Late Palaeogene Research Articles

Evidence for a floristically diverse rainforest on the Falkland archipelago in the remote South Atlantic during the mid- to late Cenozoic

Abstract We report the discovery of an ancient forest bed near Stanley, on the Falkland Islands, the second such ancient deposit identified on the South Atlantic island archipelago that is today marked by the absence of native tree species. Fossil pollen, spores and wood fragments preserved in this buried deposit at Tussac House show that the source vegetation was characterized by a floristically diverse rainforest dominated by Nothofagus-Podocarpaceae communities, similar to cool temperate Nothofagus forests/woodlands and Magellanic evergreen Nothofagus rainforests. The age limit of the deposit is inferred from the stratigraphic distribution of fossil pollen species transported by wind, birds or ocean currents from southern Patagonia, as well as similar vegetation types observed across the broader region. The deposit is suggested to be between Late Oligocene and Early Miocene, making it slightly older than the previously analysed Neogene West Point Island forest bed (200 km west of Tussac House). The combined evidence adds to our current knowledge of the role of climate change and transoceanic dispersal of plant propagules in shaping high-latitude ecosystems in the Southern Hemisphere during the late Palaeogene and Neogene.

Marsupials (Herpetotheriids) from the late Palaeogene of south-east Serbia

Three marsupial species are present in Palaeogene assemblages from south-eastern Serbia, Amphiperatherium minutum (Aymard, 1846), A. exile (Gervais, 1848–1852) and a species of Peratherium Aymard, 1850. These species are common in the late Eocene and early Oligocene of Western and Central Europe and their presence in South-Eastern Europe indicate that by the end of the Eocene, the eastwards dispersal of these marsupial species was already a fact. The presence of the same marsupial species in Serbia and in Western Europe is surprising, as the difference in composition between the Serbian and Western European rodent faunas indicates a limited faunal exchange between these areas in the late Eocene and early Oligocene. In marsupials, the stylar shelf of the upper molars shows a large morphological variation. A lesser-known variation is the presence of a transverse crista in the stylar shelf. These occur in various marsupial species, but so far were not known to be present in Amphiperatherium minutum. In our opinion, the large morphological variation of the stylar shelf is thus better not used to define a new species.

Burial in the western Central Andes through Oligocene to Miocene ignimbrite flare‐ups recorded by low‐temperature thermochronology in the Cañete Canyon, Peru

AbstractThermochronological data are essential to constrain thermal and exhumation histories in active mountain ranges. In the Central Andes, bedrock outcrops are rare, being blanketed by widespread late Palaeogene–Neogene and younger volcanic formations. For this reason, the exhumation history of the Western Cordillera (WC) in the Peruvian Andes has only been investigated locally along the mountain range. Dense thermochronological data are only available in canyons of the Arequipa (16° S) and Cordillera Negra regions (10° S). We present new apatite (U‐Th)/He and fission‐track data from the 1 km deep Cañete Canyon (13° S), where the Oligo‐Miocene deposits are preserved lying conformably on an Eocene palaeo‐topographic surface. Thermal modelling of thermochronological data indicate that the 30–20 Ma ignimbrite deposits overlying the bedrock were thick enough to cause burial reheating. We demonstrate that burial associated with thick volcanic formations should be taken into account when interpreting thermochronological data from the WC or in similar volcanic‐arc settings.

Community assembly of tropical Fagaceae-dominated forests in Thailand dates back at least to the Late Palaeogene

AbstractThe Late Oligocene to Early Miocene flora of the Ban Pa Kha Subbasin (Li Basin, northern Thailand) provides a record of montane dry tropical oak-pine forests. The rich ensemble of Fagaceae typical of these forests might have existed in the wider region of Southeast Asia since Eocene times and various fossil plant assemblages represented both lowland (Fagaceae, Dipterocarpaceae) and upland (Fagaceae, Pinaceae) tropical forests. These findings are in conflict with previous interpretations of vegetation development in northern Thailand, which stressed that stratigraphically older (possibly Late Oligocene) spore and pollen assemblages in northern Thailand were markedly different from the modern tropical flora and had a distinct northern temperate character. A major change in climate would have caused a dramatic shift to tropical conditions since the Mid-Miocene. Considering palaeobotanical data from adjacent regions in Southeast Asia, we suggest that differences in spore and pollen assemblages in intermontane basins in northern Thailand are more likely to represent different facies and lowland/upland settings. Assembly of these forest ecosystems, typically comprising Quercus sections Cyclobalanopsis, Ilex and Quercus, pollen of Castaneoideae with affinities to Castanopsis and Lithocarpus, and extinct fagaceous genera such as Eotrigonobalanus, most probably dates back to the Eocene. The absence of oaks of Quercus section Cerris in the spore and pollen assemblage of the Ban Pa Kha Subbasin, despite this group being part of the modern vegetation, might reflect the late arrival (secondary radiation) of this chiefly temperate group in tropical Southeast Asia.

