Oligocene Sediments Research Articles

3D models related to the publication: Early Oligocene chinchilloid caviomorphs from Puerto Rico and the initial rodent colonization of the West Indies

This contribution contains the 3D models of the fossil teeth of two chinchilloid caviomorph rodents (Borikenomys praecursor and Chinchilloidea gen. et sp. indet.) discovered from lower Oligocene deposits of Puerto Rico, San Sebastian Formation (locality LACM Loc. 8060). These fossils were described and figured in the following publication: Marivaux et al. (2020), Early Oligocene chinchilloid caviomorphs from Puerto Rico and the initial rodent colonization of the West Indies. Proceedings of the Royal Society B. http://dx.doi.org/10.1098/rspb.2019.2806

The upper Eocene-Oligocene carnivorous mammals from the Quercy Phosphorites (France) housed in Belgian collections

The Quercy Phosphorites Formation in France is world famous for its Eocene to Miocene faunas, especially those from the upper Eocene to lower Oligocene, the richest of all. The latter particularly helped to understand the ‘Grande Coupure’, a dramatic faunal turnover event that occurred in Europe during the Eocene-Oligocene transition. Fossils from the Quercy Phosphorites were excavated from the middle 19th century until the early 20th century in a series of sites and became subsequently dispersed over several research institutions, while often losing the temporal and geographical information in the process. In this contribution, we provide an overview and reassess the taxonomy of these barely known collections housed in three Belgian institutions: the Université de Liège, KU Leuven, and the Royal Belgian Institute of Natural Sciences. We focus our efforts on the carnivorous mammals (Hyaenodonta and Carnivoramorpha) and assess the stratigraphic intervals covered by each collection. These fossils are derived from upper Eocene (Priabonian), lower Oligocene (Rupelian), and upper Oligocene (Chattian) deposits in the Quercy area. The richness of the three collections (e.g., the presence of numerous postcranial elements in the Liège collection), the presence of types and figured specimens in the Leuven collection, and some identified localities in the RBINS collection make these collections of great interest for further studies on systematics and the evolution of mammals around the ‘Grande Coupure’.

Reconstruction of the depositional sedimentary environment of Oligocene deposits (Qom Formation) in the Qom Basin (northern Tethyan seaway), Iran

Abstract During the Rupelian–Chattian, the Qom Basin (northern seaway basin) was located between the Paratethys in the north and the southern Tethyan seaway in the south. The Oligocene deposits (Qom Formation) in the Qom Basin have been interpreted for a reconstruction of environmental conditions during deposition, as well as of the influence of local fault activities and global sea level changes expressed within the basin. We have also investigated connections between the Qom Basin and adjacent basins. Seven microfacies types have been distinguished in the former. These microfacies formed within three major depositional environments, i.e., restricted lagoon, open lagoon and open marine. Strata of the Qom Formation are suggested to have been formed in an open-shelf system. In addition, the deepening and shallowing patterns noted within the microfacies suggest the presence of three third-order sequences in the Bijegan area and two third-order depositional sequences and an incomplete depositional sequence in the Naragh area. Our analysis suggests that, during the Rupelian and Chattian stages, the depositional sequences of the Qom Basin were influenced primarily by local tectonics, while global sea level changes had a greater impact on the southern Tethyan seaway and Paratethys basins. The depositional basins of the Tethyan seaway (southern Tethyan seaway, Paratethys Basin and Qom Basin) were probably related during the Burdigalian to Langhian and early Serravallian.

Revealing exhumation of the central Alps during the Early Oligocene by detrital zircon U\u2013Pb age and fission-track double dating in the Taveyannaz Formation

