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Units with extremely variable erodibility are typical in the succession of pyroclastic-dominated volcanic fields. Welded ignimbrites are usually resistant to erosion, thus, they often appear as positive landforms, i.e., mesas or tilted plateaus after millions of years of denudation. The Bükkalja Volcanic Area being part of the most extended foothill area of the North Hungarian Mountains, is composed predominantly of Miocene ignimbrites, where the frequency distributions of elevation a.s.l., slope, aspect, as well as topographic openness, were investigated using a 30 m resolution SRTM-based digital surface model at four sample areas located at different relative distances from the assumed source localities of the ignimbrites, showing both non-welded and welded facies. The degree of dissection was also examined along swath profiles. The topography of the sample area closest to the source localities is dominated by slabs of moderately dissected welded ignimbrites, gently dipping towards SE. Farther away from the source the topography is dominated by erosional valleys and ridges, resulting in a narrower typical elevation range, a higher proportion of pixels with greater than 5° slope, higher frequencies of NE and SW exposures, and more significant incision resulted in more frequent pixels with positive topographic openness less than 1.5 radians here. Higher thicknesses and emplacement temperatures of ignimbrites, often showing welded facies are more common closer to the source vent. Thus, the erosional pattern around calderas can be used to draw conclusions on the spatial extent of the most intense ignimbrite accumulation, i.e., the location of eruption centres even in highly eroded ignimbrite fields.

Simple Summary: Cacti account for nearly 1440 species, most of them native to the American continent. These succulent plants are the most ubiquitous elements of the arid ecosystems. Mexico harbors the highest number of cacti species in the world (45%). Unfortunately, many of them are threatened by human activities. Although having this biodiversity relevance, presently the evolutionary processes of cacti have been poorly studied. Because the biological and conservation unit is the species, evolutionary studies provide relevant information. In this study, we analyzed how and when past events shaped the evolutionary relationships of 103 species. Our results showed that from 4.5 million years ago the arid regions of Mexico were the locations for abundant cacti speciation. From these lands, cacti have colonized most of the Mexican territories, the southern regions of the United States, as well as the Caribbean. The evolution of these plants was probably promoted by past temperatures that were comparable to the present ones. We identified different speciation and dispersal events in these fascinating plants. This study identified the Mexican Plateau as the place where the early stages of the evolutionary history of cacti occurred. Mexico harbors ~45% of world's cacti species richness. Their biogeography and phylogenomics were integrated to elucidate the evolutionary history of the genera Coryphantha, Escobaria, Mammillaria, Mammilloydia, Neolloydia, Ortegocactus, and Pelecyphora (Mammilloid Clade). We analyzed 52 orthologous loci from 142 complete genomes of chloroplast (103 taxa) to generate a cladogram and a chronogram; in the latter, the ancestral distribution was reconstructed with the Dispersal-Extinction-Cladogenesis model. The ancestor of these genera arose ~7 Mya on the Mexican Plateau, from which nine evolutionary lineages evolved. This region was the site of 52% of all the biogeographical processes. The lineages 2, 3 and 6 were responsible for the colonization of the arid southern territories. In the last 4 Mya, the Baja California Peninsula has been a region of prolific evolution, particularly for lineages 8 and 9. Dispersal was the most frequent process and vicariance had relevance in the isolation of cacti distributed in the south of Mexico. The 70 taxa sampled as Mammillaria were distributed in six distinct lineages; one of these presumably corresponded to this genus, which likely had its center of origin in the southern part of the Mexican Plateau. We recommend detailed studies to further determine the taxonomic circumscription of the seven genera. [ABSTRACT FROM AUTHOR]

A recent expedition in the Potwar Plateau of Pakistan has yielded dental material of three rhinocerotid species Chilotherium intermedium, Alicornops complanatum, and Brachypotherium perimense. The material came from the Nagri and Dhok Pathan formations of the Middle Siwalik Subgroup in Punjab, Pakistan. These specimens are good addition to provide additional morphological characters that show information about the variations in dental characters of theese already recorded species and contribute to recent work on Rhinocerotidae from the Middle Siwalik Subgroup of Pakistan. The studied remains of these three rhinocerotids species whose remains are relatively low in the Middle Siwaliks are good paleontological contribution with some more detailed work suggested here to understand about these genera. Presence of these Siwalik rhinocerotids indicates diverse habitats from forest to savanna environments. [ABSTRACT FROM AUTHOR]

Aplodinotus grunniens represents one of the most common, widespread, and unique freshwater fishes in North America. Understanding the evolutionary history of this sciaenid is challenging though as published palaeontological records are lacking. Existing literature documenting skeletal remains and otoliths is summarised herein to better understand divergence and biogeography of the extant A. grunniens and extinct Aplodinotus species. Fossil evidence indicates that in addition to A. grunniens, three putative, extinct, marine species in North America and two in South America existed. The North American fossil Aplodinotus range from Oligocene to early Miocene, while the genus extends to the middle Miocene in South America. All described extinct fossil Aplodinotus have been recovered from shallow marine sediments with the oldest from the U.S.A. Gulf Coastal Plain. All sites with extant A. grunniens are from freshwater deposits ranging from middle to late Miocene to Holocene in age which very closely approximate the modern geographic distribution and include a variety of preserved skeletal elements and otoliths. The disappearance of the fossil marine Aplodinotus in the early Miocene in the Gulf is interpreted to represent the genus' transition to brackish and eventually freshwater habitats and development of the extant species by the late Miocene. [ABSTRACT FROM AUTHOR]

The planktonic foraminiferal assemblages are tracked in the middle Eocene–early Miocene succession within N. El Faras‐1X Well, Qattara Depression, Egypt. This succession is composed mainly of three lithostratigraphic units the upper part of the Apollonia Formation (middle to late Eocene), Dabaa Formation (late Eocene and Oligocene) and the lower part of the Moghra Formation (early Miocene). Biostratigraphically, the recorded 77 planktonic foraminiferal species enabled the recognition of 12 planktonic foraminiferal biozones; 4 biozones belong to middle to late Eocene, 7 biozones belong to the Oligocene and 1 belongs to the early Miocene. The proposed biozones were compared with their equivalents in other Egyptian regions and other schemes. Eleven Lowest Occurrence and two Highest Occurrence planktonic foraminiferal bioevents were also recognized and correlated all over the world. The chronostratigraphy and the stage boundaries were mainly delineated according to the diagnostic planktonic foraminifera. The middle–late Eocene boundary (Bartonian–Priabonian boundary), The Eocene–Oligocene boundary (Priabonian–Rupelian boundary), the early Oligocene–late Oligocene boundary (Rupelian–Chattian boundary) and the Oligocene–Miocene boundary (Chattian–Aquitanian boundary) were accurately determined. Based on the % P, the palaeobathymetry was estimated and hence the sea‐level fluctuation. The reconstructed sea‐level curve revealed two major transgressive–regressive cycles with minor oscillation within them. These events were globally correlated and match in most parts with that of the worldwide sea‐level curves. The sequence stratigraphy framework consists mainly of two transgressive–regressive (T–R) depositional sequences (DS1 and DS2). The DS1 includes the TST1 below which is capped by mfs1 and the HST1 above. The DS2 involves the TST2 below that was capped by mfs2 and the HST2 above. [ABSTRACT FROM AUTHOR]

[Display omitted] • Shark tooth Nd isotopes reveal the origin of water masses along the Peruvian coast. • Modern-type upwelling at latest since the late Oligocene. • A late Miocene negative ԑ Nd excursion coincides with a worldwide biogenic bloom. The Humboldt Current System along the Pacific coast of South America creates one of the most productive ecosystems on Earth. To trace the origin of the water masses in this area, we measured neodymium isotope compositions (ԑ Nd) in tooth enameloid of two genera of coastal sharks from latest Oligocene to early Pleistocene strata in the Pisco and Sacaco basins in southern Peru. Most ԑ Nd values range from −4 to −1, with a strong negative excursion in the late Miocene (∼8–7 million years ago [Ma]) with values as low as −9.2. The overall trend of the ԑ Nd values resembles that of equatorial Pacific deep waters, though with an offset of about +2 ԑ Nd units until about 6 Ma. With a major input of hinterland weathering considered unlikely, we interpret this pattern as reflecting a modern-type upwelling regime, though with a lower contribution of Antarctic waters than today. Starting about 6 Ma, the contribution of Antarctic waters to the upwelling waters increased approximately to present-day levels, coincident with, and possibly driven by, increased Antarctic glaciation and the Andes reaching their present-day elevation, both of which likely enhanced the counter-clockwise circulation in the South Pacific Ocean. The negative excursion of ԑ Nd values in the Pisco/Sacaco basins ∼8–7 Ma coincides with a late Miocene biogenic bloom in the Pacific Ocean and elsewhere, and with a strongly increased northward bottom current observed on the Nazca Drift System just offshore our sampling area. Thus, the negative excursion of ԑ Nd values in the Pisco/Sacaco basins likely resulted from a southern sourced input of nutrient-rich, unradiogenic water, which could have been an important contributor to the biogenic bloom. [ABSTRACT FROM AUTHOR]

