Mike Rogerson

Northumbria University · Department of Geography and Environment

Travertine-depositing hot springs can generate various carbonate minerals with or without the participation of microorganisms. They thus serve as good natural laboratories to study abiotic and biotic factors controlling the precipitation of different carbonate minerals and CaCO3 polymorphism. Through tens of years' investigations on travertines, co...

Continental carbonates constitute an interesting topic of study since they are important archives recording climate and paleoenvironmental changes. In Tunisia, calcretes are formed during the Pliocene-early Pleistocene (Villafranchian). They mainly occur in the center and on the coastal plainof Djeffara (Southern East) while their presence is more...

This study aims to compare the fabrics of anthropogenic carbonates downstream of lime and steel disposal sites with models of carbonate precipitation from natural systems to elucidate potential drivers, precipitation mechanisms, morphological similarities, predictability in 3D facies distributions and depositional models of these systems. For this...

The influence of extracellular polymeric substances on carbonate mineral growth in natural settings remains one of the most poorly understood contributors to the growth of non-marine carbonate sediments. The influences of these materials are complicated by their association with living cells creating local microenvironments via metabolism and enzym...

Ancient and recent terrestrial carbonate-precipitating systems are characterised by a heterogeneous array of deposits volumetrically dominated by calcite. In these environments, calcite precipitates display an extraordinary morphological diversity, from single crystal rhombohedral prisms, to blocky crystalline encrustations, or spherulitic to dendr...

Ancient and recent terrestrial carbonate-precipitating systems are characterised by a heterogeneous array of deposits volumetrically dominated by calcite. In these environments, calcite precipitates display an extraordinary morphological diversity, from single crystal rhombohedral prisms, to blocky crystalline encrustations, or spherulitic to dendr...

Lacustrine non-skeletal carbonates exhibit a diversity of petrographies due to interactions between physico-chemical and biologically influenced mechanisms. Despite the suggestion that evaporative concentration was involved in the formation of spherulite and shrubby-bearing carbonate successions in the Pre-Salt Cretaceous alkaline lakes of the Sout...

The tufa deposits in the Kurkur–Dungul area, southern Egypt, date from marine isotope stage (MIS) 11 to MIS 1. Springs across the region were active during glacial periods (with sea-level below –50 m), reflecting changed atmospheric circulation over the Indian Ocean, as well as peak interglacial periods. During times of low sea-level, reduced Indon...

This data set file contains stable and clumped isotope data of calcareous tufa samples collected from the Kurkur-Dungul area (Southern Egypt) and provides further analytical information about laboratory standards, standard deviations as well as GPS coordinates, short description, mineralogy and age data of the stuided tufa samples. The data set is...

O ver the last decennia, alkaline leachates from the weathering of legacy steel slag disposal sites have affected the surrounding soils and drainage streams. The hyperalkaline and hypersaline conditions around these sites are comparable to extreme paleo environments such as alkaline lakes in rift volcanic settings. Investigating the carbonate depos...

This paper presents a route for the treatment of MSWI fly (FA) and bottom ashes (BA) using microorganisms to critically assess whether bioleaching is within reach of effective industrial application. The leaching of metals from BA and FA was investigated in a controlled laboratory environment using a culture isolated from a natural system where the...

With an estimated annual production of two billion tonnes globally, alkaline industrial wastes can be considered both major global waste streams, and materials that offer significant options for potential resource recovery. Alkaline wastes are usually derived from high temperature production (e.g. steel and alumina) or disposal (e.g. incineration)...

The South Atlantic Aptian "Pre-salt" shrubby carbonate Formations of Brazil and Angola are of major interest for the oil industry due to their potential hydrocarbon accumulations. Although the general sedimentology of these deposits is associated to saline, alkaline lakes in rift volcanic settings, the specific genesis of shrubby carbonate morpholo...