The late Eocene-to-early Oligocene Taveyannaz Formation is a turbidite series deposited in the Northern Alpine Foreland Basin (close to the Alpine orogenic front). Double dating of zircons with the fission-track and the U–Pb methods is applied on samples from the Taveyannaz Formation to reconstruct the exhumation history of the Central-Western Alps and to understand the syn-collisional magmatism along the Periadriatic lineament. Three samples from this unit show similar detrital zircon fission-track age populations that center at: 33–40 Ma (20%); 69–92 Ma (30–40%); and 138–239 Ma (40–50%). The youngest population contains both syn-volcanic and basement grains. Combined with zircon U–Pb data, it suggests that the basement rocks of Apulian-affinity nappes (Margna Sesia, Austroalpine) were the major sources of detritus, together with the Ivrea Zone and recycled Prealpine flysch, that contributed debris to the Northern Alpine Foreland Basin. Furthermore, the rocks of the Sesia–Lanzo Zone or of equivalent units exposed at that time presumably provided the youngest basement zircon fission-track ages to the basin. The Biella volcanic suite was the source of volcanogenic zircons. Oligocene sediment pathways from source to sink crossed further crystalline basement units and sedimentary covers before entering the basin from the southeast. The lag times of the youngest basement age populations (volcanic zircons excluded) are about 11 Myr. This constrains average moderate-to-high exhumation rate of 0.5–0.6 km/Myr in the pro-side of the orogenic wedge of the Central Alps during the late Eocene to early Oligocene.

THE OLIGOCENE FORAMINIFERAL BIOSTRATIGRAPHY OF PAKISTAN

The marine Oligocene deposits of Pakistan are exposed in the Baluchistan and Lower Indus Basins. The Baluchistan Basin deposits are referred to the Khojak Formation of Makran Group. They represent three planktic foraminiferal zones, the Globigerina ampliapertura Zone, G. ciperoensis Zone and Globorotalia kugleri Zone, corresponding to Early, Middle and Late Oligocene. The Lower Indus Basin deposits of Sind include the Kirthar and Nari Formations. On the basis of the larger Foraminifera these deposits are divided into Nummulites fichteli Zone (Early Oligocene), N. fichteli/Lepidocyclina (E.) dilatata Zone (Mid. Oligocene), and L. dilatata Zone (Late Oligocene). The Oligocene deposits are absent in the Upper Indus Basin due to the orogenic movement which took place at the end of the Eocene and continued in the Oligocene.

Origin of the Oligocene manganese deposit at Obrochishte (Bulgaria): Insights from C, O, Fe, Sr, Nd, and Pb isotopes

The large manganese (Mn) deposit at Obrochishte (NE Bulgaria) is part of a cluster of similar Early Oligocene deposits located around present-day Black Sea. They collectively constitute the Earth’s second largest endowment of Mn, after the Kalahari Manganese Field in Africa. We have employed a battery of isotopic techniques (C, O, Fe, Sr, Nd, Pb) to help understand the genesis of this deposit. Carbon isotope data indicates that some sections of the Mn-ore layer have diagenetic MnCO3 mineralization, formed by reaction of Mn oxides with organic carbon (Corg), whereas other sections have MnCO3 precipitated directly from the seawater column. Oxygen isotopes show that the high-grade Mn mineralization had seawater as the fluid source, whereas some lower-grade sections had a mix of ground water and seawater as fluid sources. Sr and Nd isotope values of ore leachates also indicate that the Mn deposition occurred in normal Early Oligocene seawater. Nd and Pb isotope values suggest that the clastic host sediments were sourced from continental bedrock rather than younger arc volcanic rocks to the west. Iron isotope composition of the Mn ore implies deposition in a redox-stratified basin, similar to the modern Black Sea, with much of the Fe sequestered in deep, anoxic-euxinic water as sulfides. Similar to the modern Black Sea, most of the detrital Fe was transferred from shallow oxic sediments into deep, anoxic-euxinic water by an “iron shuttle” and remobilized Mn sequestered in the upper suboxic water layer. However, during the Oligocene, the “iron shuttle” operated intermittently due to the chemocline falling mostly below the shelf break, thereby limiting the efficiency of the shuttle mechanism. We propose a model for the Lower Oligocene strata in which intense weathering during the Eocene weathering phase produced a thick lateritic crust on the southern European continent. The drastic sea-level drop at the end of the Eocene initiated downcutting of streams through this weathered material, transferring Fe- and Mn-oxides to the redox-stratified Western Black Sea. Here, these oxides were partly or entirely dissolved in the suboxic (Mn-oxides partly, Fe-oxyhydroxides entirely dissolved) and anoxic-euxinic (Mn-oxides entirely dissolved, dissolved Fe2+ re-precipitated) water layers. Eventually, Fe was re-precipitated as sulfide in the deep anoxic-euxinic water, while Mn accumulated in the suboxic water layer. Transgression in the Early Oligocene brought this Mn-rich water onto the shallow shelf where it precipitated as Mn-oxide, then converted to Mn-carbonates during early diagenesis. Some Mn was also contributed by submarine groundwater discharge. Further transgression brought lower-oxygen water onto the shelf and Mn-carbonate precipitated directly from the water column. The findings from this work provide insights about the unique Oligocene geochemical event in the region that lead to the formation of the 2nd largest cluster of Mn deposits in the world.