Structural record of polyorogenic pre-Alpine and Alpine deformations within a major thrust nappe close to a suture zone (Internal-External Zones Boundary of the central Betic Cordillera, S Spain)

ABSTRACT The Malaguide Complex occupies the highest position in a thick-skinned Alpine thrust stack. It includes polydeformed, sedimentary and low-grade metamorphic rocks of Palaeozoic basements and their Meso-Cenozoic covers. NE of Granada the complex results severely sheared and stretched along the Betic suture zone in the metamorphic hinterland (orogenic backstop). The suture developed after the Burdigalian, due to oblique collision of the Alboran Domain (including the Malaguide Complex) with the South-Eastern Iberian Paleomargin. The orogenic evolution in the backstop region started with late Palaeogene to Early Miocene N-directed pre-collisional shortening and early thrust stacking, associated with low-grade metamorphism in the lowest Malaguide units increasing downwards into the underlying Alpujarride Complex. An accretionary prism developed at the expense of deep-marine (Flysch) sediments and the sedimentary covers of the Iberian and Alboran conjugate margins (External Zones and Frontal units, respectively). Later orogenic stages were characterized by SSE-directed back-folding and -thrusting in the Middle Miocene affecting both sides of the Betic suture related to dextral wrenching causing plurikilometric displacements. In this way, the suture evolved towards a several kilometres wide megashear zone (Cogollos-Diezma Corridor), prior to a final phase of SW-directed post-orogenic extension in the Late Miocene. Despite this protracted Alpine evolution, the Malaguide basements also preserve a record of orogenic activity during Late Carboniferous stages of the Variscan Orogeny in the form of a set of NE-SW trending folds with SE vergence and associated slaty cleavage, which are not found in the post-Carboniferous cover. The temperature conditions of this event (>300°C) in the less metamorphic Malaguide units are determined by colour alteration index (CAI) data from conodonts that have also allowed biostratigraphic dating of the Devonian-Carboniferous successions.

Facies analysis and distribution of Late Palaeogene deep‐water massive sandstones in submarine‐fan lobes, NW Borneo

Deep‐water massive sandstones (DWMS) are characterized by large volumes of sand accumulations which are considered as potential reservoir intervals in deep‐marine environments. Lithological variations and bed thickness statistics are used to interpret the distribution of massive sandstones in a deep‐marine fan‐lobe system. These massive sandstones are interpreted based on lithological heterogeneities and detailed facies analysis in seventeen exposed sections of the Late Palaeogene deposits in Sabah, NW Borneo. Sedimentary logs containing details of lithology textures and structures were used to recognize nine sedimentary facies of DWMS. These lithofacies were then grouped into three sedimentary facies associations: (1) massive facies association with basal part of turbiditic Bouma sequence, (2) massive facies association having soft‐sediment deformation structures, and (3) massive facies association with erosional features. The facies analysis portrays inner to middle submarine fan deposition and was later applied to reconstruct the distribution of a channel‐lobe complex. Individual sandstone bed thicknesses vary from 1 m to more than 8 m and the number of massive sandstones in submarine lobes range from less than 10% to more than 50%. The thicknesses of massive sandstones in channels are more than 8 m, whereas distal lobes have thicknesses from 1–2 m only. These sandstones are concentrated in channels, proximal and medial lobe settings that can also be verified from calculating the average of all maximum thickness of massive sand intervals that is, 8.91 m. The lithological heterogeneities and the processes associated with the deposition of these massive sandstones are vital for potential hydrocarbon reservoirs in the deep‐marine environments around the globe.

