Paleocene Age Research Articles

Palynological Studies of Upper Creataceous-Paleocene Rocks in Auchi Sheet 266, Benin Flank, Western Extension of the Anambra Basin, Southwestern Nigeria

Out crop samples from Mamu and Nsuka Formation at different locations and ditch cutting samples gotten from a water borehole at Ugbekpe-Ekperi road at different intervals collected from Benin Flank, Western extension of the Anambra Basin, were used for sedimentologic and palynology studies with the aim of establishing palynological assemblage zones, age and paleoenvironments of the sediments. Out crops and Ditch cutting samples were lithologically described using a transmitted light microscope in order to obtain their lithofacies and latter subjected to palynological slides preparation to identify the presence of palynomorphs. Lithofacies units identified were clay, sandy clay, silt, sandstone, shale and sandy shale facies. From the analyzed palynological slides, ninety one (91) palynomorphs species were identified in the outcrop samples, eighty three (83) were Miospores (pollen and spores) and seven (7) were Dinocysts while the borehole samples recorded fifty five (55) palynomorph species, forty three (43) were Miospores while fifteen (15) were Dinocyst. Clusters analysis were used to establish four (4) Palynological Assemblage zones which are Palynological Assemblage zones 1, 2, 3 and 4. Late Maastrichtian to Early Paleocene age is suggested for Nsukka Formation because of the presence / abundance of Spinizonocolpites baculatus with admixture of Apectodinium homomorphum and Homotryblium tenuispinosum. The occurrence of Monocolpites marginatus, Retidiporites magdalenensis, and non-occurrence of Spinizonocolpites baculatus in the outcrop samples suggests that Mamu Formation did not penetrate Late Maastrichtian. Thus Early to Middle Maastrichtian is suggested for Mamu formation. The occurrence of mangrove palynomorphs Zonocostites ramonae, fresh water algae Botryococcus braunii and Concentricyst circulus indicates sedimentation in coastal to shallow marine environment close to mangrove vegetation.

Thermal evolution of Los Cuervos formation in the southern area of the Cesar sub-basin (Colombia), based on geochemical and petrophysical data

The tectonic complexity to which the post-Cretaceous Cesar-Ranchería basin has been subjected has generated alterations in the evolution of its oil system, evidence of this is the lack of stratigraphic record in the Cesar sub-basin belonging to ages ranging from the Eocene to the Early Miocene. These units that are no longer present could have been deposited and eroded during this period of time, leaving their mark on the closest overlying units. Previously mentioned hypothesis oriented this research to study how the basin filling was in the time range from the Eocene to the early Miocene based on both organic (24 Tmax and 14 %Ro data) and inorganic (514 data of porosity) paleo-geothermometer data of Paleocene age formations present in two new wells ANH-LA LOMA-2 and ANH-CR-LOS CEREZOS-1X. In addition to the data provided by the wells drilled for this study, 31 published Tmax and 13 %Ro data from Los Cuervos Formation in the Calenturitas and La Jagua Mines were used. The results obtained indicate that the continuous deposition of sedimentary units did occur from the Paleocene to the middle Eocene and it is expected that the Sedimentitas del Eoceno Formation has reached a thickness between 2.5 to 3.5km with characteristics of quartz sandstones (density and compaction). This thickness of rock began to be eroded in the late Eocene to the Miocene according to recent thermo-chronological studies. The evidence obtained allow to improve the thermal evolution models of the oil system, to establish when the greatest advances were made in the transformation ratios and to estimate how the oldest source rocks of the Cesar sub-basin are currently in the studied area.

Tromsø–Bjørnøya Composite Tectono-Sedimentary Element, Barents Sea

Abstract The Tromsø–Bjørnøya Composite Tectono-Sedimentary Element (CTSE) in the southwestern Barents Sea comprises strata of Late Paleozoic–Paleocene age. Since the Paleozoic Caledonian Orogeny, the structural evolution of the CTSE is mainly related to extension, culminating in Late Jurassic–Early Cretaceous hyperextension. Some compressive deformation observed during Late Cretaceous–Paleogene times may relate to activity in the North Atlantic prior to the Early Eocene onset of seafloor spreading between Norway and Greenland. The sedimentary succession may be up to 14 km thick. It comprises Late Paleozoic continental facies, followed by carbonates, evaporites, and eventually cherts and marine clastic material. The overlying Triassic–Paleocene succession is entirely siliciclastic, reflecting Triassic–Middle Jurassic deltaic and shallow-marine conditions followed by deeper-marine conditions during Late Jurassic–Paleocene times. Primary reservoirs are encountered in the latest Triassic–Middle Jurassic succession, with secondary reservoirs found in the Late Jurassic–Early Cretaceous synrift succession, and in Paleocene strata. The primary source rock for petroleum is of Late Jurassic–Early Cretaceous age. Other source rocks include strata of Triassic and Barremian age, and a recently observed unit of Cenomanian–Early Turonian age.

