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Earthquake slip distributions help constrain rupture behavior and return times. Here, by combining 0.5‐m‐resolution image and topographic data interpretation with fieldwork, we quantify the co‐seismic throw distribution and rupture geometry of the 1609 Hongyazi earthquake along the Qilian Shan Fodongmiao fontal thrust (NE Tibet). We measured 396 vertical offsets across mapped geomorphic units along the thrust trace. The 1609 rupture was ∼118‐km long, with average co‐seismic throw and slip amounts of ∼1.8 ± 1.0 and ∼2.9 ± 1.4 m, respectively, consistent with a magnitude Mw of 7.4 ± 0.3. Along the ∼88‐km‐long western stretch of the thrust, our data also reveal five distinct clusters with peak cumulative throws (∼4.9, 9.3, 13.8, 18.0, and 22.2 m), implying older ruptures with nearly characteristic slip during five Mw ∼ 7.6–7.8 events, three of which were also identified in trenches. Two of these earthquakes ruptured the entire thrust, while three mainly broke the western and middle segments. The thrust geometry and segmentation are influenced by geological inheritance. The middle segment emplaces Silurian granites atop Quaternary alluvium, which may account for its irregularly cusped trace, and favor rupturing during large, Mw ∼7.8 events with multi‐millennium (∼3.7 +0.5/−2.2 ka) return times. Since ∼20 ka, the Fodongmiao Thrust has kept shortening and uplifting Tibet's northeastern boundary at steady rates of ∼1.4 and 1.1 mm/a, respectively. The remaining oblique component of convergence across the ∼800‐km‐long pushup between the Altyn Tagh and Haiyuan faults is absorbed by slip partitioning along the left‐lateral Changma and Lenglongling faults. Plain Language Summary: Co‐seismic slip measurements are essential to assess earthquake return times on active faults. Across thrusts, superficial throws help corroborate paleo‐seismological observations in shallow trenches. For ∼120‐km along Qilian Shan's Fodongmiao frontal thrust, 0.5‐m resolution UAV data and detailed geomorphic mapping capture the full distribution of co‐seismic vertical displacements (averaging ∼2 m) that resulted from the 1609 Hongyazi earthquake and five older, Mw ∼7.6–7.8 events (∼average 4.1 +0.5/−1 m) all of which postdated the Last Glacial Maximum (∼20 ka). For the older events, the data is consistent with ∼characteristic slip (∼average 6.5 m) and multi‐millennial (∼3.7 +0.5/−2.2 ka) return. Geological inheritance seems to have exerted control on the rupture geometry. The broad‐scale crustal deformation across Northeastern Tibet's "pushup corner" requires partitioning of the far‐field, oblique, contemporary convergence rate (∼7 mm/yr) between the left‐lateral Altyn Tagh and Haiyuan Faults (∼1 cm/yr) and 5 parallel intervening thrusts (∼1.4 mm/yr). Key Points: The average co‐seismic throw, rupture length, and Mw magnitude of the 1609 Hongyazi Earthquake were ∼1.8 ± 1.0 m, ∼118 km, and 7.4 ± 0.3, respectivelySince the LGM, another five ∼M 7.6–7.8 earthquakes broke the Fodongmiao frontal thrust, with ∼average characteristic throws of ∼4.1 +0.5/−1.0 mThe Paleozoic to Cenozoic hanging‐wall bedrock exerted strong control on the thrust geometry and surface trace complexity [ABSTRACT FROM AUTHOR]

The Salt Range Formation is an extensive evaporite sequence in northern Pakistan that has acted as the primary detachment accommodating Himalayan orogenic deformation from the north. This rheologically weak formation forms a mylonite in the Khewra Mine, where it accommodates approximately 40 km displacement and is comprised of intercalated halite and potash salts and gypsiferous marls. Polyhalite TK2Ca2Mg(SO4)4•2H2OU] grains taken from potash marl and crystalline halite samples are used as geochronometers to date the formation and identify the closure temperature of the mineral polyhalite using the 40Ar=39Ar step-heating laser and furnace methods. The diffusion characteristics measured for two samples of polyhalite are diffusivity (D0), activation energy (Ea), and %39Ar. These values correspond to a closure temperature of ca. 254 and 277 °C for a cooling rate of 10 °C Myr-1 40Ar/39Ar age results for both samples did not return any reliable crystallisation age. This is not unexpected as polyhalite is prone to 40Ar* diffusion loss and the evaporites have experienced numerous phases of deformation resetting the closed K=Ar system. An oldest minimum heating step age of ~ 514 Ma from sample 06-3.1 corresponds relatively well to the established early Cambrian age of the formation. Samples 05-P2 and 05-W2 have measured step ages and represent a deformation event that partially reset the K=Ar system based on oldest significant ages between ca. 381 and 415 Ma. We interpret the youngest measured step ages, between ca. 286 and 292 Ma, to represent the maximum age of deformationinduced recrystallisation. Both the youngest and oldest measured step ages for samples 05-P2 and 05-W2 occur within the time of a major unconformity in the area. These dates may reflect partial resetting of the K=Ar system from meteoric water infiltration and recrystallisation during this nondepositional time. Otherwise, they may result from mixing of Ar derived by radiogenic decay after Cambrian precipitation with partially reset Ar from pervasive Cenozoic deformation and physical recrystallisation. [ABSTRACT FROM AUTHOR]

We present electrical resistivity models of the crust and upper mantle from two‐dimensional (2‐D) inversion of magnetotelluric (MT) data collected in the Rio Grande rift, New Mexico, USA. Previous geophysical studies of the lithosphere beneath the rift identified a low‐velocity zone several hundred kilometers wide, suggesting that the upper mantle is characterized by a very broad zone of modified lithosphere. In contrast, the surface expression of the rift (e.g., high‐angle normal faults and synrift sedimentary units) is confined to a narrow region a few tens of kilometers wide about the rift axis. MT data are uniquely suited to probing the depths of the lithosphere that fill the gap between surface geology and body wave seismic tomography, namely the middle to lower crust and uppermost mantle. We model the electrical resistivity structure of the lithosphere along two east‐west trending profiles straddling the rift axis at the latitudes of 36.2 and 32.0°N. We present results from both isotropic and anisotropic 2‐D inversions of MT data along these profiles, with a strong preference for the latter in our interpretation. A key feature of the anisotropic resistivity modeling is a broad (~200‐km wide) zone of enhanced conductivity (<20 Ωm) in the middle to lower crust imaged beneath both profiles. We attribute this lower crustal conductor to the accumulation of free saline fluids and partial melt, a direct result of magmatic activity along the rift. High‐conductivity anomalies in the midcrust and upper mantle are interpreted as fault zone alteration and partial melt, respectively. Key Points: We image 2‐D anisotropic electric resistivity structure beneath the Rio Grande rift in New Mexico, USA, to depths of 200 kmThe lower crust beneath and laterally adjacent to the rift is exceptionally conductive along the entire rift axisThe Rio Grande rift is electrically distinct from the Southern Basin and Range, the Colorado Plateau, and the Great Plains [ABSTRACT FROM AUTHOR]

Abstract The Guamá Sandstone, exposed in small isolated outcrops in the northeastern region of the State of Pará (Brazil), which are surrounded by Cenozoic sediments, represents a Silurian relic of the Amazonas and Parnaiba basins connected during the Paleozoic and separated only since the Triassic period through the development of the Marajó Basin. Previous outcrop-based studies showed that the Guamá Sandstone is a fine to medium-grained quartzarenite, with high compositional and textural maturity, which was deposited in a coastal marine setting (foreshore/shoreface), correlatable with the environment of the Silurian Nhamundá Formation of the Amazonas Basin. The principal primary sources of the sandstone are associated with rocks formed during the Transamazonico and Brasiliano Cycles according to isotopic dating of zircon. In order to better understand provenance and diagenesis of the Guamá Sandstone core samples of a 50 m deep bore hole, located 6 km north of the town of São Miguel do Guamá, have been studied. The sandstone is usually bioturbated and massive, but planar stratification (foreshore) and cross bedding (shoreface), the latter in the lower part of the profile, are also present indicating a transgressive to regressive coastline. In addition to quartz, the Guamá Sandstone is composed of the following detrital accessory minerals: zircon, tourmaline, rutile, epidote, mica, ilmenite and chromite while kamacite occurred only sporadically indicating, at least for the latter, origin from Fe-Ni-meteorites. Provenance data obtained from the composition of zircon and tourmaline grains, as well as from internal textures of zircon, point to primary igneous and metamorphic source rocks of the Guamá Sandstone. While zircon is principally of magmatic origin, tourmaline grains are derived dominantly from metapelitic, metapsammitic and granitoid rocks. However, pre-existing sediments probably represent, to a lesser extent, the ultimate direct source as suggested by the well-rounded grains of the quartz arenite and worn tourmaline overgrowths. The diagenetic phases of the sandstone include syntaxial quartz overgrowths, microquartz, kaolinite booklets, illite and anatase. The quartz overgrowths are pseudo-zoned and engulf parts of the kaolinite booklets. These may be surrounded by microquartz which usually replaced quartz overgrowths. Illite, which is rare, is probably the product of replacement of kaolinite, and anatase may be related to partial dissolution of ilmenite. The main diagenetic processes including precipitation of quartz and kaolinite began during eodiagenesis, in shallow burial conditions, and proceeded through mesodiagenesis as suggested by multi-episodic quartz zoning and formation of illite. The early precipitation of kaolinite is related to alteration of feldspar and mica caused through flushing of meteoric water during forced marine regression and uplift, probably still in Silurian time. The sources for quartz cementation may include kaolinitization of feldspar and pressure dissolution, the latter associated to concavo-convex and sutured grain contacts, although these types of contact are relatively rare. Therefore, external silica-rich solutions likely occurred. Highlights • Facies, petrographic and porosity in a Silurian relic of the Amazonas and Parnaiba basins of the time they were connected. • Recognition of the detrital accessory minerals related to the primary source for sandstone. • Identification of primary source rocks related to metapelitic, metapsammitic, granitoid and ultramafic rocks. • Characterization of eo-, meso- and telodiagenetic events, with identification of principal cements. [ABSTRACT FROM AUTHOR]

