ABSTRACT Recently, a set of mercury (Hg) anomalies in Valanginian sediments recovered from European sections demonstrated that an important magmatic pulse occurred at the onset of the Weissert episode. In this study, we report the distribution of Hg contents near the onset of the Weissert episode from localities outside of Europe, in the proto–Atlantic Ocean (Blake Bahama and Cap Hatteras Basins, Deep Sea Drilling Project [DSDP] Holes 534A and 603B) and southern Tethys Ocean (Argo Abyssal Plain, Ocean Drilling Program [ODP] Hole 765C), in order to evaluate the global impact of volcanism during the Valanginian. In addition, we also reinvestigated the Orpierre and Angles sections of the Vocontian Basin at a very high time resolution, to examine the potential impact of regional volcanic activity during that time interval. The onset of the Weissert episode in the proto-Atlantic and in the southern Tethyan cores is marked by significant increases in Hg contents. The persistence of the Hg anomaly in Hg/total organic carbon and Hg/Al ratios suggests that Hg enrichments were not primarily controlled by runoff processes and/or redox conditions, but instead indicate an increase in volcanic activity. The Hg enrichments recorded from localities outside of Europe at different latitudes were correlated to those previously observed in European sections, thereby confirming the presence of a global Hg peak at the onset of the Weissert episode. This peak was probably related to the emplacement of the Paraná-Etendeka large igneous province, suggesting a key role for volcanic activity during the Valanginian global environmental perturbations. In coeval intervals in the Vocontian Basin, Hg records show abrupt and short-lived enrichments, which correspond in the sedimentary successions to a goethite-rich ocher-colored layer. Two regional processes could explain Hg deposition and sequestration in this region: increased Hg sequestration by organic matter production in an oxygen-depleted environment, and/or the presence of regional volcanic activity, which is also indicated by the occurrence of a distal volcanic ash layer.

ABSTRACT Forearc basins are first-order products of convergent-margin tectonics, and their sedimentary deposits offer unique perspectives on coeval evolution of adjacent arcs and subduction complexes. New detrital zircon U-Pb geochronologic data from 23 sandstones and 11 individual conglomerate clasts sampled from forearc basin strata of the Nacimiento block, an enigmatic stretch of the Cordilleran forearc exposed along the central California coast, place constraints on models for forearc deformation during evolution of the archetypical Cordilleran Mesozoic margin. Deposition and provenance of the Nacimiento forearc developed in three stages: (1) Late Jurassic–Valanginian deposition of lower Nacimiento forearc strata with zircon derived from the Jurassic–Early Cretaceous arc mixed with zircon recycled from Neoproterozoic–Paleozoic and Mesozoic sedimentary sources typical of the continental interior; (2) erosion or depositional hiatus from ca. 135 to 110 Ma; and (3) Albian–Santonian deposition of upper Nacimiento forearc strata with zircon derived primarily from the Late Cretaceous arc, accompanied by Middle Jurassic zircon during the late Albian–Cenomanian. These data are most consistent with sedimentary source terranes and a paleogeographic origin for the Nacimiento block south of the southern San Joaquin Basin in southern California or northernmost Mexico. This interpreted paleogeographic and depositional history of the Nacimiento block has several implications for the tectonic evolution of the southern California Mesozoic margin. First, the Nacimiento forearc depositional history places new timing constraints on the Early Cretaceous unconformity found in forearc basin strata from the San Joaquin Valley to Baja California. This timing constraint suggests a model in which forearc basin accommodation space was controlled by accretionary growth of the adjacent subduction complex, and where tectonic events in the forearc and the arc were linked through sediment supply rather than through orogenic-scale wedge dynamics. Second, a paleogeographic origin for the Nacimiento forearc south of the southern San Joaquin Valley places new constraints on end-member models for the kinematic evolution of the Sur-Nacimiento fault. Although this new paleogeographic reconstruction cannot distinguish between sinistral strike-slip and thrust models, it requires revision of existing sinistral-slip models for the Sur-Nacimiento fault, and it highlights unresolved problems with the thrust model.

Abstract: A specimen of a pterodactyloid pterosaur from the Upper Tunbridge Wells Sand Formation (Early Cretaceous, Valanginian) of Bexhill, East Sussex, southern England is described. It comprises a small fragment of jaw with teeth, a partial vertebral column and associated incomplete wing bones. The juxtaposition of the bones suggests that the specimen was originally more complete and articulated. Its precise phylogenetic relationships are uncertain but it represents an indeterminate lonchodectid with affinities to Lonchodectes sagittirostris ( Owen 1874 ) which is reviewed here, and may belong in Lonchodraco Rodrigues & Kellner 2013 . This specimen is only the third record of pterosaurs from this formation.