Mechanical and Elastic Characterization of Shale Gas Play in Upper Indus Basin, Pakistan

The organic-rich shale intervals of Patala Formation of Paleocene age may be considered as potential shale gas play in the Upper Indus Basin of Pakistan. Until now, seismic and elastic properties of the Patala shales are not investigated in detail necessary to declare it as shale gas play and to differentiate shale gas pay zone from the non-pay zone. Data of eight wells in which Patala shales were encountered at various depth levels from 2000 to 4300 m were deeply investigated for shale gas characterization. This shale fulfills the basic criteria of organic-rich shale with TOC ~ 0.5–5.8%, vitrinite reflectance (level of maturity) is 0.6–1.7%, average thickness 48 m. The brittleness index (BI) of this organic-rich shale was computed by using effective mechanical properties and mineralogy to define brittle zones in the shale intervals preferable for generating the fracture network. BI data points demonstrate that a large number of values fall in the brittle zone, whereas fewer values fall in the ductile zone. However, a certain number of values fall in the brittle–ductile transition zone. The quantitative comparison between different elastic and seismic properties derived from the wireline logs guide for the delineation of the pay zone from the non-pay zone in the organic-rich shale intervals.

Stratigraphic architecture and depositional environment of the Paleocene-Lower Eocene aquifers system (Douala onshore basin, SW Cameroon)

The Paleocene-Lower Eocene N'kapa Formation has long been considered as an important groundwater and hydrocarbon resource in the eastern edge of the Douala Basin. The present study’s aim is to establish a possible link between the geological nature of this formation and the quality of potential aquifers using Gamma Ray well log, cuttings and outcrops through sedimentology and sequence stratigraphy studies. The results obtained from this study show that: lithofacies are dominated by clays, silts and sands/sandstones; gamma ray electrofacies are funnel-shaped to cylindrical-shaped with some bell-shaped; depositional environments are continental to shallow marine dominated by fluvial and sometimes tidal processes; fluvial channel-fill, tidal channel-fill and delta front bars sands are potential aquifers; sequence stratigraphy analysis reveals two transgressive–regressive cycles of second order (Danian to Selandian and Thanetian to Ypresian), two Highstand System Tracts, one Transgressive System Tract and one Lowstand System Tract; the high-resolution geometry of these sandy/sandstone sedimentary bodies shows that their distribution is linked to the hydrodynamic factors and the topography of the depositional environment. A total of two types of lithological facies of the reservoir levels were defined according to the volume of clay: clean sandstone (0–15%) and low clayey sandstone (15–30%). The gamma ray well log correlation shows that the thickness of the reservoir levels is variable and that the clay content (Vsh%) increases from the NE to the SW. As a result, the best potential aquifers appear to correspond to the fluvial channel-fill sands deposited during the base-level fall of Upper Paleocene age (Lower Thanetian).

Фаціальні особливості палеоцен-еоценових відкладів передових скиб Скибової зони Українських Карпат