PALEOECOLOGICAL ASPECTS OF WESTERN UNITED STATES NONMARINE OSTRACODS DURING THE EOCENE–OLIGOCENE TRANSITION: THE EARLY OLIGOCENE FAUNAS OF THE RENOVA FORMATION, SOUTHWESTERN MONTANA

ABSTRACTThe Renova Formation is a Paleogene sedimentary sequence from southwestern Montana that was deposited in a more extensive basin dominated by mid- to high altitude streams and small-lake paleoenvironments. The sediment infill was dissected during the Miocene–Pliocene into the remnants currently observed in several places, including the Upper Ruby River valley, Medicine Lodge valley and Horse Prairie. Ostracods from these early Oligocene strata belong to five genera of the suborder Cypridocopina: Amplocypris?, Candona (including the species Candona rangliensis? and Candona sp. aff. Candona ohioensis), Cyprois, Eucypris, and Paracypridopsis?. These ostracods, capable of producing drought-resistant eggs, likely inhabited fairly stable small lakes, characterized by arboreal surroundings reminiscent of forests in highland regions that were buffered against the drastic climatic variations of the late Eocene–early Oligocene transition (EOT) during the Eocene–Oligocene climatic deterioration. Further south, climatic change during the EOT, coupled with volcanic events, impacted the establishment of long-lasting, highly diverse ostracod faunas in lowland areas. The Upper Ruby River, Medicine Lodge and Horse Prairie early Oligocene deposits in southwestern Montana may have acted as refugia for Eocene ostracod genera that became extinct elsewhere or represented Lazarus taxa that would later diversify during the Miocene.

Characterization of microseepage-induced diagenetic changes in the Upper-Red Formation, Qom region, Iran. Part II: A new insight using reflectance spectroscopic analysis

The classic microseepage model supports the notion that hydrocarbon pools leak to the surface over time and trigger an array of diagenetic physicochemical and mineralogical changes in the overlying sediments. Mapping the induced alteration mineralogy for microseepage targeting has been an appealing yet ambiguous practice, mostly because of our incomplete understanding of the diversity of changes occurring in the environment. To close this gap, an integrated spectroscopic approach is adopted here to investigate the variability, quantity, and physicochemistry of diagenetic minerals induced by active microseepage systems over the Alborz oil reservoir in the Qom region, Iran. The area includes an effectively sealed carbonate reservoir overlain by thick Oligocene sediments of the Upper Red Formation. A large suite of samples collected from microseepage-affected zones was spectrally characterized in the 350–2500 nm wavelength region and then statistically contrasted against unaffected samples gathered from a nearby control area. The analysis reveals a novel array of mineralogic indicators for microseepage systems. It indicates that smectites (montmorillonite, nontronite), Al-rich mixed-layer illite/smectite, Fe-rich chlorite and traces of palygorskite constitute the clay alterations. This array is associated with the enrichment of K 2 O and loss of Na 2 O and MgO from the system, as indicated by X-ray fluorescence measurements. In the arid climate of the region, the iron-rich red-beds (Fe 2 O 3 > 6%) are only moderately bleached and, thus, the subsequent chemical weathering of the relict irons has triggered goethite (Al-poor), and likely ferrihydrite and maghemite precipitation. Consequently, besides the typical ferric iron bleaching, the modification in the mineralogy of iron oxides/oxyhydroxides (marked by a shift in the absorption minimum at ~ 900 nm) is suggested as an additional indicator of microseepage systems. Fe-chlorites constitute the dominant ferrous mineral present in the environment. The affected strata are also associated with prevalent calcite and gypsum cements, and occasionally jarosite occurrences. Based on the silica contents of the host-rock, the microseepage-induced alterations are classified into two categories, namely ‘felsic’ and ‘mafic’, wherein the latter is typified by the assemblages described here. This study provides new insights into microseepage-induced alterations and highlights the significance of reflectance spectroscopic techniques in facies determination and the alteration footprints mapping of onshore microseepage systems. • Novel mineralogical indicators for microseepage-induced alterations are introduced. • The illite/smectite composition tends to be Al-rich with high crystallinity degree. • The chlorite composition becomes progressively more Fe-rich in the affected zones. • The host-rock geochemistry and weathering overprint affect the diagenetic alterations.

