Early Miocene Age Research Articles

Short Communication: Calcareous nannofossil assemblages and age determination in Leuwi Kenit, Ciletuh Palabuhanratu Geopark, Indonesia

Abstract. Pratiwi SD, Nurdrajat, Pratiwy FM, Chiyonobu S. 2024. Short Communication: Calcareous nannofossil assemblages and age determination in Leuwi Kenit, Ciletuh Palabuhanratu Geopark, Indonesia. Biodiversitas 25: 3200-3207. Our meticulous and comprehensive investigation of nannofossil diversity in Leuwi Kenit, Sukabumi District, West Java Province, Indonesia, a part of the Ciletuh Palabuhanratu UGG, where the study of nannofossils is limited, is of significant importance their implications for age determination and clarifying the geological history of the region. The initial documentation of calcareous nannofossils in the Leuwi Kenit traverse of the Cikarang Member within the Jampang Formation resulted in the identification of thirty-three species from 62 samples. The studied section reveals seven nannofossil biozones, arranged from oldest to youngest as follows: LO Sphenolithus ciperoensis; LO Cyclicargolithus abisectus; FO Sp. disbelemnos; FCO Helicosphaera carteri; FO Sp. belemnos; LCO Sp. belemnos; LO Sp. conicus and FCO Sp. heteromorphus. Notably, the abundance of Coccolithus pelagicus, Cyclicargolithus floridanus, Reticulofenestra spp., and Sphenolithus spp. characterized their occurrence throughout the section. The diversity and preservation of nannofossils were found to be good, and based on nannofossil biohorizons, the age of Leuwi Kenit spans from 24.3 million years ago to around 17.7 million years ago at Paleogene (Oligocene age) to Neogen Periode (Early Miocene age). Based on the nannofossils assemblages, results show that the area has many important indicator species, making it essential for future research on ancient ocean conditions and past climate changes within this geopark.

Stratigraphy and first fossil record (Notoungulata, Toxodontidae) of the Paso de las Carretas Formation (Late Miocene), San Luis Province, Argentina

ABSTRACT A toxodontid (Notoungulata) specimen (CHN-UNLC-P-V-4) is the first fossil from the Paso de las Carretas Formation that crops out in the Río Quinto Basin (Neogene), to the east of San Luis city (Argentina). The geological study provides a new stratigraphic section and the position of sediments in the valley depocentre permits inferring an older age than that of the Río Quinto Formation, which implies an early Late Miocene age for the Paso de las Carretas Formation. This age agrees with the identified cf. Ocnerotherium intermedium (taxonomic determination supported by a phylogenetic analysis), as this species was recognised in the Chasicoan Stage/Age of San Luis Province. CHN-UNLC-P-V-4 includes a mandibular fragment with ventral extension, preserving m1–3, a symphysis fragment with incisors, and the partial upper tooth series. A body mass of ~ 1700 kg is estimated. The mandible is similar to that of Dinotoxodon and Gyrinodon, but teeth (mainly upper ones) approach CHN-UNLC-P-V-4 to O. intermedium. As the mandibular extension of this species was not established, but likely present and lower teeth have some differences, we maintain an open nomenclature for CHN-UNLC-P-V-4. The similar incisors to the holotype of ‘Neoadinotherium triangulatum’ supports the latter might belong to O. intermedium, as previously suggested.

Focused reservoir characterization: analysis of selected sand units using well log and 3-D seismic data in 'Kukih' field, Onshore Niger Delta, Nigeria