There three main types of facies of Paleocene-Eocene complexes: sandy, siltstone and argillite distinguished within the study area by the nature of the distribution of the strata of the forming components were highlighted. Тhey accumulated avalanche at the foot of the continental slope and formed various facial parts of the foehn (Upper, Middle and Lower foehn). In the upper part of the Foehn was accumulated coarse-grained sediments (clusters of deep boulders and other psephyto-psammitic material containing edaphogenic rocks). Under the action of geostrophic and bottom currents, silt streams of pelitic and psammitic material moved in the direction to the south and south-east of the Carpathian sedimentation basin, forming sandy-clay and clay facies (Middle and Lower foehn). During the turbidite movement of a large amount of sediment from the first (shelf) to the second (foot of the continental slope) level of avalanche sedimentation, sorting and distribution of sediments on the continental slope took place. Based on the analysis of the material composition of Paleocene-Eocene sediments of the study area by such criteria as the size of the fragment, sedimentary textures and the ratio of different rocks, 7 facies were identified, which were deposited as gravitational flows down on the continental slope. Reconstructions of Paleocene-Eocene age flysch deposits showed that terrigene material in the studied sedimentation basin came from two sources – one of which was northwest of the study area and was characterized by a predominance of coarse-grained sandy sediments, while the source wear, which was in the central part of the studied basin was characterized by a predominance of clay silt and fine-grained psammitic material. This nature of the distribution of terrigenous material had a decisive influence on the further formation of Paleocene end Eocene sedimentary strata in the process of sedimentogenesis and post-sedimentary transformations of sediments, and on the formation of reservoir rocks and rocks with potential reservoir properties for hydrocarbon exploration. It has been established that the composition of the Psamitolites of the flysch formation of the Paleocene and Eocene ages of the Carpathians was formed on the passive continental margin or in the inland and boundary seas, and their genesis mostly corresponds only to the platform source of material wear.

Biostratigraphy and Sequence Stratigraphy and Depositional Environment of Kolosh Formation in Dohuk Area, Northern Iraq

The present study deals with biostratigraphy, depositional environment and sequence stratigraphy of Kolosh Formation in two sections of Bekher anticline, northeastern Iraq by using the planktonic and benthonic foraminifera. Therefore, (48) species of planktonic foraminifera belonging to (14) genera and (34) species of benthonic foraminifera belonging to (19) genera have been recognized. The detailed planktonic foraminiferal investigation permits the recognition of seven well defined biozones and three subzones; they indicate that Kolosh Formation extends from the Early Paleocene (Danian) to Late Paleocene (Thanetian) age. The depositional environment of the formation was studied throughout relying on the variation in the diversity of planktonic forminifera, as well as throughout the ratio of the planktonic foraminifera to the whole mass of foraminifera, and the ratio of planktonic forminifera to the benthonic formiminifera. The lower part of the formation represents the upper bathyal environment, while the middle part deposited within the outer shelf environment, then deposition basin became within the middle shelf area in the upper parts of the formation. Sequence stratigraphic analysis for the studied sections of Kolosh Formation delineated three sequences which is interpreted as 3rd order sequences, and it is found that the deposition of Kolosh Formation in the Badi section had been occurred in shallower level for most sedimentation intervals compared to the Linwa section which represents a somewhat deeper marine environment.

An insight to the initiation of Cretaceous sedimentation in Northeast Indian Craton

The time transgressive Cretaceous sedimentation in northeast Indian craton is represented by the deposition of the Upper Cretaceous Mahadek sediments in Meghalaya. The Lower unit of these sediments is comprised of alternate sandstone and conglomerate horizons, and the Upper unit is composed of arkosic to sub-arkosic sandstones. These sediments are overlain by the calcareous litho-units of Langpar Formation of Cretaceous–Paleocene age. Lithofacies identified from various exposures and studied lithologs reflect a variation from marginal marine to marine depositional set-up in the Mahadek sediments. The Lower Mahadek facies is dominated by large-scale trough beds of medium to coarse-grained sediments which initiates with a conglomerate horizon succeeded by thin beds of shale and fine-grained sandstone with parallel laminations, which are followed by successive deposition of gritty sand and pebbly beds with coarsening upward sequence, suggesting product of delta plain in a marginal marine setting. Moreover, the bioturbated coaly fine-grained sandstone is further representative of tidal flat-tidal channel swamp formed in reducing condition and the trace fossil assemblages depict the channel fills. The Upper Mahadek facies is dominated by glauconitic-gritty fossiliferous sandstone showing fining upward sequence and hummocks, typical of marine environment. This fining upward sequence along with the vertical and lateral facies variation implies superimposition of retrograding shorelines on an earlier progradational alluvial fan sand complex. These different-scale cycles are interpreted as the sedimentary response to movements of the basin margin faults at variable frequencies, related to the contemporary faults. This depositional model of the Cretaceous sediments may further help in paleogeographic reconstruction of the northeast Indian craton during the Cretaceous period.