Oligocene-Miocene drainage evolution of NW Borneo: Stratigraphy, sedimentology and provenance of Tatau-Nyalau province sediments

Clastic sediments of Oligocene to Lower Miocene age form a major thick and widespread sequence in the Tatau-Nyalau province of the north Sarawak Miri Zone. New light and heavy mineral data, U-Pb detrital zircon geochronology and biostratigraphy are used to identify the age, depositional environment, and potential provenance of sediments to reconstruct the drainage evolution of NW Borneo. Based on the biostratigraphic ages, depositional environments and provenance characteristics we modify previous stratigraphy and divide the Oligocene to Lower Miocene sequences into the Nyalau Formation (Biban Sandstone Member and Upper Nyalau Member), Kakus Unit, and Merit-Pila Formation. Two dominant source provinces were identified: the Malay-Thai Tin Belt which supplied sediments dominated by Permian-Triassic zircons, and the Schwaner Mountains of central Borneo which are identified by abundant Cretaceous zircons. Sediments either came directly, or were recycled from older sedimentary rocks, from these sources. The Sunda River deposited the Nyalau Formation during the Oligocene to Early Miocene with a dominant Malay-Thai Tin Belt source. The Merit-Pila Formation of the Sibu Zone was deposited contemporaneously by a proto-Rajang River that drained Central Borneo (recycling the Rajang Group and Schwaner granitoids). Between c. 17 Ma the Sunda River system terminated and sedimentation was dominated by the northward prograding proto-Rajang River delta, depositing the Kakus Unit in the Miri Zone. This drainage system was active until the Late Miocene, before further uplift of Borneo terminated most sedimentation in the onshore part of present-day Borneo.

A systematic revision of herrings (Teleostei, Clupeidae, Clupeinae) from the Oligocene and early Miocene from the Eastern Paratethys and the Carpathian Basin

ABSTRACT Clupeids are one of the most diverse groups of marine fishes represented by numerous extant genera and species. The diversity of European clupeids was even greater in the past, especially during the Paleogene and early Neogene. Here we present the results of a thorough revision of numerous fish fossils assigned to the subfamily Clupeinae. They come from Oligocene and early Miocene deposits of the former Eastern Paratethys and the Carpathian Basin, and are represented by complete and fragmented skeletons. A new endemic genus—†Rupelia Baykina and Kovalchuk, gen. nov.—is established for small-sized herrings from the early Oligocene (Rupelian) of the Caucasus. It occurred only in the Eastern Paratethys and was represented by a single species—†R. rata (Daniltshenko, 1959). At that time, another herring inhabited the entire Paratethys. It completely fits into †Clupeonella (Maicopiella) sensu Menner, 1949a—a subgenus which is raised here to genus level. Based on our review, this herring was represented during the Oligocene by †Maicopiella longimana (Heckel, 1850) —a widespread species with numerous fossils found in deposits mostly of Rupelian and partly of Chattian age. †Rupelia rata went extinct at the beginning of the Miocene, while †Maicopiella longimana was replaced by †M. brevicauda (Menner, 1949a) in the Eastern Paratethys and by †Sardinella sardinites (Heckel, 1850) in the Carpathian Basin. A detailed morphological description of all mentioned taxa is presented. The results of our study shed more light on the diversity and distribution of herrings within the central and eastern parts of the Paratethys during the Oligocene and early Miocene.

Early Oligocene chinchilloid caviomorphs from Puerto Rico and the initial rodent colonization of the West Indies.