This study focuses on the comprehensive reservoir characterization of the ‘Kukih’ Field within the onshore northeastern Niger Delta region, Nigeria. The absence of its detailed description with delineated reservoir properties, lateral continuity, and their use to identify potential reservoir quality and heterogeneity necessitated this study. Integrating well log and 3D seismic data, the investigation aims to elucidate reservoir properties, lithofacies, and depositional environments to unravel hydrocarbon potential. The geological setting, encompassing the Agbada Formation of Early and Middle Miocene age, is scrutinized through detailed geologic analysis. Petrophysical evaluation of four well logs (Kukih-1, Kukih-2, Kukih-3, and Kukih-4) facilitated the determination of key parameters such as shale volume, effective porosity, and water saturation. Seismic interpretation further enriched the structural characterization of the field. Results showcase three predominant reservoir sands (A, B, and C) with distinct lithofacies and thickness variations. Effective porosity ranges from Fair to Excellent, with permeability exhibiting high values for hydrocarbon reservoir potential. Water saturation trends, lithofacies distributions, and structural features were illuminated through iso-parametric maps and seismic analyses. Depositional environments were inferred through facies analysis, revealing the presence of funnel-, cylinder-, and bell-shaped successions that hint at intricate marine sedimentary processes. Challenges owing to limited core data were acknowledged, and the integration of methodologies emerged as a pivotal strategy for enhanced reservoir understanding. This study underscores the ‘Kukih’ Field's hydrocarbon potential, accentuating the significance of multidisciplinary approaches in deciphering complex reservoir systems. In light of the petrophysical analysis derived from the well logs and the identification of structural highs through the structural maps, this study recommends the drilling of unexplored zones exhibiting promising structural characteristics.

STRATIGRAPHY AND PETROGRAPHY OF ROCKS IN KARANGTENGAH VILLAGE AND SURROUNDINGS, BABAKAN MADANG SUB-DISTRICT, BOGOR DISTRICT, WEST JAVA PROVINCE

Stratigraphy and petrography, integral components of geological science, are crucial for identifying mineral composition, rock texture, and characteristics, as well as understanding relationships between layers and layer positions. This study is located in Karangtengah Village and its Nearby Surroundings, Babakan Madang District, Bogor Regency, West Java Province. Physiographically, the study area is included in the Bogor Zone (Van Bemmelen, 1949). The research site is also incorporated in the Geological Map of Bogor Sheet, West Java. And specifically this research was conducted in the Cileungsi River. This river is included in the Jatiluhur Formation (Sudjatmiko, 1972). Stating the purpose of geological mapping, such as understanding regional geology, identifying mineral resources, or assessing geological hazards. Then, data collection in the field, such as conducting detailed field surveys to observe and record geological features, using field notebooks, GPS for plotting, and cameras for documentation, collecting rock samples for laboratory analysis (Petrography analysis and microfossil analysis). As a result of this study, there are four rock units in the Karangtengah area, with the order of formation from the oldest to the youngest. Firstly, Claystone Unit (Tmbl) consists of mudstones and sandstones, with fossils of P. transitoria and G. peripheroronda indicating an Early Miocene age (N8) and the depositional environment is the Outer Neritic. Second, the Old Andesite Intrusion (At) consists of andesite igneous rocks with Middle Miocene age and deposited in a terrestrial environment. Third, the Tuff Unit (Qt) is dominated by pyroclastic tuff rocks with Pleistocene age and deposited in a terrestrial environment. Finally, the Andesite Unit (Am) consists of andesite igneous rocks younger than the Pleistocene, penetrating the Tuff Unit (Qt) and the Claystone Unit, and deposited in a terrestrial environment.

Capitana mine, Tignamar district, a unique tin – bismuth concentration in the Chilean Central Andes, 250 km west of the Bolivian Tin Belt: Link to the Proterozoic-Paleozoic basement Belen inlier and the Arequipa-Antofalla terrane, a probable remnant of Laurentia