Abstract The fossil crocodylomorph fauna of the Cenozoic of South America is very rich and diverse. Historically, few publications have been dedicated to providing an overall review of this fauna, with most reviews focusing on specific areas. However, the fact that many new species, taxonomic reviews and description of new specimens have been proposed in the last decade makes a comprehensive review of the fossil crocodylomorph fauna of the South American Cenozoic necessary. The only crocodylomorph lineages to have a fossil record comprising Late Cretaceous and Cenozoic deposits in South America is the Dyrosauridae. Sebecidae or its predecessors, however, are very likely to have inhabited the continent during the Cretaceous-Paleogene transition as well; both Dyrosauridae and Sebecidae are considered here to have survived the Cretaceous-Paleogene extinction while inhabiting South America. Caimaninae (Alligatoroidea) arrived either in the late Cretaceous or in the early Paleocene coming from North America. The fossil record of Caimaninae is present, however, only from the Paleocene. By the Eocene, there are no records of Dyrosauridae in South America; this group was globally extinct after the Eocene, possibly due to the global cooling that occurred by the end of the epoch. Sebecids and caimanines solely comprised the crocodylomorph fauna of the continent until the Miocene, where there are the first records of Gavialoidea (Gryposuchinae) and a possible first dispersion of Crocodyloidea, through the tentative tomistomines Charactosuchus and Brasilosuchus. Gryposuchinae likely arrived in the continent from Africa or from Asia during the Oligocene. Charactosuchus and Brasilosuchus may have come from North America where tomistomines lived from the Oligocene to the Pliocene. Sebecids were extinct after the middle Miocene; Charactosuchus , Gryposuchinae, Purussaurus , Mourasuchus and durophagous caimanines such as Gnatusuchus were extinct after the late Miocene. These extinctions are related to changes in the drainage basins caused by elevation of the Andes mountain range. Only the extant caimanine Caiman , Melanosuchus and Paleosuchus would survive the Miocene, being enriched by Crocodylus from the Pliocene onwards, which is likely that Crocodylus arrived in the American continents from Africa. The current fossil record indicates that these four genera comprise the extant crocodylian fauna of the continent since the Pliocene. Although our knowledge on crocodylomorph fossil fauna of the South American Cenozoic has increased continuosly, especially in the last decade, much yet must be done, especially on the taxonomy and phylogeny of Brasilosuchus and Charactosuchus , fieldworks in Paleogene and Pliocene localities, and the evolution of the specialized Caimaninae morphotypes. Highlights • This paper is a review of the South American fossil crocodylomorph fauna. • The fauna is comprised mainly by Dyrosauride, Sebecidae and Caimanine during the Paleogene. • Gavialoids arrived between the Paleogene and the Neogene. • End of Miocene: geomorphological changes in the continent caused the extinction of many taxa. • Caiman, Melanosuchus, Paleosuchus and Crocodylus solely comprise the fauna from the Pliocene onwards. [ABSTRACT FROM AUTHOR]

Abstract This study of the seismic geomorphology of riverine deposits describes and discusses the spatial resolution at which we can detect fluvial features and how the subsequently collected data can help with our understanding of ancient fluvial reservoirs. For this assessment we use three dimensional seismic reflection data, borehole data from ancient deposits in the Marañón foredeep basin of Peru, as well as digital elevation and satellite imagery data from the present day fluvial systems of the Amazonian Basin in the same area of Peru. Based on seismic stratigraphic principles on amplitude display we test parameters to highlight the details of the internal structure of horizons interpreted on continuous wavelets. Seismic attributes such as amplitude, phase, sweetness and spectral decomposition techniques have been successfully applied to make a framework of seismic stratigraphic surfaces that highlight the internal architecture and morphologic details of the studied intervals. This work confirms the presence of a Cenozoic fluvial system in Peru with straight, meandering and anastomosing channels. The observed fluvial features are associated with narrow to medium sized channels (10–∼700 m). Evolution of parameters such as sinuosity allows the variation of load in the identified channel features to be constrained. Cenozoic Marañón Basin rivers/streams size and shape are comparable to those observed in the present-day fluvial Amazon Basin. The fluvial dynamics in the study area are identified to be at least present since the deposition of the Pozo-Chambira Formation (Eocene-Oligocene) in the Marañón Basin. Graphical abstract Image 1 Highlights • 3D seismic characterization of buried fluvial systems in the Marañón Basin of Peru. • Evidence of ancient "big rivers" scaled to the modern Amazon Basin fluvial system. • Implications for evolution of sediment load and erosion history of the Andes. [ABSTRACT FROM AUTHOR]

Abstract Terrestrial heat flow is a crucial parameter to indicate the thermal state within the Earth, containing integrated information of the ground temperature, thermal conductivity, and crustal/mantle heat flow. We present an updated heat flow dataset and map in continental China. The data increases from 862 to 1230 observations since the year 1999 and the sites cover the major tectonic units, although their spatial distribution remains uneven. Excluding the local anomalies related to hydrothermal activities, the background heat flow values display a range from 30 to 140 mW m–2 with a mean of 60.4 ± 12.3 mW m–2. The updated heat flow map exhibits a heat flow pattern consisted of four heat flow provinces in continental China: eastern mantle-induced high flow province, southwestern crust-induced high heat flow province, central normal heat flow province and northwestern low heat flow province. The major heat flow provinces correspond to the Cenozoic lithosphere-scale tectonic units. The heat flow shows good correlation with crustal thickness and elevation, agreeing with the thermal isostasy. The heat flow distribution also corresponds with the Meso-Cenozoic tectonic activities. The present heat flow-tectonic pattern in continental China is formed by the Meso-Cenozoic geodynamic processes, including the Cenozoic India-Eurasian collision and the Mesozoic-Cenozoic western subduction of the Pacific Plate. Highlights • Update the heat flow data of the continental China • Discuss the heat flow characteristics of the various tectonic units • Reveal the heat flow distribution pattern of continental China [ABSTRACT FROM AUTHOR]

Abstract This study focuses on the Mesozoic–Cenozoic tectono-thermal events in the Central Uplift of the South Yellow Sea Basin (SYSB) based on the CSDP-2 borehole. CSDP-2 is the first borehole to penetrate the integrated Paleozoic–Mesozoic sedimentary strata and recovered approximately 2736 m of core. The drilling results confirm a significant stratigraphic hiatus, i.e., Indosinian unconformity, between the Neogene–Quaternary and the underlying Lower Triassic. The eroded thickness estimated from sonic log and vitrinite reflectance data range from ∼1200 to 1400 m. Multiple paleo-thermometer data from the CSDP-2 cores, including vitrinite reflectance, apatite/zircon fission-track (AFT/ZFT) and fluid inclusions, were used to reconstruct the Mesozoic–Cenozoic thermal history in the study area. There was a continuous heating process during the early Mesozoic. The peak paleo-temperature may have reached up to 160 °C (base Permian) during the Late Jurassic, with the highest paleo-geothermal gradient of approximately 58.8 °C·km−1. The tectono-thermal evolution was dominated by the Mesozoic intracontinental collision between the Yangtze Craton and the Sino-Korean platform. The heating process was mainly caused by rapid burial on the passive continental margin and igneous activities. The paleo-temperature significantly decreased following the Late Jurassic. Two rapid cooling processes ca. 100–65 Ma and ca. 35 Ma are suggested by the AFT modeling results. Cooling history indicates that the tectonic uplift and denudation likely occurred from the Early Cretaceous to the Miocene. The reconstruction results of thermal evolution confirm that the Mesozoic–Paleozoic source rocks are mature or even highly mature, and hydrocarbon generation, migration and charge undoubtedly occurred in the Central Uplift, showing substantial hydrocarbon potential. Moreover, the reconstruction of the tectono-thermal history provides important constraints for regional tectonic studies. Highlights • Mesozoic–Cenozoic tectono-thermal events in the Central Uplift of the South Yellow Sea Basin was discussed. • Tectono-thermal history was reconstructed based on multiple paleo-thermometer data from the CSDP-2 borehole. • Substantial hydrocarbon potential in the marine deposits in the SYSB was confirmed. [ABSTRACT FROM AUTHOR]

The Laojiezi alkaline volcanic rocks, which are located in the intraplate region of the Yangtze craton, coincide with the formation of the Jinshajiang‐Ailaoshan‐Red River alkaline rock belt. Although this belt has been widely studied by geologists because of its porphyry‐related Pb‐Ag‐Au polymetallic deposit and geotectonic location, the material sources of this belt are still debate. Whole‐rock analyses show that these rocks have high total alkali contents (3.73–11.08wt%), and their aluminum saturation index (ASI) values widely vary from 0.82 to 3.07, which comprise a metaluminous‐peraluminous magma series. These rocks are characterized by high K (K2O/Na2O>1) and low Ti and Mg contents; enrichment in large‐ion lithophile elements, such as Rb, Ba, K and light rare earth elements; and depletion in high field strength elements, such as Ta, Nb, P, and Ti. These rocks exhibit moderate Eu (Eu/Eu*=0.86–1.04) and Ce (Ce/Ce*=0.63–0.96) anomalies. Their (87Sr/86Sr)i, ∊Nd(t), zircon ∊Hf(t) and δ18O values range from 0.70839 to 0.71013, from –10.16 to –12.45, from –19.6 to –5.8, and from 5.69‰ to 8.54‰, respectively, and their Nd and Hf two‐stage model ages (TDM2) are 1.67–1.86 Ga and 1.27–2.02 Ga, respectively. These data reflect the primary partial melting of Paleoproterozoic to Mesoproterozoic lower crust with minor residual continental lithospheric mantle and supracrustal metasediments. The lithosphere was likely thickened along the southeastern margin of the Tibetan Plateau following the Indian‐Asian continent‐continent collision (65–41 Ma). During the post‐collision phase (36–16 Ma), the transition from a compressional to extensional setting triggered the convective removal of the over‐thickened CLM beneath the Yangtze craton, which led to the upwelling of asthenospheric materials. This process created alkali‐rich and high‐K magma through the partial melting of the thickened lower crust. Magma that carried Cu‐Au‐Pb‐Ag minerals was emplaced by strike‐slip motion along the E‐ to W‐ or ENE‐ to WSW‐trending tectonically weak zone, finally forming an alkaline porphyry Cu‐Au‐Pb‐Ag polymetallic deposit. [ABSTRACT FROM AUTHOR]