The scanning of paleontological collections is increasingly important for morphological studies and science outreach. In addition to ensuring data sharing, digitization contributes to preserving morphological information in case of damage to the original specimens. In this communication, we aim to report digital versions of the holotypes from the Vertebrate Paleontology Collection at the Museu Paraense Emilio Goeldi, Brazil. For this purpose, eighteen holotypes of Early/Middle Miocene Teleostei from Pirabas Formation, northern Brazil, were scanned using microtomography, and cybertypes were proposed. The CT‐Scan data were stored in a virtual repository, can be freely accessed, and are available for future studies on the morphology of these specimens. Furthermore, these specimens are tiny and fragile, and digital versions can be an alternative to safely handling them. Finally, the digitization of important specimens, at least of holotypes, needs to be a standard practice in museum collections over the next years. [ABSTRACT FROM AUTHOR]

Introduction The Guri member deposits spread in the south of the Zagros basin (Khuzestan, coastal and interior Fars), and the type section is around 111 meters thickness in the Tange Guri in the southeast of Lar city (Fars zone) (James & Wynd, 1965). The Guri member thickness changes hugely in the Zagros basin and is considered the main gas reservoir in the Sarkhon gas field in the southeast part of the Zagros basin (Rahmani et al., 2010); because of this, stratigraphy and sedimentology of this member are very important. The Guri member is in the lower part of the Mishan formation and is composed of cream to brown limestones with interbedded layers of grey marl (James & wynd, 1965; Fanati et al., 2014). Except for internal Fars, which Razak formation is the lower boundary of the Guri member; in other areas, this member is underlaid by the Gachsaran formation conformably and is overlain by the marly units of Mishan formation gradually (Rahmani et al., 2010; Fanati et al., 2014). Most of the studies on the Guri member have been on the depositional environment, Paleoecology and diagenetic processes in the coastal and interior Fars. The conclusions led to the point that the Guri member has been deposited in a carbonate ramp with warm marine conditions (Rahmani et al., 2010; Fanati et al., 2014). So far, there are no studies about the trace fossils and ichnofacies of the Guri member. All biological structures in the sedimentary layers (separated or completely bioturbated with ambiguous trace fossils) are named ichnofabric (Abbasi & Amini, 2006). Since trace fossils are formed during or shortly after sedimentation, they reflect their biological and non-biological conditions. Thalassinoides suevicus in the Y, T, cylindrical, arc and question mark-shaped burrows dominate the Guri member layers. Thalassinoides are smooth and ungrooved trace fossils, common in the Mesozoic and Cenozoic periods and form by decapod crustacean and thallasinid shrimp in the new sedimentary environment (Myrow, 1995). Therefore, the ongoing research aims at identifying the paleoenvironment based on trace fossils, ichnofabrics, the types of facies and depositional environment of the Guri member in the Dezful embayment (Omidieh, Shahid Rajaei village and Milaton sections) south-west Iran. Material and methods This study contains detailed facies, depositional environment, and paleoenvironment features in 3 stratigraphy sections of the Guri member (Milaton, Omidieh and Shahid Rajaei village sections) Zagros basin, south-west Iran. Milaton, Omidieh, and Shahid Rajaei village thicknesses are 103, 63 and 60 meters, respectively. Sampled numbers in these sections, respectively, are 110, 70 and 68 samples. The sections were described based on lithology, sedimentary structures and facies compositions. Around 200 thin sections of the non-weathered layers were prepared and then analyzed by a polarized microscope to define various facies. Textural identification and carbonate classification are also conducted using Dunham (1962) and Embry and Klovan (1971). Facies identification and sedimentary environment interpretation were made using studies such as Avarjani et al. (2015) and Moradi et al. (2018). Droser and Bottjer's (1986) standard cards were used to identify ichnofabric classes. Results and discussions The Thalasinoides suevicus is the only known trace fossil in the Guri member in the studied areas. Burrows showed regular branching with Y, T, Question mark (?), arc and cylindrical shapes and were filled with the host sediments (Pemberton et al., 1992). Trace fossils assigned to Thalassinoides in new sedimentary environments due to vagile to semi-vagile crustaceans, probably, Thalassinid Decapods. In the studied sections, Portunus sp. is found among limestone layers. The bioturbations in the layers are categorized into five ichnofabric classes in the Omidieh section and three ichnofabric classes in the Parsi section, which are equal to standard ichnofabric indexes of 1 to 5. The greater frequency of ichonfabrics in the Omidieh section is due to marked changes in environmental conditions such as depth and oxidation. Thalassinoides frequently are belonged to oxygenated environments in soft but fairly cohesive substrates (El-Sabbagh et al., 2017). The Guri Member fauna includes benthic imperforate foraminifera such as (Pyrgo sp., Dendritina rangi, and Miliolids), benthic perforate foraminifera (Rotalia viennoti, Oprculina complanata, Elphidium sp.) and bivalve, gastropod, Echinoid fragments. Dendritic rangi and Miliolid assemblage are evidence of a restricted lagoon environment and indicate a variety of very shallow, mesohaline environments and are also common in sand shoal environments with normal salinity (Bassi and Nebelsick, 2010). The association of Ammonia, Elphidium and bivalve fragments reveals a eutrophic environment with normal marine conditions only exposed to short-term salinity variations (Reuter and Brachert, 2007). The presence of bryozoans and microfossil assemblages with their relatively high diversity in some samples probably indicates that the environmental conditions changed from unstable with salinity fluctuations to more stable and normal salinity (Filipescu et al., 2014). The presence of Thalassinoides in the Guri member indicates very shallow and warm marine conditions. Petrographic analysis and biological association led us to define nine facies deposited in three facies belts: tidal flat, lagoon, and shoal--the flat tidal facies including Anhydrite, mudstone and Fenestrate mudstone (A1, A2, A3). Anhydrite facies (A1) are the shallowest because they settle in the supratidal environment. Mudstone facies (A2) is the shallower facies than Fenestrate mudstone (A3) due to the presence of dolomites. Depositing in a stressful area caused no trace fossils in mudstone facies (A2). On the other hand, fenestrate mudstone facies (A3) has foraminifera and contains only gastropod and bivalve shells and the effects of bioturbation. Restricted lagoon facies are Imperforate foraminifera, bioclast wackestone to grainstone (B1), bioclast pellet wackestone to packstone (B2) and Marl facies (B3). In Imperforate foraminifera, bioclast wackestone to grainstone facies (B1), Textural characteristics and abundant porecelain foraminifera suggest a medium energy-restricted lagoon nearby a flat tidal environment (Vaziri Moghaddam et al., 2006). Two facies, bioclast pellet wackestone to packstone (B2) and Marl (B3), have the same fauna. Marl facies (B3) deposited farther from the shoreline due to settling in no oxygenated environment. Semi-restricted lagoon facies are composed of foraminifera (perforate and imperforate) bioclast wackestone to packstone (C1) and Bryozoir bioclast wackestone to packstone (C2). Foraminifera (perforate and imperforate) bioclast wackstone to packstone (C1) is characterized by the cooccurrence of imperforate and perforate foraminifera (Vaziri Moghaddam et al., 2010). The co-occurrence of porcelaneous foraminifera and bryozoir fragments in facies (C2) indicates an internal ramp environment (Vaziri Moghaddam et al., 2006). The absence of mud and well-sorted ooid grains in ooid peloid grainstone facies (D1) indicates a shoal environment with high-energy conditions (Hearty et al., 2010). Conclusion The Guri member of the Mishan formation is composed of 9 facies that are belonged to shoal, lagoon, and flat tidal environments of a carbonate ramp. Thalassinoides suevicus is the only known trace fossil in the Guri member of Mishan formation in the studied area. Thalassinoides suevicus is present in the Omidieh and Shahid Rajaei sections, but no trace fossil exists in the Milaton section. The bioturbations in the layers are categorized into five ichnofabric classes, equal to standard ichnofabric indexes of 1 to 5. The presence of Thalassinoides in the Guri member indicates a very shallow and warm marine condition. The more various shapes of Thalassinoides suevicus at the Shahid Rajaei village section (Y, T, question mark, arc and cylindrical shaped burrows) rather than the Omidieh section (most cylindrical burrows) indicate trace makers presented for a longer time and different biological activities such as feeding, escaping and hosting. [ABSTRACT FROM AUTHOR]

Tarkhanian and Chokrakian representatives of the family Amathinidae are revised. Two genera, Leucotina and Carinorbis, are identified. The species L. ventosa (Bajarunas, 1910), L. belskayae (L. Iljina, 1993), L. costata sp. nov., L. excussa sp. nov., L. ovata sp. nov., and L. ovatoides sp. nov. are described from the genus Leucotina. L. ventosa is known from the confirmed Tarkhanian and continued into the Chokrakian, whereas the other species were only collected from the Chokrakian. Relationships between the species of Leucotina remain unclear, although they can be divided into several morphological groups. It is concluded that the Chokrakian diversity of the genus Leucotina results from its earlier (Tarkhanian) history. The genus Carinorbis is represented by rare, very juvenile shells, which occur in the uppermost Tarkhanian and Lower Chokrakian. The shells have been determined as the species C. clathrata (Philippi). It has been suggested that Carinorbis did not have a reproducing population in the Eastern Paratethys, and that its finds result from drift of its larvae from neighboring basins (Central Paratethys or Mediterranean). [ABSTRACT FROM AUTHOR]