By their past and present diversity, rodents are among the richest components of Caribbean land mammals. Many of these became extinct recently. Causes of their extirpation, their phylogenetic affinities, the timing of their arrival in the West Indies and their biogeographic history are all ongoing debated issues. Here, we report the discovery of dental remains from Lower Oligocene deposits (ca 29.5 Ma) of Puerto Rico. Their morphology attests to the presence of two distinct species of chinchilloid caviomorphs, closely related to dinomyids in a phylogenetic analysis, and thus of undisputable South American origin. These fossils represent the earliest Caribbean rodents known thus far. They could extend back to 30 Ma the lineages of some recently extinct Caribbean giant rodents (Elasmodontomys and Amblyrhiza), which are also retrieved here as chinchilloids. This new find has substantial biogeographic implications because it demonstrates an early dispersal of land mammals from South America to the West Indies, perhaps via the emergence of the Aves Ridge that occurred ca 35-33 Ma (GAARlandia hypothesis). Considering both this new palaeontological evidence and recent molecular divergence estimates, the natural colonization of the West Indies by rodents probably occurred through multiple and time-staggered dispersal events (chinchilloids, then echimyid octodontoids (spiny rats/hutias), caviids and lastly oryzomyin muroids (rice rats)).

Oligocene molasse sedimentation in Central Taurides: Records of the onset of extensional tectonic regime

The lacustrine units have been deposited in the Ermenek, Bucakkisla, Korucuk and Camliyayla basins in the Central Taurides since early Oligocene. In this study, structural features and stratigraphical properties of Oligocene basins have been described in detail and the lacustrine units have been dated. Regional geological interpretations have been made by using tectono-stratigraphic and age data of the basins. Lacustrine Oligocene sedimentation in these basins, which were opened on the tectonic units of Taurides due to normal faults, constitute the first records of the sedimentation occurring under the extensional tectonic regime after the orogeny of the Central Taurides. All the pre-Oligocene units that had been emplaced in the region due to a north-south compressional movement in the Central Taurides, continued to be compressed until the end of Eocene, and completed their orogenic development as napped structures. The bedrock units, reaching the maximum elevation, have been subjected to “orogenic collapse” due to the strain or gravity forces as a result of an interruption or termination of the compression which lasted until the end of Eocene. Thus, “orogenic collapse” basins have started to be formed in the Central Taurides since Oligocene. The orogeny and the compressional tectonic regime forming the Taurides lasted until late Miocene in the Eastern Taurides. On the other hand, extensional basin formation since early Oligocene on the Taurus units, which had been emplaced in the region due to nappe tectonics, indicates that a new tectonic period has started in the Central Taurides.

A new homolid crab, Cherpihomola italica gen. nov., sp. nov. (Decapoda, Brachyura), from the Rupelian of the LigurePiemontese Basin (Alessandria, northern Italy)

A new genus and species of homolid from lower Oligocene (Rupelian) strata in the Ligure-Piemontese Basin (northern Italy) is introduced. Cherpihomola italica gen. nov., sp. nov. represents the first record of homolids from Oligocene deposits across Europe and extends the palaeogeographical distribution of extinct homolids.

Analysis of Medicine Bow-Laramie River Drainage Divide Using Topographic Map Interpretation Techniques, Southeastern Wyoming, USA

Detailed topographic maps provide much of the information needed to understand how drainage divides like the southeast Wyoming Medicine Bow River-Laramie River drainage divide originated. Topographic map evidence for each Medicine Bow-Laramie River drainage divide segment is here described and analyzed first using a commonly published interpretation (accepted paradigm) in which drainage routes developed on a surface of now mostly absent Oligocene and Miocene sediments that previous investigators have hypothesized to have once filled the Laramie Basin and to have also buried (or partially buried) the surrounding Laramie and Medicine Bow Mountains. Second, the same map evidence is analyzed using a recently proposed interpretation (new paradigm) in which massive and prolonged floods flowed across Wyoming as the Laramie and Medicine Bow Mountains began to be uplifted and as the southeast-oriented North Platte River valley eroded headward along the rising Laramie Mountains northeast flank. Low points along the drainage divide (referred to as divide crossings) are interpreted to be places where water once flowed across the drainage divide with the drainage divide being formed when capture events diverted the water in other directions. Valleys leading away from divide crossings are used to determine the nature of observed capture events, many of which are difficult or impossible to explain from the accepted paradigm perspective, but which are consistent with the mountain uplift, headward erosion of deeper valleys, and/or draining of floodwaters trapped in the Laramie Basin as the new paradigm predicts. However, the new paradigm requires a North American continental ice sheet heavy enough to raise entire regions and mountain ranges as massive and prolonged meltwater floods flowed across them, something the accepted paradigm does not recognize.

