Search

An incomplete posterior dorsal vertebra ZIN PH 2646/16 from the Upper Cretaceous (Turonian) Bissekty Formation of Uzbekistan has a highly pneumatized centrum and neural arch. The centrum has a lateral pneumatic foramen that is divided by a septum. The neural arch is invaded through a lateral pneumatic foramen above the neurocentral suture and has deeply excavated prezygapophyseal-centrodiapophyseal and centrodiapophyseal fossae. The interior of the preserved portion of the neural spine is pneumatic. In the structure of the fossae on the neural arch and the presence of a double pneumatic foramen on the centrum, ZIN PH 2646/16 closely resembles the carcharodontosaurid Acrocanthosaurus from the Early Cretaceous of North America. Thus, we identify ZIN PH 2646/16 as Carcharodontosauridae indet. Carcharodontosauridae were previously known from the Bissekty Formation from Ulughbegsaurus uzbekistanensis, which is based on an incomplete maxilla. [ABSTRACT FROM AUTHOR]

A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin. Based on the study of more than 1 000 rock samples, nine carbonate microfacies and three terrigenous facies were identified. The study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros Basin. Three (Gandom Kar area), two (Ardal area), seven (Gardbishe area), five (Shirmard area), two (Kuh-e-Kamaneh area), three (Kuh-e-Balghar area), and six (Murak area) of depositional sequences (3rd order) were identified. The thickness of the lowstand systems tract (LST) due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle Maastrichtian. During the Middle Maastrichtian, the shallow and deep marine deposits were formed during the transgressive systems tract (TST) and highstand systems tract (HST) in this basin and the rate of subsidence in the center of this basin (Gardbishe area) is higher than in other areas and the platform was drowned in this area. The falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin (except the south part) during the Late Maastrichtian. Paleogeographical studies on the Zagros Basin during the Late Campanian–Maastrichtian showed the following results: shallow marine environments were developed in the south-east of this basin, and the turbidite, delta, and fluvial environments in the northwest were developed more than in other areas. [ABSTRACT FROM AUTHOR]

The S saturation and oxidation states of arc magmas are important factors in the formation of porphyry Cu–Au deposits. The Milin juvenile lower crustal cumulates (86.7–84.3 Ma) in the Gangdese provide insights into how sulfide saturation and oxidation states control porphyry mineralization. Zircons from the cumulates have low Ce4+/Ce3+ ratios (21–90) and reduced oxygen fugacities (ΔFMQ–1.8±0.5), which cannot be explained by fractional crystallization or crustal contamination, suggesting inheritance from a mantle source. Partial melting of the mantle under reduced conditions produced a sulfide-saturated primary arc magma with low chalcophile element contents owing to the residual sulfide in the mantle. The Milin lower crustal cumulates contain sulfides, indicating that the magma reached sulfide saturation in the early stages of magmatic differentiation. Based on our model, the primary arc magma before sulfide saturation contained 66.7 ppm Cu and 1.0 ppb Au. The residual magma after sulfide saturation in the lower crust contained 33–66 ppm Cu, 0.13–0.93 ppb Au; i.e., lower contents than those in arc basalts worldwide. Both these factors hindered the formation of Late Cretaceous large porphyry Cu–Au deposits in the Gangdese belt. Remelting of the Milin sulfide-rich cumulates can generate a Cu-rich andesitic magma only under high temperature and high-fO2 conditions, and a melt with low Cu content under low temperature even high-fO2 conditions. Thus, the temperature plays a crucial role in the remelting of the lower crust whether provide enough metals to match the Gangdese Miocene post-collisional porphyry Cu deposit. [ABSTRACT FROM AUTHOR]

Early Cenomanian (100.5–95.7 Ma) ammonite faunas from East and North-East Greenland collected by the late Simon Kelly and colleagues are described. The assemblages are dominated by typically boreal Schloenbachia varians (J. Sowerby 1817). Also present are Parapuzosia (Austiniceras) austeni (Sharpe 1855) and species of more typically Tethyan genera. These include Phylloceras (Hypophylloceras) lombardense (Joly 2000), Gaudryceras (Gaudryceras) cassisianum (d’Orbigny 1850), Gaudryceras (Mesogaudryceras) leptonema (Sharpe 1855), and the hypermorphic tetragonitine Titanoleioceras boreale gen. et sp. nov. Previously known only from Geographical Society Ø and Traill Ø, the newly described material extends the distribution of these early Cenomanian faunas northwards to Hold with Hope and south to the Kangerlussuaq Basin. The phylloceratids, gaudryceratids, and tetragonitids in these assemblages are probably not preserved in their preferred original habitats, but rather drifted to their respective sites of burial during or after their lifetime.

The nitrogen isotopes of the organic matter preserved in fossil fish otoliths (ear stones) are a promising tool for reconstructing past environmental changes. We analyzed the 15N/14N ratio (d15N) of fossil otolith-bound organic matter in Late Cretaceous fish otoliths (of Eutawichthys maastrichtiensis, Eutawichthys zideki and Pterothrissus sp.) from three deposits along the US east coast, with two of Campanian (83.6 to 77.9 Ma) and one Maastrichtian (72.1 to 66 Ma) age. d15N and N content were insensitive to cleaning protocol and the preservation state of otolith morphological features, and N content differences among taxa were consistent across deposits, pointing to a fossil-native origin for the organic matter. All three species showed an increase in otolith-bound organic matter d15N of ~4‰ from Campanian to Maastrichtian. As to its cause, the similar change in distinct genera argues against changing trophic level, and modern field data argue against the different locations of the sedimentary deposits. Rather, the lower d15N in the Campanian is best interpreted as an environmental signal at the regional scale or greater, and it may be a consequence of the warmer global climate. A similar decrease has been observed in foraminifera-bound d15N during warm periods of the Cenozoic, reflecting decreased water column denitrification and thus contraction of the ocean's oxygen deficient zones (ODZs) under warm conditions. The same d15N-climate correlation in Cretaceous otoliths raises the prospect of an ODZ-to-climate relationship that has been consistent over the last ~80 My, applying before and after the end-Cretaceous mass extinction and spanning changes in continental configuration. [ABSTRACT FROM AUTHOR]

[Display omitted] • We describe a Cretaceous endemic Neotropical freshwater catfish from Morocco. • Overlooked evolutionary events took place at the outset of the break-up of Gondwana. • Iconic Neotropical freshwater lineages diversified after surviving the K/Pg extinction. Siluriformes are considered as primarily freshwater and have frequently been a model for the study of historical biogeography. Among catfishes, the most diverse clade is the Loricarioidei, a Neotropical group for which the fossil record extends back to the Palaeocene of Argentina. Here we describe a fossil from the early Late Cretaceous of Morocco, exhibiting typical morphological traits of the Loricariidae. A phylogenetic analysis integrating morphological characters with a multigene database for the main loricarioid lineages and outgroups highly supports inclusion of the fossil within the Loricariidae. A time-calibrated analysis corroborates the origin of loricarioids at about 112 MYA. The presence of this loricariid in Africa provides evidence that loricarioids have diversified before the separation of Africa and South America. The Moroccan loricariid shows an ancient evolutionary history that, in Africa, ended in the Late Cretaceous but persisted in South America, later surviving the K/Pg extinction. [ABSTRACT FROM AUTHOR]