Understanding the behavior of past upwelling cells is paramount when assessing f 17 uture climate changes. Our present understanding of nutrient fluxes throughout the world's oceans emphasizes the importance of intermediate waters transporting nutrients from the Antarctic divergence into the middle and lower latitudes. These nutrient-rich waters fuel productivity within wind-driven upwelling cells in all major oceans. One such upwelling cell is located along the Oman Margin in the Western Arabian Sea (WAS). Driven by cross-hemispheral winds, the WAS upwelling zone's intense productivity led to the formation of one of the most extensive oxygen minimum zones known today. In this study covering the Middle to Late Miocene at ODP Site 722, we investigate the inception of upwelling derived primary productivity. We combine novel data with existing model- and data-based evidence, constraining the tectonic and atmospheric boundary conditions for an upwelling cell to exist in the region. With this research, we build upon the original planktonic foraminifer-based research by Dick Kroon in 1991 as part of his research based on the Ocean Drilling Project (ODP) LEG 117. We show that monsoonal winds likely sustained upwelling since the emergence of the Arabian Peninsula after the Miocene Climatic Optimum (MCO) ~14 Ma, with fully monsoonal conditions occurring since the end of the Middle Miocene Climatic Transition (MMCT) ~13 Ma. However, changing nutrient fluxes through Antarctic Intermediate and sub-Antarctic Mode Waters (AAIW/SAMW) were only established by ~12 Ma. Rare occurrences of diatoms frustules correspond to the maximum abundances of Reticulofenestra haqii and Reticulofenestra antarctica, indicating higher upwelling-derived nutrient levels. By 11 Ma, diatom abundance increases significantly, leading to alternating diatom blooms and high-nutrient-adapted nannoplankton taxa. These changes in primary producers are also well reflected in geochemical proxies with increasing δ15Norg. values (> 6‰) and high organic carbon accumulation also confirm high productivity and beginning denitrification simultaneously. Our multi-proxy-based evaluation of Site 722B primary producers thus indicates a stepwise evolution of productivity in the western Arabian Sea related to the intensity of upwelling and forcing SAM dynamics throughout the Middle to Late Miocene. The absence of full correspondence with existing deep marine climate records also suggests that local processes, such as lateral nutrient transport, likely played an important role in modulating productivity in the western Arabian Sea. Finally, we show that using a multi-proxy record provides novel insights into how fossil plankton responded to changing nutrient conditions through time in a monsoon wind-driven upwelling zone. [ABSTRACT FROM AUTHOR]

In the Bhagirathi River Transect of the Garhwal Himalaya, India, the existence of the Jhala Normal Fault (JNF) and its movement sense are disputed. The JNF has been considered either as part of the South Tibetan Detachment System (STDS) or as a distinct, more southerly discontinuity within the Higher Himalayan Crystalline Sequence (HHCS). Field studies reveal that the JNF lies entirely within the HHCS, with both the JNF footwall and hanging-wall preserving thrust-related shear markers within amphibolite facies HHCS rocks. Rare extensional shear markers are, however, observed at the base of the JNF hanging-wall. New U–Pb zircon rim and monazite SHRIMP ages of 33.8 ± 0.8 Ma and 30.7 ± 0.5 Ma obtained in this study represent the timing of metamorphism in the JNF hanging-wall and footwall, respectively. Together, the field and geochronological evidence suggest that during Eocene–Oligocene channel flow in the HHCS, the slow-moving marginal part of the channel representing the JNF hanging-wall was trailing its more rapidly extruding footwall, resulting in apparent normal-sense movement across the JNF. The intrusion of 21.4 ± 2.3 Ma (monazite U–Pb age) tourmaline-bearing leucogranites within the JNF hanging-wall testifies to its ongoing uplift as part of the exhuming Miocene HHCS channel. The absence of any metamorphic break or distinct extensional shear zone at the JNF indicates that it originated as an intra-channel discontinuity rather than a major lithotectonic boundary. Highlights: The normal/reverse sense of movement at Jhala Normal Fault (JNF) is controversial Melt proportion and shear intensity sharply decrease in JNF hanging-wall No extensional shear zone or break in metamorphic grade observed at JNF Pulsed channel in footwall causes apparent normal movement along JNF Normal movements along JNF and STDS are coeval with ~21 Ma leucogranite intrusion [ABSTRACT FROM AUTHOR]

Diatomites are sedimentary rocks rich in siliceous algae, mainly diatoms, and are evident in Greece mainly in Neogene successions. Despite their significance and worldwide potential as source rocks for hydrocarbons, little is known about them in the wider area of Greece, limited in their biostratigraphic characteristics and industrial use. This study assesses for the first time the Neogene diatomites in Western Crete and focuses on their source rock quality and hydrocarbon generation potential on top of their stratigraphic characteristics. The studied synthetic outcrop is of the Miocene age and is located in the Apokoronas sedimentary basin, in the Chania province. It is subdivided into four subsections reaching heights of 13 m. It has a total documented, visible extend of 90–100 m and presents adequate thickness in relation to other reported diatomitic occurrences in Crete. A SEM study and bulk sampling of 28 samples has been carried out on this outcrop and geochemical analysis has been conducted by means of a Rock-Eval 6 pyrolysis to facilitate the understanding of hydrocarbon potential. Stratigraphic analysis supports the establishment of system tracts (ST), with transgressive ones (TST) illustrated by fining-upward sequences including highstands (HST). At the top, a final coarsening-upwards sequence suggests a regressive sequence (RST) most probably related to the Messinian Salinity Crisis (MSC) event. Total organic carbon (TOC, %wt.) values are found to reach 3.4% in the diatomites, while siltstone/mudstone interlayers encounter lower TOC (%wt.), yet with exceptions reaching TOC levels as high as the diatomaceous facies. Overall, Rock-Eval pyrolysis shows that organic matter from the studied cross sections is immature with the hydrocarbon generation potential ranging from poor to excellent. The kerogen type is proved to be type III with poor to almost good quality. This suggests the presence of a prolific diatomaceous source rock in Western Crete demonstrating a high significance for the offshore hydrocarbon exploration in the Eastern Mediterranean that could potentially be related to the offshore Western and Southern Crete E&P-awarded blocks. [ABSTRACT FROM AUTHOR]

Fossil species of bethyline wasps from Dominican amber are revised. Based on a cladistic analysis of female morphological data we recognize a new genus and species, †Crassibethylus dominicanus gen. et sp. nov., which came out as sister group of the clade Odontepyris + Prosierola. We also transfer to Bethylidae a fossil taxon originally described in Sclerogibbidae, placing †Pterosclerogibba Olmi as a new junior synonym under Goniozus Förster, in the new combination †Goniozus antiquus (Olmi). Additionally, the third species of Bethylinae known from Dominican amber, †Goniozus respectus Sorg, is diagnosed and illustrated with color images of the holotype. An identification key to the species of Bethylinae from Dominican amber is provided. [ABSTRACT FROM AUTHOR]

Otoliths represent a well-established tool to reconstruct bony fish faunas of the past. However, they have remained underexplored in many regions of the world. Here we describe the first otolith-based fish fauna from the Neogene of India and the entire Indian Ocean, from the Burdigalian (Quilon Formation) of Kerala, southern India. The faunal composition is dominated by the Apogonidae and Gobiidae. The depositional environment is interpreted as a seagrass meadow in a sheltered back-reef environment, less than 10 m water depth, with no open marine influence, and possibly with mangroves on land. Some shared faunal elements observed in the Gobiidae with the coeval western Tethys and Paratethys suggest a possible faunal exchange during the late stages of the Tethyan Seaway. Coeval faunas from Indonesia (Java and Borneo) also show shared faunal elements, thus indicating that the typical Indo-West Pacific fish fauna was firmly established in the Burdigalian, at least for the Apogonidae and Gobiidae. The Quilon fauna is more diverse in Apogonidae than in any other contemporary region, and this aspect is briefly discussed with respect to the tropical Neogene marine diversity development. A total of 29 otolith-based taxa have been identified in the Quilon Formation, of which the following 11 species are described as new to science: Jaydia? quilonica, Siphamia minor, Fibramia keralensis, Acentrogobius matsya, Ancistrogobius indicus, Drombus thackerae, Gobiodon burdigalicus, Amblyeleotris kireedam, Fusigobius? venadicus, Cirripectes biconvexus, and Callionymus vyali. [ABSTRACT FROM AUTHOR]

A new species of crayfish, Cambarus nyx n. sp. , is described from the Kentucky/Tennessee border in the Dissected Appalachian Plateau sub-ecoregion of the US. Of the recognized species of Cambarus Erichson, 1846, it is morphologically most similar to Cambarus deweesae Bouchard & Etnier, 1979, found primarily in the Southern Limestone/Dolomite Valleys and Low Rolling Hills sub-ecoregion. Cambarus nyx n. sp. , is distinguishable from other recognized congeners, except for C. deweesae, by the strongly serrated lateral margin of the propodi of the chelae, closed areola, two rows of palmar tubercles, truncate rostrum with convergent margins, and Form I male (MI) gonopod having a central projection shorter than the mesial process. The new species differs from C. deweesae in coloration (blue vs. red, respectively) and size at maturity only. There is considerable genetic, morphometric, and color variation among populations herein considered as members of the new species. The species has a limited range and highlights once more the need for increased conservation efforts for North American crayfishes. Genetic analysis of C. nyx n. sp. sheds light on the evolutionary process occurring in the crayfishes of the Appalachian Mountains after the origin of Cambarus. [ABSTRACT FROM AUTHOR]