The seismic merging dataset, wireline logs, core photographs, thin sections, and other geological information were employed to investigate sequence architecture and reveal depositional evolution of Enping Formation in Lufeng Depression, Pearl River Mouth Basin. The results showed that one second‐order sequence and four third‐order sequences were identified based on the unconformities along basin margin/slope and correlative conformities in the basin centre. In addition, several associated sedimentary facies or microfacies (including braided channel deposits, subaqueous distributary channel deposits, beach‐bar deposits, and so on) that were recognized within sequence stratigraphic framework and depositional evolution were revealed by well tie–seismic correlations with seismic attributes extracted from the stratal slicing in terms of sand sections/units in Enping Formation. It was characterized by progradational process from seismic attributes in general that the delta deposits gradually retrograded. Through comprehensive analysis, it can be concluded that episodic tectonic movements and subsequent uplift played an important role in controlling sequence architecture. Sediment supply and lacustrine level fluctuations derived from accommodation space changes exerted an essential effect on depositional evolution. This study provides new and robust insights into understanding the sequence architecture, depositional evolution, and hydrocarbon exploration in Enping Formation. In addition to the significance for academia, study of sequence architecture and depositional evolution are of great importance for hosting potential hydrocarbon reserves, because they are frequently related to important and potential reservoirs. Consequently, investigating sequence architecture and depositional evolution are significant economically as well. [ABSTRACT FROM AUTHOR]

This paper reports mineral and whole‐rock geochemical data (major and trace elements, Sr–Nd isotopes, and in situ plagioclase Sr‐isotope analysis) for Cenozoic volcanic rocks from Sabeto, NW Fiji, with the aim of constraining the origin of Cenozoic shoshonitic rocks found throughout Fiji. The most mafic shoshonitic lavas (absarokites) exhibit porphyritic textures and massive structure with phenocrysts of olivine (Fo = 76–78), clinopyroxene (Mg# = 73.9–80.0), and plagioclase (An = 71.9–92.1). Major element geochemical data include SiO2 = 47.31–48.46 wt%, MgO = 4.20–5.76 wt%, Mg# = 49–51, Al2O3 = 17.64–18.93 wt%, and (Na2O + K2O) = 5.12–7.01 wt%. The trace element geochemistry is typically arc like, with enrichment in the large ion lithophile elements (LILEs), the light rare earth elements (LREEs), and P, along with depletion in the heavy rare earth elements (HREEs) and high‐field‐strength elements (HFSEs; e.g., Nb, Ta, Zr, Hf, and Ti). Whole‐rock (87Sr/86Sr)i ratios and εNd(t) values vary from 0.7037 to 0.7039 and from +7.62 to +8.45, respectively. The former is near equal to the 87Sr/86Sr ratios of plagioclase phenocrysts (0.7034–07039). Based on these geochemical data and the results of previous studies, we propose that the Sabeto shoshonitic primary magma was derived from partial melting of the depleted lithospheric mantle, modified by subduction‐related fluids. The thermobarometric calculation indicates that the P–T conditions of Fiji shoshonitic magma chamber are ~1100 °C and ~2.8 GPa (~90 km depth), with an average H2O fraction of ~6 wt%. In addition, the shoshonitic melts experienced fractional crystallization of clinopyroxene, olivine, and plagioclase during magma evolution. These volcanic rocks formed in an extensional setting following collision of the Vitiaz arc and the Ontong Java Plateau during the Pliocene. [ABSTRACT FROM AUTHOR]

Abstract Deep crustal and mantle rocks are exhumed in core complex mode of extension in three types of structures: metamorphic core complexes, oceanic core complexes and magma poor passive margins. Using available analogue and numerical models and their comparison with natural examples, the present paper reviews the mechanical processes involved in these different types of extensional setting. Three main aspects are considered: i) the primary role of lithosphere rheology, ii) the lithosphere-scale patterns of progressive deformation that lead to the exhumation of deep metamorphic or mantle rocks and iii) the initiation and development of detachment zones. Crustal core complexes develop in continental lithospheres whose Moho temperature is higher than 750 °C with "upper crust-dominated" strength profiles. Contrary to what is commonly believed, it is argued from analogue and numerical models that detachments that accommodate exhumation of core complexes do not initiate at the onset of extension but in the course of progressive extension when the exhuming ductile crust reaches the surface. In models, convex upward detachments result from a rolling hinge process. Mantle core complexes develop in either the oceanic lithosphere, at slow and ultra-slow spreading ridges, or in continental lithospheres, whose initial Moho temperature is lower than 750 °C, with "sub-Moho mantle-dominated" strength profiles. It is argued that the mechanism of mantle exhumation at passive margins is a nearly symmetrical necking process at lithosphere scale without major and permanent detachment, except if strong strain localization could occur in the lithosphere mantle. Distributed crustal extension, by upper crust faulting above a décollement along the ductile crust increases toward the rift axis up to crustal breakup. Mantle rocks exhume in the zone of crustal breakup accommodated by conjugate mantle shear zones that migrate with the rift axis, during increasing extension. Highlights • Review of the mechanisms of crust and mantle exhumation in core complex-type extension. • Analogue and numerical modeling support the rolling hinge process for core complex development. • Large-scale detachments do not form at the onset of deformation but during progressive extension. [ABSTRACT FROM AUTHOR]

The Cenozoic post collisional magmatism in NW Turkey produced several granitic emplacements during the Eocene and Late Oligocene-Early Miocene. Both Eocene and Late Oligocene-Early Miocene plutons are represented by high Ba Sr granitoids. We document here whole-rock chemical and Sr–Nd–Pb-O isotopic compositions of the Solarya plutonic association (SPA) with the age of 21 Ma (Lower Miocene) to evaluate the nature and genesis of potassic, high Ba Sr granites. SPA is one of the major plutons representing the Late Oligocene- Early Miocene high Ba Sr granitoids. The SPA consists of three coeval granitic members (K-Feldspar megacrystalline granodiorite, microgranite-granodiorite and haplogranite) with associated mafic microgranular enclaves (MME) and mafic dikes of gabbroic diorite to diorite in composition. Along the southern contact of the pluton, hypabyssal rocks having quartz diorite and granodiorite composition were injected into the ring fault system coeval with SPA. Hypabyssal rocks (HA) display similar mineralogical, geochemical and isotopic characteristics with SPA which indicate that HA and SPA are temporally and spatially related. K-Feldspar megacrystalline granodiorite, microgranite-granodiorite and haplogranite display high K-calcalkaline affinity whereas the mafic dikes and MME's present mid-alkaline and shoshonitic character. SPA presents Ba values between 710 and 1505 ppm and Sr values between 305 and 706 ppm. They display low Y, Yb and HREE contents and an insignificant negative Eu anomaly, which are typical geochemical signatures of high Ba Sr granitoids. SPA has initial 87 Sr/ 86 Sr values of 0.70702–0.70805 and 143 Nd/ 144 Nd values vary from 0.51235 to 0.51250. They display ƐNd values of −4.9 and −2.05. 207 Pb/ 204 Pb and 206 Pb/ 204 Pb isotopic values range between 15.68 and 15.73 and 18.75 to 18.88, respectively. Quartz and whole rock δ 18 O isotopic values vary from 8 to 10.6. These similar Sr-Nd-Pb and O isotopic features of MME/mafic dikes and host granodiorites points out to a common igneous precursor for the magma source. All these major-trace element and isotopic compositions of SPA suggest an enriched mantle (EMII) or sub-continental lithospheric mantle source for their parental magma. Bulk mixing model between ƐNd and 87 Sr/ 86 Sr isotopic data suggests that, the crustal contribution to the enriched mantle source is about 30–45%. Regarding the Cenozoic tectonic history of NW Anatolia, the inferred mantle source and magma evolution suggest that the melt generation to produce high Ba Sr granitic magmatism was most probably the result of syn -convergent extension. [ABSTRACT FROM AUTHOR]

Abstract: The Andes of southern Patagonia experienced a Miocene shift towards faster and higher angle subduction followed by the approach and collision of the Chile oceanic ridge. We present a kinematic study characterizing palaeostress fields computed from brittle tectonics to better constrain upper crustal deformation during this complex scenario. Although previous studies already suggested variable kinematics, it is striking that in a long‐lasting subduction environment, the computed palaeostress tensors are mostly strike‐slip (55%), while 35% are extensional, and only 10% compressive which are concentrated along a main frontal thrust. Cross‐cutting relationships and synsedimentary deformation indicate that a long‐lived strike‐slip regime was punctuated by a lower Miocene extensional event in the foreland before the main compressional event. The results are discussed in contrasting geodynamic models of plate coupling/decoupling versus direction and rate of convergence of the subducting plate, to explain the main mechanisms that control back‐arc deformation. [ABSTRACT FROM AUTHOR]

Aridification of the Asian interior is one of the most significant paleoenvironmental events during the Cenozoic. However, continuous paleoclimatic records from desert interiors are scarce because of the lack of outcrops, erosion and discontinuous sediment accumulation. Here we report a multi-proxy climatic record for the last ∼3.55 Ma from paleomagnetically-dated drilling core WEDP01 from the central Tengger Desert, which is one of the most important sediment source areas for Northern Hemisphere atmospheric dust and the Chinese Loess Plateau. Analysis of grain-size components indicates the onset of continuous dust deposition at 2.6 Ma and desert formation at 0.9 Ma. In addition, analysis of major element content and sediment color reveals a stepwise process of increasing aridification and significant cooling in the Tengger Desert area. Simultaneous aridification events in northwest China during the Quaternary were probably induced by the uplift of the Tibetan Plateau. Northern Hemisphere glaciation may have been another important factor for Asian aridification; meanwhile, the increased dust emission from sources such as the Tengger Desert may provide a positive feedback mechanism for global cooling. [ABSTRACT FROM AUTHOR]