Two nanhsiungchelyid carapaces from the Upper Cretaceous of Ganzhou Basin, Jiangxi Province, Southern China, are reported and assigned to Nanhsiungchelys sp. The new material reveals an unusual carapace morphology that was either not or poorly preserved in previously known Nanhsiungchelys specimens, including differentiated neurals, alternating costals, significantly modified scutes with vertebrals 4–5 contacting each other at a point, reduced pleurals 2–4 and greatly expanded lateral and posterior marginals. The discovery extends the geographical distribution of Nanhsiungchelys to the Ganzhou Basin. [ABSTRACT FROM AUTHOR]

The paper reports data on the age and composition of poorly studied Cretaceous clastic rocks of the Lower Amur River area, which are part of the Zhuravlevka–Amur terrane and are attributed to the Berriasian–Valanginian Komsomolsk series. U/Pb dating of detrital zircons yielded reliable dates of 99 and 90 Ma for the Gorin and Pioneer formations, respectively. Thus, a sedimentary complex with a Late Cretaceous sedimentation age was identified for the first time in the Sikhote-Alin orogenic belt based on detrital zircon geochronology. In composition and detrital zircon age distribution pattern, the studied rocks are more similar to sediments of the upper, Hauterivian–Albian part of the Zhuravlevka–Amur terrane section rather than to those of the lower, Berriasian–Valanginian part. In rocks of the Pioneer Formation, the youngest zircon population with an age of about 90 Ma makes up more than 40% of all dated grains. The main source of detrital material of this age was probably proximal andesites hosting the Mnogovershinnoe deposit and granitoids of the Nizhneamurskii Complex. The source of detritus for sediments of the ∼99 Ma Gorin Formation was probably felsic rocks from the Albian–Cenomanian igneous province of Pacific Asia. The discrepancy between the Late Cretaceous age obtained by us and the paleontologically established Berriasian–Valanginian stratigraphic age of the formations requires additional research. New data on the Late Cretaceous age of the Zhuravlevka–Amur sediments of strike-slip marginal-continental basin requires revision of the geologic evolution of the terrane and the entire Sikhote-Alin orogenic belt. [ABSTRACT FROM AUTHOR]

Based on newly acquired inclusions in Taimyr amber, we have described new taxa (Sidorchukaphis katyae Ogłaza & Wegierek gen. et sp. nov.; Baikuraphis abdominalis gen. et sp. nov.; Canadaphis ugolyaki Ogłaza & Wegierek sp. nov.) of aphids or redescribed previously reported forms (Ambaraphis baikurensisPalaeoaphis incognita Tajmyraphis zherichini; Retinaphis glandulosa). The presented species belong to both extinct and extant families from the Late Cretaceous stage of aphid evolution. A cladistic analysis of the morphological characters of the Tajmyraphidoidea has been performed. We assign Burmitaphididae, as the subfamily Burmitaphidinae, to the Tajmyraphididae, which now comprises the subfamilies Tajmyraphidinae and Burmitaphidinae. We also suggest elevating the Mongolaphidinae to family rank (Mongolaphididae). [ABSTRACT FROM AUTHOR]

The Late Cretaceous magmatic history of the Eastern Pontides Orogenic Belt (NE Turkey) was generally characterized by common I-type and lesser A-type plutons in varying size and composition. Of these, A-type plutons from the Şebinkarahisar (Giresun) area yield SHRIMP zircon U-Pb age of 77.36 ± 0.96 Ma. The rocks of these plutons display a wide range of SiO2 contents (53.63 to 70.96 wt.%) and Mg-numbers (6.2–32.19) with A-type affinities characterized by enrichment in K2O and Na2O, Ga, Zr, and strong negative Eu anomalies. They also show arc-type petrochemical features including enrichment of large-ion lithophile elements (e.g. Cs, K, Rb) and light rare earth elements (LaN/LuN = 6.27–15.61), but depletion in high strength field elements (e.g. Nb, Ta, Ti, and P). The (87Sr/86Sr)i ratios and ɛNd(i) values of the studied rocks are in the range of 0.705129 to 0.0705347 and −3.64 to −3.12, respectively, while bulk rock ɛHf(i) values are between 1.86 and 4.36. They are characterized by positive zircon ɛHf(i) (1.74 to 10.88) plotting between the chondrite and depleted mantle evolutionary line values. Our data combined with the previous studies suggest that the magmas, that formed the Late Cretaceous plutons, were generated in an extensional tectonic environment due to slap roll-back and trench ward migration of the subduction zone to the south. The generation of hybrid magmas forming the studied plutons is in response to the melts derived from a metasomatized lithospheric mantle source, a relatively deeper mantle source, and the juvenile crust along with the heat transfer and decompression. Multi-sourced magmas rise through the continental crust and reach the final composition by predominantly fractional crystallization processes. [ABSTRACT FROM AUTHOR]

Past responses to environmental change provide vital baseline data for estimating the potential resilience of extant taxa to future change. Here, we investigate the latitudinal range contraction that terrestrial and freshwater turtles (Testudinata) experienced from the Late Cretaceous to the Paleogene (100.5-23.03 mya) in response to major climatic changes. We apply ecological niche modeling (ENM) to reconstruct turtle niches, using ancient and modern distribution data, paleogeographic reconstructions, and the HadCM3L climate model to quantify their range shifts in the Cretaceous and late Eocene. We then use the insights provided by these models to infer their probable ecological responses to future climate scenarios at different representative concentration pathways (RCPs 4.5 and 8.5 for 2100), which project globally increased temperatures and spreading arid biomes at lower to mid-latitudes. We show that turtle ranges are predicted to expand poleward in the Northern Hemisphere, with decreased habitat suitability at lower latitudes, inverting a trend of latitudinal range contraction that has been prevalent since the Eocene. Trionychids and freshwater turtles can more easily track their niches than Testudinidae and other terrestrial groups. However, habitat destruction and fragmentation at higher latitudes will probably reduce the capability of turtles and tortoises to cope with future climate changes.