Middle Miocene (Serravallian; upper Badenian–lower Sarmatian) strata recovered in 10 cored boreholes (83 samples) from Bad Deutsch-Altenburg, Vienna Basin, Austria, were analysed palynologically for the first time. The strata belong to the Rabensburg Formation of the Baden Group. The lateral distribution of the boreholes in reference to a Mesozoic ridge makes this area interesting for studying various aspects such as distribution of deposits, stratigraphy and palaeoenvironmental reconstruction. A diverse and well-preserved in situ dinoflagellate cyst association has been identified. Middle Miocene age-diagnostic species including Cannosphaeropsis passio, Cerebrocysta poulsenii, Habibacysta tectata, Labyrinthodinium truncatum, Operculodinium? borgerholtense and Unipontidinium aquaeductum are recorded. Their occurrences allow correlation with dinoflagellate cyst biozonations on a regional scale. Based on the identified dinoflagellate cysts and by correlation with calcareous nannoplankton and ostracods, from the same set of samples, a Serravallian age – corresponding to a late Badenian and early Sarmatian age (regional Paratethys stages) – is confirmed. Reworked (Cretaceous and Paleogene) dinoflagellate cyst assemblages, also well preserved, were recorded abundantly from boreholes HA 521 and HA 573 (south-west of the Mesozoic ridge). In accordance with ostracods, the Badenian–Sarmatian boundary can be traced in the upper part of borehole HA 66 based on an abrupt change in the dinoflagellate cyst assemblages. The upper Badenian strata were deposited in a coastal to inner shelf environment with terrigenous (siliceous sand and clay) and carbonate sediments. The recorded dinoflagellate cysts reflect marine, tropical to warm-temperate climatic conditions. The composition of the recorded dinoflagellate cyst assemblages is very close to that of the Middle Miocene assemblages of the Mediterranean, indicating water exchanges between the Central Paratethys and the Mediterranean during the late Badenian (early Serravallian). [ABSTRACT FROM AUTHOR]

The number of late Neogene Spanish micromammal-containing continental sections with a correlation to the Geomagnetic Time Scale is steadily growing. Nonetheless, well-calibrated sections with dense micromammal records are still rare, biostratigraphic correlations between basins are not straightforward, and ages of uncalibrated sites are poorly constrained. Here, we aim at improving the chronology of Iberian micromammal sections and sites for the interval 8.5–2 Ma by: (i) analyzing qualitative and quantitative similarities between rodent assemblages and turnover in the different basins, (ii) formulating a system of fifteen Iberian assemblage biozones, and (iii) constraining the ages of zone boundaries, assuming isochroneity across basins. Age uncertainty ranges for most known Iberian micromammal sites are obtained by combining regional biozone boundary ages with local magnetostratigraphic records, sedimentation rates and/or evolutionary rates. In addition, our results include new, integrated stratigraphic records from the Jumilla-La Celia and Teruel Basins, which are used to constrain the thus far poorly dated interval covering the latest Tortonian and earliest Messinian (8–7 Ma). [ABSTRACT FROM AUTHOR]

The halogenesis of the Messinian Tuz Gölü Basin corresponds to the sulfate type and the magnesium sulfate subtype. Compared to the Messinian Sea brines, they have a slightly higher [Na+] concentration, which is 96.6–116.4 g/L, and a much lower [K+] concentration, ranging from 0.1 to 2.35 g/L. During salt sedimentation, the [Mg2+] concentration ranged from 6.1 to 14.0 g/L, and the [SO42−] concentration from 18.2 to 4.5 g/L. Physical–chemical reactions in the basin's near-surface and bottom waters during the suspension of halite deposition had a decisive influence on the significant reduction of [SO42−] sedimentation brines. During these periods, there was an intensive influx of Ca(HCO3)2 into the sedimentation basin and the formation of glauberite layers. The formation of the glauberite resulted from the slow dissolution of pre-deposited finely dispersed metastable minerals—gypsum, sodium syngenite, or mirabilite. In fluid inclusions in the halite, the sulfate minerals being allogenic crystals of calcium sulfate, are represented by gypsum, bassanite, and anhydrite. Additionally, as the other sulfate minerals, glauberite, anhydrite, and thenardite are found within halite crystals. Sharp fluctuations in daytime air temperatures characterized climatic indicators of the summer period in the Tuz Gölü region: 15.6–49.1 °C. In the spring or cool summer–autumn period, the daytime air temperature in the region ranged from 15.7–22.1 °C, and in late spring and early summer, it ranged from 20.6 °C to 35.0 °C. During some periods, the Tuz Gölü halite crystallized at 61.8–73.5 °C. The extreme high-temperature crystallization regime at the bottom of the salt-bearing basin was achieved due to the emergence of a vertical thermohaline structure. The "greenhouse effect" in the Tuz Gölü was established only briefly but was periodically renewed due to the influx of "fresh" waters. [ABSTRACT FROM AUTHOR]

Three sections of Guri Member of the Mishan Formation in the Bandar Abbas area are investigated for foraminifera biozonation and lithostratigraphic correlation. The base of Guri Member conformably overlies Gachsaran Formation (or Razak Formation in some sections), whereas the top of the member is overlain by marls. Thirty-four foraminifer species are identified and prove the age of Burdigalian for the Guri Member in the Gery Sheikh and Anguran sections and Burdigalian–Langhan range in the Bāz section. Two assemblage zones are recognized based on the distribution range of species. Correlation to other sections shows the eastward marine progression and age change from the Burdigalian in the west to the Burdigalian–Langhian in the east of Bandar Abbas area. [ABSTRACT FROM AUTHOR]

Understanding latitudinal variations in biodiversity is central for biogeography. Along the coasts of the Southeast Pacific, several taxa show inverse latitudinal patterns of biodiversity, i.e. increasing species numbers from lower to higher latitudes. A plausible explanation for these patterns is that fjords, formed during the Pleistocene glaciations, increased the diversity of available biotopes that allowed for higher diversity in high latitudes. Assessing this hypothesis requires us to analyze latitudinal patterns of functional diversity (which is intimately related to niche use) in the absence of fjords, i.e. earlier than their formation. Here we test if the fossil record before the generation of fjords shows higher functional diversity at lower than at higher latitudes (a 'regular' functional diversity gradient). We analyzed four components of functional diversity (functional richness, functional divergence, functional dispersion and functional evenness) for a fossil marine mollusk fauna from the lower Miocene (~18 million years ago) across four regions spanning more than 10 latitudinal degrees of the Chilean coast (between ~34°S and 45°S). The functional richness of gastropods and bivalves decreased non‐linearly from low to high latitudes. Contrarily, the functional evenness of gastropods remained relatively constant across the region and that of bivalves peaked at 45°S. The functional divergence and functional dispersion of taxonomic groups did not exhibit clear patterns of latitudinal variation. The multivariate analysis uncovered non‐linear latitudinal patterns in the abundance of functional groups (gastropods and bivalves), with the largest abundance towards lower latitudes. These results suggest that the niche breadth of mollusk assemblages might have decreased with latitude in the lower Miocene. This work can shed light on the mechanisms underlying the latitudinal variation of diversity observed today, offering a better understanding of how these patterns changed over time. [ABSTRACT FROM AUTHOR]

We provide a new study of previously published eurhinodelphinid materials from the early Miocene of Piedmont (NW Italy) based on a new preparation of the fossil specimens. We studied specimens previously assigned to Tursiops miocaenus and Dalpiazella sp. and provide new anatomical data on the eurhinodelphinid skull and ear bones. In particular, we suggest that a skull that was previously assigned to Tursiops miocaenus must be reassigned to Ziphiodelphis sigmoideus (Cetacea, Odontoceti, Eurhinodelphinidae) based on new comparisons of the squamosal. This finding enabled us to provide new anatomical information on the ear bone anatomy of Z. sigmoideus that was previously unknown. The material originally assigned to Tursiops miocaenus is currently lost. For this reason and due to the fact that the partial illustration of this species by Portis does not allow us to find diagnostic characters for this species, we decided that Tursiops miocaenus is a nomen dubium. Analysis of additional isolated teeth previously assigned to Tursiops miocaenus led to the conclusion that these specimens represent Odontoceti incertae sedis. We performed a new phylogenetic analysis by adding newly discovered character states to a previous dataset and a paleobiogeographic analysis of Eurhinodelphinidae. We found two monophyletic clades within this family. The paleobiogeographic pattern found by the present work suggests the existence of North Atlantic and Mediterranean clades with some species distributed among both basins. We analyzed the virtual endocast of Ziphiodelphis sigmoideus and found that it resembles that of Schizodelphis in several respects, suggesting that some of the more derived characters of the odontocete brain were still absent in these early Miocene eurhinodelphinids. [ABSTRACT FROM AUTHOR]