Paleoclimate records reveal elusive ~200-kyr eccentricity cycle for the first time

The main cycles of Earth's eccentricity as recorded in paleoclimate archives signify 2nd order terms, combining two g-frequencies associated with the precession of perihelia of the inner planets and Jupiter. However, many weaker cycles are present and may be documented as well. Here we report on a thus far unnoticed ~200-kyr cycle observed in rhythmically bedded marine marls and limestones of early Paleocene age in NE Spain and adjacent France. This cycle is expressed as alternating distinct and less distinct ~100-kyr CaCO3 maxima and associated magnetic susceptibility (MS) minima, which correspond to successive minima of the short ~100-kyr eccentricity cycle. The most plausible explanation is that this ~200-kyr cycle represents a weak but real cycle in eccentricity. Due to its weakness, this cycle is only expressed as alternatingly strong and weak ~100-kyr minima in eccentricity time series, a pattern that is identical to what we observe in the proxy records and outcrop. Its origin as eccentricity cycle is complex as it is composed of 4 to 6 individual components. A simplified solution solely based on the five leading g-frequencies reveals that most of these components originate from combinations of these 5 frequencies. However, they do not correspond to 2nd order terms, which underlie the principal short and long eccentricity cycles, but to much weaker higher order terms. Three of them have been identified as 4th order terms and two as 6th order terms, representing combinations of 2nd order terms, such as the first harmonic, 2(g2 – g5), of the 405-kyr cycle and related components. It is for the first time that the combined effect of such weak components has been identified in paleoclimatic records, which is only possible because they are not overwhelmed by much stronger 2nd order terms in this frequency band. Finally, the typical pattern that results from interference with the much stronger ~100-kyr cycle might be used as a template for testing the accuracy of astronomical solutions in the future.

Provenance of Tanjero and Red Bed clastic sedimentary rocks revealed by detrital zircon SHRIMP dating, Kurdistan region, NE Iraq: Constraints on ocean closure and unroofing of Neo-Tethyan allochthons

Closure of Neo-Tethys between the Late Cretaceous and Miocene caused obduction of intra-Neo-Tethys volcanic arc allochthons onto the northern margin of the Arabian-Nubian Shield. This loading led to downwarping of the shield forming a flexural basin in which the Tanjero Formation and later Red Beds accumulated. Analysis of the detrital zircon populations in these sedimentary units provides additional evidence supporting the petrographic data for the presence and unroofing of the allochthons. Both the Tanjero Formation and Red Beds show evidence of initial derivation of detritus from the Nubian-Arabian Shield together with minor Paleozoic detritus from Egypt, Turkey and/or Iran. The youngest detrital zircon grains in the Tanjero Formation are of Paleocene age and probably represent northern derivation from the Sanandaj-Sirjan Zone. In contrast, the upper Miocene Red Beds contain detrital zircon of Eocene age that confirms the petrographic evidence for derivation from, and hence emplacement of, the lower allochthon of intra-Neo-Tethys Walash-Naopurdan rocks.

Morphology and Affinities of Ampelocissites Seeds (Vitaceae: Ampelopsis clade) from the Paleogene of Texas, USA

Abstract—The type material on which the fossil genus name Ampelocissites was established in 1929 has been reexamined with the aid of X-ray micro-computed tomography (μ-CT) scanning and compared with seeds of extant taxa to assess the relationships of these fossils within the grape family, Vitaceae. The specimens were collected from a sandstone of late Paleocene or early Eocene age. Although originally inferred by Berry to be intermediate in morphology between Ampelocissus and Vitis, the newly revealed details of seed morphology indicate that these seeds represent instead the Ampelopsis clade. Digital cross sections show that the seed coat maintains its thickness over the external surfaces, but diminishes quickly in the ventral infolds. This feature, along with the elliptical chalaza and lack of an apical groove, indicate that Ampelocissites lytlensis Berry probably represents Ampelopsis or Nekemias (rather than Ampelocissus or Vitis) and that the generic name Ampelocissites may be useful for fossil seeds with morphology consistent with the Ampelopsis clade that lack sufficient characters to specify placement within one of these extant genera.