The east-west trending Taurides form a curved area in central eastern Anatolia known as the Gürün Curl. In order to understand the origin of the Gürün Curl and Tauride evolution in general, the results of a new field study of this region have been synthesized together with previously published data. We suggest that the geodynamic evolution of the area began with the likely presence of a Tethys Ocean transform fault. This fault separated the Taurides into the Akdere Sector in the west and the Munzur Sector in the east in the Late Cretaceous. During the late Santonian–early Campanian, ophiolites obducted onto the Munzur Sector, while platform sediments continued to accumulate in the Akdere Sector. This was followed by the development of an Andean-type arc-type magmatism (the Baskil Arc) during the early–middle Campanian in the Munzur Sector. Continued closure of the Tethys led to the collision of the Bitlis Massif in the south of the Munzur Sector in the Campanian. This, in turn, resulted in continental subduction and slab roll-back that was controlled by a Subduction Transform Edge Propagator (STEP) Fault that lay on the original transform fault between the Akdere and Munzur sectors. Because the subducted slab was free at its western corner, the western edge rolled back faster than in the east, leading to an asymmetrical extensional regime on the upper plate that created the late Campanian Hekimhan Basin. While these geodynamic events were taking place in the Munzur Sector, the Akdere Sector was in a platform setting. During the Palaeocene, the Late Mesozoic units of the Akdere Sector began to overthrust on the Hekimhan Basin and the ophiolites. Following the Palaeocene, all these tectonostratigraphic units were covered by Eocene sediments around the Gürün Curl of which the modern appearance was completed by the Miocene to Recent movements along the strike-slip faults. [ABSTRACT FROM AUTHOR]

Allodaposuchids were among the most common crocodyliforms in the Upper Cretaceous of Europe. The clade, recently erected to include a large number of species described in the last decade, seems to hold a remarkable diversity that has generated systematic controversies. Here we describe an interorbital fragment of an eusuchian crocodyliform, collected in the late 1950s in the locality of Suterranya-Mina de lignit (Lleida, Spain), from the lower Maastrichtian deposits of the Tremp Group, in the southern Pyrenees. The specimen is here identified as an allodaposuchid; some already described teeth, probably found together with the cranial remains and therefore here assigned to the same individual, reinforce this interpretation. The interorbital region of the specimen shows some important similarities with Allodaposuchus subjuniperus, reported only from the upper Maastrichtian levels of the Tremp Group, while it clearly differs from Allodaposuchus palustris, which is already reported in the lower Maastrichtian transitional deposits close to Suterranya-Mina de lignit locality. This study shows that at least three different species of allodaposuchids can be found in the lower Maastrichtian deposits of the Tremp Group. [ABSTRACT FROM AUTHOR]

Lizards are poorly known from the Mesozoic of South America, including several specimens from the Lower and Upper Cretaceous of Brazil, and only a few from the Upper Cretaceous of Patagonia. Here, we describe a new lizard assemblage from a single bone-bearing level in the Allen Formation (upper Campanian – lower Maastrichtian), cropping out at the Cerro Tortuga locality, Río Negro Province, northern Patagonia, Argentina. We recognise the presence of three different taxa, all of them represented by partially isolated maxillae, belonging to different lizard lineages: pleurodontan Iguania; Teiioidea; and possibly Scincoidea. These specimens support the presence of a quite diverse lizard assemblage during the Late Cretaceous in southern South America, suggesting that their absence in other Cretaceous deposits from Patagonia represents preservational and/or sampling bias. The taxonomic diversity also points to a broad ecological diversity, because the three taxa strongly differ in their dental morphology and inferred dietary habits. The assemblage from Cerro Tortuga indicates that lizards, along with snakes and sphenodontians, were an important component of the Late Cretaceous lepidosaurian fauna of South America and, likely, Gondwana. [ABSTRACT FROM AUTHOR]

Since the first discovery of dinosaur eggs announced by the American Museum of Natural History (central Asiatic expeditions to Mongolia) in 1923, these fossils became widely recognised from Mesozoic strata in Asia and elsewhere. In the 1920s, and actually before 1923, dinosaur eggs had been collected from another part of Asia, specifically Liaoning Province in northeastern China. From 1921 to the late 1920s, five eggs were collected from the Cenomanian Quantou Formation during construction, and thus represent an important historic collection as some of the earliest dinosaur eggs discovered in Asia. Here, we describe one egg from this collection and assign it to Paraspheroolithus irenensis, an egg taxon that likely belonged to hadrosaur dinosaurs. The egg is approximately 7 × 8 cm in diameter, with eggshell that displays typical spheroolithid microstructure and is just over a millimetre in thickness. Paraspheroolithus irenensis is shown to be the most widespread spheroolithid oospecies in China, and our comparative work extends its geographic range to northeastern most China. The Quantou Formation thus has yielded at least three spheroolithid oospecies, indicating the potential for a diversity of hadrosaur or related ornithopod species in the region at that time. [ABSTRACT FROM AUTHOR]

In the Upper Cretaceous of the Middle East, rotaliid Foraminifera have conventionally been attributed to Rotalia skourensis Pfender (= Rotorbinella skourensis), a key element of biozones #30 and #31 as commonly recognized in the Iranian Zagros. However, R. skourensis is a Paleocene species and is morphologically distinct from the rotaliid specimens present in the Upper Cretaceous of theMiddle East. Through detailed sampling of the Ilam Formation (Turonian?--Campanian) in the Zagros basin, two new species previously classified as R. skourensis have been described. Rotorbinella pachypila n. sp. andOrbitokathina parva n. sp. contribute to our understanding of the diversity of rotaliids during the Late Cretaceous of the Arabian Plate and highlight biogeographic connections with the western Tethys carbonate platform domains. [ABSTRACT FROM AUTHOR]

The fossil fish Ptychodus Agassiz, 1834, characterized by a highly distinctive grinding dentition and an estimated gigantic body size (up to around 10 m), has remained one of the most enigmatic extinct elasmobranchs (i.e. sharks, skates and rays) for nearly two centuries. This widespread Cretaceous taxon is common in Albian to Campanian deposits from almost all continents. However, specimens mostly consist of isolated teeth or more or less complete dentitions, whereas cranial and post-cranial skeletal elements are very rare. Here we describe newly discovered material from the early Late Cretaceous of Mexico, including complete articulated specimens with preserved body outline, which reveals crucial information on the anatomy and systematic position of Ptychodus. Our phylogenetic and ecomorphological analyses indicate that ptychodontids were high-speed (tachypelagic) durophagous lamniforms (mackerel sharks), which occupied a specialized predatory niche previously unknown in fossil and extant elasmobranchs. Our results support the view that lamniforms were ecomorphologically highly diverse and represented the dominant group of sharks in Cretaceous marine ecosystems. Ptychodus may have fed predominantly on nektonic hard-shelled prey items such as ammonites and sea turtles rather than on benthic invertebrates, and its extinction during the Campanian, well before the end-Cretaceous crisis, might have been related to competition with emerging blunt-toothed globidensine and prognathodontine mosasaurs. [ABSTRACT FROM AUTHOR]