Studies on the tectono-thermal evolution of the western Bohai Bay Basin (WBBB), including the Jizhong Sub-basin and Cangxian Uplift, are important for further petroleum exploration and exploitation. This study aims to reconstruct the tectono-thermal history of the WBBB based on a combination of 125 vitrinite reflectance (Ro) data and seven apatite fission track (AFT) and nine apatite (U-Th)/He (AHe) ages. The effective AFT ages range from 60.3 to 97.0 Ma, with mean track lengths of 10.86–12.64 μm. The variable single-grain AFT ages are explained to be due to the parameter D par . The effective AHe ages range from 21.1 Ma to 75.0 Ma. Two rapid cooling events revealed by the thermal modeling results occurred during the Early-Late Cretaceous (130–90 Ma) and Late Eocene-Early Miocene (40–18 Ma), respectively. The Fuping Complex, which is located in the western margin of the WBBB and mainly composed of the Paleo-proterozoic high-grade gneisses, experienced the intensive extension-detachment during the Early-Late Cretaceous along with the subduction of the Izanagi Plate, that was probably responsible for the first cooling event. The second cooling event was caused by the subduction of the Pacific Plate during the Middle Eocene-Early Miocene (43–23 Ma), as well as the collision of the Indian and Eurasian Plates and the rollback of the subducting Pacific Plate during the Early Miocene (23–18 Ma). The WBBB experienced two heat flow peaks of ∼75 and ∼80 mW/m 2 during the Early Cretaceous and the Late Eocene, respectively. During the Late Eocene-Early Miocene, rapid subsidence in the Baxian Depression (one secondary tectonic unit of the Jizhong Sub-basin) coupled with the rapid uplift in the Cangxian Uplift caused the Shahejie Formation of the middle-upper Eocene to generate gas during the Early Miocene. Meanwhile, tectonic movement during the Early Miocene also caused faults to become migration paths, as revealed by the homogenization temperature of the fluid inclusion. This study provides new insights regarding the tectonic and hydrocarbon evolution of the WBBB. [ABSTRACT FROM AUTHOR]

In the central sector of the Sierra Madre del Sur in Southern Mexico, between approximately 36 and 16 Ma ago and in the west to east direction, a diachronic process of the formation of ∼north-south trending fault-bounded basins occurred. No tectono-sedimentary event in the period between 25 and 20 Ma is recognized in the study region. A period during which subduction erosion truncated the continental crust of southern Mexico has been proposed. The chronology, geometry and style of the formation of the Eocene Miocene fault-bounded basins are more congruent with crustal truncation by the detachment of the Chortís block, thus bringing into question the crustal truncation hypothesis of the Southern Mexico margin. Between Taxco and Tehuacán, using seven new Laser Ablation- Inductively-coupled plasma mass spectrometry (LA-ICP-MS) U-Pb ages in magmatic zircons, we refine the stratigraphy of the Tepenene, Tehuitzingo, Atzumba and Tepelmeme basins. The analyzed basins present similar tectono-sedimentary evolutions as follows: Stage 1, depocenter formation and filling by clastic rocks accumulated as alluvial fans and Stage 2, lacustrine sedimentation characterized by calcareous and/or evaporite beds. Based on our results, we propose the following hypothesis: in Southern Mexico, during Eocene-Miocene times, the diachronic formation of fault-bounded basins with general north-south trend occurred within the framework of the convergence between the plates of North and South America, and once the Chortís block had slipped towards the east, the basins formed in the cortical crust were recently left behind. On the other hand, the beginning of the basins’ formation process related to left strike slip faults during Eocene-Oligocene times can be associated with the thermomechanical maturation cortical process that caused the brittle/ductile transition level in the continental crust to shallow. [ABSTRACT FROM AUTHOR]

The utility of genetic stratigraphy lies with the fundamental relationship between genetic stratigraphic units and correlative intervals of geologic time. While high-resolution studies may reveal varying degrees of diachroneity that are associated with their bounding surfaces, genetic stratigraphic units are generally viewed as chronostratigraphic in nature, representing specific periods of basin fill. Despite the vast literature on basin analysis, an evaluation of the temporal character of the boundaries between genetic stratigraphic units, particularly in cases where they are conformable, has not yet been undertaken. The Cenozoic Ebro basin is a foreland basin on the north-eastern Iberian Peninsula that provides a case for assessing the temporal character of the boundaries between genetic stratigraphic units. These units are termed “tecto-sedimentary units”, following the method of tecto-sedimentary analysis that is used in some continental basins. In the Ebro basin tecto-sedimentary analysis is based on direct field observations. In this work, magnetostratigraphic data from four tecto-sedimentary units (units T4 to T7) that span rocks of lower and middle Miocene age (ca. 1000 m thick) in the central and western areas of the basin are analysed. The study area contains alluvial, fluvial and lacustrine deposits that were sourced from Pyrenean and Iberian areas, whose catchments were structured during the collision of Iberia and Eurasia. New magnetostratigraphic data from this study and previously published magnetostratigraphic data enable us to determine the ages of these tecto-sedimentary unit boundaries throughout a 200-km-long, east–west transect that extends from the basin centre to the southwestern margin. The results indicate that the diachrony of the three boundaries between the Miocene tecto-sedimentary units through the central Ebro basin is less than 0.3 Ma where they are conformable. This low degree of diachroneity may be attributed to the effects of allogenic, largely tectonic processes that operate in the catchment areas and methodological inaccuracies. These results provide empirical support to the idea that genetic stratigraphic units are bounded by surfaces that exhibit low amounts of diachroneity where they are conformities. [ABSTRACT FROM AUTHOR]

Although alkali basalts are common in oceanic islands and continental rifts, the lithology of their mantle sources is still controversial. While the peridotite is usually viewed as a common source lithology, there are increasing studies suggesting significant contributions from ultramafic metasomatites such as carbonated peridotite, pyroxenite and hornblendite to the origin of alkali basalts. The present study indicates that carbonated peridotite plus hornblendite would have served as the mantle sources of Cenozoic alkali basalts from the West Qinling orogen in China. The target basalts show low SiO 2 contents of 36.9 to 40.8 wt% and highly variable Na 2 O + K 2 O contents from 0.86 to 4.77 wt%, but high CaO contents of 12.5 to 16.3 wt% and CaO/Al 2 O 3 ratios of 1.42 to 2.19. They are highly enriched in the majority of incompatible trace elements, but depleted in Rb, K, Pb, Zr, Hf, and Ti. Furthermore, they exhibit high (La/Yb) N , Zr/Hf, Ce/Pb and Nb/Ta ratios, but low Ti/Eu and Hf/Sm ratios. Generally, with increasing (La/Yb) N and CaO/Al 2 O 3 ratios, their Ti/Eu and Hf/Sm ratios decrease whereas their Zr/Hf, Ce/Pb and Nb/Ta ratios increase. These major and trace element features are similar to those of carbonatites and hornblendite-derived melts to some extent, but significantly different from those of mid-ocean ridge basalts (MORB). This suggests that the alkali basalts would be originated from metasomatic mantle sources. A comparison of the major-trace elements in the alkali basalts with those of some representative mantle-derived melts indicates that the source lithology of alkali basalts is a kind of ultramafic metasomatites that are composed of carbonated peridotite and hornblendite. Such metasomatites would be generated by reaction of the depleted MORB mantle peridotite with hydrous, carbonate-bearing felsic melts derived from partial melting of the subducted Paleotethyan oceanic crust. Therefore, the melt-peridotite reaction at the slab-mantle interface in the Paleotethyan subduction channel plays the key role in transferring the geochemical signatures from the subducted Paleotethyan oceanic crust to the alkali basalts in the fossil convergent plate margin. [ABSTRACT FROM AUTHOR]

Intra-plate basalts of ~ 35–0 Ma in East Eurasia formed in a broad backarc region above the stagnant Pacific Plate slab in the mantle transition zone. These basalts show regional-scale variations in Nd-Hf isotopes. The basalts with the most radiogenic Nd-Hf center on the Shandong Peninsula with intermediate Nd-Hf at Hainan and Datong. The least radiogenic basalts occur in the perimeters underlain by the thick continental lithosphere. Shandong basalts possess isotopic signatures of the young igneous oceanic crust of the subducted Pacific Plate. Hainan and Datong basalts have isotopic signatures of recycled subduction materials with billions of years of storage in the mantle. The perimeter basalts have isotopic signatures similar to pyroxenite xenoliths from the subcontinental lithospheric mantle beneath East Eurasia. Hainan basalts exhibit the highest mantle potential temperature ( T p ), while the Shandong basalts have the lowest T p . We infer that a deep high- T p plume interacted with the subducted Pacific Plate slab in the mantle transition zone to form a local low- T p plume by entraining colder igneous oceanic lithosphere. We infer that the subducted Izanagi Plate slab, once a part of the Pacific Plate mosaic, broke off from the Pacific Plate slab at ~ 35 Ma to sink into the lower mantle. The sinking Izanagi slab triggered the plume that interacted with the stagnant Pacific slab and caused subcontinental lithospheric melting. This coincided with formation of the western Pacific backarc marginal basins due to Pacific Plate slab rollback and stagnation. [ABSTRACT FROM AUTHOR]

A Cenozoic structural inversion event from transtension to transpression involving salt tectonics has been uncovered in the Yingxiong Range, the western Qaidam Basin. Seismic reflection data show that there are two common structural styles in the Yingxiong Range: (1) the positive flower structure; (2) the thrust-controlled fold at shallow depth and the positive inverted flower structure at deep levels, which are separated by a salt layer in the upper Xiaganchaigou Formation. The Yingxiong Range experienced a first stage of transtension in the Eocene, induced by the Altyn Tagh Fault, and a second stage of transpression from the early Miocene to present, jointly controlled by the Altyn Tagh and Eastern Kunlun Faults. The Eocene transtension produced numerous NW-striking right-stepping en-échelon transtensional normal faults or fractures in the Yingxiong Range. At the same time, evaporites and mudstone were deposited in the vicinity of these faults. In the early Miocene, the Eocene transtensional normal faults were reactivated in a reverse sense, and the thrust-controlled folds at shallow depth started to form simultaneously. With transpression enhanced in the late Cenozoic, positive flower structures directly formed in places without evaporites. The Cenozoic transtension to transpression inversion of the Yingxiong Range is the result of strike-slip superimposition controlled by the Altyn Tagh and Eastern Kunlun Faults in time and space. [ABSTRACT FROM AUTHOR]