We report a new fluid inclusion dataset from northeastern Libyan speleothem SC-06-01, which is the largest speleothem fluid inclusion dataset for North Africa to date. The stalagmite was sampled in Susah Cave, a low-altitude coastal site, in Cyrenaica, on the northern slope of the Jebel Al-Akhdar. Speleothem fluid inclusions from the latest Marine...

The South Atlantic Aptian “Pre-Salt” shrubby carbonate successions offshore Brazil and Angola are of major interest due to their potential hydrocarbon accumulations. Although the general sedimentology of these deposits is widely recognized to be within saline, alkaline lakes in rift volcanic settings, the specific genesis of shrubby carbonate morph...

Constructed wetlands can treat highly alkaline leachate resulting from the weathering of steel slag before reuse (e.g. as aggregate) or during disposal in repositories and legacy sites. This study aimed to assess how metal(loid)s soluble at high pH, such as arsenic (As), chromium (Cr), and vanadium (V) are removed in constructed wetlands and how th...

We report a new fluid inclusion dataset from Northeast Libyan speleothem SC-06-01, which is the largest speleothem fluid inclusion dataset for North Africa to date. The stalagmite was sampled in Susah cave, a low altitude coastal site, in Cyrenaica, on the northern slope of the Jebel Al-Akhdar. Speleothem fluid inclusions from latest Marine Isotope...

ABSTRACT Current understanding of sapropel formation in the Mediterranean suggests a combination of anoxia and enhanced primary productivity. Enhanced anoxia should have resulted from freshwater input most likely triggered by the northward expansion of the African monsoon during the last interglacial when sapropels S5, S4 and S3 formed at ~125 ka,...

Steelmaking wastes stored in landfill, such as slag and spent refractory liners, are often enriched in toxic trace metals (including V). These may become mobile in highly alkaline leachate generated during weathering. Fresh steelmaking waste was characterised using XRD, XRF, and SEM-EDX. Batch leaching tests were performed under aerated, air-exclud...

Management of steel slag (a major by-product of the steel industry) includes the treatment of highly alkaline leachate (pH > 11.5) from rainwater infiltration of slag deposits to prevent adverse impact upon surface or ground waters. This study aims to compare different treatment options for steel slag leachate through a life cycle assessment (LCA)....

Vanadium is a toxic metal present in alkaline leachates produced during the weathering of steel slags. Slag leaching can therefore have deleterious effects on local watercourses due to metal toxicity, the effects of the high pH (9 – 12.5) and rapid carbonation (leading to smothering of benthic communities). We studied the fate and behaviour of V in...

PURPOSE There is a need for an efficient technology that overcomes environmental and financial constraints associated with massive production of solid incineration end-products, i.e., fly ash (FA) and bottom ash (BA) from Municipal solid waste incineration (MSWI). Therefore, a bio-assisted approach has been tested using different experimental setup...

Lacustrine carbonate chimneys are striking, metre‐scale constructions. If these were bioinfluenced constructions, they could be priority targets in the search for early and extraterrestrial microbial life. However, there are questions over whether such chimneys are built on a geobiological framework or are solely abiotic geomorphological features p...

Continental carbonate deposition represents an important archive for the determination of climate changes (Marinova et al., 2014). Indeed, calcrete crusts have a wide geographical spread in many Mediterranean regions, where they constitute the Plio-Pleistocene boundary marker. However, the climatic significance of this important stratigraphic Forma...

Alkalinity generation and toxic trace metal (such as vanadium) leaching from basic oxygen furnace (BOF) steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5-...

The management of alkaline (pH 11–12.5) leachate is an important issue associated with the conditioning, afteruse or disposal of steel slags. Passive in-gassing of atmospheric CO2 is a low cost option for reducing Ca(OH)2 alkalinity, as Ca(OH)2 is neutralised by carbonic acid to produce CaCO3. The relative effectiveness of such treatment can be aff...

Current understanding of sapropel formation in the Mediterranean suggests a combination of anoxia and enhanced primary productivity. Enhanced anoxia should have resulted from freshwater input most likely triggered by the northward expansion of the African monsoon during the last interglacial when sapropels S5, S4 and S3 formed at ~125 ka, ~105 ka a...

