The evolutionary process of anagenesis is thought to control distributions of members of the Zaphrentites delanouei species group, the Tournaisian‐Viséan solitary rugose corals, within the Carboniferous Limestone. We present alternative interpretations specific to the Friars Point Limestone Formation, which point to composite evolutionary processes closer to anacladogenesis. We use a Markov Chain Monte Carlo process to organize fossils into matrices representing states of concurrence, where concurrence is the number of species coexisting in each bed. We analyse their distributions according to transitions between states. Data testing by matrix multiplication shows whether stochastic equilibrium or convergence is reached, to determine probabilities of species coexistence. Taking the probabilities from the Markov Chain Monte Carlo process to represent the first generation of a branching process, we proceed to calculate the second to fourth generations. Finally, we model these values in a Galton–Watson process to determine the likelihood of ultimate extinction, and whether the species belong to the same population without immigration or emigration. Results show that the species distribution is both anagenetic (0.725) and cladogenetic (0.275). Therefore, we define the evolutionary process as anacladogenetic with the potential for up to eight species in addition to the six defined in the literature. This represents some evidence for a population unaffected by immigration or emigration, with a high likelihood of ultimate extinction for most localities. We deduce that second or third‐generation concurrences are a requisite for survival, even with anacladogenesis. As an environmental corollary, the amplification of extinction rates was exacerbated within a regressive marine system, and our techniques will allow further exploration of evolutionary mechanisms and energy within coral ecosystems.
<p>The Bristol Channel contains major Variscan thrusts juxtaposing distinct tectonostratigraphic terranes: &#160;the Upper Carboniferous Rhenohercynian, Culm (south) and Sub-Variscan Foredeep, Coalfield (north). There is agreement the contrasts across the Channel are not restricted to this, since underlying marine Devonian differs from continental ORS and Lower Carboniferous radiolarian-chert differs from the Main Limestone. The famous basins were mapped intricately over 100+ years by the UK geological survey and by academics across Europe, and questions about their juxtaposition date back to 1895 in the Quarterly Journal of the Geological Society, London.</p><p>Our aim, is to use structural styles and shortening to determine an upper limit for displacements upon the major thrusts. We investigate the magnitudes of shortening from south to north through the Culm and north Devon basins, and from west to east across SW Dyfed, central South Wales, Bristol, Mendips, Oxfordshire, and Kent, using an immense legacy of sections drawn by various authors, including the recent basin dynamics group of Wales.</p><p>Estimates corrected for Mesozoic negative inversion show 45% shortening due to accommodation-chevron and box folding in the Culm, 40% due to folds, back-thrusts, and fore-thrusts in the north Devon basin, 30% beneath northern parts of the Channel, and 33% along the strike of the foredeep from Wales to Kent. There is also great contrast in deformation style, between the Culm continuous-folds and the foredeep with reactivated faults, rounded folds, and thrusts, related to preferential slip along seams within central parts of the Middle Coal Measures.</p><p>Shortening can be 70%, close to underthrusts in the southern Culm; adjacent to regional thrusts along the north Devon coast; and, proximal to disturbances within the foredeep. This intensity of composite deformation would not be out of place close to tectonic-scale thrusts, between these terranes. Additionally, thrusts of this scale are detectable on regional seismic profiles and were the topics of recent studies. Structural inspection reveals significant 1km-scale displacements along NW-SE strike-slip faults common to both terranes and upon WSW-ENE oblique-ramp thrusts local to the Vale of Glamorgan and Severn estuary. WNW-ESE frontal ramps with ~10km-scale displacements are considered candidate &#8216;stems&#8217; to tectonic-scale thrusts and are found in Gower, Devon, and inner Channel.</p><p>Further investigations could elaborate the style of transmission of major thrust displacement from beneath the hinterland into the foredeep, whether by reactivation, decapitation, translation, and rotation of structural fabrics. There are complications of Mesozoic negative and Cenozoic positive inversions to consider in section restoration and adjustments are required to reveal how large displacements were dissipated exactly.</p><p>Reservations are that shortenings in hanging-walls can be poor indicators of displacement magnitude upon individual thrusts within sequences. Nevertheless, we conclude there is nothing contrary to the occurrence of a 100km-scale displacement, especially if accounting the tectonic-scale dimension and 300-500km geographic separations of modern terranes analogous to facies equivalent to the Culm and foredeep.</p>