The Victoria Land Basin forms part of the failed West Antarctic Rift, and preserves a Cenozoic succession up to 4 km thick that records the onset of Cenozoic glaciation, and the history of Antarctic glaciation over the past 34 Myr. This succession is relevant both to investigations of modern climate change and to studies of long-term palaeoclimate change in general. This study provides a sedimentological and stratigraphic review of the Victoria Land Basin succession, based on analysis of several continuous drillcores acquired since the 1970s, and supported by seismic stratigraphic analysis of a large array of seismic reflection data. An array of fifteen lithofacies is recognized within the Victoria Land Basin Cenozoic succession, including fossiliferous and diversely bioturbated mudrocks and diatomites, texturally mature sandstones and conglomerates, mixed mudstones and sandstones with dispersed gravel with restricted bioturbation, and diamictites and associated lithologies. These facies record a variety of marine, glaciomarine, proglacial and subglacial environments. Locally, volcanic and volcaniclastic deposits are interbedded in the succession. Lithofacies are arranged in repetitive vertical stacking patterns (depositional sequences) that record glacial advance-retreat cycles with attendant relative sea-level changes. Seven varieties of depositional sequences (stratigraphic motifs) are recognized within the succession as a whole, and interpreted to record a range of depositional settings from rifts unaffected by glacial ice (Motif 7), through varying degrees of glacial influence with abundant meltwater contributions (Motifs 6 to 3), to cold, polar glaciated environments such as that of today (Motifs 2 and 1). Overall, there is a gradual trend upward through the succession from Motif 7 at the base towards Motif 1 at the top, but the trend is not monotonic. A significant conclusion of this work is that a record of dynamic climate and glacial conditions is preserved through the entire 34 Myr period of the Cenozoic icehouse, at least in the Victoria Land Basin. Intervals characterized by consistent stratigraphic style (motifs) are recognized throughout the Victoria Land Basin succession. These intervals are of 1 to 6 Myr duration, each containing numerous depositional sequences; they are one to two orders of magnitude longer than glacial-interglacial cycles, and record periods during which environmental conditions varied in an internally consistent manner. These intervals are considered to reflect convolutions of orbital parameters that remained stable for periods of 106 a, and then switched to alternative configurations. Such intervals are directly analogous to 1 to 8 Myr intervals characterized by glaciogenic strata that are preserved within the late Palaeozoic of eastern Australia among other areas, and may be a recurring stratigraphic response to icehouse climate regimes through geological time. [ABSTRACT FROM AUTHOR]

The Dongpu depression is located in the southern Bohai Bay Basin, North China, and it has abundant oil and gas reserves. There has been no systematic documentation of this depression's temperature field and thermal history. In this article, the present geothermal gradient and heat flow were calculated for 68 wells on the basis of 892 formation-testing data from 523 wells. Moreover, the Cenozoic thermal history was reconstructed using 466 vitrinite reflectance data from 105 wells. The results show that the Dongpu depression is characterized by a medium-temperature field between stable and active tectonic areas, with an average geothermal gradient of 34.8 °C/km and an average heat flow of 66.8 mW/m 2 . The temperature field in the Dongpu depression is significantly controlled by the Changyuan, Huanghe, and Lanliao basement faults and thin lithosphere thickness. The geothermal gradient twice experienced high peaks. One peak was during the Shahejie 3 Formation depositional period, ranging from 45 °C/km to 48 °C/km, and the second peak was in the middle and late of the Dongying Formation depositional period, ranging from 39 °C/km to 40 °C/km, revealing that the Dongpu depression experienced two strong tectonic rifts during the geothermal gradient high peak periods. The geothermal gradient began to decrease from the Neogene, and the geothermal gradient is 31–34 °C/km at the present day. In addition, these results reveal that source rock thermal evolution is controlled by the paleo temperature field of the Dongying Formation depositional period in the Dongpu depression. This study may provide a geothermal basis for deep oil and gas resource evaluation in the Dongpu depression. [ABSTRACT FROM AUTHOR]

The objective of this paper is to elaborate a geological-geotechnical model in three dimensions for the Cenozoic section which is the shallowest of Pinar del Rio City. It is intended that the model obtained is used in future as an interpretative basis for geotechnical phenomena arising in the urban environment. The procedure fallowed can be easily applied to other worldwide studies, mainly in the areas that exist a big volume of geotechnical information. The procedure fallowed can be easily reproduced in other study cases worldwide, specifically counting on a wide volume of geotechnical information. Six Engineering Geological Types (EGT) are identified in the model, namely, Artificial fill, Vegetation layer, Marine alluvial coarse grained soil, Marine alluvial fine grained soil, Eluvial soil and Bed rock. The 3D geological-geotechnical model illustrates the spatial arrangement of the EGT above, and can contribute significantly at decision making in urban planning. [ABSTRACT FROM AUTHOR]

Deep-sea sediments record changes in oceanic carbonate chemistry and CaCO 3 sedimentation rate through temporal variations in the total burial of CaCO 3 and the position of the carbonate snowline, i.e., the ocean depth at which CaCO 3 -free sediments are first recorded. This paper links mathematically secular changes in snowline to those in the burial rate through a set of relatively simple equations. When the available Cenozoic deep-sea burial records are employed to predict secular variations in snowline, the process fails at some time in the past, indicating that these records are not consistent with each other. The burial records are more likely the source of this problem, as they involve far more uncertainties than the snowline records. As a consequence, we introduce a method for estimating carbonate burial through the use of a canonical CaCO 3 -depth profile, which can respond dynamically to secular changes in carbonate sedimentation and the positions of both the snowline and the carbonate saturation horizon. The resulting synthetic CaCO 3 burial record is consistent with snowline records and indicates that the burial rates offered by Davies and Worsley (1981) are generally too high, with highly questionable maxima at 25 and 47 Ma BP. Our estimates of burial are more consistent with the range advanced by Mackenzie and Morse (1992) ; nevertheless, our results differ from the latter with respect to timing and magnitude of the variations. Our approach allows simultaneous calculation of the mean carbonate ion concentration of the deep sea. We find that carbonate-ion levels fell through the Cenozoic and are similar to those calculated by Tyrrell and Zeebe (2004) , using a different model. Secular variations in CaCO 3 burial are found to be primarily driven by changes in the Ca 2+ –CO 3 2 − ion product within the bottom-waters, with an increase in the sedimentation rate of CaCO 3 of secondary importance over the Cenozoic. [ABSTRACT FROM AUTHOR]

The results of the study on diatoms revealed in Eocene deposits of the Cenozoic sequence of the Pervoocherednaya hole, which was drilled near the Southwestern Kamchatka coast, are presented. The taxonomic composition of the studied diatom assemblage including marine diatom plankton is characterized. These are the first findings of Middle Eocene planktonic diatoms having a stratigraphic value in sequences of the eastern Sea of Okhotsk region. [ABSTRACT FROM AUTHOR]

The Kachchh sedimentary basin in the western continental margin of India is a peri-cratonic rift basin which preserves a nearly complete rock record from Middle Jurassic to Recent, punctuated by several stratigraphic breaks. The Cenozoic sediments exposed in the western part of the Kachchh mainland extend offshore into the present-day continental shelf. The unique feature of the outcropping area is a nearly complete, richly fossiliferous and easily accessible Cenozoic succession. Detailed field mapping and litho-biostratigraphic studies have made it possible to identify the chronostratigraphic units, map them in the field and extend the correlation into the offshore, aided by the development of continuously recognizable key biostratigraphic horizons and time boundaries. Detailed field mapping of key sections integrated with the litho-biostratigraphic information has helped in working out a sequence stratigraphic framework for the Cenozoic succession in the basin. The succession comprises a first-order passive margin sequence. Excellent biostratigraphic control has enabled identification of unconformities of various magnitudes which in turn have helped in mapping 5 second-order and four third-order sequences. Each sequence is discussed with respect to its extent, nature of sequence boundaries, sedimentary fill, key sequence stratigraphic surfaces and depositional setup, to understand the Cenozoic sequence stratigraphic architecture of the basin. [ABSTRACT FROM AUTHOR]

The Jabal Qusaybah Anticline, in north Oman, is affected by syn-folding strike-slip and extensional fault zones developed during foreland deformation ahead of the Northern Oman Mountains thrust wedge, in Cenozoic times. Migration of fluids in fault-damage zones is recorded in complex calcite vein networks. By employing the microthermometric and compositional microanalysis of the fluid inclusions (crush-leach), two distinct generations of veins have been studied. The aim was to determine the source of elevated salinity in fluids involved in their cementation and explain their compositional evolution through fluid-rock interactions. The ionic ratios (Na/Br and Cl/Br) obtained from crush-leach analysis give supporting evidence that the elevated salinity of fluid inclusions in both vein groups originated from an evaporated seawater beyond the onset of halite precipitation (residual brines). The results reveal a gradual increase in salinity of the fluids, F/Cl molar ratios, as well as Li/Cl molar ratios. These results imply the progressively increasing contribution of evaporitic residual brines and fluids that interacted with, or were derived from siliciclastic rocks. We suggest that the most likely origin of the former fluids is provided by residual brines associated with precipitation of the Ara evaporites (Cambrian). The regional driving mechanism for such a significant fluid migration is believed to be compaction-driven upward flow that was channeled into faults and fractures during major deformational events. [ABSTRACT FROM AUTHOR]