The Geological Museum of the Korea Institute of Geoscience and Mineral Resources (KIGAM) houses a large collection of microfossils. From these collections, 14 species belonging to six genera of non-marine ostracods from the Banyaweol and Geoncheonri formations of the Gyeongsang Basin, South Korea are identified: Cypridea sp. 1, C. sp. 2, C. sp. 3, C. sp. 4, C. sp. 5, C? sp. 6, Lycopterocypris triangularis, L. cf. profunda, Candona declivis, C. sp. Cypria cf. elata, Djungarica sp. Ziziphocypris costata and Z. rugosa. The biostratigraphic correlation based on L. triangularis and C. declivis from the Cenomanian Banyaweol Formation suggests that these species appeared at a much earlier stage than the previous records from China. Ostracods of the Banyaweol Formation may represent a transitional fauna during the mid-Cretaceous faunal turnover in East Asia. However, L. cf. profunda and C. cf. elata suggest a Turonian – Santonian age (probably extend upwards into Campanian) for the Geoncheonri Formation. Many non-endemic species of both formations indicate that these faunas were linked with ostracod faunas of East Asia, providing evidence of active faunal exchanges and migration. The palaeoenvironments of both formations are interpreted as ephemeral waterbodies and unstable shallow-littoral zone of lakes based on faunal compositions. [ABSTRACT FROM AUTHOR]

Late Cretaceous lateral facies and thickness changes are common in the southern Tethyan margin, especially during the final rifting stages of the Tethys and its early onset of closure. Particularly, northern Tunisia, being located closure to a plate boundary, represents an important area to investigate the tectonic influence on sedimentation. In this paper, detailed sedimentological, biostratigraphical and tectonic studies carried out in north-central Tunisia (Serj-Bargou area) to provide more data and precisions on the lithostratigraphy framework and tectonic control on Late Cretaceous deposits. Investigation of field data, high-resolution biostratigraphy, gravity data analysis and lithostratigraphic correlations of strata deposited during the Late Cretaceous allowed us to precisely determine the timing of unconformities and constrain the history of the subsidence inversion of the basin. Three major unconformities have been identified in the SW of Jebel Bargou and span the period from Coniacian to Maastrichtian. These unconformities are marked by Paleocene marls (containing the G. trinidadensis biozone) that unconformably overlie the Late Coniacian series (containing the D. concavata biozone), indicating an early tectonic compressional event in the Late Cretaceous, that probably started in Turonian. Similar tectonic inversion events have already been identified in other Tunisia areas and in the surrounding regional context within the northern and southern Tethyan margin during the Late Cretaceous. This inversion could be explained by a Santonian compressional event, which might have started earlier, in the context of the convergence between African and European plates. The inversion is reflected stratigraphically across the African margin and the intraplate basins, such as the Serj Bargou basin, by a highly reduced accommodation space and unconformities. This tectonic inversion indicates the effects of the change in the poles of rotation related to the opening of the Atlantic at about 83–85 Ma on the former North African passive margin. [ABSTRACT FROM AUTHOR]

The aim of present contribution is to describe the osteohistology of an articulated skeleton of an unnamed elasmosaurid coming from Santa Cruz province, Argentina, and recovered in late Cretaceous beds of Calafate Formation (Maastrichtian). Histological analysis indicates that the specimen reached somatic and sexual maturity. The specimen exhibits a unique combination of histological features that suggest complex palaeobiological and palaeocological implications. One remarkable aspect of the specimen is the presence of an external fundamental system (EFS) in the gastralia, a feature only cursorily described for plesiosaurs. Occurrence of EFS indicates a somatic maturation for the specimen. The transverse section of the phalanx and vertebral apophysis are osteoporotic, whereas those of the dorsal rib and gastralia show two layers of thick pachyostosic cortical tissue surrounding osteoporotic bone. This contradicts previous hypotheses that proposed that in elasmosaurids, the juveniles (characterised by osteoporotic histology) inhabited coastal waters and migrated to the open sea after reaching adulthood after an ontogenetic shift in bone density. [ABSTRACT FROM AUTHOR]

The present study is focused on evaluation of deep marine pelagic sediments of Late Cretaceous Kawagarh Formation of Kala-Chitta Range in the context of microfacies analysis, paleoenvironmental interpretation, planktonic foraminiferal biostratigraphy, sequence stratigraphy and diversification of species. A total of thirty three rock samples were collected from the measured section. Three microfacies are interpreted, namely planktonic foraminifera wackestone, planktonic foraminifera mudstone and sandy mudstone indicating low energy depositional environment i. e., outer ramp. The biostratigraphic studies show plentiful planktonic foraminifera species of Globotruncana, Heterohelix and Globotruncanita. However, no association of benthic or siliceous organisms was observed. On the basis of available species assemblage, a single local planktonic foraminifera biozone i. e., Globotruncana-Heterohelix-Globotruncanita Assemblage Biozone is established. The biozone information is combined with published literature and Lower Santonian to Middle Maastrichtian age has been assigned to the Kawagarh Formation. The trend of species occurrences evinces that species number decreases over time with pulsated rise in the Kawagarh Formation. The Kawagarh Formation carbonates show an overall Transgressive Systems Tract (TST). The Kawagarh Formation of Pakistan evinces analogous characteristics to that of the Late Cretaceous Gurpi Formation of Iran based on the geologic age, outcrop lithology, microfacies, planktonic foraminiferal assemblages, depositional setting and sequence stratigraphy. [ABSTRACT FROM AUTHOR]

The Rouana formation consists of Turonian interbedding dolostones, breccias and marls that developed in Sidi Bouzid area in middle central Tunisia. The study of a geological section in the Jebel Rouana, complemented by the microscopic observations of thin sections allowed distinguishing different types of breccias and non-breccias deposits. The Rouana formation includes five different types of breccias arranged into eight levels generally interbedded by laminated tidalitic dolomites. The succession of breccias occurred in a marginal paleogeographic environment between continental and marine domains; it consists of a shallow-water uplift on which developed alternating shallow-marine and continental deposits. The sedimentation was controlled by third-order sea level variation. Indeed, during the sea level rise, the Sidi Bouzid uplift was covered with shallow-marine waters where tidalitic dolomites occurred, simultaneously the shoreline extended southward beyond this uplift and reaches the supratidal evaporitic domain in Gafsa area. During the sea level fall, the shoreline retreats toward the North and the uplift became exposed and continental conditions occurred materialized especially by the development of polygenic, alluvial, palustrine, collapse and desiccation breccias. The Rouana formation records third-order eustatic fluctuation during the Turonian interval, materialized by the development of depositional sequences bounded by subaerial exposure surfaces. The studied depositional sequences may be correlated, respectively, with the coeval open-marine sequences (Annaba and Bireno formations) in North central Tunisia as well as with the coeval supratidal evaporitic sequences (Beida formation) in south central Tunisia. [ABSTRACT FROM AUTHOR]