Nomenclatural novelties in the fossil genus Spinopalmoxylon (Arecaceae) from the Central European Oligocene and Miocene: A whole-plant concept for Spinopalmoxylon daemonorops

Abstract The fossil genus Spinopalmoxylon from the Central European Oligocene and Miocene comprises three species: S. daemonorops, S. parvifructum sp. nov. and S. cicatricosum sp. nov. Here the species S. daemonorops is amended and its name is proposed as nomen conservandum against S. teutonicum. A series of synonyms is provided. In addition, two new species are described from late Oligocene deposits of Niederpleis: S. parvifructum sp. nov. (pistillate inflorescence, fruits, and seeds) and S. cicatricosum sp. nov. (staminate inflorescence and pollen). These three Spinopalmoxylon species together are proposed as a whole plant. Floras with the Spinopalmoxylon palm reflect the vegetation of the near-shore fluvial floodplain and back-swamp environments of the late Oligocene (Chattian) Köln Formation (Clay 1) and early Miocene (Burdigalian) Ville Formation (Seam 6A) in the northern foreland of the Siebengebirge Volcanic Field near Bonn, at the southeastern margin of the Lower Rhine Basin.

Morphometric analysis of fossil bumble bees (Hymenoptera, Apidae, Bombini) reveals their taxonomic affinities.

Bumble bees (Bombus spp.) are a widespread corbiculate lineage (Apinae: Corbiculata: Bombini), mostly found among temperate and alpine ecosystems. Approximately 260 species have been recognized and grouped recently into a simplified system of 15 subgenera. Most of the species are nest-building and primitively eusocial. Species of Bombus have been more intensely studied than any other lineages of bees with the exception of the honey bees. However, most bumble bee fossils are poorly described and documented, making their placement relative to other Bombus uncertain. A large portion of the known and presumed bumble bee fossils were re-examined in an attempt to better understand their affinities with extant Bombini. The taxonomic affinities of fossil specimens were re-assessed based on morphological features and previous descriptions, and for 13 specimens based on geometric morphometrics of forewing shape. None of the specimens coming from Eocene and Oligocene deposits were assigned within the contemporary shape space of any subgenus of Bombus. It is shown that Calyptapis florissantensis Cockerell, 1906 (Eocene-Oligocene boundary, Florissant shale, Colorado, USA) and Oligobombus cuspidatus Antropov, 2014 (Late Eocene, Bembridge Marls) likely belong to stem-group Bombini. Bombus anacolus Zhang, 1994, B. dilectus Zhang, 1994, B. luianus Zhang, 1990 (Middle Miocene, Shanwang Formation), as well as B. vetustus Rasnitsyn & Michener, 1991 (Miocene, Botchi Formation) are considered as species inquirenda. In the Miocene, affinities of fossils with derived subgenera of Bombus s. l. increased, and some are included in the shape space of contemporary subgenera: Cullumanobombus (i.e., B. pristinus Unger, 1867, B. randeckensis Wappler & Engel, 2012, and B. trophonius Prokop, Dehon, Michez & Engel, 2017), Melanobombus (i.e., B. cerdanyensis Dehon, De Meulemeester & Engel, 2014), and Mendacibombus (i.e., B. beskonakensis (Nel & Petrulevičius, 2003), new combination), agreeing with previous estimates of diversification.

Provenance of Eocene–Oligocene sediments in the San Jacinto Fold Belt: Paleogeographic and geodynamic implications for the northern Andes and the southern Caribbean

