Palynological, geochemical, and mineralogical characteristics of the Early Jurassic Liasidium Event in the Cleveland Basin, Yorkshire, UK

This is the final version. Available on open access from Borntraeger Science Publishers via the DOI in this record.A previously proposed hyperthermal episode in the Early Jurassic (mid- Sinemurian) is investigated from the shallow marine succession at Robin Hood’s Bay, Cleveland Basin, Yorkshire, UK. Palynological study confirms that the stratigraphical extent of the distinctive dinoflagellate cyst Liasidium variabile corresponds very closely to the oxynotum Zone. The range of Liasidium variabile also corresponds to an overall negative excursion in carbon-isotopes measured in bulk organic matter, which here exhibits a double spike in the middle oxynotum Zone. Additionally, Liasidium variabile abundances track overall transgressive-regressive facies trends with peak abundance of dinoflagellate cysts corresponding to deepest water facies and maximum flooding. Lithological cycles (parasequences), defined by visual description and hand-held X-ray fluorescence analysis of powdered samples, match previously suggested short eccentricity cycles, and allow a total duration for the event of at least one million years to be suggested. Changes in clay mineralogy throughout the section determined by whole rock X-ray diffraction and scanning electron microscopy are shown to be largely related to authigenic 33 processes, and neither support nor refute the proposition of coeval palaeoclimate changes. The combined characteristics of the Liasidium Event described from Robin Hood’s Bay are similar to, but much less extreme than, the Early Jurassic Toarcian Oceanic Anoxic Event albeit, at this locality, there is no evidence for the development of significant bottom water deoxygenation.Natural Environment Research Council (NERC)University of OxfordBritish Geological Survey (BGS)Leopoldina, German National Academy of Science

Geochemistry of macrofossil, bulk rock and secondary calcite in the Early Jurassic strata of the Llanbedr (Mochras Farm) drill core, Cardigan Bay Basin, Wales, UK

This is the final version. Available on open access from the Geological Society via the DOI in this recordData availability: All data generated during this study are included in the Supplementary information files for this article.The Llanbedr (Mochras Farm) core (Wales, UK) yielded a >1300 m long mudrock sequence that has excellent potential for establishing an integrated stratigraphic scheme for the entire Early Jurassic Epoch. Lithological variations in the core are predominantly driven by hierarchical changes in the carbonate content. These changes also dominate – or may impact upon – many geochemical and physical properties of the core. The bulk carbonate C isotope record displays systematic fluctuations, the largest of which correspond to previously identified phases of environmental perturbation. The magnitudes of negative C isotope excursions in carbonate are inflated compared with equivalents previously described elsewhere as a result of diagenesis and the concomitant loss of primary carbonate. The marine macrofossil record of Mochras reveals biological and isotopic patterns that are generally comparable with other UK basins. Potentially significant differences between the Cleveland and Cardigan Bay basins are observed in the Pliensbachian and Toarcian fossils. This different expression may be related to different habitat structures or palaeoceanographic and water depth differences between these basins. Minima in macrofossil δ18O values generally coincide with peaks in macrofossil wood abundance and sea-level lowstands inferred from sequence stratigraphic interpretation of other UK sections. This relationship suggests a possible relative sea-level control on the observed O isotope records and sediment provenance.Natural Environment Research Council (NERC

A single multi-scale and multi-sourced semi-automated lineament detection technique for detailed structural mapping with applications to geothermal energy exploration

This is the author accepted manuscript. The final version is available on open access from the Geological Society via the DOI in this recordData availability: The bathymetry data used in this study have been sourced from the UK Hydrographic Office and accessed via the Admiralty Marine Data Portal. The LiDAR data used in this study have been sourced from the Centre for Ecology and Hydrology. The British Geological Survey is thanked for making the BGS Geology 625k (DiGMapGB- 625), BGS Geology 250k (DiGMap250k) and BGS Geology 50k (DiGMapGB-50) data available on an Open Government Licence.Semi-automated algorithms incorporating multi-sourced datasets into a single analysis are increasingly common, but until now operate at a fixed pixel resolution resulting in multi-sourced methods being limited by the largest input pixel size. Multi-scale lineament detection circumvents this issue and allows increased levels of detail to be captured. We present a semi-automated method using a bottom-up Object-Based Image Analysis approach to map regional lineaments to a high level of detail. The method is applied to onshore LiDAR data and offshore bathymetry around the Land's End Granite (Cornwall, UK). The method uses three different pixel resolutions to extract detailed lineaments across a 700 km2 area. The granite displays large-scale NW-SE fault zones that are considered analogous to those being targeted as onshore deep geothermal reservoirs (2-5 km in depth). Investigation of the lineaments derived from this study show along-strike variations from NW-SE orientations within granite to NNW-SSE within slate and reflect structural inheritance of early Variscan structures within Devonian slates. This is furthered by analysing these major structures for reservoir potential. Lineaments proximal to these broadly NW-SE features indicate a damage zone approximately 100-200 m wide is present. These observations provide a preliminary understanding of reservoir characteristics for fault-hosted geothermal systems.Natural Environment Research Council (NERC

The Cyclostratigraphy Intercomparison Project (CIP): consistency, merits and pitfalls