The Silk Road Economic Belt and the 21st-Century Maritime Silk Road Initiative, abbreviated as the Belt and Road Initiative, is a primary development strategy of China's future international cooperation. Especially, the energy resource cooperation, including oil and gas resources cooperation, is an important part of this initiative. The Belt and Road has undergone complicated geological evolution, and contains abundant mineral resources such as oil, gas, coal, uranium, iron, copper, gold and manganese ore resources. Among these, Africa holds 7.8% of the world's total proven oil reserves. The oil and gas resources in Africa are relatively concentrated, with an overall low exploration degree and small consumption demand. Nigeria and Libya contain the most abundant oil resources in Africa, accounting for 2.2% and 2.9% of the world's total reserves, respectively. Nigeria and Algeria hold the richest natural gas resources in Africa, occupying 2.8% and 2.4% of the world's total reserves, respectively. Africa's oil and gas resources are mainly concentrated in Egypt, Sultan and Western Sahara regions in the northern Africa, and the Gulf of Guinea, Niger River and Congo River area in the western Africa. The Russia-Central Asia area holds rich petroleum resources in Russia, Kazakhstan, Turkmenistan and Uzbekistan. The potential oil and gas areas include the West Siberia Basin, East Siberia Basin and sea continental shelf in Russia, the northern and central Caspian Basin in Kazakhstan, the right bank of the Amu-Darya Basin, the East Karakum uplift and the South Caspian Basin in Turkmenistan, and the Amu-Daria Basin, Fergana Basin, Afghan-Tajik Basin and North Ustyurt Basin in Uzbekistan. The Middle East oil and gas resources are mainly distributed in the Zagros foreland basin and Arabian continental margin basin, and the main oil-producing countries include Saudi Arabia, Iran and Iraq. The Asia Pacific region is a new oil and gas consumption center, with rapid growth of oil and gas demand. In 2012, this region consumed about 33.6% of the world's total oil consumption and 18.9% of the world's total natural gas consumption, which has been ranked the world's largest oil and gas consumption center. The oil and gas resources are concentrated in China, Indosinian, Malaysia, Australia and India. The abundant European proven crude oil reserves are in Norway, Britain and Denmark and also rich natural gas resources in Norway, Holland and Britain. Norway and Britain contain about 77.5% of European proven oil reserves, which accounts for only 0.9% of the world's proven reserves. The Europe includes main petroliferous basins of the Voring Basin, Anglo-Dutch Basin, Northwest German Basin, Northeast German-Polish Basin and Carpathian Basin. According to the analysis of source rocks, reservoir rocks, cap rocks and traps for the main petroliferous basins, the potential oil and gas prospecting targets in the Belt and Road are mainly the Zagros Basin and Arabic Platform in the Middle East, the East Barents Sea Basin and the East Siberia Basin in Russia-Central Asia, the Niger Delta Basin, East African rift system and the Australia Northwest Shelf. With the development of oil and gas theory and exploration technology, unconventional petroleum resources will play an increasingly important role in oil and gas industry. [ABSTRACT FROM AUTHOR]

The graphic correlation method provides better and higher resolution to the stratigraphic problems than zonation biostratigraphy. The measured total stratigraphic ranges of 44 palynomorphs present in five wells from the Niger Delta Basin have been assembled by graphic correlation method into a chronostratigraphic framework. The analysis by graphic correlation reveals that for a meter of sediment accumulation in Well E, correspondingly amounted to only 0.8794 m, 0.7586 m, 0.8677 m and 0.8686 m of sediments that were deposited in wells A, B, C and D, respectively. These relative rates of sediment accumulation indicate that either there was less erosion taking place and/or more accommodation space in Well E than Wells A, B, C and D. A graphic correlation horizontal terrace was recorded in each of the Wells A, C and D, which are interpreted as condensation of sediments that had truncated the sediments accumulation profile in these wells. These condensed sections are interpreted as sediment starvation and very slow rates of sedimentation during the Early Pliocene, Late Pliocene and Late Pleistocene due to marine transgression(s) at these stages in the Niger Delta Basin. The generated correlation equations, slopes and intercept values from graphic correlation plots allow the correlation of six biostratigraphic and sedimentological events in Wells A, B, C, D and E. The resulting chronostratigraphic framework in this study is essential for sequence stratigraphic interpretations and basin analysis, and in particular, to correlate widely separated wells. [ABSTRACT FROM AUTHOR]

It has been demonstrated on basis of Sm-Nd isotopic analyses of the Cenozoic sands from the Chara and Tokkin Basins in the eastern flank of the Baikal rift zone that the Chara-Olekma Geoblock of the Aldan Shield is an area of intense crust growing processes occurred not only in the Paleoarchaean but in the Mesoarchaean as well. [ABSTRACT FROM AUTHOR]

Mineral exploration of prospective areas concealed by extensive post-mineralization cover is growing, being very complex and expensive. The projection of rich and giant Paleocene to early Oligocene porphyry-Cu-Mo belts in northernmost Chilean Andes (17.5–19.5°S) has major exploration potential, but only a few minor deposits have been reported to date, due to the fact that the area is largely covered by post-mineral strata. We integrate the Cenozoic stratigraphic, structural and metallogenic evolution of this sector, in order to identify the most promising regions related to lesser post-mineral cover and the projection of different metallogenic belts. The Paleocene to early Eocene metallogenic belt extends along the Precordillera, with ca. 30 km wide, and includes porphyry-Cu prospects and small Cu (±Mo-Au-Ag) vein and breccia-pipe deposits. Geochronological data indicate an age of 55.5 Ma for an intrusion related to one deposit and ages from 69.5 to 54.5 Ma for hydrothermal alteration in one porphyry-Cu prospect and largest known Cu deposits. The middle Eocene to early Oligocene porphyry belt, in the Western Cordillera farther east, is associated with 46–44 Ma intrusions. It is estimated to be 40-km wide, but is largely concealed by thick post-mineral cover. The youngest Miocene to early Pliocene metallogenic belt, also in the Western Cordillera, is well-exposed and includes Au-Ag epithermal and polymetallic veins and manto-type deposits. The Oligocene-Holocene cover consists of a succession of continental sedimentary and volcanic rocks that overall increase in thickness from 0 to 5000 m, from west to east. These strata are subhorizontal in the west and folded-faulted towards the east. Miocene gentle anticlines and monocline flexures extend along strike for 30–60 km in the Precordillera and were generated by propagation of high-angle east-dipping blind reverse faults with at least 300–900 m of Oligocene bedrock offset. The thickness of cover exceeds 2000 m in the eastern Central Depression, whereas it is generally less than 1000 m in the Precordillera along the Paleocene to early Eocene porphyry-Cu belt and it can reach locally up to 5000 m in the Western Cordillera, above the middle Eocene to early Oligocene belt. In the studied Andean segment, the Miocene to early Pliocene metallogenic belt is superimposed on the Paleocene to Oligocene belts in a 40–50 km wide zone. This overlap may be explained by an accentuated migration of the magmatic front, from east to west, since ca. 25 Ma, as a consequence of subduction slab steepening after a period of magmatic lull and flat subduction from ca. 30–35 to 25 Ma. The identified areas of lesser cover thickness are prone to exploration for concealed deposits, especially along the projection of major porphyry-Cu-Mo belts. [ABSTRACT FROM AUTHOR]

The Makran accretionary prism in SE Iran and SW Pakistan is one of the most extensive subduction accretions on Earth. It is characterized by intense folding, thrust faulting and dislocation of the Cenozoic units that consist of sedimentary, igneous and metamorphic rocks. Rock units forming the northern Makran ophiolites are amalgamated as a mélange. Metamorphic rocks, including greenschist, amphibolite and blueschist, resulted from metamorphism of mafic rocks and serpentinites. In spite of the geodynamic significance of blueschist in this area, it has been rarely studied. Peak metamorphic phases of the northern Makran mafic blueschist in the Iranshahr area are glaucophane, phengite, quartz±omphacite+epidote. Post peak minerals are chlorite, albite and calcic amphibole. Blueschist facies metasedimentary rocks contain garnet, phengite, albite and epidote in the matrix and as inclusions in glaucophane. The calculated P–T pseudosection for a representative metabasic glaucophane schist yields peak pressure and temperature of 11.5–15 kbar at 400–510 °C. These rocks experienced retrograde metamorphism from blueschist to greenschist facies (350–450 °C and 7–8 kbar) during exhumation. A back arc basin was formed due to northward subduction of Neotethys under Eurasia (Lut block). Exhumation of the high-pressure metamorphic rocks in northern Makran occurred contemporarily with subduction. Several reverse faults played an important role in exhumation of the ophiolitic and HP-LT rocks. The presence of serpentinite shows the possible role of a serpentinite diapir for exhumation of the blueschist. A tectonic model is proposed here for metamorphism and exhumation of oceanic crust and accretionary sedimentary rocks of the Makran area. Vast accretion of subducted materials caused southward migration of the shore. [ABSTRACT FROM AUTHOR]

The Mesozoic-Cenozoic uplift history of South Tianshan has been reconstructed in many ways using thermochronological analyses for the rocks from the eastern Kuqa Depression. The main difference in the reconstructions concerns the existence and importance of Early Cretaceous and Paleogene tectonic activities, but the existence of a Cenozoic differential uplift in the Kuqa Depression remains enigmatic. Here, we present new apatite fission-track ages obtained for 12 sandstone samples from the well-exposed Early Triassic to Quaternary sequence of the Kapushaliang section in the western Kuqa Depression. The results reveal that there were four pulses of tectonic exhumation, which occurred during the Early Cretaceous (peak ages of 112 and 105 Ma), Late Cretaceous (peak age of 67 Ma), Paleocene-Eocene (peak ages at 60, 53, and 36 Ma), and early Oligocene to late Miocene (central ages spanning 30-11 Ma and peak ages of 23 and 14 Ma), respectively. A review of geochronological and geological evidence from both the western and eastern Kuqa Depression is shown as follows. (1) The major exhumation of South TiansShan during the Early Cretaceous was possibly associated with docking of the Lhasa block with the southern margin of the Eurasian plate. (2) The Late Cretaceous uplift of the range occurred diachronically due to the far-field effects of the Kohistan-Dras Arc and Lhasa block accretion. (3) The Paleogene uplift in South Tianshan initially corresponded to the far-field effects of the India-Eurasia collision. (4) The rapid exhumation in late Cenozoic was driven by the continuous far-field effects of the collision between India and Eurasia plates. The apatite fission-track ages of 14-11 Ma suggest that late Cenozoic exhumation in the western Kuqa Depression prevailed during the middle to late Miocene, markedly later than the late Oligocene to early Miocene activity in the eastern segment. It can be hypothesized that a possible differential uplift in time occurred in the Kuqa Depression during the late Cenozoic. [ABSTRACT FROM AUTHOR]