Comparisons Between Tethyan Anorthosite‐Bearing Ophiolites and Archean Anorthosite‐Bearing Layered Intrusions: Implications for Archean Geodynamic Processes

AbstractElucidating the petrogenesis and geodynamic setting(s) of anorthosites in Archean layered intrusions and Tethyan ophiolites has significant implications for crustal evolution and growth throughout Earth history. Archean anorthosite‐bearing layered intrusions occur on every continent. Tethyan ophiolites occur in Europe, Africa, and Asia. In this contribution, the field, petrographic, petrological, and geochemical characteristics of 100 Tethyan anorthosite‐bearing ophiolites and 155 Archean anorthosite‐bearing layered intrusions are compared. Tethyan anorthosite‐bearing ophiolites range from Devonian to Paleocene in age are variably composite, contain anorthosites with highly calcic (An44–100) plagioclase and magmatic amphibole. These ophiolites formed predominantly at convergent plate margins, with some forming in mid‐ocean ridge, continental rift, and mantle plume settings. The predominantly convergent plate margin tectonic setting of Tethyan anorthosite‐bearing ophiolites is indicated by negative Nb and Ti anomalies and magmatic amphibole. Archean anorthosite‐bearing layered intrusions are Eoarchean to Neoarchean in age, have megacrystic anorthosites with highly calcic (An20–100) plagioclase and magmatic amphibole, and are interlayered with gabbros and leucogabbros and intrude pillow basalts. These Archean layered intrusions are interpreted to have predominantly formed at convergent plate margins, with the remainder forming in mantle plume, continental rift, oceanic plateau, postorogenic, anorogenic, mid‐ocean ridge, and passive continental margin settings. These layered intrusions predominantly crystallized from hydrous Ca‐ and Al‐rich tholeiitic magmas. The field, petrographic, and geochemical similarities between Archean and Tethyan anorthosites indicate that they were produced by similar geodynamic processes mainly in suprasubduction zone settings. We suggest that Archean anorthosite‐bearing layered intrusions and spatially associated greenstone belts represent dismembered subduction‐related Archean ophiolites.

First report of the Eocene bivalve Schedocardia (Mollusca, Cardiidae) from Cuba

Herein we provide the first report of the cardiid bivalve Schedocardia from Cuba. The single, partial, valve external mold was derived from the Madruga Formation which is characterized by a richly diverse marine fauna including echinoderms, brachiopods, benthic and planktonic foraminiferans, but from which bivalves were not previously reported. The unit is considered late Paleocene in age (Thanetian), but the presence of Schedocardia supports a possible age extension of the formation into the early Eocene (Ypresian). Moreover, we provide a reconsideration of the historical factors that affected the accepted type locality of the outcrop, which allows for an alternative interpretation of the fauna found therein.

A new hydrocarbon exploration play: Upper Cretaceous–Paleocene sand injection complexes in the Austral-Magallanes Basin

Abstract Recent exploration activity in the Austral-Magallanes Basin revealed the presence of sand injection complexes of Upper Cretaceous–Paleocene age. The discovery of these large-scale sandstone intrusions documents the first onshore example of sand injection complexes as hydrocarbon exploration targets and confirms a more widespread phenomenon than previously known. Integration of regional understanding, three-dimensional seismic reflection data, exploration wells, and whole core have allowed the interpretation of large sand injectites associated with a deep-water depositional system in the Austral-Magallanes Basin. These injectites are characterized seismically by circular to elongate amplitude anomalies with cross-cutting and discordant stratigraphic relationships. Additionally, detailed sedimentological analysis from exploration wells and core confirm the presence of facies consistent with injected sand commonly associated with deep-water depositional systems. The presence of giant sand injection complexes in the Austral-Magallanes Basin records a previously undocumented period of pore-fluid overpressure that led to large-scale hydraulic fracturing of the overburden and subsequent fluidization of sand derived from a deep-water depositional system. The discovery of intrusive traps such as sand injection complexes defines a new play with significant exploration potential; however, additional evaluation is required to understand the nature and degree of primary sandbody geometrical modification and the subsequent impact on reservoir distribution, trap geometry, migration pathways and seals.