Spatio‐temporal evolution of the catuaba clade in the Neotropics: Morphological shifts correlate with habitat transitions

AbstractAimThe biotic assembly of one of the most species‐rich savannas, the Brazilian Cerrado, has involved recruitment of lineages from several surrounding regions. However, we lack a clear understanding about the timing and pathways of biotic exchanges among these regions and about the role those interchanges had in the assembly of Neotropical biodiversity. We investigated the timing and routes of species movements between wet or seasonally dry habitats across Neotropical regions and assessed the potential for ecological adaptation by evaluating the habitat transitions correlated with morphological shifts.LocationNeotropics.TaxonThe plant genus Anemopaegma (Bignonieae, Bignoniaceae).MethodsWe inferred a Bayesian molecular phylogeny of Anemopaegma using one nuclear and two chloroplast markers. We sampled more than 90% of the known species diversity of Anemopaegma, covering its full geographical range. We estimated divergence times using a Bayesian relaxed‐clock approach and inferred ancestral ranges as well as shifts in habitat and morphological characters.ResultsPhylogenetic analyses recovered seven main clades within Anemopaegma. The genus likely originated in Amazonia in the late Oligocene. Early‐diverging lineages diversified in situ in Amazonia, particularly during the Miocene, with independent dispersal events to the Andes, Atlantic Forest and Cerrado. Shifts from seasonally dry forest to savanna habitats were correlated with shifts from liana to shrub and the loss of tendrils.Main ConclusionsThe timing of diversification of major lineages within Anemopaegma is consistent with major geological and climatic events that occurred during the late Palaeogene and Neogene, such as the Andean uplift and the Middle Miocene Climatic Optimum. Movements across different regions within the Neotropics were relatively common but shifts between habitats were not. The correlation in the evolution of the shrubby habit, the loss of tendrils and the shifts from forest to savanna are consistent with a scenario of ecological adaptation.

Dating of granite-related tin mineralisation at Quy Hop, Vietnam: Constraints from zircon and cassiterite U–Pb and muscovite 40Ar/39Ar geochronology

Quy Hop is an important tin mining district in the North Central Coast province of Vietnam. The exposed magmatic plutons include Late Oligocene – Early Miocene granitoid and Middle Triassic granitic gneiss. Tin mineralisation in the area is spatially associated with biotite granite of the Ban Chieng Complex. Quartz vein-type and greisen-type tin ores occur in quartz-sericite-graphite schist of the Ordovician-Silurian Song Ca Formation and the greisenised granite of the Late Oligocene Ban Chieng Complex, respectively. The lack of accurate geochronological dates for the tin deposits and spatially associated granitic rocks limits our understanding of the genetic relationship between tin mineralisation and granitoid intrusions. In this study, granitic zircon and cassiterite laser ablation and inductively coupled plasma mass spectrometry U–Pb and muscovite 40Ar/39Ar dating techniques were applied to address this lack of understanding. Granitic zircon U–Pb dating of two biotite granite samples obtained from Ban Chieng yielded intersection ages of 26.65 ± 0.33 and 23.89 ± 0.15 Ma, interpreted here as representative igneous emplacement ages. Cassiterite U–Pb analyses yielded 207Pb/206Pb–238U/206Pb intersection ages of 26.81 ± 1.92 Ma for the quartz vein ore from Suoi Bac and 23.23 ± 0.89 Ma for greisen ore from Ban Ngoc. Muscovite 40Ar/39Ar laser step heating of the greisen ore yielded a plateau age of 23.87 ± 0.14 Ma and a corresponding inverse isochron age of 23.85 ± 0.16 Ma. These geochronological results strongly suggest that tin mineralisation at Quy Hop occurred in the period between 26 and 23 Ma and, therefore, is closely genetically related to the Late Palaeogene granites of the Ban Chieng Complex. The exploration implication of the new age data is considerable, indicating that biotite granite intrusions may be favourable for tin mineralisation across the entire Phu Hoat Terrane.

The rise of grasslands is linked to atmospheric CO2 decline in the late Palaeogene

Grasslands are predicted to experience a major biodiversity change by the year 2100. A better understanding of how grasslands have responded to past environmental changes will help predict the outcome of current and future environmental changes. Here, we explore the relationship between past atmospheric CO2 and temperature fluctuations and the shifts in diversification rate of Poaceae (grasses) and Asteraceae (daisies), two exceptionally species-rich grassland families (~11,000 and ~23,000 species, respectively). To this end, we develop a Bayesian approach that simultaneously estimates diversification rates through time from time-calibrated phylogenies and correlations between environmental variables and diversification rates. Additionally, we present a statistical approach that incorporates the information of the distribution of missing species in the phylogeny. We find strong evidence supporting a simultaneous increase in diversification rates for grasses and daisies after the most significant reduction of atmospheric CO2 in the Cenozoic (~34 Mya). The fluctuations of paleo-temperatures, however, appear not to have had a significant relationship with the diversification of these grassland families. Overall, our results shed new light on our understanding of the origin of grasslands in the context of past environmental changes.