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Based on inferences from proxy records the Miocene (23.03–5.33 Ma) was a time of amplified polar warmth compared to today. However, it remains a challenge to simulate a warm Miocene climate and pronounced polar warmth at reconstructed Miocene CO2 concentrations. Using a state‐of‐the‐art Earth‐System‐Model, we implement a high‐resolution paleobathymetry and simulate Miocene climate at different atmospheric CO2 concentrations. We estimate global mean surface warming of +3.1°C relative to the preindustrial at a CO2 level of 450 ppm. An increase of atmospheric CO2 from 280 to 450 ppm provides an individual warming of ∼1.4°C, which is as strong as all other Miocene forcing contributions combined. Substantial changes in surface albedo are vital to explain Miocene surface warming. Simulated surface temperatures fit well with proxy reconstructions at low‐ to mid‐latitudes. The high latitude cooling bias becomes less pronounced for higher atmospheric CO2 concentrations. At such CO2 levels simulated Miocene climate shows a reduced polar amplification, linked to a breakdown of seasonality in the Arctic Ocean. A pronounced warming in boreal fall is detected for a CO2 increase from 280 to 450 ppm, in comparison to weaker warming for CO2 changes from 450 to 720 ppm. Moreover, a pronounced warming in winter is detected for a CO2 increase from 450 to 720 ppm, in contrast to a moderate summer temperature increase, which is accompanied by a strong sea‐ice concentration decline that promotes cloud formation in summer via enhanced moisture availability. As a consequence planetary albedo increases and dampens the temperature response to CO2 forcing at a warmer Miocene background climate. Key Points: At a CO2 level of 450 ppm, a Miocene simulation shows a global mean surface warming of +3.1°C relative to the preindustrial stateAtmospheric CO2 increase from 280 to 450 ppm causes a warming of ∼1.4°C, which is as strong as all other forcing factors combinedAt higher atmospheric CO2 levels, the Miocene climate shows a reduced polar amplification linked to a breakdown of seasonality in the Arctic [ABSTRACT FROM AUTHOR]

The Sarmatian Paleaglaja jolkii V. Anistratenko from the family Aglajidae is transferred to the genus Chelidonura A. Adams. Additional morphological characteristics and data on the stratigraphic range are given for this species. It is proposed assumption the Sarmatian Ch. jolkii derived from the Badenian Ch. radwanskii Bałuk, 2018. [ABSTRACT FROM AUTHOR]

Imaging the subsurface is a major challenge due to many aspects; the most notable is the resolution of the data, which often leads to misinterpretation of reservoir behaviour and depositional environment. Even with the robust tools available to precisely model the subsurface reservoir and depositional architecture, a precise result is still incorrect if derived from an inaccurate subsurface description. Recent advances in 3D seismic geomorphology analytical methods, particularly the application of root mean square (RMS) and frequency decomposition analysis, have enabled detailed imaging, description and classification of subsurface channel networks. Typically, it is easier to image shallow subsurface channels (<500 m depth), but it gets increasingly challenging to recognize channel features at subsurface depths ≥1.5 km. This paper presents the characterization of channel features imaged from such depths within the Miocene section of the Malay Basin, offshore Peninsular Malaysia. An integrated dataset from a selected area in the central region of the Malay Basin was used for this study, including a high-quality 3D seismic cube (1563 km2) and data from one well penetrating the Miocene section of the Malay Basin. We have identified five seismic geobody groups and 10 channel types from both planform and cross-section views. The dimensions, shapes, sinuosities and thicknesses of these channel types vary. Additionally, they display various seismic characteristics in cross-section and planform views. Variability in channel geometries is related to the complex interplay between fluvial and marine processes. [ABSTRACT FROM AUTHOR]

Although the Neogene deposits of the Calchaquíes Valleys, northwestern Argentina, have been intensively studied, there are only a few works dealing with the calcareous microfauna. Thus, this study aims to provide detailed systematic descriptions of the calcareous microfauna recorded at the Playa del Zorro Alloformation and Chiquimil Formation, units exposed at the El Cajón Valley and Pampa hill respectively, Catamarca Province. Also, an assessment of the paleoenvironment, based on the calcareous microfossil association was carried out for both units. As a result, a new species of the ostracod genus Cyprideis Jones was recognized, namely Cyprideis calchaquiensis nov. sp., which was found associated with Perissocytheridea carrenoae Nicolaidis & Coimbra, Limnocythere spp. and the foraminifera Ammonia tepida Cushman. The low diversity assemblage, the predominance of rounded sieve pores on the valve surface of C. calchaquiensis nov. sp., and the presence of abnormal tests of A. tepida point to a shallow stressed water body that suffered evaporation episodes, resulting in fluctuating salinity. Interestingly, close similarities were observed between the Playa del Zorro Alloformation and Chiquimil Formation with the upper section of the Yecua Formation, Bolivia. This affinity could be explained by the passive dispersal capacities of the ostracods and foraminifers, the ecological preferences of the recognized taxa and the proximity of the outcrops, assisted by the development of mega wetlands.

Sedimentological and palynostratigraphical studies were performed on 189 ditch-cutting samples composited at 50 ft intervals from four well sections located in KW field, onshore western Niger Delta Basin, Nigeria, using sieving and visual microscopic observations, hydrochloric and hydrofluoric acids digestion methods to determine their lithological character and palynologic content of the sedimentary successions. The basis of these data is to interpret the lithofacies and biostratigraphy, establish the age of the strata, establish the palynological zones and infer the environments of deposition. Five lithofacies delineated based on the sedimentological study were very coarse sand, coarse to fine sand, shaly sand, muddy sand, and sandy to silty shale. The age of the sedimentary successions ranges from Early Miocene to Pliocene based on the bio-assemblages of these key species. The Early Miocene age is characterized by the occurrence of Magnastriatites howardi, Psilatricolporites triangularis, Praedapollis africanus, Pachydermites diederixi, Spirosyncoilpites spiralis, Praedapollis flexibility, Racemonocolpites hians, Verrutricolporites rotundiporus, Verrutricolporites microporus, and Psilatricolporites divisus. The Middle Miocene age is characterized by the FAD of Crassoretitriletes vanraadshooveni, the occurrence of Belskipollis elegans, in association with Striatricolporites catatumbus, Verrutricolporites rotundiporus, Verrutricolporites microporus, Crassoretitriletes vanraadshooveni, Racemonocolpites hians, Retibrevitricolpites obodoensis, and Retibrevitricolpites protrudens. The Late Miocene age is characterized by the occurrence of Multiareolites formosus, Cyperaceaepollis sp., Stereiosporites sp., Peregrinipollis nigericus, Gemmamonoporites sp. (Cleistopholis patens), Laevigatosporites sp., Verrutricolporites sp., Nymphaeapollis clarus, and Verrutricolporites usmensis. The Pliocene age is characterized by the basal occurrence of Retistephenocolpites gracilis in association with Nymphaeapollis clarus, Cyperaceaepollis sp., Laevigatosporites sp., Verrutricolporites sp., and Crassoretitriletes vanraadshooveni. The boundary between the Early Miocene and Middle Miocene from the studied oil well sections is marked by the first appearance datum (FAD) and numerical maximum occurrence of Striatricolporites catatumbus and Belskipollis elegans and FAD of Crassoretitrilettes vanraadshooveni. The boundary between the Middle and late Miocene is defined by the LAD of Verrutricolporites rotundiporus, the quantitative top and numerical maximum occurrence of Racemonocolpites hians, and the numerical maximum occurrence of Zonocostites ramonae. The boundary between the late Miocene and the Early Pliocene is marked by the first appearance datum (FAD) and the numerical maximum occurrence of Retistephenocolpites gracilis, the numerical maximum occurrence of Echiperiporites icacinoides, and the highest abundance of Monoporites annulatus. Four palynozones PAZ-1, PAZ-2, PAZ-3, and PAZ-4, and ten sub-zones were erected. Finally, Fluvial-coastal to shallow marine environments of deposition were inferred for the sedimentary successions using sedimentological study, nature of organic matter, and association of key environmentally-sensitive biomarker species.

This study investigates for the first time the subsurface Miocene evaporite facies (Gachsaran Formation) in Abu Dhabi, United Arab Emirates. Forty-five evaporite rock samples were selected for petrographic, mineralogical, and geochemical investigations and stable isotope analyses to decipher their origin and constrain their age. Secondary gypsum with anhydrite relics dominates the investigated evaporitic rocks, with minor amounts of clays, dolomicrite, Fe/Ti oxides, and celestite. These samples are characterized by their excellent purity and low variability in geochemical composition. The distribution of trace element concentrations is significantly influenced by continental detrital intake. The main focus of the study is to determine the strontium, sulfur, and oxygen stable isotope compositions. The measured 87Sr/86Sr values of 0.708411–0.708739 are consistent with Miocene marine sulfates and indicate ∼21.12–15.91 Ma (Late Aquitanian-Burdigalian). The δ34S and δ18O values are 17.10‰–21.59‰ and 11.89‰–19.16‰, respectively. These values are comparable to those of Tertiary marine evaporites. The relatively low values of δ34S suggest that non-marine water possesses little influence on S distribution. The geochemical composition and Sr, S, and O isotope distributions of the Abu Dhabi gypsum facies from the Gachsaran Formation reveals that their source brines were marine (coastal saline/sabkha) with subordinate continental input.