The Late Cretaceous Simsima Formation is a post-obduction mixed carbonate–sliciclastic sequence exposed in isolated outcrops in the Oman Mountains. This study utilizes an integrated facies analysis to interpret the depositional environment of the Simsima Formation in the Jabel Al-Rawdah section, Oman. The Simsima Formation in the study area is 75 m thick and unconformably overlies the Semail ophiolite complex. The formation consists of six lithofacies, including (i) paraconglomerate, (ii) laminated mudstone, (iii) arenaeous bioclastic grainstone, (iv) bioclastic grainstone, (v) greyish massive pack to rudstone, and (vi) rudist grainstone. The Simsima Formation is highly fossiliferous, containing corals, crinoids, rudists, Larger Benthic Foraminifera (Omphalocyclus macroporus, Siderolites calcitrapoide, and Orbitoides sp.), gastropods, and bivalves. According to petrographic analysis, the fabric texture of limestone is mainly grainstone (lower part), a few packstone intervals (middle part), and boundstone in the upper part of the formation. The most common non-skeletal grains are peloids, a few intraclasts, and coated grains. Terrigenous detritus grains are also present. The lithologic properties, fossil content, and sedimentary structures and textures of the six lithofacies that constitute the formation allow to decipher the deposition of the formation in a well-agitated shallow marine environment. The vertical arrangement of the various lithofacies of the Al-Rawdah section indicates an overall deepening-upward succession. The deposition of the formation was influenced by both tectonic and climatic factors. [ABSTRACT FROM AUTHOR]

IODP Site U1509 (Expedition 371), New Caledonia Trough, provides a rare latest Cretaceous–Paleocene record from offshore northern Zealandia. We present new palynomorph and benthic foraminiferal assemblage data that show a transition from a latest Cretaceous vegetated sediment source region to a fully oceanic environment in the Paleocene. Latest Cretaceous (c. 68–66 Ma) non-calcareous claystone was deposited in upper bathyal paleodepths, with abundant plant microfossils that were likely transported in a northwest direction through the Aotea Basin region. A 2–3 Myr unconformity is identified at the Cretaceous/Paleogene boundary. Middle early–late Paleocene (c. 63.5–56 Ma) calcareous claystone shows evidence of deepening, deposited in middle bathyal or deeper paleodepths, and terrestrial input is minor. This latest Cretaceous to Paleocene deepening trend is consistent with inferred evolution of the Aotea and Northland basins further to the east, and other sparse northern Zealandia records, which show a common pattern of post-rift transgression consistent with long-term subsidence. Site U1509 allows for biogeographic extension and modification of the New Zealand Paleocene dinoflagellate zonation, description of a new dinoflagellate and pollen species, better inference of regional paleogeography, and may provide insights into the onset of western Pacific subduction initiation. [ABSTRACT FROM AUTHOR]

Late Cretaceous metamorphic events are known in Crete and the Cyclades from klippen above the External Hellenides. This work extends their occurrence to the North Aegean area within the tectonic units of the Internal Hellenides. New 40Ar/39Ar white mica ages from garnet-bearing micaschists of the Upper Metamorphic Unit of Skyros Island, cropping out in the Skyrian Olympus Mountain, document a Late Cretaceous tectono-metamorphic evolution. Several mica generations have been distinguished using electron probe microanalyses and were dated using the 40Ar/39Ar method: a relict mica older than 96 Ma, followed by a foliation-forming mica of about 88–84 Ma and alteration phases ≤ 68 Ma were recognized. This Cretaceous tectono-metamorphic evolution falls between the closure of the internal Axios/Vardar oceanic basin in the Late Jurassic–Early Cretaceous, and the closure of the external Pindos–Cyclades oceanic basin in the Early Cenozoic. The position of the Upper Metamorphic Unit of Skyros was probably within the evolving Hellenic volcanic/magmatic arc during the continuous subduction of the African plate beneath the European plate. The present tectonic position of the units bearing the Late Cretaceous metamorphic event is the result of the Cenozoic tectonic emplacement onto the more external units across the Hellenides from the Pelagonian to the Pindos–Cyclades domain. [ABSTRACT FROM AUTHOR]

Palynological analysis of Upper Cretaceous marine rocks from the Rabot and Snow Hill Island formations, James Ross Basin, northeastern Antarctic Peninsula, has revealed the record of a previously undescribed dinoflagellate cyst species, previously assigned to Oligosphaeridium sp. A. Here, we provide a formal description of this new species, which we name Stiphrosphaeridium sobralii sp. nov. and we add some features to the description of the genus Stiphrosphaeridium. The new species is found in Campanian strata, which are calibrated with magnetostratigraphic data. It is considered an important Late Cretaceous biostratigraphic marker commonly recorded in offshore environments of Antarctica.

Abstract The Cretaceous was punctuated by episodic flooding of continental margins forming epicontinental seas. The Trans‐Sahara Seaway was one of these epicontinental seas, connecting the Gulf of Guinea with the Tethys Ocean. In this study, data including microplankton abundances, stable carbon isotopes of organic material and elemental geochemistry were integrated with traditional sedimentological analyses from the Trans‐Sahara Seaway. The carbon isotopic data provide the first evidence that oceanic anoxic event 2 was present in the Trans‐Sahara Seaway, and palynology shows it was associated with an increase in peridinioid dinocyst abundance. A combined study of microplankton assemblages and sedimentology reveals palaeoenvironmental trends linked to sea‐level change. Lowstand system tracts were characterised by increased siliciclastic grain size, low microplankton diversity, and were dominated by Chlorophyceae. Transgressive system tracts were associated with diversity increases during rising sea level, with open marine gonyaulacoid dinocysts dominating the assemblages. Maximum flooding surfaces were recognised by the highest increase in biological diversity in argillaceous deposits. As sea level started to fall, the peridinioid dinocysts became dominant, with decreased microplankton diversity during highstand systems tracts. This combination of sedimentology and interpretation of dinocyst assemblages allows the identification of shallow to deeper marine depositional sequences of Cenomanian–Santonian strata within the Yola Sub‐basin. This approach could be used to delineate marine depositional sequences where using conventional sedimentological methods alone is very challenging.

Based on newly acquired inclusions in Taimyr amber, we have described new taxa (Sidorchukaphis katyae Ogłaza & Wegierek gen. et sp. nov.; Baikuraphis abdominalis gen. et sp. nov.; Canadaphis ugolyaki Ogłaza & Wegierek sp. nov.) of aphids or redescribed previously reported forms (Ambaraphis baikurensis Palaeoaphis incognita Tajmyraphis zherichini; Retinaphis glandulosa). The presented species belong to both extinct and extant families from the Late Cretaceous stage of aphid evolution. A cladistic analysis of the morphological characters of the Tajmyraphidoidea has been performed. We assign Burmitaphididae, as the subfamily Burmitaphidinae, to the Tajmyraphididae, which now comprises the subfamilies Tajmyraphidinae and Burmitaphidinae. We also suggest elevating the Mongolaphidinae to family rank (Mongolaphididae).http://www.zoobank.org/urn:lsid:zoobank.org:pub:2140429C-686C-4EE2-BF7A-67A368C1FFAC

Abstract Saxochelys gilberti is a baenid turtle from the Late Cretaceous Hell Creek Formation of the United States of America known from cranial, shell, and other postcranial material. Baenid turtles are taxonomically diverse and common fossil elements within Late Cretaceous through Eocene faunas. Detailed anatomical knowledge is critical to understanding the systematics and morphological evolution of the group. This is particularly important as baenids represent an important group of continental vertebrates that survived the mass extinction event associated with the Cretaceous/Paleogene boundary. High-resolution micro-computed tomography scanning of the holotype skull reveals additional anatomical details for the already well-known Saxochelys gilberti. This includes the revision of some anatomical statements from the original description, but also detailed knowledge on internal anatomical features of the braincase and the description of a well-preserved axis (cervical vertebra 2). Our new detailed description and previous work on the shell and postcrania make Saxochelys one of the best-described, nearly complete baenid turtles, which are often only known from either isolated shell or cranial material. A revised phylogenetic analysis confirms the position of Saxochelys gilberti as a derived baenid (Eubaeninae) more closely related to Baena arenosa than to Eubaena cephalica.