The Capitana mine, Tignamar District, is a unique Sn-Bi concentration in the highlands of Arica, in the Chilean Central Andes. Tin deposits associated with Triassic to Pliocene age igneous rocks are plentiful in the Tin Belt of Peru, Bolivia, and NW Argentina, but have not been reported in Chile, where contemporaneous rocks formed metallogenic belts rich in Fe, Cu, Mo, Ag and Au. We describe vein ore from Capitana mine, a small but exceptional Sn-bearing Pb-Bi-Ag-Cu-Sb-As epithermal deposit in the Tignamar (or Ticnamar) district in the high Andes of Arica, Chile, ca. 250 km west of the Bolivian Tin Belt. Fluid inclusions in vein quartz trapped a non-boiling, low salinity (<∼4 wt% NaCl equiv.), moderate T fluid (minimum T ∼ 220 °C) prior to metal precipitation. Flashing of this fluid, likely due to rapid changes in confining P, was synchronous with metal deposition; sulfosalt textures show evidence of syn-deformational growth. Although located within a district considered a porphyry copper system of Early Miocene age, it is likely that the Capitana deposit formed later, mainly as a result of regional hydrothermal activity related to compressive and transpressional tectonics as young as Pliocene. Common lead is 206Pb/204Pb 18.18; 207Pb/204Pb 15.61; and 208Pb/204Pb 38.53, significantly less radiogenic than that of Bolivian Sn deposits, and has a Paleozoic model lead age. These values point to affinities with a tectonically-emplaced inlier of crystalline basement of Proterozoic – Early Paleozoic age known as the Belen Metamorphic Complex, and with the Arequipa-Antofalla basement terrane, a probable remnant of Laurentia (North America), left behind during the dismemberment of the Rodinia Supercontinent. The complex mineralogy of Capitana vein, unlike other Chilean deposits, includes various sulphides and sulphosalts with Cu, Fe, Zn, Pb, Bi, Sn, Ag, As, Sb, Ga and In, and is exceptionally rich in U.

Early Miocene Aprotodon (Perissodactyla, Rhinocerotidae) from Northern China

ABSTRACT The genus Aprotodon is a special group of rhinoceroses, which has a very long survival time frame but a relatively limited distribution in Asia. Herein, we report on a well-preserved and complete skull found in the lower layers of the Zhang’enbao Formation from the Early Miocene age in Tongxin County, China. The morphology of the new specimen is different from all the known species of Aprotodon in its smaller size, with both sides of the parietal crest fused and forming a sagittal crest, the V-shaped anterior edge of the posterior nares positioned at the level of M2, the weak supraorbital tuberosity, the developed and multiple crista on premolars, and the reduced lingual cingulum, forming a pillar around the entrance of the medisinus on molars. Based on these, we refer the Tongxin specimen to a new species, A. qiui sp. nov. Phylogenetic analysis reveals that A. qiui sp. nov. and other members of Aprotodon are in a stable monophyletic clade. A. qiui sp. nov. is the sister taxon to A. lanzhouensis.

The Age and the Accumulation Conditions of the Upper Paleogene–Lower Neogene Kurshskaya Formation Stratotype (Kaliningrad Oblast) by Palynological Data

The results of the palinologycal study of the Kurshskaya Formation stratotype (Primorsky quarry, Kaliningrad Oblast) are presented. In the lower part of the Kurshskaya Formation (Member of “chocolate” clays), a complex of dinoflagellate cysts with Areosphaeridium diktyoplokum, Glaphyrocysta semitecta, and Cordosphaeridium funiculatum of latest Eocene age was found. The formation is characterized by four spore-pollen assemblages: (1) Pinuspollenites–Inaperturopollenites–Sciadopityspollenites assemblage of latest Eocene age in the “chocolate” clays and in the lower part of brown sands; (2) Sequoiapollenites–Betulaepollenites betuloides assemblage of early Oligocene age in the lower part of the brown sands member; (3) Boehlensipollis hohli–Carpinipites carpinoides assemblage of early Oligocene age in the middle part of brown sands member; (4) Alnipollenites–Corylopollis assemblage of late Oligocene–early Miocene age in the upper part of the brown sands of the Kurshskaya Formation. The general age of the Kurshskaya Formation is terminal Eocene–early Miocene. In the lower parts of the Zamland Formation, which overlies the Kurshskaya Formation, the Pinuspollenites–Tricolporopollenites pseudocingulum–T. euphorii assemblage presumably of middle Miocene age was found. Based on the obtained palynological data, the conditions of sedimentation at the end of the Eocene–Oligocene–early Miocene in the South Baltic region are reconstructed. The regression of the sea basin began as early as the end of the Priabonian, the climate was still quite warm and humid, close to subtropical. Mesophytic mixed coniferous-broad-leaved forests grew along the shores of the strait, low-lying areas of land were occupied by marsh vegetation. Cooling at the Eocene/Oligocene boundary resulted in the appearance of hemlock in plant communities and an increase in the proportion of catkins (alder, birch, hornbeam). Presumably, in the late Oligocene–early Miocene, the proportion of small-leaved trees, especially alder and hazel, sharply increased in mesophytic forests, while the number of pine trees decreased. Wetter and warmer climatic conditions are assumed for the early Miocene: this time is characterized by an increase in the number of walnut, cypress, and Cyrillaceae. In the middle Miocene, the climate was still quite warm, but drier, and such moisture-loving species as podocarpus, spruce, glyptostrobus, and swamp cypress disappeared from plant communities.