<p>Geoscientists identifying as LGBTQIA+ (Lesbian, Gay, Bisexual, Trans, Queer, Intersexual, Asexual, plus) are currently likely to face several more obstacles throughout their career compared to their cisgender/heterosexual colleagues. Additionally, they could experience the cumulative effect of an intersection of sexism, racism, and colonialism, if coming from one or more under-represented communities. With the aim to gather an EGU-based LGBTQIA+ group to coordinate and encourage a positive change within EGU and the broader geoscience community, a first social event was organized during the General Assembly (GA) in 2019, followed by a similar event during the GA in 2020 and 2021. Last year, the working group (WG) created a Discord forum to meet more frequently online and have a place for mutual support. The series of bottom-up initiatives - all community-driven -&#160; aimed at raising awareness or promoting initiatives for changes. These have included thus far: gathering feedback, promoting initiatives toward the inclusion of LGBTQIA+ scientists in the EGU community, and doing research in general (i.e., conducting fieldwork as LGBTQIA+ individuals in locations where it can be considered more dangerous, due to the illegality of belonging to the LGBTQIA+ community). An additional task the WG has undertaken is to engage with the wider community via webinars and represent the WG in meetings with other stakeholders. The WG also works closely with the Equality, Diversity, and Inclusion (EDI) Committee of EGU for improving the representation and inclusion of their members at EGU and across the scientific organizations. In this presentation, we summarise our work since the last General Assembly and highlight areas where we hope to attract further support for institutional and cultural changes that will foster an inclusive culture for LGBTQIA+ geoscientists.</p>
<p>Decades of work has been completed on Variscan geology of the inner Bristol Channel and Severn Estuary, yet there are few structural models that correctly portray their regional framework. Many published charts loosely depict the positions, strikes and nature of the Variscan deformation front and its geometry across SE Wales. Thus, we correlate seismic data with coastal outcrop at appropriate scales and detail, to present a refined model for the front.</p><p>Coastal outcrops, in conjunction with known crustal-scale seismic data: BIRPS, SWAT and LISPB, are combined with archives of intermediate scale: wide-angle reflection, seismic refraction and reflection records. They justify a reinterpretation of the front and may explain the geometry and kinematics of its foreland. Using these data, we draw new sections from north Devon to South Wales showing the position of structural units, both Palaeozoic and Mesozoic, affected either directly by thrusts, folds and disturbances or indirectly through structural inheritance during reactivation.</p><p>We correlate extracts from SWAT lines 2 and 3, a reinterpretation of LISPB data and the new fine-scale sections, S-N across the inner channel and W-E across the estuary. They enable the synopsis of crustal-scale data and regional maps. We find from measurement of several hundred lineaments and planes along the borderlands that the predominant orientation is ENE-WSW, unlike the central Bristol Channel which is WNW-ESE. All these, plus outcrop scale geometries and striation analyses, support the new tectonic partition of SE Wales and west of England.</p><p>Much information on the partition boundaries can be gathered from the marine geography of the estuary using Admiralty charts that yield accurate soundings. Seabed profiles across the estuary illustrate the positions of bedrock. Many align with onshore structure both locally and on the grander scale and through 3D reconstruction, we find that a crucial confluence of three discrete trends of lineament converge near Flat Holm and Steep Holm and may represent the pristine Variscan WNW, the Caledonoid NE and pervasive NNW trends. These islands in the estuary are sentinels at a boundary to the hybrid terrane that underlies SE Wales.</p><p>Mesozoic strata of marginal to distal facies, preserved close to negatively inverted faults with partial growth, mark the reactivated stems of Variscan ramps and NE disturbances with significant thrust displacements. We note two phases of negative inversion require restoration in order to reconstruct the orientations within the Variscan basement. In addition, close examination of late (Tertiary) fault history of the estuary is required to adjust basement trends and displacements to get a better sense of rotation within the Palaeozoic foreland.</p><p>Through restoration the new hybrid sub terrane preserves characteristics of Variscan and Caledonoid trending faults and we deduce that a rotation in major thrust trajectory occurred contemporaneously with reactivation of deeper lineaments. This was followed by a structural decapitation as shallow-level thrusts encroached SE Wales, during late stages of the Variscan Orogeny. Finally, the detached stems were incorporated into an imbricate fan which was significantly affected by post-Carboniferous inversion. &#160;&#160;</p><p>&#160;</p><p>&#160;</p>
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