The 1:10,000 geological map here presented extends over about 32 km2around the Col de Braus pass in the Maritime Alps (SE France). This area has attracted the attention of geologists since the late eighteenth century due to superb exposures of the Jurassic–Cretaceous Provençal succession, and has become a classic geological locality continuously studied until the present day. In this area, Early Cretaceous synsedimentary tectonics is evidenced by important lateral thickness and facies variations. This sector is presently placed at the western termination of a large structural domain extending from the westernmost Ligurian Alps into the French–Italian Maritime Alps, thus representing a key-area for understanding the structural setting of this part of the Western Alps. [ABSTRACT FROM PUBLISHER]

Geochronological (LA–ICP–MS) U–Th–Pb studies of detrital zircon of the Late Cenozoic sand deposits on Ol'khon Island have been performed. It has been shown that their main source is represented by Early Paleozoic igneous and metamorphic complexes of the Ol'khon Terrane of the Central-Asian Mobile belt and Late Carboniferous–Early Permian granitoids of the Angara–Vitim batholite. Sands from the source were transported over a distance of no less than 100 km. It is supposed that it was effectuated by strong air flows, over the ice on the Lake Baikal in particular. [ABSTRACT FROM AUTHOR]

Thermal structure of the lithosphere studies the partition of crustal and mantle heat flow of the continental area and is of significant importance to understand various energy-related geodynamic processes. The study addresses the spatial distribution of the Meso-Cenozoic mantle heat flow and Moho temperatures in the region of the Bohai Bay Basin based on the thermal history of the sedimentary basin, radioactive heat production rate and thickness of crustal layering. The results show that the ratio of the mantle and surface heat flow (qm/qs) experienced two peaks in the late period of the Early Cretaceous (qm/qs ~ 68%) and the Middle to Late Palaeogene (qm/qs ~ 75%), respectively. Based on the qm/qs ratio, the lithosphere of the Bohai Bay Basin transformed its thermal structure during the Meso-Cenozoic, from the 'cold mantle but hot crust' stage in the Triassic-Jurassic to the 'hot mantle but cold crust' stage in the Cretaceous and Cenozoic. The Moho temperatures (Tm) during the Meso-Cenozoic were also calculated by using the equation of one-dimensional heat conduction, and the result shows that there exist three Tm peaks occurring in the late period of the Early Cretaceous (930-1080 °C), the Middle-Late Palaeogene (820-890 °C) and the Early Neogene (770-810 °C). The qm/qs ratio began to exceed 50%, and the Moho temperature started to go over 700 °C from the Cretaceous to the present day, which revealed that the activity of the upper mantle in the eastern North China Craton (NCC) increased significantly accompanied by the strong crustal movement in the Cretaceous. The thermal structure revealed the Cretaceous to be a revolutionary period during the evolution of the Bohai Bay Basin, and this paper may provide some thermal evidence for the studies of the geodynamic evolution during the destruction of the NCC. [ABSTRACT FROM AUTHOR]

The Cenozoic stratigraphy of the southern Guanajuato Mining District (GMD) was established 40 years ago. The existence of a caldera structure that produced the Cenozoic volcanic cover was postulated and the world-class silver ore deposit of the Oligocene age has been closely related to magmatism. In this context, we present a new geological map of the southern GMD, U–Pb and Ar–Ar ages of the volcanic units, and structural data for the Cenozoic faults. Our results document that the volcanic centre was active between ca. 33.5 Ma and ca. 31.3 Ma, coeval with NW–SE normal faulting. We propose that the Bufa, Calderones, and Cedro formations are stratigraphic units directly related to the volcanic centre. Although the younger Chichíndaro Rhyolite scarcely crops out within the study area, it appears to be more extensive outside of the study area, forming part of the rhyolitic volcanism of the Mesa Central of Mexico. In the study area, the Chichíndaro Rhyolite buries major faults, demonstrating that it was emplaced after the peak of faulting. The two main structures are the El Cubo and Veta Madre grabens; also there are several faulted and brecciated zones where silver–gold mineralization was emplaced. The extension direction changed from NE to NW producing normal faulting, reactivating older structures and allowing dike intrusion. The extensional phase continued to be active throughout the Oligocene. The age of the volcanic event and a new K–Ar age of the Veta Madre vein of 29.8 ± 0.8 Ma (K–Ar in adularia) indicate that the hydrothermal event began immediately after the emplacement of the Cedro Formation. The emplacement of the Chichíndaro Rhyolite allowed hydrothermal activity to be active for two million years or more. [ABSTRACT FROM PUBLISHER]

The southern South African continental margin documents a complex margin system that has undergone both continental rifting and transform processes in a manner that its present-day architecture and geodynamic evolution can only be better understood through the application of a multidisciplinary and multi-scale geo-modelling procedure. In this study, we focus on the proximal section of the larger Bredasdorp sub-basin (the westernmost of the five southern South African offshore Mesozoic sub-basins), which is hereto referred as the Western Bredasdorp Basin. Integration of 1200 km of 2D seismic-reflection profiles, well-logs and cores yields a consistent 3D structural model of the Upper Jurassic- Cenozoic sedimentary megasequence comprising six stratigraphic layers that represent the syn-rift to post-rift successions with geometric information and lithology-depth-dependent properties (porosities and densities). We subsequently applied a combined approach based on Airy's isostatic concept and 3D gravity modelling to predict the depth to the crust-mantle boundary ( Moho) as well as the density structure of the deep crust. The best-fit 3D model with the measured gravity field is only achievable by considering a heterogeneous deep crustal domain, consisting of an uppermost less dense prerift meta-sedimentary layer [ρ = 2600 kg m−3] with a series of structural domains. To reproduce the observed density variations for the Upper Cenomanian-Cenozoic sequence, our model predicts a cumulative eroded thickness of ca. 800-1200 m of Tertiary sediments, which may be related to the Late Miocene margin uplift. Analyses of the key features of the first crust-scale 3D model of the basin, ranging from thickness distribution pattern, Moho shallowing trend, sub-crustal thinning to shallow and deep crustal extensional regimes, suggest that basin initiation is typical of a mantle involvement deep-seated pull-apart setting that is associated with the development of the Agulhas- Falkland dextral shear zone, and that the system is not in isostatic equilibrium at present day due to a mass excess in the eastern domain of the basin that may be linked to a compensating rise of the asthenospheric mantle during crustal extension. Further corroborating the strike-slip setting is the variations of sedimentation rates through time. The estimated syn-rift sedimentation rates are three to four times higher than the post-rift sedimentation, thereby indicating that a rather fast and short-lived subsidence during the syn-rift phase is succeeded by a significantly poor passive margin development in the post-rift phase. Moreover, the derived lithospheric stretching factors [β = 1.5-1.75] for the main basin axis do not conform to the weak post-rift subsidence. This therefore suggests that a differential thinning of the crust and the mantle-lithosphere typical for strike-slip basins, rather than the classical uniform stretching model, may be applicable to the Western Bredasdorp Basin. [ABSTRACT FROM AUTHOR]

Elephant Island, located in the vicinity of the present-day active boundary of the South Shetland Block and the Antarctic and Scotia plates, is a region of particular interest for understanding the past and present geodynamic evolution of the southern Scotia Arc. Lineament from different data sources, field-measured fractures and geomorphological evidences have been analysed in this context. The lineaments extracted from aerial photographs (1,624), from a DEM (348) and from RADARSAT-2 satellite data (1,365) indicate four dominant lineament sets with NE-SW, NW-SE, N-S and W-E strikes. All data sources identified similar lineament families, but differences in the frequency distributions and subsequently on the dominant orientations were observed. The measurements direct of fractures were obtained from 23 sites in the field at which 278 planes were measured. Fracture planes indicate main modes trending in the NNE-SSW and NNW-SSE directions and a secondary mode in the E-W. The major trends of the fracture measurements and the lineaments display a good correlation in the E-W direction. However, there is an angular variation in the azimuth values of the NNE-SSE and NNW-SSE fractures with respect to the N-S, NE-SW and NW-SE orientations of the lineaments of approximately 20°. This trend deviation may be due to the fact that mapped lineaments are composed of small fracture sets that may be related to shear fractures that cannot be distinguished at the aerial photograph or radar satellite data scales. Submerged sea-floor morphological feature orientations match the studied morphostructures on the island and the main tectonic structures in this part of the Scotia Arc. A linkage of the main lineament families to the tectonic stages from the Oligocene to the present has been proposed, taking into account the information of the orientation and sense of movement of the fractures and stresses in the Elephant Island region. [ABSTRACT FROM AUTHOR]

Zhang, L.; Xu, J., and Peng, Y., 2015. Neotectonic movement and seismic activity in the East China Sea. The East China Sea region in this paper mainly includes the continental shelf of East China Sea and Okinawa trough. The geological structure in the region basically belongs to the extension part of China's east mainland to the sea area. In Cenozoic, this area developed the East China Sea shelf basin, Diaoyu uplift fold zone, and Okinawa trough basin. Since East China Sea is located in the bonded zone of continental plate and the Philippines Sea plate, the neotectonics and the geological structure generated since the Middle Miocene are unique and complex. Basing on fully interpreting the related data and research achievements of previous researchers, this study profoundly analyzed and studied the characteristics of the neotectonics in East China Sea region from a perspective of tectonic landform, geological structure, and seismic activity etc. On this basis, it further discussed the dynamic conditions and seismic activity characteristics of neotectonics in East China Sea area. [ABSTRACT FROM AUTHOR]