The present study aims dating the topmost 50 m of a 115 m-long core retrieved from a valley located in the Cadarache Area (Upper Provence, South East France). Based on burial dating by in situ produced cosmogenic nuclides (10Be, 26Al and 21Ne), and paleomagnetic analyses, a Tortonian age was determined for the sedimentary succession exhibited in the core. In addition, thin sections, grain size analyses and quartz morphoscopy were used to characterize a shallow marine environment and to correlate the sediment core to the surrounding exposed sections. When comparing the studied sedimentary record to global sea level estimates, we establish that the local Tortonian transgression was not synchronous with the global scale sea level high-stand, but happened more likely later, during a global regressive trend. The timing of the Tortonian flooding in Upper Provence was therefore most probably driven by regional tectonic forcing. Finally, the Tortonian shallow marine sediments are topped by lacustrine tight carbonates. These carbonates protect the marine sediments from the following major erosional events resulting from the Messinian sea level drop and from interglacial-glacial fluctuations that both yielded to the present-day valley topography.

Microfacies studies were carried out on the Middle Miocene Marmarica Formation exposed at the Gabal Western Bahi El-Din and Gabal El-Najdeen, the Siwa Oasis, northwestern Desert (Egypt). It was distinguished into the lower, middle, and upper members. Eleven microfacies types were recognized, which include skeletal lime-mudstone, dolomitic lime-mudstone, intraclastic wackestone, bryozoan wackestone, foraminiferal wackestone, foraminiferal bryozoan packstone, glauconitic molluscan packstone, molluscan intraclastic packstone, pelletal peloidal skeletal packstone, dolostones, and claystone microfacies. This formation includes several types of emergence- meter-scale cycles (shallowing-upward). Field observations and petrographic analyses revealed that these cycles consist of pure carbonates and mixed siliciclastic carbonates. These cycles consist of four types of gradual cycles and six types of non-gradual cycles. The gradual emergence cycles indicate a balance between the rate of subsidence, sea level oscillations, and sedimentation rate. The non-gradual cycles indicate an irregular balance between sedimentation rate and subsidence rate. The non-gradual cycles denote high-frequency sea level variation and/or short-term sea level oscillations, which are associated with high carbonate formation. The depositional environments of the Marmarica Formation are restricted to lagoonal at the base, followed upward to open marine conditions. Both environments most probably characterize the platform setting.

Pronounced tectonic and paleogeographic changes were detected in the Alpine–Pannonian region during the Miocene at the interface between the Alps, the Dinarides, and the Pannonian Basin. To understand the major tectonic, paleogeographic, and paleoclimatic changes during this period, geochemical and mineralogical investigations were carried out on the fine-grained clastic sedimentary rocks in the Tunjice Hills. The paleoweathering indicates a cold and/or arid to a warm and humid period. The paleoclimate and the regional climatic conditions correspond well with the Middle Miocene Climatic Optimum. The mineral composition shows an abundance of quartz and calcite. Quartz is associated with detrital origin from volcanic and metamorphic rocks of the Eastern and Southern Alps and with authigenic processes in sediments. Calcite is related to authigenic origin formed in shallow marine environments and to detrital provenance from the Southern Alps. Not all discriminant functions based on major oxides provided adequate results in determining the tectonic setting. The source rocks were subjected to oceanic island arc and collision. Moreover, sedimentation was influenced by both active and passive margin settings. The former is related to the Alpine collision, which continued from the Cenozoic onward, and the latter is connected to the processes associated with the formation of the Pannonian Basin System, which began in the late Early Miocene.

The Miocene volcanic-intrusive complex in the Slovenský Raj Mountains, middle Slovakia, comprises a swarm of subalkaline basalts and basaltic andesites with alkaline basalts, trachybasalts and basaltic trachyandesites. Basaltic to doleritic feeder dykes and sporadic hyaloclastite lavas are exposed in contact with the Triassic Bódvaszilas Formation of the Silica Nappe. The primary clinopyroxene, plagioclase, and Fe-Ti oxide assemblage also contains calcite spheroids inferred to represent carbonatitic melt. These spheroids are associated with subsolidus chlorite, actinolite, magnetite, titanite, calcite, and epidote. Micropoikilitic clinopyroxene, albite, and Ti-magnetite formed due to rapid quenching. There was an incorporation of host rock carbonate during the eruption. The erupted products are the result of magmatic differentiation of the parental basaltic tholeiitic magma with a redox of ∆QFM = +1 to +3, affected by varying degrees of 0%–50% fractionation and the assimilation of carbonate material in a shallow magmatic reservoir. REE geochemistry shows N-MORB-like type patterns with both LaN/YbN and LaN/SmN < 1 at near constant Eu/Eu* (~0.9). This is supported by εNd(t=13 Ma) values of +8.0 to +7.4 determined from the basaltic rocks. The REE values can be modeled by 1% fractional melting of garnet peridotite mixed with 7% melting of spinel peridotite of PM composition (1:9 proportions). SIMS and LA-ICP-MS U/Pb analysis of zircons yields a concordant age of 12.69 ± 0.24 Ma and a 13.3 ± 0.16 Ma intercept (Serravallian) age. The Middle Miocene volcanic activity was related to subduction-collision processes along the boundary of the Cenozoic ALCAPA (Alps–Carpathians–Pannonia) microplate and the southern margin of the European plate.

The Mojave Region preserves a rich and continuous Miocene mammal-fossil record that formed during a time of significant tectonic activity and climate change. We will visit exposures of the Crowder, Cajon Valley, and Barstow formations to look at the evolution of three different sedimentary basins through the middle Miocene. Participants will learn how depositional environments and habitats changed through time in relation to tectonics and climate and how they influenced patterns of mammal diversity and biostratigraphy.

Old World monkeys (Cercopithecoidea) are a highly successful primate radiation, with more than 130 living species and the broadest geographic range of any extant group except humans. Although cercopithecoids are highly variable in habitat use, social behavior, and diet, a signature dental feature unites all of its extant members: bilophodonty (bi: two, loph: crest, dont: tooth), or the presence of two cross-lophs on the molars. This feature offers an adaptable Bauplan that, with small changes to its individual components, permits its members to process vastly different kinds of food. Old World monkeys diverged from apes perhaps 30 million years ago (Ma) according to molecular estimates, and the molar lophs are sometimes incompletely developed in fossil species, suggesting a mosaic origin for this key adaptation. However, critical aspects of the group's earliest evolution remain unknown because the cercopithecoid fossil record before ∼18 Ma consists of only two isolated teeth, one from Uganda and one from Tanzania. Here we describe a primitive Old World monkey from Nakwai, Kenya, dated at ∼22 Ma, that offers direct evidence for the initial key steps in the evolution of the cercopithecoid dentition. The simple dentition and absence of bilophodonty in the Nakwai monkey indicate that the initial radiation of Old World monkeys was first characterized by a reorganization of basic molar morphology, and a reliance on cusps rather than lophs suggests frugivorous diets and perhaps hard object feeding. Bilophodonty evolved later, likely in response to the inclusion of leaves in the diet.

The paper presents the results of studies of ferromagnetic minerals and their distribution in the Tarkhanian and transition Tarkhanian-Chokrakian deposits of the Kop-Takyl section (Kerch Peninsula, Eastern Paratethys). Magnetic minerals were identified by petromagnetism and scanning electron microscopy. The main ferrimagnetic mineral in the rocks of the upper part of the Argunian strata of Tarkhanian deposits and the Tarkhanian-Chokrakian deposits, which correspond to the regressive stage of the paleobasin under consideration, is magnetite (maghemite). In addition to magnetite (maghemite), the sediments of most of the Tarkhanian deposits, which were formed mainly during marine transgression, contain magnetic iron sulfides: monoclinic pyrrhotite (greigite). These minerals of the detrital and early diagenetic origin may be indicators of sedimentation conditions. The obtained data on the distribution of ferromagnetic minerals in the studied Tarkhanian and Tarkhanian-Chokrakian deposits are generally consistent with the sequence of changes in the sedimentation modes that existed in the past.