Thickness change of the Tibetan lithosphere since Early Cretaceous as revealed by Ce/Yb and Sm/Yb ratios of volcanic rocks

ABSTRACT The growth of lithospheric thickness beneath the Tibetan Plateau since Early Cretaceous is demonstrated by changes in partial melting depth of the mantle as reflected in the Ce/Yb and Sm/Yb ratios of volcanic rocks. The ratios indicate that the lithospheric thickness of the Tibetan blocks ranged between 50–90 km in most areas and between 100–120 km in several areas during the Cretaceous. It increased from 60–110 km in Eocene to 170–200 km in Early Miocene in the Lhasa block, from 110–120 km in Early Oligocene to 170–180 km in Early Miocene in the Qiangtang block, and from ~130 km in Late Palaeogene to 160–190 km in Early Miocene for the Hohxil and Kunlun blocks. The thickness of the Lhasa block thus increased ~100 km at an average rate of 3.0 mm/a during Early Cenozoic. The indicated increase in Early Miocene for the Lhasa, Qiangtang, and Hohxil and Kunlun blocks to 160–195 km nearly matches the present 160–200 km plateau lithospheric thickness as inferred from seismic tomography. It is reasonable to assume that the crust, as well as the lithospheric mantle for all blocks thickened during the Palaeogene and reached its present thickness in Early Miocene.

New insights on the petroleum migration and accumulation in the basal conglomerate reservoir of Cretaceous Qingshuihe Formation of Yongjin area, Central Junggar Basin

The Junggar Basin is one of the largest and most petroliferous superimposed petroleum basins in China. This study focussed on the characteristics of the unconformity between the Jurassic and Cretaceous (J/K) and its influence on hydrocarbon accumulation in the Yongjin area, Junggar Basin. Based on the seismic reflection characteristics and wireline well logging response, we identified the structure of the unconformity, which consists of three layers: the basal conglomerate layer, weathered clay layer, and semi‐leached layer. Geochemical studies show that the crude oils of the Lower Cretaceous Qingshuihe (K1q) Formation in the Yongjin area are mainly derived from Permian source rocks and partly from Cretaceous source rocks. The abnormally high value of acoustic time and the low value of resistivity of mudstone indicate that the overpressure condition is pervasive in the Yongjin area and may act as the driving force for the vertical migration of hydrocarbon‐containing palaeo‐fluids. The poor sealing ability of the weathered clay layer of the unconformity between the Jurassic and Cretaceous (J/K) and the high abnormal overpressure indicate that the petroleum from Permian source rocks may break through the sealing of the weathered clay layer and migrate upward to the Cretaceous conglomerate to accumulate. In addition, the combination of faults, sheet sand bodies, and unconformities constitutes a three‐dimensional petroleum migration pathway. The evolution of the Che‐Mo palaeo‐uplift also affected the formation of source rocks and petroleum migration. Accordingly, the hydrocarbon accumulation model of the Cretaceous in the Yongjin area indicated that Late Palaeogene is the first accumulation period. Permian source rocks have entered a mature to high‐mature stage, where a large amount of generated oil and gas migrated along faults and unconformities and accumulated in the braided river channel sand bodies of the K1q Formation. The second accumulation period was the Neogene. The basin experienced a regional tilt leading to a south‐inclined stratum. The oil and gas migrated upwards along the Late Hercynian deep reverse fault (Carboniferous–Permian) and then passed through the shallow faults and migrated to the bottom sandstone of Cretaceous reservoirs.

New data about the oldest european lagomorpha: Description of the new genus Ephemerolagus nievae gen. nov. et sp. nov.