During the Late Cretaceous, a magmatic arc extended from the Lesser Caucasus through the northern margin of the Pontides into Srednogorie, Timok, Banat, and Apuseni (ABTS) in the Balkans for a distance of 2700 km. We studied the arc volcanic rocks in three regions in the Western Pontides and reviewed the geological data on the Lesser Caucasus-Pontide-ABTS magmatic arc, which shows several common features. Prior to the start of the arc magmatism, the region underwent uplift and erosion. New and published geochronologic and biostratigraphic data show that magmatism in the Lesser Caucasus-Pontide-ABTS arc started in the Turonian (ca. 93 Ma) peaked in the middle Campanian (80–78 Ma) and became rare and sporadic after the late Campanian (ca. 75 Ma). Magmatism was dominantly calc-alkaline to high-K calc-alkaline and shows typical subduction geochemical signatures. Late Cretaceous volcanism took place in a submarine and extensional environment. In the Lesser Caucasus-Pontide-ABTS belt, the arc volcanic rocks are overlain by Maastrichtian to Palaeocene marine limestones and sandstones, marking the end of the main phase of arc magmatism. However, in the Kefken region in the Western Pontides, Maastrichtian limestone sequence includes a volcanic horizon with a U-Pb zircon age of ca. 71 Ma. The Maastrichtian volcanic rocks show a more varied geochemistry than the older arc volcanic rocks, and include alkaline basalts, calc-alkaline basalts, and adakites. The coeval start of arc magmatism in the 2700-km-long Lesser Caucasus-Pontide-ABTS belt is related to the inception of the Africa-Eurasia convergence at ca. 96 Ma, which is also independently indicated by the beginning of intra-oceanic subduction, inferred from the ages of sub-ophiolite metamorphic rocks in Anatolia. The end of magmatism is linked to a marked decrease in the convergence rate during the Campanian, which was also partitioned between the northern and southern Tethyan subduction zones. [ABSTRACT FROM AUTHOR]

Although the fossil record of turtles in the Cretaceous of Patagonia is diverse and abundant, the record from the Austral-Magallanes Basin (Santa Cruz Province, Argentina, and Magallanes Region, Chile) is scarce and fragmentary. This contribution presents a new record of a turtle from the Piedra Clavada Formation (early Cenomanian) found near Tres Lagos Village, Santa Cruz Province, Argentina. This new fossil is characterized by a unique combination of character states: medium-sized carapace (length circa 50 cm), shell with a smooth surface, having narrow vertebral scutes, regular neural bones longer than wide, the tips of thoracic ribs seen in dorsal view, posterior marginals reaching costal bones, and not having costo-peripheral fontanelles. Furthermore, based on paleolatitudinal reconstructions, the new turtle from the Piedra Clavada Formation lived in the circumpolar region (54º S), representing the oldest southernmost record of turtles in the Late Cretaceous of South America. Considering this unique combination of characters and the comparison with other Early--early Late Cretaceous turtles from Gondwana, we can suggest that MSV103 does not only belong to a new species but a new, previously unrecognized lineage of turtles in southern Patagonia [ABSTRACT FROM AUTHOR]

Background The Chloranthaceae comprise four extant genera (Hedyosmum , Ascarina , Chloranthus and Sarcandra), all with simple flowers. Molecular phylogenetics indicates that the Chloranthaceae diverged very early in angiosperm evolution, although how they are related to eudicots, magnoliids, monocots and Ceratophyllum is uncertain. Fossil pollen similar to that of Ascarina and Hedyosmum has long been recognized in the Early Cretaceous, but over the last four decades evidence of extinct Chloranthaceae based on other types of fossils has expanded dramatically and contributes significantly to understanding the evolution of the family. Scope Studies of fossils from the Cretaceous, especially mesofossils of Early Cretaceous age from Portugal and eastern North America, recognized diverse flowers, fruits, seeds, staminate inflorescences and stamens of extinct chloranthoids. These early chloranthoids include forms related to extant Hedyosmum and also to the Ascarina , Chloranthus and Sarcandra clade. In the Late Cretaceous there are several occurrences of distinctive fossil androecia related to extant Chloranthus. The rich and still expanding Cretaceous record of Chloranthaceae contrasts with a very sparse Cenozoic record, emphasizing that the four extant genera are likely to be relictual, although speciation within the genera might have occurred in relatively recent times. In this study, we describe three new genera of Early Cretaceous chloranthoids and summarize current knowledge on the extinct diversity of the group. Conclusions The evolutionary lineage that includes extant Chloranthaceae is diverse and abundantly represented in Early Cretaceous mesofossil floras that provide some of the earliest evidence of angiosperm reproductive structures. Extinct chloranthoids, some of which are clearly in the Chloranthaceae crown group, fill some of the morphological gaps that currently separate the extant genera, help to illuminate how some of the unusual features of extant Chloranthaceae evolved and suggest that Chloranthaceae are of disproportionate importance for a more refined understanding of ecology and phylogeny of early angiosperm diversification. [ABSTRACT FROM AUTHOR]

A small collection of coprolites (fossilised faeces) is described from the Upper Couche III Bone Bed (latest Maastrichtian) phosphate horizon, approximately 2 m below the K/Pg boundary of Sidi Chennane Quarry in the Ouled Abdoun phosphate basin, Khouribga Province, Morocco. The coprolites have a distinctive morphology that identifies them as belonging in the ichnogenus Alococopros. This is the first record of the ichnogenus from the Late Cretaceous of Morocco. The coprolites are assigned to A. milnei isp. nov. Inclusions of triturated and polished phosphate debris in some specimens suggest that crocodilians or chelonians may have been the possible producer. [ABSTRACT FROM AUTHOR]