The South Atlantic Aptian ‘Pre-salt’ reservoirs are formed by a combination of spherulitic carbonates and Mg-rich clays accumulated in volcanic alkaline lake settings with exotic chemistries. So far, outcrop analogues characterised by metre-thick successions deposited in lacustrine scenarios are elusive so disentangling the genesis of spherulitic c...

Lacustrine carbonate deposits with spherulitic facies are poorly understood, but are key to understanding the economically important “Pre-Salt” Mesozoic strata of the South Atlantic. A major barrier to research into these unique and spectacular facies is the lack of good lacustrine spherulite-dominated deposits which are known in outcrop. Stratigra...

Phase diagrams are extremely powerful interpretive tools for converting qualitative observations about a sediment into quantitative constraints on the environment in which it was deposited. We present a new phase diagram for growth forms in non-marine calcite sediments, showing the competing influence of the chemical " driving force " (saturation i...

Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative averag...

We present the first speleothem-derived central North Africa rainfall record for the last glacial period. The record reveals three main wet periods at 65-61 ka, 52.5-50.5 ka and 37.5-33 ka that lead obliquity maxima and precession minima. We find additional minor wet episodes that are synchronous with Greenland interstadials. Our results demonstrat...

Bauxite residue is an important by-product of the alumina industry, and current management practices do not allow their full valorisation, especially with regard to the recovery of critical metals. This work aims to test the efficiency of ion exchange resins for vanadium (V) removal and recovery from bauxite residue leachates at alkaline pH (11.5 a...

Current understanding of sapropel formation in the Eastern Mediterranean suggests a combination of anoxia and enhanced primary productivity. Enhanced anoxia is thought to have resulted from freshwater input into the Eastern Mediterranean most likely originating from the Nile and from wadis draining Saharan lakes. We investigated Mediterranean sedim...

The origin of spherical-radial calcite bodies – spherulites – in sublacustrine, hyperalkaline and saline systems is unclear, and therefore their palaeoenvironmental significance as allochems is disputed. Here, we experimentally investigate two hypotheses concerning the origin of spherulites. The first is that spherulites precipitate from solutions...

Around two billion tonnes of alkaline residues are produced globally each year by industries such as steel production, alumina refining and coal-fired power generation, with a total production estimate of 90 billion tonnes since industrialisation. These wastes are frequently stored in waste piles or landfills, and can be an environmental hazard if...

The ability to distinguish the features of a chemical sedimentary rock that can only be attributed to biology is a challenge relevant to both geobiology and astrobiology. This study aimed to test criteria for recognizing petrographically the biogenicity of microbially influenced fabrics and fossil microbes in complex Quaternary stalactitic carbonat...

The role of extracellular polymeric substances (EPS) and aminoacids in the nucleation of calcium carbonate spherulites and associated carbonate species is well-known, but still poorly constrained. Moreover, alkaline and saline lacustrine carbonate environments are also prone to generate authigenic hydrated magnesium clays (stevensite group). Here w...

Although carbonate spherulites are well known to form in a wide range of carbonate environments, the environmental conditions that underpin their origin are poorly constrained. To understand the sedimentology of spherulitic carbonate deposits, we must disentangle the chemistry and origin of the water involved in the precipitation of these sort of f...

It is widely agreed that stable oxygen isotope values in riverine carbonates can represent near-equilibrium isotopic conditions once the resurgent spring water has equilibrated with atmospheric carbon dioxide. The concept that these deposits offer an attractive complementary climate archive to speleothems is well established. However, oxygen isotop...

Understanding the geochemical origin and timing of formation of unusual non-marine carbonate precipitates formed in highly alkaline and saline sublacustrine settings is a hot topic of research in carbonate sedimentol-ogy. The East Kirkton Limestone (West Lothian, Lower Carboniferous, Scotland) is constituted by an interesting array of uncommon fres...