Early Oligocene lagomorphs from south-western France were previously known only from one isolated molar (Desmatolagus sp.) from Ravet (Quercy), an early Oligocene fissure-filling (MP21 level, 33 Ma). New material, a left lower jaw bearing P/3 to M/1, allows for the description of a new genus and a new species: Ephemerolagus nievae, on the bases of morphological analysis and micro-computed tomography (μCT) scan sections. It has been compared to the German contemporaneous specimens (“Shamolagus” franconicus from Möhren 19 and Möhren 20, MP21), and to the Asian and North American Palaeogene genera. This species displays peculiar derived characters, like the very short incisor (ending below P/3), not found in Asian or North American early lagomorphs, or in late Palaeogene European genera, or the lack of M/3 and the highly molarized P/4

Recovery of the Cretaceous palaeo‐uplifts and its implications for hydrocarbon systems in the Kuqa Depression, Tarim Basin, western China

The Kuqa Depression is an important oil and gas exploration area in the Tarim Basin, and exploration practices indicate that the gas reservoirs such as Dabei, Kela, and Keshenare distributed in the Cretaceous palaeo‐uplift area. However, few studies have been done on the Cretaceous palaeo‐uplifts. On the basis of the logging gamma curve, the spectrum analysis of the Bashijiqike Formation shows that the sedimentation of the Lower Cretaceous stratum was controlled by the Milankovitch cycles. As the stratum exhibits the characteristic Milankovitch periodicities, 133, 124, 100, and 95 ka eccentricity, 46.5 and 36.6 ka obliquity, and 22.2 ka precession periods are identified in the residual Bashijiqike Formation. By combining the results of cyclic analysis and thermal simulation of apatite fission track (AFT), the stratum denudation amount of Dabei‐Tubei palaeo‐uplift and Kelasu palaeo‐uplift in the Late Cretaceous was calculated, and the palaeo‐uplifts were restored. The results show that the original thickness of the Cretaceous stratum in the core of the Dabei‐Tubei palaeo‐uplift was ~1,500 m and was more than 1,800 m in the core of the Kelasu palaeo‐uplift. The AFT modelling results indicate that there were two cooling phases in provenance, that is, since the Late Triassic–Early Jurassic (ca. 200 Ma) and the Late Jurassic–Early Cretaceous (ca. 160–130 Ma). In addition, the depositional area also experienced two cooling phases, namely, since the Late Cretaceous (ca. 110–60 Ma) and the Late Palaeogene–Early Neogene (ca. 20 Ma).

Multistage structural evolution of the end-Cretaceous–Cenozoic Wleń Graben (the Sudetes, NE Bohemian Massif) – a contribution to the post-Variscan tectonic history of SW Poland

Results of a new mapping and structural field study of the Wleń Graben (North Sudetic Synclinorium, SW Poland), made up of a post-Variscan volcano-sedimentary succession, were used to set up a new model of its multiphase tectonic evolution. The Wleń Graben constitutes a narrow tectonic trough, ca. 17.5 km long and up to 3.5 km wide, superimposed on the low-grade metamorphic rocks of the Kaczawa Metamorphic Unit and bounded by steep, NW−SE-oriented, normal and reverse faults. Previously, a simple, one-stage evolution of the graben was considered, with a single Alpine age intraplate compressional event responsible for the formation of the unit. The present study shows that the Late Cretaceous (post-Santonian?) evolution of the Wleń Graben was dominated by NW−SE-oriented, normal faults during the first, extensional stage of its formation. The central and southern parts of the graben were strongly affected by NW−SE-trending reverse faults and overthrusts, which reflect the second, probably latest Cretaceous to early Palaeogene(?) compressional event of tectonic deformation. Moreover, the whole area of the graben is dissected by sinistral strike-slip faults oriented perpendicular to the graben margins, representing the third stage of deformation (late Palaeogene–Neogene). The latest stage of evolution of the Wleń Graben includes a possible Neogene to Quaternary development of normal faults, interpreted here as gravitational collapse structures related to present-day morphology, rather than tectonically induced ones.

Geomorphometry-based detection of enhanced erosional signal in polygenetic medium-altitude mountain relief and its tectonic interpretation, the Sudetes (Central Europe)

