed and critically evaluated.

Bayesian facies inversion on a partially dolomitized isolated carbonate platform: A case study from Central Luconia Province, Malaysia

We have developed a case study of geophysical reservoir characterization in which we use elastic inversion and probabilistic prediction to estimate nine carbonate lithofacies and the associated porosity distribution. The study focuses on an isolated carbonate platform of middle Miocene age, offshore Sarawak in Malaysia that has been partly dolomitized — a process that increased the porosity and permeability of the prolific gas reservoir. The nine lithofacies are defined from one reference core and include a range of lithologies and pore types, covering limestone and dolomitized limestone, each with vuggy varieties, as well as sucrosic and crystalline dolomites with intercrystalline porosity, and argillaceous limestones and shales. To predict the lithofacies and porosity from geophysical data, we adopt a probabilistic algorithm that uses Bayesian theory with an analytical solution for conditional means and covariances of posterior probabilities, assuming a Gaussian mixture model. The inversion is a two-step process, first solving for P- and S-wave velocities and density from two partial seismic stacks. Subsequently, the lithofacies and porosity are predicted from the elastic parameters in the borehole and across a 2D inline. The final result is a model that consists of the pointwise posterior distributions of the facies and porosity at each location where seismic data are available. The facies posterior distribution represents the facies proportions estimated from seismic data, whereas the porosity distribution represents the probability density function at each location. These distributions provide the most likely model and its associated uncertainty for geologic interpretations of lithofacies associated with distinct stages of carbonate platform growth.