Non-marine carbonates comprise a hugely diverse family of deposits, which reflect a constellation of forcing factors from local hydraulics to regional climatology. However, the two dominant controls on precipitation are solution chemistry and benthic microbial biogeochemistry. Here, we present a unifying concept for understanding how these controls...

We present results from in vitro flask and flume experiments using freshwater biofilms sourced and cultivated from a mine-impacted stream in North Yorkshire, UK. Flask experiments showed rapid uptake of Zn from the water column into biofilms. This uptake was not light dependant and suggests that chelation of Zn by negatively charged functional grou...

The ratio of magnesium to calcium (Mg/Ca) in carbonate minerals in an abiotic setting is conventionally assumed to be predominantly controlled by (Mg/Ca)solution and a temperature dependant partition coefficient. This temperature dependence suggests that both marine (e.g. foraminiferal calcite and corals) and freshwater (e.g. speleothems and surfac...

Determining the processes which generate terrestrial carbonate deposits (tufas, travertines and to a lesser extent associated chemical sediments such as calcretes and speleothems) is a long-standing problem. Precipitation of mineral products from solution reflects a complex combination of biological, equilibrium and kinetic processes, and the diffe...

Sahara rivers in Google Earth from PLOS ONE publication "Were Rivers Flowing across the Sahara During the Last Interglacial? Implications for Human Migration through Africa"

We demonstrate that changes in the behavior of the Mediterranean Outflow Water (MOW) prior to and through the last deglaciation played an important role in promoting Meridional Overturning Circulation (MOC). Estimation of past MOW salt and heat fluxes indicates that they gradually increased through the last deglaciation. Between 17.5 and 14.6 thous...

Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palae...

Determining the processes which generate terrestrial carbonate deposits (tufas, travertines and associated chemical sediments) is a long-standing problem. Deposition of mineral products from solution reflects a complex combination of biological, equilibrium and kinetic processes, and the differences in products these processes produce are yet to be...

Recent studies have shown up to 6 % of rivers in England and Wales to be impacted by discharges from abandoned metal mines. Despite the large extent of impacts, there are still many areas where mine water impact assessments are limited by data availability. This study provides an overview of water quality, trace element composition and flux arising...

The Mediterranean Sea provides a major route for heat and freshwater loss from the North Atlantic and thus is an important cause of the high density of Atlantic waters. In addition to the traditional view that loss of fresh water via the Mediterranean enhances the general salinity of the North Atlantic, and the interior of the eastern North Atlanti...

The Gibraltar Exchange regulates the amount of water supplied to the Mediterranean to balance net evaporation, but also the a major term in the of buoyancy (i.e., heat and freshwater) budget of the North Atlantic Ocean. As such, it is a critical term to determine in order for the palaeoceanographic behaviour of two ocean basins to be understood. We...

Two stalagmites, SLO-1 and SLO-2, collected from Postojna cave, Slovenia show very high growth rates (~0.28mmyr-1), and grew to impressive lengths - SLO-1 measures 2.2m (2200mm) and SLO-2 measures 1.38m (1380mm). This record is constrained by U-Th and α-mass spectrometry dates collected on both stalagmites, indicating growth between 16 and 0.6ka BP...

Past changes in the density and momentum structure of oceanic circulation are an important aspect of changes in the Atlantic Meridional Overturning Circulation and consequently climate. However, very little is known about past changes in the vertical density structure of the ocean, even very extensively studied systems such as the North Atlantic. H...

Palaeoceanography relies on the assumption that parameters measureable in sediment cores correlate reliably to hydrographic parameters. Areas of dynamic watermass mixing, which generally have steep hydrographic gradients, therefore provide both a tempting target (large spatial and temporal differences in temperature and salinity) and a significant...

Past changes in the density and momentum structure of oceanic circulation are an important aspect of changes in the Atlantic Meridional Overturning Circulation and consequently climate. However, very little is known about past changes in the vertical density structure of the ocean, even very extensively studied systems such as the North Atlantic. H...