Phylogenetic history of golden moles and tenrecs (Mammalia: Afrotheria)

Abstract We conducted a phylogenetic analysis of genetic and anatomical data focusing on golden moles (Chrysochloridae) and tenrecs (Tenrecidae). Our results support the now well-resolved topology for extant tenrecids, in addition to the paraphyly of ‘Chrysochlorinae’ and the genera Chrysochloris and Chlorotalpa as traditionally used. Carpitalpa arendsi is the sister taxon to Neamblysomus; together, they compose the sister clade of Amblysomus. Unexpectedly, Calcochloris obtusirostris is the sister taxon of Chrysospalax. The oldest divergence within crown Chrysochloridae is likely to be the node separating Eremitalpa–Huetia or Eremitalpa alone from the remaining species. A Chrysochloris–Cryptochloris root appears most frequently under equally weighted parsimony or with few or no sampled tenrecids, suggesting that it is artefactual. The tropical genus Huetia is among the most widely distributed and anatomically polymorphic in our sample. Eremitalpa and Huetia have a relatively unspecialized hyoid apparatus and short angular process of the dentary. These elements in Huetia show a particular resemblance to those of the Namibian fossil Namachloris, which we reconstruct as a stem chrysochlorid. Crown chrysochlorids are geologically younger than crown tenrecids and probably diversified in the Miocene around the same time as the tenrecid genus Microgale. Fossils of both groups from Eocliff in Namibia are probably late Eocene to early Miocene in age.

A wealth of P–T–t information from metasediments in the HP–UHP terrane of the Pohorje Mountains, Slovenia, elucidates the evolution of the Eastern Alps

AbstractContrasting views exist in regard of the evolution of metamorphic rocks in the southeastern Pohorje Mountains (Mts), located in the southeastern Eastern Alps. Major debated points are whether micaschists have experienced ultrahigh‐pressure metamorphism in the Late Cretaceous (Eo‐Alpine) and whether they were continuously exhumed or experienced a multiple subduction–exhumation process from that time on. Therefore, we studied micaschist sample 18Slo39 with two generations of garnet and phengitic muscovite from this area. Our detailed study of this rock included petrographic observations, chemical analyses of minerals with the electron microprobe, pseudosection modelling, conventional geothermometry, and monazite in‐situ U‐Th‐Pb dating using laser‐ablation inductively coupled plasma (ICP) mass spectrometry. The following results were obtained: The studied micaschist was subject to a peak pressure of 1.31 ± 0.14 GPa at 603 ± 26°C in Eo‐Alpine times: 90.62 ± 2.78 (2σ) Ma (Stage I). Contact metamorphism at pressure–temperature conditions of 0.66 ± 0.10 GPa and 577 ± 23°C was induced by the intrusion of the Pohorje pluton (Stage III). We determined an early Miocene age of 18.33 ± 0.43 (2σ) Ma for this intrusion. Based on this study and the previously reported data for a micaschist (16Slo12) taken in the vicinity of sample 18Slo39, a geodynamic model is proposed for the region of the Pohorje Mts considering Eo‐Alpine subduction of oceanic crust and European continental crust, of which the micaschist was part of. Another high‐pressure event in the Eocene (Stage II) was the result of intracontinental subduction because of transpression by the Periadriatic fault system that separates the Eastern Alps from the Southern Alps. This type of subduction gave rise to magma generation and ascent to form the Pohorje pluton, which caused contact metamorphism in its vicinity.