Upper Cretaceous Abiod and El Haria Formations in Jebel Rhorfa (Grombalia area, northeastern Tunisia): lithology and biostratigraphy revised—with extended comments on Ahlem Amri, Moez Ben Fadhel, Asma Chermiti, and Mohamed Ben Youssef (2018)

In the present work, we comment on Amri et al. Arab J Geosci 11(253) (2018) publication. This latter contains many taxonomic misinterpretations and confusions. That is why, in the present work, we propose accuracy on the chronostratigraphy of the Abiod Formation. So, we demonstrate that this Formation remains in the Late Cretaceous in age as originally defined by its author, Burollet Ann Mines Geol 18:388 (1956), and widely accepted by other geologists working on Cretaceous and Paleogene series in the Grombalia area as well as elsewhere in northern and central Tunisia. It cannot be Paleocene in age indeed. We discuss also much incoherence both in the text and illustrations (figures and plates) provided by Amri et al. Arab J Geosci 11(253) (2018). In order to correct their taxonomic misinterpretation, we use the main characters allowing the distinction of globotruncanids from morozovellids and globigerinids. We also describe Rh section in Jebel Rhorfa from the Grombalia area and we plot the genuine respective range of foraminiferal species. Consequently, we demonstrate that the Abiod Formation is rich in globotruncanids including Upper Cretaceous species belonging to genera Globotruncana, Globotruncanita, Globotruncanella, Radotruncana, and Rugoglobigerina. This formation is well and truly devoid of morozovellids and globigerinids indicative of Paleocene. Hence, no possible reworked Paleocene fauna exists and their proposed scenario with an assumed reworking can be no longer defensible.

The Kanaka Creek fossil flora (Huntingdon Formation), British Columbia, Canada — paleoenvironment and evidence for Paleocene age using palynology and macroflora

Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neighbouring Washington State, USA, are exposed in the Greater Vancouver area, British Columbia, Canada. Palynology and plant macrofossils suggest the Kanaka Creek section is Paleocene rather than Eocene in age. Detrital zircon dating is less decisive, yet indicates the Kanaka rocks are no older than Maastrichtian. Analyses of plant macro- and micro-fossils suggest an early to middle Paleocene age for the Kanaka fossil flora. Paleocene indicators include macrofossils such as Platanus bella, Archeampelos, Hamamelites inequalis, and Ditaxocladus, and pollen taxa such as Paraalnipollenites, Triporopollenites mullensis, and Duplopollis. Paleogene taxa such as Woodwardia maxonii, Macclintockia, and Glyptostrobus dominate the flora. Fungal spores including the Late Cretaceous Pesavis parva and the Paleogene Pesavis tagluensis are notable age indicators. Physiognomy of 41 angiosperm leaf morphotypes from Kanaka Creek yields mean annual temperatures in the microthermal to lower mesothermal range (11.2 ± 4.3 to 14.6 ± 2.7 °C from leaf margin analysis; 14.8 ± 2.1 °C from Climate Leaf Analysis Multivariate Program), with mild winters (cold month mean temperature 3.9 ± 3.4 °C). Paleoclimate was cooler than the upper Paleocene and Eocene members of the Chuckanut Formation. Mean annual precipitation is estimated at ∼140 cm with large uncertainties. The Kanaka paleoflora is reconstructed as a mixed conifer–broadleaf forest, sharing common taxa with other western North American Paleocene floras and growing in a temperate moist climate. Kanaka Creek is a rare coastal Paleocene plant locality that provides new insights into coastal vegetation and climate prior to the Paleocene–Eocene Thermal Maximum.

Phylogenetic relationships and palaeobiology of a new xenungulate (Mammalia: Eutheria) from the Palaeogene of Argentina

Xenungulates are a peculiar group of bilophodont ungulates, widespread over South America during the Paleocene and early Eocene. Here we describe, illustrate and analyse a new Xenungulata, Rodcania kakan gen. et sp. nov., the first from the lower latitudes of Argentina. It was recovered from the Río Loro Formation (Tucumán Province), for which a Paleocene age was estimated. The material comprises a fragment of the left dentary with an incomplete m2, eroded over the enamel surface, and an almost complete m3. Both teeth share with Xenungulata strong enamel, vertically oriented Hunter–Schreger bands (HSB), and wear facets sloping distally. Rodcania kakan differs from other xenungulates in the m3 trigonid, simplified and mesiodistally short; absence of a paraconid; more oblique protolophid in relation to the mesiodistal axis and a straight cristid obliqua, pointing to the protoconid position; and has a wider and longer talonid. A phylogenetic analysis of 13 species and 36 craniodental characters recovered R. kakan as a basal member of the Carodniidae, supported by 10 synapomorphies in the four most parsimonious trees. The body mass estimation of the Río Loro Fauna and of the rest of the xenungulate taxa revealed that R. kakan is the largest mammal of the Río Loro assemblage, weighing around 165 kg and with a size comparable to Carodnia feruglioi. The increase in body mass showed no clear relation with evolutionary trends in xenungulates.http://zoobank.org/urn:lsid:zoobank.org:pub:FFCB8A36-1CE1-4D5F-90D7-A5D773CF121B