This paper is concerned with results from the interpretation of continuous seismic profiling (CSP) data that were acquired during the 21st cruise of the R/V Pegas in 1980. The data are of relevance for the structure of conical seamounts and sea-hills at the foot of the Sea of Okhotsk margin of the Kuril island arc. The seamounts are extrusive domes (volcanoes) or magmatic diapirs with thick sedimentary caps of contrasting (at the top) and transparent (at the bottom) Cenozoic deposits. They were mostly formed in the Cenozoic, largely during Pliocene to Quaternary time; they resulted from viscous magma being emplaced into the sediments. There are also several small, buried domes with flattened bottoms that were formed by liquid magma being emplaced into the sediments (laccoliths or subvolcanoes). We also touch on questions relating to the terminology, geography, and history of submarine volcanism in the region and its relationship to the Benioff zone. [ABSTRACT FROM AUTHOR]

The NNW striking Wudalianchi Cenozoic volcanic belt (WVB) in NE China is mainly composed of volcanoes in Menlu River area, Keluo, Wudalianchi and Erkeshan. K–Ar radiometric dating suggests two episodes of volcanism in the WVB. Specifically, the Pliocene to early Pleistocene volcanism is distributed only in the northern part of WVB, whereas middle Pleistocene to Holocene volcanism occurred over the entire WVB. Geomorphological analyses further delineate four northeast-striking linear alignments of cones in the Wudalianchi and Keluo volcanic fields, probably related to magma feeding fractures with en echelon arrangement. No age progression is observed along these alignments. We propose that a NNW-trending rift may have controlled the eruption from Pliocene to early Pleistocene and a dextral transpression stress field may have influenced the volcanism from middle Pleistocene to Holocene. We suggest that the Pliocene and early Pleistocene volcanism is associated with far effect of the India–Eurasia collision, while the middle Pleistocene to Holocene volcanism in WVB may have resulted from interaction between the India–Eurasia collision and the subduction of the Pacific plate. [ABSTRACT FROM AUTHOR]

Within the interior of the Yangtze Craton, the dome-like Huangling anticline exposes ca. 1000 km2 of Archaean basement and Neoproterozoic granitoid rocks in the Three Gorges region, providing a natural laboratory for studying the mechanism of intracontinental exhumation. Cretaceous shortening of the Qinling Orogen and Cenozoic reorganization of the Yangtze River have been considered by previous thermochronology studies to account for the two-phase exhumation of the Huangling anticline. However, little is known about when and how the batholithic rocks were exposed to the surface. To fully reveal the exhumation history of the Huangling anticline, we focus on the Cenozoic sedimentary record in the western Jianghan Basin, downstream of the Three Gorges, and examined spatio-temporal changes in sedimentation dynamic and provenance on the basis of sedimentary facies, palaeocurrents and clast compositions, as well as zircon U-Pb geochronology. Our results indicate continuous unroofing of the Huangling anticline since the Eocene and provide a solid evidence for first exposure of the Huangling batholith during the Neogene. Cenozoic exhumation of the Huangling anticline is synchronous with incision of the Three Gorges, indicating a mechanism of intracontinental exhumation due to Yangtze River reorganization through which the Middle Yangtze River was progressively captured by the Lower Yangtze River with locally increased erosion rates in the Three Gorges. [ABSTRACT FROM AUTHOR]

In the Colorado Rocky Mountains, the association of high topography and low seismic velocity in the underlying mantle suggests that recent changes in lithospheric buoyancy may have been associated with surface uplift of the range. This paper examines the relationships among late Cenozoic fluvial incision, channel steepness, and mantle velocity domains along the western slope of the northern Colorado Rockies. New 40Ar/39Ar ages on basalts capping the Tertiary Browns Park Formation range from ca. 11 to 6 Ma and provide markers from which we reconstruct incision along the White, Yampa, and Little Snake rivers. The magnitude of post-10 Ma incision varies systematically from north to south, increasing from ∼500 m along the Little Snake River to ∼1500 m along the Colorado River. Spatial variations in the amount of late Cenozoic incision are matched by metrics of channel steepness; the upper Colorado River and its tributaries (e.g., Gunnison and Dolores rivers) are two to three times steeper than the Yampa and White rivers, and these variations are independent of both discharge and lithologic substrate. The coincidence of steep river profiles with deep incision suggests that the fluvial systems are dynamically adjusting to an external forcing but is not readily explained by a putative increase in erosivity associated with late Cenozoic climate change. Rather, channel steepness correlates with the position of the channels relative to low-velocity mantle. We suggest that the history of late Miocene-present incision and channel adjustment reflects long-wavelength tilting across the western slope of the Rocky Mountains. [ABSTRACT FROM AUTHOR]

Impact cratering can destroy life from local to global scales and result in sudden turnovers of dominant genera and/or species. Here we report that it can also preserve components of the local biology present at the time of impact. We have investigated floral matter encapsulated within Cenozoic Era impact glasses produced by separate bolide impacts into the loessoid sediments of Argentina that occurred between 9.2 Ma (Miocene) and 6 ka (Holocene). The encapsulation preserved not only macro-scale morphological biosignatures such as vascular bundles, veins, phytoliths, and papillae, but also structures down to the cellular level. In the best-preserved samples we also found evidence for organic matter. While fossilization typically occurs over an extended time period as minerals slowly replace organic matter and the host rock lithifies under pressure, the process documented here is instantaneous. Preservation of morphological and chemical biosignatures in impact events can provide snapshots of the ecology in environments that do not otherwise promote a diverse fossil record. We suggest that this would provide a new strategy for identifying signs of possible early life on ancient Mars, where similar target conditions once existed. [ABSTRACT FROM AUTHOR]

When and how the central Rocky Mountains (Rockies) of western North America gained modern topography remain controversial questions. We reconstruct the middle and late Cenozoic topography along a transect that extends from the Great Plains of western Nebraska across the central Rockies in Wyoming, based on reconstructed surface-water δD values from volcanic glass δD values. Our data show gradual increases of surface-water δD values in both the central Rockies and adjacent Great Plains during middle and late Cenozoic time, and the establishment of a similar-to-present surface-water δD gradient between the central Rockies and western Great Plains before earliest Oligocene time. These observations suggest that the region underwent differential uplift to form relief similar to that of today before earliest Oligocene time. This uplift has caused regional drying and the gradual increase of surface-water δD values over the past 35 m.y. When placed in the context of other paleoaltimetry studies, our work suggests that along our transect, the central Rockies and adjacent Great Plains underwent uplift during the late Eocene, and have not undergone any large-magnitude (>~500 m) uplift since that time. [ABSTRACT FROM AUTHOR]

Tectonic and environmental patterns and evolution of the present North Tibetan Plateau (NTP) prior to the India collision with Asia is significant to understand the formation of the Tibetan Plateau and its influence on the environment. In this study, we integrated and analyzed the tectonostratigraphy and the special sedimentary layers whose climatic implications are clear in the NTP. Additionally, we stressed the tectonic and environmental events and their evolutions from the Mesozoic to the Early Cenozoic. Our results show that four tectonic phases, which sequentially took place during the Triassic, Jurassic, Cretaceous and Paleogene, played an important role on the formation of the North Tibet. The climate was basically dry and hot from the Triassic to the Eocene and became dry and cool since the Oligocene in this region. The climatic evolution was characterized by a transition from a wet and hot phase during the Triassic - Middle Jurassic, to a dry and hot phase during the Late Jurassic - Eocene. Both phases encompassed 5 wet and hot periods followed by 5 dry and hot climate events, respectively. In addition, we found that the tectonic deformation and the climatic conditions were spatially and temporally different. In detail, in the regions north of the Paleo-Tian Shan and Paleo-Qilian Mts. the tectonic deformation and climatic condition were stronger and wetter than in regions south of the Paleo-Tian Shan and Paleo-Qilian Mts. during the Late Triassic - Jurassic. Whereas in the Cretaceous, the tectonic movement was intensive in the west but steady in the east, and climate was dry in the south but wet in the north of NTP. The formation of the tectonic and climatic patterns in NTP were the consequence of either global climate change or regional tectonics, including the Paleo-Asian Ocean closure and the Qiangtang block, Lhasa block and India plate collision subsequently to Asia. Furthermore, the regional tectonic events occurred before any global climate change and drove the climatic change in the NTP. [ABSTRACT FROM AUTHOR]

The sources of the tremendous amount of Cenozoic siliciclastic sediment deposited in the Gulf of Mexico region remain debated because of a lack of definitive provenanceidentifying characteristics. In an effort to build on prior provenance analysis, we present 101-160 single-grain detrital zircon U-Pb ages for each of 10 outcrop samples from Upper Paleocene to Upper Miocene sandstones from a ~10,000 km2 swath of central Louisiana corresponding to the ancient Mississippi River Delta, the largest Cenozoic depocenter in the northern Gulf of Mexico region. Sample depositional age control is derived from biostratigraphy and/or regional lithostratigraphic correlation. U-Pb ages in each of the samples range from Cenozoic to Archean, and correspond to the ages of various geologic terranes that underlie the modern Mississippi River drainage basin. However, the prominence of various age distributions changes systematically through the Cenozoic stratigraphy, and pronounced shifts in the abundance of certain age distributions between stratal packages appear to be correlated to shifts in heavy mineral assemblages recorded across the northern Gulf of Mexico coastal plain. Comparison of coastal plain detrital zircon age distributions to age distributions from North American sedimentary cover and the ages of major North American crystalline basement rocks, aided by a sediment mixing model, illuminates the provenance of each of the stratal packages, and suggests that (1) the Mississippi River catchment has resembled its present configuration, at least in the eastwest dimension, for much, if not all, of the Cenozoic, and (2) depositional episodes on the Louisiana coastal plain characterized by high sediment supply also corresponded to high proportions of sediment sourcing from the Sevier-Laramide region of the interior western United States. Sediment supply to the Louisiana coastal plain by the paleo-Mississippi River has generally been high during the Cenozoic, except for an anomalous low during the Middle Eocene, when the abundance of sediment derived from the Rocky Mountain region decreased dramatically relative to sediment derived from the Appalachian region. [ABSTRACT FROM AUTHOR]