Middle Eocene Succession of Dammam Formation, Biostratigraphy and Microfacies Study, North Karbala Area, Western Iraq

Stratigraphic and sedimentary study to Dammam Formation (Eocene age) at well Kr-1, Karbala Government, Western Desert of Iraq. Lithologically, Dammam Formation consists of Nummulitic limestone and dolomitic limestone. The contact between the upper and lower of Dammam Formation is unconformable, the lower contact is represented by Umm Er-Radhuma Formation by the unconformable surface in the Upper Paleocene age, while the upper is an unconformable surface with Euphrates Formation in the Early Miocene age. The rock section of the well Kr-1 is divided into several beds depending on Petrographical and paleontological contents, the results of the identified foraminifera are indicated to several groups and genera which are: Nummulites, Lindrina, Lockhartia, Rotaliid, Miliolid, also other groups of fossils like Ostracoda, Echinoderms, Bryozoa, Gastropod, Pelecypod, and different fragments. Based on the petrographic study and type of microfacies, the formation was divided into three main and secondary microfacies which are: Nummulitic packstone, Dolomitic and Bioclastic Packstone, and Floatstone. One main biozone was recognized in the studied section which is Nummulites gizehensis- Nummulites planulatus - Nummulites discorbinus Assemblage Zone with age Middle Eocene (Lutetian), this biozone is divided into two secondary biozones: Nummulites millecaput Rang zone Middle Eocene (Middle-Upper Lutetian) age and Nummulites elevate Rang zone Middle Eocene (Late Upper Lutetian) age. After collecting all the sedimentary and planetology data for the studied section, the Dammam Formation was deposited in shallow warm marine, tropical water, as well as, the absence of planktonic foraminifera crowds is another evidence that the environment is a shallow basin close to the coast. The basin is located at the Interior Platform represented by the evaporites basin, the restricted, and then the open sea environments.

Biostratigraphical investigation of middle-early Miocene sediments from a section of AK-1 well, onshore Niger Delta: Insights from calcareous nanofossils

Biostratigraphic analysis was carried out on KA-1 well, onshore Niger Delta Basin of Nigeria. A total of forty (40) ditch cutting samples were collected from the studied section at 30 feet depth intervals with the studied section ranging from 7590-4800feet. The objectives of this study are to determine the age and biozonation of the studied section. Using simple smear slide method, the samples were processed and analyzed for nannofossils using a reflected binocular microscope. Calcareous nannofossil assemblages from the well are of low diversity and abundance. Some depths yielded almost monospecific assemblages while some have no records of calcareous nannofossils. Species include Helicospharea ampliaperta, Sphenolithus heteromorphus, Cyclicargolithus floridanus, Helicospharea scissura and Discoaster deflander. These belong to the NN4 zone of middle to early Miocene age. Keywords: Biozonation, Calcareous nannofossils, Helicospharea ampliaperta, Oligotrophic, Niger Delta.

Biostratigraphy and Paleoecology of the Anah Formation in Kurdistan Region, Iraq

In the current study, biostratigraphy and paleoecology of the Anah Formation have been investigated.The study area is located in the Sulaimanyah Governorate, Kurdistan Region, Northeast Iraqwhere the Darzila section hasbeen sampled. Twenty-five species of larger foraminifera and skeletal fragments of coral, echinoid spine, pelecypods,and gastropods are described in seven samples collected from the Darzila section. Based on the distribution of the larger-benthic foraminifera andother skeletal grains, two assemblage biozones of the Late Oligocene–Early Miocene age have been recognized. According to the paleoecological parameters,such as temperature, nutrients, depth, and salinity in the study area, the Anah Formation hasdeposited the euphotic zone, abundant imperforate foraminifera are present, sub-tropical waters under oligotrophic to mesotrophic middle ramp environment with normal to a higher salinity inner ramp setting and at water depths that ranged from 40 m to 80 m, anda temperature about 18–25ºC.