Sediment provenance of pre- and post-collisional Cretaceous–Paleogene strata from the frontal Himalaya of northwest India

Whereas the timing for India–Asia collision remains debated, contrasting collisional models provide testable predictions in terms of sediment source contributions during the accumulation of Paleocene to middle Eocene deposits now exposed in the frontal Himalayan system. Within the Lesser Himalaya and frontal thrust system of northwest India, discontinuous exposures of the Cretaceous Singtali Formation and upper Paleocene–middle Eocene Subathu Formation yield a record of these early collisional stages. To test competing collisional models, we analyze the provenance of these deposits with new detrital zircon U-Pb and Hf isotopic data which can distinguish among Indian plate, Asian plate, Kohistan-Ladahk arc, and various Himalayan sources. Detrital zircon age distributions for the Singtali Formation are dominated by Paleoproterozoic zircons with a distinct Cretaceous age component, whereas age data from the Subathu Formation record (1) a marked increase in the relative abundance of Cambrian–Neoproterozoic grains, (2) a decrease in the proportion of Paleoproterozoic grains, and (3) distinct Permian and Late Cretaceous–Paleocene age components. All Cretaceous grains from the Singtali Formation yielded crustal Hf isotopic signatures, indicating a distinctive pre-collisional source of Cretaceous grains of Indian affinity. Zircon Hf isotopic signatures from <320 Ma grains in the Subathu Formation show a significant lower to middle Eocene increase in source diversity, including juvenile grains most likely originating from the Asian plate and Kohistan-Ladakh arc. This requires inception of India-Asia collision by ∼44–50 Ma—the depositional age of the uppermost Subathu Formation. This major provenance shift is similar to that observed for pre- and post-collisional Tethyan Himalayan strata in the north, which is suggestive of a single contiguous basin linking the Lesser Himalaya by ∼44–50 Ma and contests the notion that the Lesser and Tethyan Himalaya were separated by a “Greater India Basin” during the Eocene. When coupled with the well documented Paleocene–early Eocene provenance record of the Tethyan Himalaya, these new data provide support for a collisional model in which Asian detritus reached the northernmost edge of India by ∼59 Ma with terminal closure of both the Shyok and Indus-Yarlung suture zones by ∼54 Ma.

The oldest fungus gnat of the tribe Exechiini in the lowermost Eocene Oise amber (Diptera: Mycetophilidae).

Eoexechia gallica gen. n. and sp. n., oldest record of the fungus gnat tribe Exechiini, is described from the Lowermost Eocene amber of France. It falls as sister group of all the extant Exechiini after its addition to the morphological phylogenetic analysis of the tribe. Its discovery suggests a Paleocene age for the Exechiini, in accordance with the current phylogenetic dating. This new discovery will help to date the whole clade in future phylogenies.

Foraminifera from the Aruma Formation of Central Saudi Arabia

The Aruma Formation is well exposed in central Saudi Arabia as a thin northwest-southeast trending outcrop. It consists of a carbonate-dominated succession dated asCampanian to Paleocene. Of the three members, theKhanasir and Hajajah are confirmed as being Cretaceous, but the uppermost Linah Shale Member is assigned a Paleocene age. Dolomitization and differential erosion of the Aruma has left exposures for which the lithostratigraphy can only be confirmed by biostratigraphy. At the study location, the Khanasir Member contains the dasyclad algae Cymopolia tibetica, radiolitid rudist fragments and rare small rotalid and miliolid foraminifera. The HajajahMember is confirmed by the presence of the characteristic larger benthonic foraminiferal assemblage including Loftusia persica, Omphalocyclus macroporus, Rotalia trochidiformis and Fissoelphidium cf. operculiferum of Maastrichtian age. The sparse microfossil assemblages indicate deposition undifferentiated shallow marine, normal salinity, probably lagoon depositional setting.