AbstractThe study of the effect of global regression on the Middle Miocene (upper parts of the Qom Formation and Lower parts of the Upper Red Formation) strata has been carried out on two stratigraphic sections in the Zanjan area, northwest Iran. Lithological and microfacies analysis shows that these carbonate strata gradually turn to clastic (sandstone and conglomerate) and, in some regions, turn to evaporate deposits. Microfacies studies also confirm this sedimentary facies changes. Thus, the pelagic wack/packstone microfacies gradually change to sandy bioclast pelagic wack/packstone and finally, at the top of the section changes to the continental sandstone. Facies and lithological changes confirm the shoreline regression that can be correlated with the eustatic sea-level curve. Evaporitic strata in some parts of this area show small restricted basins because of this event. The eustatic sea-level curve in the Langhian and Serravallian ages shows global sea-level fall that can be correlated with the global oxygen isotope changes and glaciation events at this time. Therefore, we can conclude that the Middle Miocene strata have been affected by this global regression in the Zanjan area. Keywords: Regression, Miocene, Microfacies, Zanjan. IntroductionThe Qom Formation is cropped out in central, north and northwest Iran (Daneshain and Dana 2019). The Burdigalian (Daneshian and Saiedi Mehr 2005; Daneshian et al. 2009; Noroozpour 2020; Rabbani and Zohdi 2021) and the Aquitanian–Burdigalian (Daneshian et al. 2010) ages have been proposed for these successions from northwest of Iran. The extinction of Borelis melo curdica confirms a the Burdigalian age in this formation (Rabbani et al. 2022). The Middle Miocene regression is one of the most important global sea-level fluctuations in the world (Haq et al. 1987; Thomas 2008). Some glaciation evidence in the South pole at this time can confirm this global regression (Lewis et al. 2014; Halberstadt et al. 2021). This study tries to find the effect of this global regression in the Zanjan area of northwest Iran. Material & Methods Tow stratigraphic outcrop sections have been measured, sampled and studied in detail in the southwest (Ghachoghay) and Northwest (Aghbolagh) of Zanjan. Thin section of 48 samples from the Aghbolagh section and 42 samples from the Ghamchoghay section have been studied by polarized microscope at the Geology of Department, University of Zanjan. All microfacies have been identified using standard limestone classification (Dunham, 1962; Embry and Klovan, 1971) and correlated with standard microfacies (Flugel 2010) for the depositional environmental interpretations. Discussion of Results & ConclusionsBased on the stratigraphic range of two index fossils (Borelis melo curdica and Praeorbulina glomerosa), we can propose the Burdigalian–Langhian (Middle Miocene) age for the upper parts of the Qom Formation strata that are composed of limestones and sandy limestones. Facies studies led to the identification of two microfacies and two facies as follows:Pelagic wack/packstone: this microfacies can be seen in Q39 and Q40 (Aghbolagh), and S37, S38 and S39 (Ghamchoghay) samples. The high abundance of planktonic foraminifera fossils (Globigerina praebulloides) in wackestone texture is the most important feature in these microfacies. These microfacies can be correlated with SMF3 related to the toe of the slope and distal part of the carbonate platform.Sandy bioclast pelagic wack/packstone: This facies is observed in the Q43, Q46, and Q47 samples of the Aghbolagh section, and S40, S41 and S42 samples of the Ghamchoghay section. Benthic foraminifera, bioclast and a low abundance of planktonic foraminifera and sand grains can be seen within the wack/packstone texture of these samples. This microfacies can be correlated with SMF4 related to the slope area of the carbonate platform. Other studies confirm carbonate shelf as a sedimentary environment for these strata (Rabbani et al. 2020; Rabbani and Zohdi 2021). The sand grains originated from terrestrial to the marine environment by submarine channels between bioclastic reefs. Thus, we propose an open carbonate shelf as a sedimentary environment for the Qom Formation in this area. Some sedimentary structures such as asymmetrical ripple marks and cross-bedding in these strata can confirm unidirectional flow in the submarine channels in the slope area.3 and 4- Clastic and evaporitic facies: The uppermost layers of the Qom Formation have been followed by the lowermost parts of the Upper Red Formation in this area that contains sandstones and conglomerates. An evaporative unit in the Ghamchoghay section can be considered the lower part of the Upper Red Formation. This unit also has been reported from the Andabad area in the south of the Aghbolagh section.The result shows a very good correlation with the eustatic curve in the Middle Miocene age (Haq et al. 1987) that confirms the connection of the Neo-Tethys Ocean with open marine (Reuter et al. 2009). This regression can be correlated with the global ice house in the Middle Miocene that was reported from different parts of the continents on Earth (Passchier et al. 2013; Griener et al. 2015; Bassant et al. 2017; Raitzsch et al. 2021)

Carbonate rocks of Neoproterozoic to Silurian age are abundantly distributed around the coasts of North and North-East Greenland. Palaeokarst horizons are particularly well developed within the Portfjeld Formation (Ediacaran – earliest Cambrian) and beneath the Buen Formation (Cambrian Series 2), and there are caves within Ordovician limestones infilled by Caledonian molasse of Middle Devonian age. The youngest karst is a series of caves distributed from Hall Land in western North Greenland to Kronprins Christian Land in eastern North Greenland. Caves within Ordovician carbonates in Freuchen Land are currently the northernmost documented karst caves globally. The caves are mainly open phreatic conduits, any fill that is present is unlithified, and cave collapse is limited to minor breakdown associated with frost shattering. These geologically young caves are consistently located up to a few 100 m beneath the distinctive plateau that characterises the topography of the northern coast, and their identical context suggests that they developed in a single phase of speleogenesis. The caves are exposed where the plateau has been incised by outlet glaciers from the Greenland ice sheet. The timing of cave development in North Greenland is constrained by the mid- to late-Miocene (15–5 Ma) uplift of the plateau surface and the onset of fjord-forming glaciation in the latest Pliocene – earliest Pleistocene (c. 2.7–2.5 Ma). The evidence suggests that phreatic caves in the southern part of North-East Greenland, on C. H. Ostenfeld Nunatak, are of a broadly similar age. The caves of North and North-East Greenland offer a glimpse of large-scale phreatic drainage systems that developed below an uplifted coastal peneplain during Neogene time. They preserve an important part of the geological history of North and North-East Greenland that is otherwise absent from the physical geological record.

During the middle Miocene, forearc alkaline magmatism occurred in the Outer Zone of Southwest Japan and the northern Ryukyu Arc, resulting in the formation of forearc alkaline basaltic rocks with ocean island basalt (OIB)-like chemical signatures. In contrast, subduction-related magmatism was present in the central Ryukyu Arc. However, the southwestern margin of the forearc alkaline magmatism was poorly constrained in the Ryukyu Arc. We examined two basaltic dikes in the Chichibu accretionary complex of Amami-Oshima Island, the central Ryukyu Arc. The dikes cut massive basalt, reddish chert, varicolored shale, and grey chert. The chemical compositions of basaltic dikes are characterized by the enrichment of incompatible trace elements, possibly representing a low degree of partial melting from a deep mantle source. 40Ar/39Ar dating analyses indicate that the basaltic dikes yield ages of 16.37 ± 0.14 Ma and 16.51 ± 0.10 Ma. The paleomagnetic analyses on stepwise thermal demagnetizations allowed extracting the direction of stable magnetizations with unblocking temperatures of 450–575 °C for the two dikes [(Dec, Inc) = (138.1°, − 13.3°), (124.0°, − 24.9°)]. The magnetization could be primary, acquired either as part of a secular variation or a geomagnetic excursion during reversed polarity chron/subchron. The 40Ar/39Ar ages and paleomagnetic directions within the error range imply that they intruded almost simultaneously during C5Cn.2r (16.532–16.434 Ma). The age and trace element patterns of the basaltic dikes are comparable to those of Miocene alkaline basaltic rocks, which resulted from forearc alkaline magmatism during the initial subduction of the young and warm Shikoku Basin. The discovery of alkaline basaltic dikes on Amami-Oshima Island suggests that the distribution of middle Miocene forearc alkaline magmatism may extend to the central Ryukyu Arc. Hence, the northern end of the Kyushu-Palau Ridge (i.e., southern end of Shikoku Basin) could have been located south of Amami-Oshima Island around 16.5–16.4 Ma, then moved eastward to the current location. [ABSTRACT FROM AUTHOR]

Sedimentological and biochronological analyses were undertaken on carbonate deposits from 20 seamounts belonging to the Marcus–Wake Seamount Group, the Magellan Seamounts, and the Marshall Islands Seamounts in the JA area, northwestern Pacific Ocean. Deposition of carbonates on the JA seamounts varied markedly with age. The oldest carbonate deposits are Lower to middle Cretaceous shallow‐water limestones containing mollusks (including rudists), scleractinian corals, and calcareous sponges. Upper Cretaceous and Paleocene carbonates are rare, and no Oligocene carbonates may exist. In contrast, Eocene foraminiferal packstones are widespread, and Miocene–Pleistocene foraminiferal ooze covers the JA seamounts. The limited occurrence of Paleogene carbonate deposits on the JA seamounts is consistent with global observations (i.e., a paucity of Paleogene carbonates). The Cretaceous–Eocene carbonates have been phosphatized, whereas Miocene and later limestones have not. This fact, along with the results of previous studies, suggests that carbonate rocks on seamounts were phosphatized globally during the Oligocene. Upwelling of nutrient‐rich bottom waters during this time is likely responsible for the limited occurrence of Oligocene carbonate rocks on the JA seamounts. The thicknesses of the pelagic caps, which consist mainly of Miocene and younger foraminiferal oozes, varies among the seamounts and depends at least partly on the topography of the top of the seamount. [ABSTRACT FROM AUTHOR]