Middle-late Eocene to Early Miocene micropaleontology of the ANH–TIERRALTA–2–X–P well: Biostratigraphic implications for southwestern deposits of the Sinú-San Jacinto belt (Colombian Caribbean)

The Eocene and Oligocene deposits of the southwestern region of the Sinú-San Jacinto Belt (SSJB) in NW South America were formed in marine environments influenced by fluvial discharges from the northern Andes of Colombia. However, these deposits are not well-exposed on the surface, which has limited the study of micropaleontological assemblages that could improve our understanding of the chronostratigraphic and paleoenvironmental characteristics of these rocks. In this study, we analyzed two cores of one of the thickest Cenozoic stratigraphic sections in the Caribbean region, from the ANH-TIERRALTA-2-X-P stratigraphic well, using palynomorphs and calcareous nannofossils. Our analysis allowed us to determine the age of deposition and understand the biostratigraphic patterns of marine and terrestrial microfossils in these nearshore deposits. We found that the first cored interval, from 2122 m to 2026.9 m, corresponds to marine rocks accumulated between the middle and late Eocene. The second interval, from 1130 m to 731.6 m, showed patterns of terrestrial and marine microfossils, which indicate the middle-late Eocene to the Early Miocene age. Palynological and calcareous nannofossil biostratigraphy were consistent in the middle to upper Eocene and Lower Miocene deposits, but discrepancies were observed in the Oligocene deposits. We attributed this to reworking or broader biostratigraphic ranges of certain palynological markers used in the biozones. Determining the age of the middle to upper Eocene and upper Eocene to lower Oligocene deposits was challenging due to the limited number of well-calibrated biostratigraphic markers. As a result, accurate correlation with the late Eocene – early Oligocene stratigraphic record from other parts of the SSJB is hindered, demonstrating that regional stratigraphic correlations based on biostratigraphy alone are problematic.

Sedimentological and palynostratigraphical modeling of sediments penetrated by KW field wells, onshore western Niger Delta Basin, Nigeria

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.

Early-middle Miocene Inversion of the Abu Jir Fault in the Western Iraq: a Possible Consequence of the Arabian Plate Northward Movement

The Abu Jir fault zone in western Iraq that marks the western limit of the Zagros foreland basin merges with the Anah graben in the north. The northern segment of the Abu Jir fault zone and the western Anah graben are inverted structures. In this study, we investigated the timing and mechanism of the northern Abu Jir fault zone inversion in comparison with other inverted structures like Tel Hajar and Sinjar, which are located in the north and closer to Arabia–Eurasia collision zone. In the study area the Abu Jir fault zone is characterized by a local-scale northwestern-trending asymmetric fold, associated with inverted normal faults, positive flower structures, right–lateral strike-slip faults, and seismically induced early middle Miocene slump structures. Based on the structural synthesis of the surface geology and age constraints from syntectonic deposits at the northern Abu Jir fault area, the Abu Jir fault inversion and its western block northward movement were inferred to be resulted from forces that originated from the south to the north, unlike the northern younger inverted structures. This early middle Miocene age of the Abu Jir fault inversion is comparable to the arrival time of the Afar plume hot mantle material flow from the south to the north in western Arabia. Therefore, we argue that the Abu-Jir fault inversion is more likely to be due to dragging of the Arabian plate by mantle flow from the south to the north rather than shortening propagation from the north to the south.

Revised stratigraphy and first geochronology of the Miocene submarine volcanic succession at Kennaook/Cape Grim, northwestern Tasmania

Kennaook/Cape Grim in far northwestern Tasmania, Australia, was a site of submarine intraplate basaltic volcanism during the Miocene. The succession is exceptionally well preserved and is dominated by pillow lava, massive lava and pillow fragment breccia. The total volume of volcanic products (1.1 km3) is relatively small on a global scale, but the preservation is world class. The oldest unit, the Woolnorth Tuff lies unconformably on the Neoproterozoic Rocky Cape Group. The first 40Ar/39Ar dating of the volcanic rocks reveals an early Miocene (24.5–23 Ma) age for the entire sequence. The Woolnorth Tuff is composed almost entirely of devitrified basaltic glass shards and olivine crystal fragments. The Woolnorth Tuff is overlain by the Slaughter Bluff Volcanic Breccia (23.12 ± 0.19 Ma) at Kennaook/Cape Grim. The Slaughter Bluff Volcanic Breccia is dominated by diffusely bedded pillow fragment breccia. North of Kennaook/Cape Grim, the Little Trefoil Basalt (ca 24 Ma) intrudes the Woolnorth Tuff. To the south of Kennaook/Cape Grim, the Woolnorth Tuff is overlain by the Studland Bay Basalts (23.73 ± 0.08 Ma) and intruded by a newly recognised unit, the Hippo Basalt (24.52 ± 0.12 Ma). The Studland Bay Basalts comprise mounds of basaltic pillow lavas followed by a succession of diffusely bedded, matrix-dominated, pillow fragment breccia and basaltic breccia. Detailed field mapping and sampling have revealed that the environment of deposition of all Kennaook/Cape Grim units was submarine and that they were emplaced in relatively rapid succession. KEY POINTS First 40Ar/39Ar geochronology for the Kennaook/Cape Grim volcanic succession. Little Trefoil Basalt has been re-interpreted from a subaerial extrusive unit to a submarine intrusive unit. A new intrusive unit, the Hippo Basalt, has been recognised. The stratigraphy of the Kennaook/Cape Grim volcanic succession has been revised.