Abstract The reservoir rock of the Schoonebeek oil field is formed by the sandstones of the Bentheim Sandstone Member. The sedimentology and depositional environment of this sandstone have been extensively studied, but the relationship between the geometry of the sandstone and tectonic activity in the Schoonebeek area remains poorly understood. 355 boreholes and two three-dimensional (3D) seismic surveys were used to study this relationship. An eroded zone in the west of the field and an area where the original depositional thickness is still intact were identified. Using the ezValidator software package it can be seen that uplift of a local anticline played an important role in the erosion of the sandstone. Deposition of the sands of the Bentheim Sandstone Member and the overlying Vlieland Sandstone and Claystone formations occurred on an unstable changing palaeotopography, whereby the instability was probably driven by halokinetic movement of the underlying Late Permian Zechstein salt. Syndepositional tectonic movements affected local thickness variations in the Bentheim Sandstone Member in the west of the field, leading to westwards thinning.

Abstract It has become accepted in recent years that the fossil record can preserve labile tissues. We report here the highly detailed mineralization of soft tissues associated with a naturally occurring brain endocast of an iguanodontian dinosaur found in c. 133 Ma fluvial sediments of the Wealden at Bexhill, Sussex, UK. Moulding of the braincase wall and the mineral replacement of the adjacent brain tissues by phosphates and carbonates allowed the direct examination of petrified brain tissues. Scanning electron microscopy (SEM) imaging and computed tomography (CT) scanning revealed preservation of the tough membranes (meninges) that enveloped and supported the brain proper. Collagen strands of the meningeal layers were preserved in collophane. The blood vessels, also preserved in collophane, were either lined by, or infilled with, microcrystalline siderite. The meninges were preserved in the hindbrain region and exhibit structural similarities with those of living archosaurs. Greater definition of the forebrain (cerebrum) than the hindbrain (cerebellar and medullary regions) is consistent with the anatomical and implied behavioural complexity previously described in iguanodontian-grade ornithopods. However, we caution that the observed proximity of probable cortical layers to the braincase walls probably resulted from the settling of brain tissues against the roof of the braincase after inversion of the skull during decay and burial. Supplementary material: Information regarding associated fossil material, and additional images, can be found at https://doi.org/10.6084/m9.figshare.c.3519984 Gold Open Access: This article is published under the terms of the CC-BY 3.0 license .

Abstract This study provides an assessment of two source-to-sink sediment routing systems of the Early Cretaceous and highlights sedimentologic changes that occurred in response to major tectonic reorganization of the eastern Gulf of Mexico during the Valanginian-Hauterivian stages. Depth-imaged 2D and 3D seismic data, well log correlation, sand grain size, and detrital zircon U-Pb data obtained from the Valanginian intervals of the cores of a key well, facilitates source-to-sink analysis of Early Cretaceous deep-water deposits, as well as construction of a new depositional model of Hosston equivalent-siliciclastics previously investigated only in the western Gulf of Mexico onshore areas. U-Pb dating of detrital zircon grains suggests that Hosston siliciclastics observed in the 200-km-long base-of-slope sandy progradational delta-fed apron at the Florida Escarpment originated in a peninsular Florida source terrane – the Ocala Arch. Interpretation of 3D seismic data with nearby well control also allows conclusions to be drawn about the Appalachian-sourced Hosston fan system in Mississippi Canyon. This Appa-lachian-sourced sandy fan is believed to have terminated updip of a series of salt-related asymmetric expulsion rollovers, although we know sediment accommodation in these inverted basins was not confined to the Valanginian-Hauterivian age Hosston interval and extended from the Jurassic Cotton Valley-Bossier supersequence to the Late Cretaceous Navarro-Taylor supersequence. Two plausible models of Appa-lachian-sourced fan length are considered, incorporating calculations of salt rafting to estimate a best-case scenario fan length of 90-km, while a more probable fan geometry is determined from seismic observations and well control, yielding a Valanginian-Hauterivian submarine fan of 70-km length. The study presents a new paleogeographic model, with special focus on the eastern Gulf of Mexico and the interpreted sand-prone fan and progradational delta-fed apron. It also provides a robust model for source to sink transport during a critical phase of Gulf of Mexico basin evolution. The shorter fan length calculated in this study suggest the majority of asymmetric expulsion rollovers in Mississippi Canyon are either sandstone-poor or were sourced from a different, likely younger, source-to-sink system ( e.g. , Late Cretaceous, Cenomanian-Turonian-age Tuscaloosa fluvial system).