Cyclostratigraphy is an important tool for understanding astronomical climate forcing and reading geological time in sedimentary sequences, provided that an imprint of insolation variations caused by Earth’s orbital eccentricity, obliquity and/or precession is preserved (Milankovitch forcing). Numerous stratigraphic and paleoclimate studies have applied cyclostratigraphy, but the robustness of the methodology and its dependence on the investigator have not been systematically evaluated. We developed the Cyclostratigraphy Intercomparison Project (CIP) to assess the robustness of cyclostratigraphic methods using an experimental design of three artificial cyclostratigraphic case studies with known input parameters. Each case study is designed to address specific challenges that are relevant to cyclostratigraphy. Case 1 represents an offshore research vessel environment, as only a drill-core photo and the approximate position of a late Miocene stage boundary are available for analysis. In Case 2, the Pleistocene proxy record displays clear nonlinear cyclical patterns and the interpretation is complicated by the presence of a hiatus. Case 3 represents a Late Devonian proxy record with a low signal-to-noise ratio with no specific theoretical astronomical solution available for this age. Each case was analyzed by a test group of 17-20 participants, with varying experience levels, methodological preferences and dedicated analysis time. During the CIP 2018 meeting in Brussels, Belgium, the ensuing analyses and discussion demonstrated that most participants did not arrive at a perfect solution, which may be partly explained by the limited amount of time spent on the exercises (∼4.5 hours per case). However, in all three cases, the median solution of all submitted analyses accurately approached the correct result and several participants obtained the exact correct answers. Interestingly, systematically better performances were obtained for cases that represented the data type and stratigraphic age that were closest to the individual participants’ experience. This experiment demonstrates that cyclostratigraphy is a powerful tool for deciphering time in sedimentary successions and, importantly, that it is a trainable skill. Finally, we emphasize the importance of an integrated stratigraphic approach and provide flexible guidelines on what good practices in cyclostratigraphy should include. Our case studies provide valuable insight into current common practices in cyclostratigraphy, their potential merits and pitfalls. Our work does not provide a quantitative measure of reliability and uncertainty of cyclostratigraphy, but rather constitutes a starting point for further discussions on how to move the maturing field of cyclostratigraphy forward

Pleosporales

One hundred and five generic types of Pleosporales are described and illustrated. A brief introduction and detailed history with short notes on morphology, molecular phylogeny as well as a general conclusion of each genus are provided. For those genera where the type or a representative specimen is unavailable, a brief note is given. Altogether 174 genera of Pleosporales are treated. Phaeotrichaceae as well as Kriegeriella, Zeuctomorpha and Muroia are excluded from Pleosporales. Based on the multigene phylogenetic analysis, the suborder Massarineae is emended to accommodate five families, viz. Lentitheciaceae, Massarinaceae, Montagnulaceae, Morosphaeriaceae and Trematosphaeriaceae

Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic

This is the final version. Available on open access from Copernicus Publications via the DOI in this recordData availability: Full core scan data (https://doi.org/10.5285/91392f09-25d4-454c-aece-56bde0dbf3ba, BGS Core Scanning Facility, 2022) will be available after 1 November 2024 via the Natural Environment Research Council (NERC) National Geoscience Data Centre (https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#, last access: 12 October 2023). Downhole logging data (https://doi.org/10.5880/ICDP.5065.001​​​​​​​, Wonik, 2023) will be made available via the ICDP (https://www.icdp-online.org/projects/by-continent/europe/jet-uk/, last access: 12 October 2023). The JET Operational Report is published as Hesselbo et al. (2023); full information about the operational dataset, the logging dataset, data availability and the explanatory remarks is available on the ICPD-JET project website: https://www.icdp-online.org/projects/by-continent/europe/jet-uk/ (last access: 12 October 2023). A subset of data, additional biostratigraphic tables, and vector graphics files for Figs. 3–5 are included as the Supplement. Supplementary Data File 1 tabulates the corrected depth scale for Prees 2C. Supplementary Data File 2 summarizes the ammonite-based chronostratigraphy of the Prees 2 cores (ammonite identifications by Kevin N. Page). Supplementary Data File 3 summarizes the ammonite-based chronostratigraphy for the Hettangian to Early Pliensbachian of the Llanbedr (Mochras Farm) borehole (updated by Kevin N. Page). Supplementary Data File 4 tabulates the organic carbon-isotope ratios, TOC, and carbonate content of low-resolution samples taken at the Prees drill site; TOC and carbonate data are calculated using calibration based on portable XRF (Supplementary Data File 5) and a gas source isotope ratio mass spectrometer (Supplementary Data File 6). Supplementary Data File 5 tabulates portable XRF results for bulk rock powders of low-resolution samples taken at the Prees drill site; uncertainties stated in the table are given for the fit to the raw data and do not reflect the true reproducibility of the data. Empty fields indicate values under the detection limit. Sample SSK116001 acted as a repeat sample which was measured 70 times over the course of the data acquisition to determine the repeatability and drift of the instrument. LE stands for “light elements”. Supplementary Data File 6 tabulates gas source isotope ratio mass spectrometry (GS-IRMS) data (oxygen- and carbon-isotope ratios of carbonate as well as carbonate content calculated as calcite) for a set of 24 samples covering the entire core length and reflecting a representative spread of carbonate content. Comparison of GS-IRMS data with p-XRF data was used to create a calibration curve to calculate the carbonate (and TOC) content of all low-resolution samples. Supplementary Data File 7 tabulates pyrolysis data (Rock-Eval 6) for Prees 1 well cuttings and Wilkesley borehole samples. Supplementary Data File 8 contains vector graphics files (.svg) for Figs. 3–5.Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.ICDPNatural Environment Research Council (NERC)German Research FoundationHungarian Scientific Research FundNational Science Centre, PolandPolish Geological Institut