Middle to Late Miocene organic‐rich siliceous mudstones (Onnagawa Formation) in the Akita Basin, Northeast Japan have been an important target for both paleoceanographic studies and hydrocarbon exploration in Japan. However, the reliable age of their formation has remained poorly constrained. Here, we report new zircon U–Pb and fission‐track ages of the Onnagawa Formation from a previously well‐studied outcrop route in the Yashima area, central Akita Basin. The thin tuff bed in the lower Onnagawa Formation was dated at around 11.6 Ma, whereas thin tuff beds in the upper Onnagawa Formation was dated at 10.4–9.6 Ma. The new age model constrains the base of the succession as older than 15.6–13.8 Ma and the top of the succession as 8.7–8.2 Ma. The results suggest that the lowest part of the succession was deposited before the Onnagawa Stage. The new age model indicates a rapid deposition in the lower Onnagawa Stage. The new age model also clarifies a temporary decrease in the sedimentation rate during 10.9–9.4 Ma, which coincided with a hiatus or slow deposition reported from other areas along the Sea of Japan coast. The new age model also revises the timing of paleoceanographic changes, of the best hydrocarbon source horizon, and of hydrothermal activity responsible for seafloor chemoautotrophic communities in the Akita Basin. This revised timing reveals that the onset of paleoceanographic changes from oxidizing to anoxic bottom environments favorable for hydrocarbon source rock formation was closely related to the tectonic uplift of the Northeast Japan Arc at ~12 Ma, whereas the timing of hydrothermal activity was related to the following extensional tectonics at ~9 Ma. The results of this study thus shed light on hitherto unclarified relationships between tectonics, volcanism, and paleoceanographic changes in the Sea of Japan. [ABSTRACT FROM AUTHOR]

An overview of the Serravallian (Middle Miocene) turritellid gastropod genus Helminthia Handmann, 1882 from the Slovak part of the Vienna Basin is presented. New records of Helminthia come from the upper Badenian (lower Serravallian) shallow- to deep sublittoral marine facies of the Studienka Formation exposed in the former clay pit and its vicinity located near the Rohožník village. Two species of Helminthia have been identified, Helminthia tricincta (Borson, 1821) and Helminthia vermicularis (Brocchi, 1814). These taxa are briefly discussed, and their stratigraphic and geographic distribution in the Miocene deposits of Slovakia is summarized. Rarely, early whorls including protoconch were recorded in examined specimens, which represent the first protoconch evidence of Helminthia from the Central Paratethys. The peculiar intraspecific variability in shells of H. tricincta is observed. Prevailing paleoecological conditions in the study area during the upper Badenian are discussed. [ABSTRACT FROM AUTHOR]

To understand how past geological events and climate changes have shaped extant patterns of diversity is a central goal in biogeography. The uplift of the Himalayan-Tibetan region profoundly changed the environment in Eastern Asia, especially in the development of vast evergreen broadleaf forests (EBLFs) in the Subtropical Zone. However, when and how these forests developed remains unclear. Here we focus on Quercus section Cyclobalanopsis, a dominant component of EBLFs since the Miocene in Eastern Asia. In this study we integrated occurrence data, climate data, and a published phylogeny of 35 species of section Cyclobalanopsis with ecological niche modeling (MaxEnt) to explore the evolution of climatic tolerance of section Cyclobalanopsis since the late Eocene (34 Mya). The intensification of the East Asian monsoon system and occupation of new climatic niches by the ancient clades already present in the Himalayas and in tropical Asia may have jointly promoted the formation of subtropical EBLFs in Eastern Asia since the Miocene, especially the late Miocene. [ABSTRACT FROM AUTHOR]

The presence of Cainozoic marine sediments in the Sperrgebiet, Namibia, was noted as early as 1908 when diamonds were found at Kolmanskop. Because of the economic interest of these deposits, geological investigations were undertaken, which led to detailed mapping of their distribution, initially by Beetz (1926). In the Central Sperrgebiet early investigators correlated the 'highest' beach deposits (ca 160 metres above present-day mean sea-level) to the Eocene, referred to in the old literature as 'Höchster Stand der Eocänsee' or the 'Eocäne Marine Inundation' (Kaiser, 1926). Liddle (1971) extended this « ancient » strandline a few kilometres northwards to Elfert's Tafelberg. Dingle et al. (1983) dated it to the late Palaeocene - early Eocene. In contrast, along the Namaqualand coastal plain in South Africa, marine deposits attributed by Pether (1986, 1994) to the 90 metre package, the 50 metre package, and the 30 metre package were correlated to the Miocene. Re-examination of the conglomerates at Eisenkieselklippenbake and Buntfeldschuh which crop out at ca 150-160 metres above sea level, reveals that some of the deposits are considerably younger than the Eocene, being instead of early Miocene (Aquitanian-Burdigalian) age. The beach conglomerates at both of these localities contain well-rounded and polished cobbles of densely ferruginised gravel and sand associated with cobbles of a great variety of other rock types (quartzite, silcrete, silicified freshwater limestone, vein quartz, agates, pebbles of banded ironstone formation (BIF), jasper etc.). The conclusion about the Miocene age of the beaches follows from the observation that the ferruginisation of near-surface deposits in the sector of the Sperrgebiet between Kerbehuk in the south and Elisabethfeld-Grillental in the north occurred during the Oligocene (more precisely, the Chattian) the process petering out during the Early Miocene (Aquitanian-Burdigalian), and ceasing altogether with the establishment of hyper-aridity in the region (onset of fully desert conditions in the Namib) ca 17 Ma. This means that cobbles derived from the break-up of the ferruginised deposits must be younger than the Chattian. Many of the cobbles of ferruginised sediment contain clasts of agate, BIF and jasper, vein quartz, silicified limestone etc. which were already present in the superficial deposits of the region prior to the Chattian, supporting the old conclusions concerning the presence of Eocene marine deposits in the Sperrgebiet. The revised age of the Eisenkieselklippenbake and Buntfeldschuh beach conglomerates means that the timing of the geomorphological development of the region, such as the back-cutting of the Buntfeldschuh Escarpment, requires revision, as do the correlations of near-surface deposits such as the fluvial Blaubok and Gemsboktal formations (Pickford, 2015) which are of Eo-Oligocene and Miocene age respectively. [ABSTRACT FROM AUTHOR]

Fossil ostracods belonging to seven genera, including Schizocythere, were reported from mudstone, correlated to the Early-Middle Miocene Tomioka Group (possibly Zone N8 of Blow; ca. 16.4--15.1 Ma), from the three slime cutting samples obtained from a 1500-m-deep hot spring well drilled in Meiwa Town, Ora-gun, southeastern Gunma Prefecture, northwestern Kanto Plain, central Japan. Based on previous study of Miocene ostracods in Japan, this species composition and the morphologically-similar species have been mostly reported from the Middle Miocene Kobana Formation(ca. 14-13 Ma) in eastern Tochigi Prefecture, central Japan. The fossil ostracod assemblages in the shallow marine environment of the Kobana Formation indicated sublittoral zones under subtropical to warm-temperate conditions. Therefore, the shallow-marine palaeoclimate in the northwestern Kanto Plain between the Kanto and Ashio Mountains may have also had subtropical to warm-temperate conditions. The water temperature in this period, in the area studied, may have been almost the same or slightly higher than the temperature at the present Kanto coast, which is under warm-to mild-temperate conditions. The fossil ostracods from Meiwa in this study are significant for understanding the palaeogeography and palaeoenvironment of the present northwestern Kanto Plain as well as the palaeobiogeography of the shallow-marine benthic fauna along the Japanese Islands in the Miocene. [ABSTRACT FROM AUTHOR]

Planktonic foraminiferal fossils of 24 species belonging to 11 genera were obtained in seven Miocene mudstone samples from a hot spring well(drilling depth 1,500 m) in Meiwa Town, Ora-gun, Gunma Prefecture, Japan. The genus Praeorbulina, which is effective for age determination, is included. Its suggests that the 870 to 820 m depth mudstone corresponds to the N.8 zone(Blow, 1969). From the composition of the occupying species, it is presumed that this area was strongly affected by warm currents. The N.8 zone sediments were found in the Meiwa hot spring well, revealing a structural and age gap between the Tatebayashi observation well and the Meiwa hot spring well. As a result, the data supported the indication that a large fault(Tonegawa Tectonic Line) lies between the two wells. [ABSTRACT FROM AUTHOR]

Gunma and its neighboring region consist mainly of Tertiary to Quaternary sediments and volcanic rocks, with limited exposures of pre-Miocene basement units. Active volcanoes and their detritus also cover wide areas. Sr isotope ratios(87Sr/86Sr)of Quaternary volcanoes in this region show a large variation from about 0.704 to over 0.708. The large variation appears to represent diverse magma processes beneath this region, but the genesis of the wide variation is still a matter of discussion. Here we present new data of Sr isotope ratios for Miocene to Quaternary igneous rocks, which were collected from the border region between Gunma and Nagano Prefectures and were dated by the K-Ar method. The analyzed nine samples, seven andesites and two granitoids, yielded low initial 87Sr/86Sr ratios around 0.704, which is nearly the lowest values represented by Asama volcano in this region, suggesting limited contribution of continental crustal components. Large differences of 87Sr/86Sr ratios between Haruna and Akagi volcanoes and their basement volcanic rocks appear to reflect complicated crustal structure beneath these volcanoes, although detailed studies are required to clarify the genesis of the large differences. [ABSTRACT FROM AUTHOR]