Karstification Processes in Haditha Vicinity, West Iraq

In the valley of the Euphrates River to the south of the Haditha city (West Iraq), the dissolution of the carbonate rocks which underlie residual soil gives rise to numerous sinkholes. These sinkholes are a potential hazard to human safety and damage to the existing infrastructure. The exposed rocks in the area under consideration belong to the Euphrates Formation of the Early Miocene age, specifically the Middle Member of the formation. Tens of sinkholes have developed with different shapes, sizes, activities, and maturities, others are under development indicating that the karstification process is still ongoing. Some of the sinkholes have spectacular scenes and can be used for touristic purposes. The karstification process has a negative impact on the infrastructure in the Haditha vicinity, especially the Hadith Dam, where extraordinary treatments to the foundation of the dam were considered to be in a safe status. We have studied different published articles and reports, which dealt with the karstification in the Haditha vicinity. Moreover, we have interpreted satellite images, and topographical and geological maps to recognize the existing sinkholes and study them. Filed trips were performed for long interrupted intervals (1984 until 2022) to collect significant data and perform field photographs for the interesting scenes.

Palynological Study and Age Dating of the Early Miocene Dukku Claystone Type Section of Gwandu Formation, Sokoto Basin, Northwestern Nigeria

Outcrop samples were collected from Dukku area for the purpose of subjecting them to palynological analysis in order to determine the relative age of Gwandu Formation and palaeoenvironment of deposition of the deposit. Field and laboratory methods were carried out in order to obtain lithological sequence description of the outcrop. The samples obtained went through processes of acid digestion with hydrochloric acid, hydrofluoric acid and separation of macerals by floatation with the use of zinc bromide. The prepared slides were observed under microscope for palynomorph contents. Diagnostic palynomorphs that are stratigraphically important for palynozonation were retrieved such as Belskipollis eligans, Verrutricolporites laevigatus. Striamonocolpites sp., Retibrevitricolporites sp., Retibrevitricolporites obodoensis, Retistephanocolpites sp., Cingulatisporites ornatus, Longapertites marginatus and Proteacidites sp. The marker fossils belong to Magnatariatites horwardii zone; Zone P600 and Subzone P630 and C1 Zone of Nigerian Niger Delta sedimentary basin zonal schemes, dated Early Miocene age. Dinoflagellate forms recovered include Batiacasphaera sp., Senegalinium sp., Andalusiella polymorpha Selenophemphix nephroides, Andalusiella sp., Andalusiella laevigata, Histrichosphaera turocona and undifferentiated dinoflagellate cysts of peridinacean forms that belong to marginal marine setting.

Oligo-Miocene subduction-related volcanism of the Loyalty and Three Kings ridges, SW Pacific: a precursor to the Tonga-Kermadec arc

