A5010653213- Geology and Paleoclimatology Research
- Paleontology and Stratigraphy of Fossils
- Geological formations and processes
- Hydrocarbon exploration and reservoir analysis
- Geological and Geophysical Studies
- Geological and Geophysical Studies Worldwide
- Geological and Geochemical Analysis
- Methane Hydrates and Related Phenomena
- Hydrology and Sediment Transport Processes
- Karst Systems and Hydrogeology
- Paleontology and Evolutionary Biology
- Marine Biology and Ecology Research
- Geochemistry and Geologic Mapping
- Pleistocene-Era Hominins and Archaeology
- earthquake and tectonic studies
- Soil erosion and sediment transport
- Archaeological and Geological Studies
- Marine and coastal plant biology
- Clay minerals and soil interactions
- Building materials and conservation
- Calcium Carbonate Crystallization and Inhibition
- Groundwater and Isotope Geochemistry
- Reservoir Engineering and Simulation Methods
- Geochemistry and Elemental Analysis
- Marine and environmental studies
Cardiff University
2004-2024
National Museum Wales
2014-2023
BG Group (United Kingdom)
2004-2018
University of Wales
1997-2002
University of Reading
1989-1997
University of Oregon
1990
University of Bristol
1985-1988
The Open University
1982-1985
Hong Kong Metropolitan University
1983
Abstract The cyclic distribution of various types carbonates and Mg-clays in early Cretaceous rift-sag phase lacustrine from the subsurface South Atlantic provides an insight into how evolving lake chemistries highly alkaline settings control facies development. typically subdecametre scale symmetrical asymmetrical cyclothems exhibit three main components: mud-grade laminated carbonates, millimetre-diameter spherulites with evidence having been a matrix Mg-silicates, millimetre–centimetre...
Palaeosols (fossil soils) are abundant in the alluvial late Silurian–early Devonian Moor Cliffs Formation and Rat Island Mudstone (Freshwater West Formation) of south Dyfed, South Wales. The palaeosols occur thick mudstones deposited on floodplains under a seasonal, semi-arid climate, represent Vertisol-type soils. Simple, single profiles rare most mudstone intervals exhibit complex overprinted profiles. However, major difference exists between palaeo-Vertisols each two units studied....
ABSTRACT Paleosols in the Lower Carboniferous limestones of South Wales commonly contain needle‐fibre calcite which is an unusual form recently shown to by calcification fungal hyphae present day soils. The occurs two associations paleosols: as coatings on sediment grains and rhizocretions. former can be compared with microbial grain Quaternary calcretes. latter represent sites coats roots are interpreted probable ectomycorrhizae, a symbiotic sheath‐root association. These findings suggest...
ABSTRACT Laminar calcretes are described from the Lower Carboniferous of South Wales, Upper Jurassic southern England and Jurassic‐Lower Cretaceous northern Spain. They interpreted as calcified root‐mats (horizontal root systems) compared with other examples in geological record possible modern analogues. All three occurrences consist virtually identical, centimetre to decimetre‐thick, locally organic carbon‐rich, laminar micrites containing up 50% by volume millimetre‐sized typically...
Abstract The relatively simplistic facies models for lacustrine carbonates do not currently incorporate either the diversity of microbialite carbonate development or influence volcanic-related processes found in rift settings. basic nature factories these systems, whether microbial, macrophytic, skeletal abiogenic, is resolved. Lacustrine microbialites can develop shallow lakes as concentrations mounds covering many hundreds square kilometres, bathymetrically controlled belts, but settings...
Abstract The lacustrine carbonate reservoirs of the South Atlantic host significant accumulations chemically reactive and Al-free Mg-silicate minerals (e.g. stevensite, kerolite talc). Petrographic data from units such as Cretaceous Barra Velha Formation in Santos Basin suggest that strongly influenced, perhaps created, much observed secondary porosity. diagenetic interactions between sediments are, however, poorly known. Here we develop a conceptual model for origin porosity guided by...
Research Article| September 01, 2000 Missing molluscs as evidence of large-scale, early skeletal aragonite dissolution in a Silurian sea Lesley Cherns; Cherns 1Department Earth Sciences, Cardiff University, Box 914, CF10 3YE, UK. Also at BG International, 100 Thames Valley Park Drive, Reading RG6 1PT, UK Search for other works by this author on: GSW Google Scholar V. Paul Wright Geology (2000) 28 (9): 791–794. https://doi.org/10.1130/0091-7613(2000)28<791:MMAEOL>2.0.CO;2 Article history...
Studies of depth sensitive carbonate successions in the UK indicate that regular, orbitally forced glacio-eustatic sea-level oscillations, which characterized late Palaeozoic, started abruptly around 330 Ma (early Asbian). The Gondwanan ice sheet was highly to variations solar insolation and resultant oscillations had an approximate 100 ka periodicity. fossil soils palaeokarst from low latitude settings suggest pre-Asbian climates were relatively stable with infrequent changes. However,...
ABSTRACT During early Carboniferous times a major sea‐level rise led to the development of an extensive carbonate ramp over what is now South Wales. Differential subsidence and changes resulted in distinctive facies sequences succession model offered which recognizes three distinct geomorpho‐tectonic settings; inner, mid‐ outer ramp. The inner zone occurs more landward part province was area undergoing little or no subsidence. sequence dominated by oolitic grainstones peritidal limestones...
Abstract Current classifications of carbonate platforms use depositional gradient as the main criterion for separating systems into two end-member types, ramps and flat-topped (FTPs). However, many examples do not conform to this simple classification. To investigate why is better understand probable controls on platform development, we have used a series 2D numerical forward model runs how sediment production, diffusional transport, other such tectonic subsidence, antecedent topography,...
Abstract During the Aptian (Cretaceous), in what is now South Atlantic, largest chemogenic (abiotic) carbonate factory so far identified Phanerozoic geological record developed as a vast hyper‐alkaline lake system. This covered at least 330 000 km 2 , producing carbonates, locally over 500 m thick, are offshore Santos and Campos basins (Brazil), Kwanza Basin (Angola). Current evidence supports view that almost all of this was origin, precipitated from hyper‐alkaline, shallow waters, probably...
The current understanding of the origins modern carbonate muds and their early stages transformations are reviewed. fine-grained nature such sediments makes them susceptible to intensive structural chemical alteration at relatively shallow burial depths driven especially by mineral instability under microbially mediated reactions within sediment associated with decay organic matter. Whereas transformation high Mg calcite (HMC) low magnesian (LMC) generally takes place incongruently in situ,...