The Cretaceous was punctuated by episodic flooding of continental margins forming epicontinental seas. The Trans‐Sahara Seaway was one of these epicontinental seas, connecting the Gulf of Guinea with the Tethys Ocean. In this study, data including microplankton abundances, stable carbon isotopes of organic material and elemental geochemistry were integrated with traditional sedimentological analyses from the Trans‐Sahara Seaway. The carbon isotopic data provide the first evidence that oceanic anoxic event 2 was present in the Trans‐Sahara Seaway, and palynology shows it was associated with an increase in peridinioid dinocyst abundance. A combined study of microplankton assemblages and sedimentology reveals palaeoenvironmental trends linked to sea‐level change. Lowstand system tracts were characterised by increased siliciclastic grain size, low microplankton diversity, and were dominated by Chlorophyceae. Transgressive system tracts were associated with diversity increases during rising sea level, with open marine gonyaulacoid dinocysts dominating the assemblages. Maximum flooding surfaces were recognised by the highest increase in biological diversity in argillaceous deposits. As sea level started to fall, the peridinioid dinocysts became dominant, with decreased microplankton diversity during highstand systems tracts. This combination of sedimentology and interpretation of dinocyst assemblages allows the identification of shallow to deeper marine depositional sequences of Cenomanian–Santonian strata within the Yola Sub‐basin. This approach could be used to delineate marine depositional sequences where using conventional sedimentological methods alone is very challenging. [ABSTRACT FROM AUTHOR]

The results of a comprehensive study of an Upper Maastrichtian reference Mt. Klementyev section (Southeastern Crimea), consisting of a terrigenous–carbonate sequence, are presented. It is established that sedimentation occurred in relatively deep-sea conditions. Biostratigraphic analysis of assemblages of benthic and planktonic foraminifers made it possible to recognize the foraminiferal zones in the section and to confirm deep-sea sedimentation during this period. [ABSTRACT FROM AUTHOR]

Saxochelys gilberti is a baenid turtle from the Late Cretaceous Hell Creek Formation of the United States of America known from cranial, shell, and other postcranial material. Baenid turtles are taxonomically diverse and common fossil elements within Late Cretaceous through Eocene faunas. Detailed anatomical knowledge is critical to understanding the systematics and morphological evolution of the group. This is particularly important as baenids represent an important group of continental vertebrates that survived the mass extinction event associated with the Cretaceous/Paleogene boundary. High-resolution micro-computed tomography scanning of the holotype skull reveals additional anatomical details for the already well-known Saxochelys gilberti. This includes the revision of some anatomical statements from the original description, but also detailed knowledge on internal anatomical features of the braincase and the description of a well-preserved axis (cervical vertebra 2). Our new detailed description and previous work on the shell and postcrania make Saxochelys one of the best-described, nearly complete baenid turtles, which are often only known from either isolated shell or cranial material. A revised phylogenetic analysis confirms the position of Saxochelys gilberti as a derived baenid (Eubaeninae) more closely related to Baena arenosa than to Eubaena cephalica. [ABSTRACT FROM AUTHOR]

The Maastrichtian age dinosaur-bearing Lameta Formation in Central India is a pedogenically modified sedimentary succession. This succession records various pedogenic signatures such as the obliteration of bedding, root traces, burrows, soil structures, and soil horizons, indicating distinct paleosol types, which provide information about the associated paleoclimatic and paleoenvironmental conditions. In the present study, combining soil morphology and micromorphology, we recognized, classified, and interpreted eleven paleosol profiles preserved in the Lower Limestone and Mottled Nodular Bed Unit of the Lameta Formation, exposed in the Jabalpur subregion in Central India. The studied paleosols were divided into five different pedotypes (soil types) based on the majority/stage of development of pedogenic features. The observed pedotypes are compound and composite paleosol profiles, composed of entisols, hydromorphic calcic-inceptisols, gleyed alfisols, and well-developed alfisols. This variation in observed pedotypes represent the characteristics of a soil catena. In this soil catena, the variation in paleosol profiles is related to the variation in hydrology and relief of the landscape. The better-drained paleosols are forming on higher grounds, whereas poorly drained paleosols are forming in lowlands. The identified pedotypes with varying drainage and maturity are used to reconstruct the paleolandscape as an agglomeration of seasonal wetlands and dry lands. Further, based on several pedogenic features, the Lameta sediments are interpreted to have been deposited in tropical warm, humid climatic conditions. [ABSTRACT FROM AUTHOR]

New U–Pb geochronological and geochemical data for granitoids of the Mainitskii terrane of the Koryak folded region are presented. It is shown that granitoids intrude the folded-thrust structures of the Mainitskii terrane, which include ophiolites of the Late Paleozoic–Late Mesozoic and volcanogenic–siliceous–terrigenous deposits of the Middle Jurassic–Turonian. Granitoids belong to low-alkaline quartz diorites and I-type granodiorites, compose the Late Cretaceous volcanic–plutonic association, and were formed in a convergent margin. The U–Pb ages of zircons are 82–90 Ma. [ABSTRACT FROM AUTHOR]

The nitrogen isotopic composition (15N/14N ratio, or δ15N) of enameloid‐bound organic matter (δ15NEB) in shark teeth was recently developed to investigate the biogeochemistry and trophic structures (i.e., food webs) of the ancient ocean. Using δ15NEB, we present the first nitrogen isotopic evidence for trophic differences between shark taxa from a single fossil locality. We analyze the teeth of four taxa (Meristodonoides, Ptychodus, Scapanorhynchus, and Squalicorax) from the Late Cretaceous (83–84 Ma) Trussells Creek site in Alabama, USA, and compare the N isotopic findings with predictions from tooth morphology, the traditional method for inferring shark paleo‐diets. Our δ15NEB data indicate two distinct trophic groups, with averages separated by 6.1 ± 2.1‰. The lower group consists of Meristodonoides and Ptychodus, and the higher group consists of Scapanorhynchus and Squalicorax (i.e., lamniforms). This δ15NEB difference indicates a 1.5 ± 0.5 trophic‐level separation between the two groups, a finding that is in line with paleontological predictions of a higher trophic level for these lamniforms over Meristodonoides and Ptychodus. However, the δ15NEB of Meristodonoides is lower than suggested by tooth morphology, although consistent with mechanical tests suggesting that higher trophic‐level bony fishes were not a major component of their diet. Further, δ15NEB indicates that the two sampled lamniform taxa fed at similar trophic levels despite their different inferred tooth functions. These two findings suggest that tooth morphology alone may not always be a sufficient indicator of dietary niche. The large trophic separation revealed by the δ15NEB offset leaves open the possibility that higher trophic‐level lamniforms, such as those measured here, preyed upon smaller, lower trophic‐level sharks like Meristodonoides. [ABSTRACT FROM AUTHOR]