The SW Pacific region contains several ridges and basins that are inferred to represent pre-Quaternary volcanic arcs and back-arc basins. The geology of these features is less well characterized than that of the active Tonga-Kermadec and Vanuatu arcs. We report new major and trace element, and Pb, Hf, Sr and Nd isotope data for 27 lavas dredged from the Loyalty and Three Kings ridges during the 2015 VESPA cruise of R/V l'Atalante. Low-K basalts were dredged from the seabed deeper than 3300 m, and high-K to shoshonitic suites from shallower ridge crests at 2000–3300 m. The samples are mainly basalts, with lesser trachybasalts, basaltic andesites, trachyandesites andesites, dacites, and one granite (anhydrous SiO2 and K2O + Na2O range from ∼47 to 64 and 1.5 to 11 wt% respectively). Trace element patterns allow discrimination of three geochemical signatures, identified as i) depleted, ii) transitional and iii) enriched, based on their light to heavy rare earth element (REE) ratios (with La/Sm ranging from 0.4 to 8). Depleted and transitional samples are basalts, featuring REE concentrations similar to MORB, but with high field strength element and large ion lithophile element contents, typical of back-arc basin basalts. The most enriched samples are basaltic andesites, andesites, trachyandesites and trachytes with island arc magma trace element signatures. Pb isotope ranges are limited (208Pb/204Pb ∼38 to 39.8, 207Pb/204Pb ∼15.51 to 15.64 and 206Pb/∼17.9 to 20.1), while Hf isotopes display more diverse compositions (εHf ranging from +7.7 to +14). Both Nd (εNd = 2.8–9.3) and Sr (87Sr/86Sr = 0.7026–0.7048) isotopes are correlated with Hf data. Trace element and isotopic compositions can be explained in terms of mixing between three distinct geochemical endmembers in the mantle resembling DMM, HIMU and EM-2 sources. Our study confirms voluminous subduction-related magmatism on the Loyalty and Three Kings ridges, mostly of Late Oligocene – Early Miocene age. The issue of polarity of subduction to generate these rocks remains open, but the composition-space-time distribution of the igneous rocks can be explained in the context of SW Pacific geodynamics using a west-dipping Pacific slab model.

Miocene Cupressinoxylon from Gökçeada (Imbros), Turkey with Protophytobia cambium mining and the study of ecological signals of wood anatomy.

The recognition of the Miocene Climate Optimum (MCO) in terrestrial palaeoenvironments of the Eastern Mediterranean is restricted to Lesbos and Lemnos Islands, Greece. This area is significant for its wood microfossils. A recently-discovered fossil wood assemblage from Gökçeada (Imbros) Island, Turkey, including tree species similar to the Greek findings, is thought to have an early Miocene age. Here, we revise the age of the latter plant fossiliferous locality, re-evaluate the area for the study of MCO for the terrestrial palaeoecosystems of the Eastern Mediterranean and the nomenclature errors referring to the occurrence of fossil wood. We present the plant-insect-environment interactions using detailed anatomical descriptions, of an extinct conifer and its extinct cambium miner feeding traces observed in its secondary xylem. Three thin sections were prepared with standard palaeoxylotomical techniques from a small section of the silicified wood; the sections were observed under a light microscope. The anatomy of the conifer and its damage patterns were compared with those of extant and fossil Cupressaceae and Agromyzidae, respectively. The common anatomical features of the studied wood specimen and Hesperocyparis macrocarpa (Hartw.) Bartel and a shared characteristic (the number of the cross-field pits - a feature we consider of diagnostic value) with Xanthocyparis vietnamensis Farjon & T.H. Nguyên led to its assignment to the Hesperocyparis-Xanthocyparis-Callitropsis clade. The detailed study of the wound scars and anatomical abnormalities, the anatomical-environmental associations, and structural-functional reactions follow the identification of the wood's anatomy sensu Carlquist providing decisive results. Based on the distinctive characteristics presented, we identify our macrofossil as Cupressinoxylon matromnense Grambast, a stem or an extinct lineage of the Hesperocyparis-Xanthocyparis vietnamensis-Callitropsis nootkatensis clade with feeding traces of the fossil cambium miner of the genus Protophytobia Süss (Diptera: Agromyzidae), and anatomical damage and reaction tissue on adventitious shoots. The use of Protopinaceae and Pinoxylon F. H. Knowlton from the eastern Mediterranean are re-evaluated and corrections are provided. The age of the studied plant fossiliferous locality in Gökçeada is revised as middle Miocene, allowing the proposal of an eastern Mediterranean MCO hotspot, including Lesbos, Lemnos, and Gökçeada (Imbros) Islands.