AbstractMesozoic and Cenozoic strata of the San Jacinto Fold Belt (Colombian Caribbean) provide insights about sedimentary environments and paleogeographic evolution in the transition between the northern Andes and the South Caribbean deformed belt. We report new provenance (conventional sandstone petrography, heavy mineral analysis, and detrital zircon U-Pb geochronology and typology) and micropaleontologic data (palynology, calcareous nannofossils, and foraminifera) in samples collected from the lower Eocene (San Cayetano Formation) and upper Eocene–Oligocene (Toluviejo and Ciénaga de Oro Formations) rocks in boreholes drilled by the Colombian Agencia Nacional de Hidrocarburos as well as from recently exposed Oligocene outcrops from the Ciénaga de Oro Formation. Sandstone petrography shows modal variations, with high feldspar content in the lower Eocene rocks and high quartz content in the Oligocene deposits. This shift in compositional maturity may be due to climatic variations, tectonic activity, and/or changes in source areas. Heavy mineral analyses indicate variations that suggest sources primarily related to felsic igneous and/or low-grade metamorphic and mafic and ultramafic rocks. Zircon U-Pb geochronology displays age populations mainly in the Late Cretaceous, Late Jurassic, Permian–Triassic, and Precambrian (ca. 900–1500 Ma). In addition, zircon typology analyses indicate that the igneous zircons came primarily from monzogranites and granodiorites. Finally, the micropaleontologic and sedimentary data sets indicate that the sediments were deposited in tropical coastal and shallow marine environments. The sediments were transported by short rivers from the crystalline massifs of the Lower Magdalena Valley and the northern Central Cordillera basements, while distal transport of sediments may have occurred along longer rivers, which brought sediments from southern regions located between the Central and Western Cordilleras.

Bone detritus in sediments of Tethis ocean

The comparative study of the Oligocene bone breccia geochemistry in the lower part of the Oligocene deposits (Mangishlak, Oligocene Miocene) has been studied along with the recent uranium deposits. Studies of the Namibian shelf samples where the series of macro- and microelements have been analized, including major and minor elements, which showes their similarity of major elements and miner elements in the both deposits old and Recent samples. From the other side the similarity between uranium mineralization has been found in the uranium mineralization in Maikop and recent bones on the Namibian shelve. The paleogeographic data of the Maikop Basin showed that the ore deposits have been formed in the productive shallow sea where mass mortality of the fish happened often as well as in present Ocean. The high values of metal concentration is the older bones in the Tethis are related to evaporation and saturation of marine water.

An Oligocene tubeshoulder (Teleostei, Alepocephaliformes) from the Central Paratethys (Czech Republic): the first skeletal record for the family Platytroctidae

ABSTRACT A new fossil fish, Vachalia moraviensis, gen. et sp. nov., is described based on a single articulated specimen collected from lower Oligocene deposits exposed in the vicinity of Kelč, Czech Republic. The morphological analysis of the specimen reveals a series of features that unambiguously support its recognition as a new member of the alepocephaliform family Platytroctidae. Vachalia moraviensis, gen. et sp. nov., is characterized by a very large head; elongate and ribbon-like body; two premaxillary tusks, of which the posterior is distant from the anterior one and almost perpendicular to it; posterior border of the maxilla behind the orbit; two supramaxillae; nine branchiostegal rays; 22 abdominal and 18 or 19 caudal vertebrae; dorsal fin with 16 or 17 rays; pectoral fin reduced and composed of approximately 12 short rays; pelvic fin larger than pectoral fin; and photophores (apparently) absent. The specimen described herein represents the first and only known fossil belonging to the family Platytroctidae based on articulated skeletal remains.

Paleoclimate of Upper Oligocene-Lower Miocene Temburong Formation, Klias Peninsula, Sabah, Base on Planktonic Foraminifera Assemblage

Planktonic foraminifera assemblages were studied for biostratigraphy and paleoclimatic interpretation of the Upper Oligocene-Lower Miocene of Temburong Formation, Klias Peninsula, Sabah. The Temburong Formation is composed of mainly flysh-type argillaceous deposit intercalations of slightly calcareous pelagic shale. Recently we discovered abundance of moderate to well-preserved planktonic foraminifera at the measured section and its planktonic assemblages are useful for biostratigraphy and paleoclimatic studies of Temburong Formation. A total of nine samples of shale were collected from three outcrops and processed based on standard micropaleontology method. Twenty-eight species of planktonic foraminifera were identified and grouped into three zones, namely: P21-P22 Globorotalia opima opima-Globigerina angulisuturalis zone, N4 Globigerinoides primordius-Globigerinoides quadrilobatus zone, and N5-N6 Catapsydrax dissimilis-Globigerinoides altiapetura zone. For paleoclimate studies, the relative abundance of planktonic foraminifera was obtained and grouped into climatic indices namely cool, cool-temperate, warm, warm-temperate and none climatic diagnostic. The result shows the changes of planktonic foraminifera assemblages and the paleoclimatic indices through Oligocene-Miocene boundary. The cool climate indices were identified at the lower part of the study section of Upper Oligocene sediment and gradually shifted to warm climatic indices at Lower Miocene section.