We explore the assumption that uplift drives erosion and hence, more dissected (eroded) terrains may indicate areas subject to more intense uplift than others, especially if other factors such as elevation and geology can be demonstrated as inconsistent with the spatial pattern of dissection. Geomorphometry and statistics are employed to recognize the enhanced erosional signal within a medium-altitude mountain terrain of the Sudetes in Central Europe, considered as a representative for moderately uplifted areas of complex bedrock diversity. This signal is understood as a meso-scale reflection of relief properties, whereas the recognition of homogeneous terrain units, different in terms of strength of erosional signal, is carried out by means of multi-criteria terrain classification, involving Principal Component Analysis and k-means grouping. Four groups covering 45% of the area have been identified. They were quantitatively compared with independent variables of altitude, lithology, structural units and rock strength, and also assessed in relation to rainfall pattern. It is concluded that their dependence on altitude and geology is only partial. Then, three types of dissected terrain are distinguished and interpreted in terms of uplift intensity, rock strength as a factor modulating erosional response to uplift and timescale. The spatial distribution of these types of terrain indicates several isolated ‘hot spots’ of erosional dissection on predominantly strong rocks, linked by less elevated areas, underlain by rocks of variable strength. The former are considered as having longer history of uplift and dissection, dated back to the late Palaeogene, whereas the latter record more recent history of endo-exogenic interactions, possibly since the late Miocene. The presence of canyon-like valleys incised into planar or gently sloping relief may indicate the most recent pulse of relief rejuvenation. The procedure proposed in the paper is suitable to be used in various settings, given that good quality topographic data are available.

Sequence architecture and depositional evolution of the late Palaeogene in southwestern slope of Lufeng Depression, Pearl River Mouth Basin: Responses to tectonic processes and base‐level changes

The southwestern slope of Lufeng Depression, which is located in the central part of Zhu I Depression is a significant geomorphic unit due to its petroliferous discoveries and tectonic evolutions since early Palaeogene. Based on the comprehensive analysis of cores, wireline logs, seismic volumes, and other related geological and geophysical information, the sequence architecture and depositional evolution was analysed, and their responses to regional tectonic processes and base‐level changes were revealed. The results indicated that two second‐order sequences and six third‐order sequences defined by different types of sequence boundaries are recognized. The second‐order and third‐order sequences were bounded by regional erosional unconformities on the depression margin or slope and unconformities in the central depression with the assist of stacking patterns of wireline logs and depositional characteristics of cores. The second‐order sequence generally consists of two regional transgressive–regressive cycles which can be further subdivided into several local sub‐cycles equivalent to corresponding third‐order sequences which can be identified from wireline logs and cores. The palaeogeomorphology resulted from compound and complex tectonic events in the early Palaeogene plays an important and main role in controlling sequence architecture. In contrast, the base‐level changes largely controls the sequence architecture in the late Palaeogene. The depositional systems within the sequence stratigraphic framework are mainly composed of braided delta deposits and shore deposits, which respectively includes braided channel, subaqueous distributary channel, lacustrine shale, beach bar, maximum flooding surface, shoreface, and foreshore. The base‐level changes, which apparently originated from tectonic uplift and subsidence and sediment supply, controlled the regional transgressions and regressions in sedimentary facies distributions. The development of subsequence (what we call it sand units or sections) from 2,980 to 2,880 in Enping Formation in the Early Palaeogene is obviously influenced by a decrease in tectonic subsidence (rifting stage) and an increase in accommodation space (base‐level rising), while the case is opposite in subsequence 2,850 of Enping Formation. However, the subsequence in Zhuhai Formation in the late Palaeogene from 2,760 to 2,600 was formed in stable tectonic settings (transition stage), and thereby, it was mainly dominated by base‐level changes which were caused by sediment supply and accommodation space changes.

The Origin and Diversification of Plant Family Dipterocarpaceae

The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of Dipterocarpaceae in SE Asian rain forests suggests its origin from SE Asia. However, its fossil history is much younger, from Oligocene, from the region. Based on the pollen fossil records from the late Cretaceous-early Paleogene sedimentary sequences of Indian subcontinent and the contemporaneous distribution of its extant taxa, evolutionary history of Dipterocarpaceae has been traced. The study suggests a West Gondwanan origin for this family. Present study also provides first evidence of Dipterocarpaceae genus Vateriopsis (endemic in Seychelles) type fossil pollen record from the late Cretaceous and early Palaeogene sedimentary sequences of western Indian margin.