This paper presents the results of seismostratigraphic interpretation of the Upper Cretaceous sedimentary succession preserved within two synclines flanking the Szamotuły diapir in northwestern Poland. This succession is characterized by a complex Santonian--Campanian internal geometry characteristic of contourites -- that is, deposits formed by contour (bottom) currents. The aim of the present paper is to document these contourites using 2D seismic reflection profiles calibrated by the Obrzycko 1 well. The contourite drifts in the immediate vicinity of the Szamotuły structure exhibit elongated mounded shapes, with adjacent concave moats. At greater distances from the diapir, gradual aggradational patterns are observed. The formation of these Santonian--Campanian contourites was associated with growth of the Szamotuły diapir during regional compression and Polish Basin inversion. These contour currents and associated contourites formed an integral part of a regional axial depositional system developed within the flanks of the Mid-Polish Anticlinorium. Furthermore, this paper discusses the potential role of contourites as palaeomorphological indicators of palaeoslopes in varied geodynamics settings, such as inverting sedimentary basins, as opposed to the passive margins upon which they have been most commonly documented. [ABSTRACT FROM AUTHOR]

A palynological, palynofacies and organic geochemical investigation of the Upper Cretaceous continental vertebrate site of Oarda de Jos allowed us to constrain its age and to make more detailed inferences about its depositional environment. The recovered palynomorph assemblage is represented mainly by angiosperm pollen and fern spores, alongside rare taxa of gymnosperms. Biostratigraphically significant taxa identified in the assemblage restrict the age of the studies deposits to the later early Maastrichtian. The palynofloral evidence indicates plant communities that mainly preferred higher-altitude areas and cooler-wetter conditions. However, a spore and pollen assemblage which derives from vegetation typical of lacustrine areas or riverbanks also occurs in the studied deposits. The studied palynoflora shows quite significant differences compared to previously published palynological assemblages from the same geological unit (the Sebeș Formation), although from deposits located slightly to the north, at Pâclișa. Organic geochemical data show that certain organic biomarkers such as n-alkanes n-C16 to n-C18 reach the highest values, and indicate that they may derive from freshwater colonial green algae such as Scenedesmus. The palynofacies constituents used to reconstruct the depositional environment suggest an exclusive terrestrial organic matter deposited in a stagnant-water fluvial/lacustrine environment [ABSTRACT FROM AUTHOR]

Ginebra's gold mineralization is hosted by the Ginebra Ophiolitic Massif and the Buga Batholith, in the western flank of the Central Cordillera of Colombia. Gold occurs as disseminations, quartz-carbonate stockwork veinlets and quartz lodes with a strong structural control and are composed by small amounts of sulfides, mostly pyrite, with galena, sphalerite and chalcopyrite in at least two different deposition events and related to strong sericite-chlorite-epidote haloes, indicative of near-neutral and reduced fluids. Petrography and Raman spectroscopy allowed to identify two main fluid inclusions assemblages primary to pseudo-secondary in origin, both of them aqueous and CO2-rich, with variable N2. Microthermometric analysis indicates the hydrothermal fluids associated with the gold were low saline (0.75-6.22 wt% NaCl equiv.) and presented a minimum trapping temperature ranging from 237.4 to 301.6°C. Petrography and microthermometric results suggest an isothermal fluid mixing and/or H2S loss as the main mechanisms related to gold bi-sulfide/thio-sulfide complexes destabilization and precipitation. Sulfur isotopes indicates a close to zero range (-8.2-+4.8?), suggesting a restricted fluid circulation through the magmatic rocks of the Buga Batholith and the Ginebra Ophiolitic Massif. Besides, the oxygen and deuterium isotopes from hydrothermal sericite and chlorite accompanying to gold events, indicates a metamorphic origin for the hydrothermal fluids. 40Ar-39Ar dating of the hydrothermal alteration haloes, from El Retiro and La Esperanza, indicates a late Cretaceous-Paleocene age, between 67 and 65 Ma, contemporaneous with a regional strong dextral transpressive deformation related to subduction to obduction and exotic terrane accretion against the north-western part of the South American Plate. Although the hydrothermal fluid characteristics of the Ginebra Gold Disctrict are compatible with both the Intrusion-Related and Orogenic Gold deposit types, the metamorphic nature of the hydrothermal fluids and the tectonic regime at the time of mineralization event, allow us to propose they are compatible with an Orogenic Gold deposit. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi National Journal of Earth Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tectonic evolution of the Neo‐Tethys Ocean remains highly controversial, with several models existing in the community that conflict with each other. Here, we present new geochronologic and geochemical data for orthogneisses and amphibolites from the Greater Himalayan Sequence, eastern Himalayan orogen, which indicate that these rocks have Cenozoic metamorphic ages (∼52–3 Ma), but were derived from Late Cretaceous (∼89 Ma) magmas with arc‐like and depleted mantle geochemical signatures. Considering that northern India was a passive continental margin during the Mesozoic, and the previously reported Late Cretaceous magmatic rocks in the eastern Himalaya formed in a continental rifting setting, we suggest that the studied Late Cretaceous arc‐type magmatic rocks formed in an intraoceanic arc setting within the Neo‐Tethys, and accreted onto the passive margin of the Indian continent prior to the terminal continental collision. When combined with the existence of Late Mesozoic and intraoceanic arc‐type magmatic rocks in the western Himalaya, we suggest that a huge Late Cretaceous subduction system operated within the eastern Neo‐Tethys Ocean. This study supports two subduction zones having been responsible for the consumption and closure of the Neo‐Tethys basin, and a two‐stage collision history between India, Asia, and the intermediate island arc system. Our data therefore provide important constraints on the evolution of the Neo‐Tethys Ocean and India‐Asia collisional orogeny in southern Tibet. Plain Language Summary: We have conducted petrological, geochronologic and geochemical studies of high‐grade metamorphic rocks from the Greater Himalayan Sequence, eastern Himalayan orogen. Our results show that the rocks have Cenozoic metamorphic ages, but were derived from Late Cretaceous arc‐type magmatic rocks. We suggest that the magmatic rocks formed in an intraoceanic arc setting within the Neo‐Tethys, and accreted onto the passive margin of the Indian continent prior to the terminal continental collision, and that a huge intraoceanic subduction system operated within the eastern Neo‐Tethys Ocean during the Late Cretaceous. Key Points: Late Cretaceous subduction‐related magmatic rocks with Cenozoic metamorphic ages occur in the eastern HimalayaThe rocks formed in an intraoceanic arc setting, and accreted onto the India passive margin prior to the continental collisionA huge and Late Cretaceous northward subduction system operated within the entire Neo‐Tethys Ocean [ABSTRACT FROM AUTHOR]

Two nanhsiungchelyid carapaces from the Upper Cretaceous of Ganzhou Basin, Jiangxi Province, Southern China, are reported and assigned to Nanhsiungchelys sp. The new material reveals an unusual carapace morphology that was either not or poorly preserved in previously known Nanhsiungchelys specimens, including differentiated neurals, alternating costals, significantly modified scutes with vertebrals 4–5 contacting each other at a point, reduced pleurals 2–4 and greatly expanded lateral and posterior marginals. The discovery extends the geographical distribution of Nanhsiungchelys to the Ganzhou Basin.