The low-temperature thermo-tectonic evolution of the western Tian Shan, Uzbekistan

The Kyzylkum-Nurata region represents a key area in understanding the tectonic evolution of the western Tian Shan. In this study, we present new thermochronological data (apatite fission track and apatite (U-Th-Sm)/He) and associated thermal history models for 45 igneous samples from the Kyzylkum-Nurata Segment of South Tian Shan on the territory of Uzbekistan and Tajikistan. Our data show that the Kyzylkum-Nurata Segment experienced a multi-phase Mesozoic thermal history that differs from previously studied segments of the Tian Shan. A Triassic (~220–200 Ma) cooling signal is widespread throughout the Tian Shan and is interpreted as being associated with exhumation following the closure of the Palaeo-Asian Ocean. Following this period of fast cooling, the Kyzylkum-Nurata Segment experienced a period of slow cooling and erosion in the Early Jurassic (~190–160 Ma). However, in contrast to other parts of the Tian Shan, our study area preserves evidence for rapid cooling during the Late Jurassic–Early Cretaceous (~160–120). Given that this rapid cooling signal was only recorded for samples in association with major structures (e.g., relic suture-shear zones), we interpret this event as a period of fault reactivation related with tectonic processes at the Eurasian margin of the Tethys Ocean. Subsequently, the Late Cretaceous–early Palaeogene (~100–50 Ma) is characterised by slow cooling and erosion. Since the late Palaeogene, the basement of the Tian Shan experienced cooling related to the India-Eurasia collision. The thermal signal of this collision has been extensively recorded in the high-altitude Kyrgyz Tian Shan. Within the low-relief Kyzylkum-Nurata Segment, this Cenozoic overprint is not recorded, allowing for a detailed assessment of the Mesozoic thermal and landscape evolution of the western Tian Shan. Our study demonstrates that the Cretaceous Uzbek Tian Shan was characterised by a series of parallel, linear mountain belts that formed along suture zones during fault reactivation.

Cenozoic stage of development of local structures of the Lower Kura Depression and Baku Archipelago related to their oil and gas prospectivity

The South Caspian Basin (SCB), including the Lower Kura Depression (LKD), was one of the deep‐sea basins of Tethys before the Late Palaeogene. During the Late Palaeogene, due to the convergence of the Iranian‐Afghan and Anatolian plates with the Eurasian Plate, the SCB was transformed into a marginal sea. By the end of the Miocene, the Arabian Plate converged between Anatolian and Irano‐Afghan, which contributed to fold deformations of north‐eastern orientation in the north‐western part of the Iranian‐Afghan Plate. It led to the development of the western side of SCB and drainage of Kura Depression; since then, the LKD became a western onshore continuation of SCB. A compressive stress regime, established there since the end of the Miocene, directly influenced the structures development process in LKD and Baku Archipelago (BA). Although LKD is located onshore and its eastern edge belongs to SCB west board, together with BA they form a single structural and tectonic zone, which is evidenced by the evolution, spatial orientation of local structures and anticlinal zones. To establish the correlation of the evolution features of LKD and BA, we performed the palaeoanalysis on the basis of reconstructed palaeoprofiles for several LKD and BA structures. From palaeoprofiles, we constructed diagrams of fold growth intensity. The results of the correlation of these diagrams indicate at the consedimentational and continuous character of the development of structures in both zones (except for the buried structures) but featuring different intensity at different intervals of geological time. During the formation time of the Lower Production Series (LPS), both zones were characterized by a relatively rapid growth of the folds. At the time of formation of the Upper Production Series (UPS), Absheron‐Aghjagil structures growth intensity was roughly the same but lower than that of LPS. The most intense growth of folds in both zones occurred in Quaternary time.

Transient temperature asymmetry between hemispheres in the Palaeogene Atlantic Ocean

During the Late Palaeogene between ~40 and 23 million years ago (Ma), Earth transitioned from a warm non-glaciated climate state and developed large dynamic ice sheets on Antarctica. This transition is largely inferred from the deep-sea oxygen isotope record because records from independent temperature proxies are sparse. Here we present a 25-million-year-long alkenone-based record of surface temperature change from the North Atlantic Ocean. Our long temperature record documents peak warmth (~29 °C) during the middle Eocene, a slow overall decline to the Eocene/Oligocene transition (EOT, ~34 Ma) and high-amplitude variability (between ~28 and 24 °C) during the Oligo–Miocene. The overall structure of the record is similar to that of the deep-sea record, but a distinct anomaly is also evident. We find no evidence of surface cooling in the North Atlantic directly coinciding with the EOT when Antarctica first became cold enough to sustain large ice sheets and subantarctic waters cooled substantially. Surface ocean cooling during the EOT was therefore strongly asymmetric between hemispheres. This transient thermal decoupling of the North Atlantic Ocean from the southern high latitudes suggests that Antarctic glaciation triggered changes in ocean circulation-driven heat transport and influenced the far-field climate response.