Ernest Chi Fru

Cardiff University | CU · School of Earth and Environmental Sciences

Debates on the formation of banded iron formations in ancient ferruginous oceans are dominated by a dichotomy between abiotic and biotic iron cycling. This is fuelled by difficulties in unravelling the exact processes involved in their formation. Here we provide fossil environmental evidence for anoxygenic photoferrotrophic deposition of analogue b...

Protection against arsenic damage in organisms positioned deep in the tree of life points to early evolutionary sensitization. Here, marine sedimentary records reveal a Proterozoic arsenic concentration patterned to glacial-interglacial ages. The low glacial and high interglacial sedimentary arsenic concentrations, suggest deteriorating habitable m...

Significance Redox-sensitive transition metals and their isotopes provide some of the best lines of evidence for reconstructing early Earth’s oxygenation history, including permanent atmospheric oxygenation following the Great Oxidation Event (GOE), ∼2.45−2.32 Ga. We show a shift from dominantly negative to permanently positive copper isotope compo...

Significance The 2.1 billion-year-old sedimentary strata contain exquisitely preserved fossils that provide an ecologic snapshot of the biota inhabiting an oxygenated shallow-marine environment. Most striking are the pyritized string-shaped structures, which suggest that the producer have been a multicellular or syncytial organism able to migrate l...

The Great Oxidation Event (GOE) at 2.45 Ga facilitated the global expansion of oxidized compounds in seawater. Here, we demonstrate that the GOE coincided with a sharp increase in arsenate and arsenic sulfides in marine shales. The dramatic rise of these oxygen-sensitive tracers overlaps with the expansion of key arsenic oxidants, including oxygen,...

The Tibetan Plateau is a key region to understand the evolution of the Tethys Oceans. To better constrain the tectonic evolution of the Proto-Tethys Ocean on the western margin of the Yangtze plate, we present an integrated petrography, geochemistry, and zircon U-Pb-Lu-Hf isotope study on newly recognized early Silurian gabbro and serpentinite rock...

Bound to the north by the Sahara and to the south by the Sudanian savannah, watersheds in the African Sahelian belt supply food and water to an estimated 135 million people. Being one of the Earth's most vulnerable zones to climate change impacts, the Sahel covers a 3.1 million km2 corridor from the Atlantic Ocean in the west to the Red Sea in the...

Banded iron formations (BIFs) are important sedimentary rocks used for reconstructing the geochemical and environmental evolution of Precambrian Earth surface conditions. Here, we describe the oldest BIFs of Meso- archean age in the Yemadong Formation, and their implications for paleo-environmental evolution of the Mesoarchean Ocean in the northern...

The Moroccan High Atlas (MHA) hosts phosphate-rich sediments extending from the Maastrichtian to Lutetian based on pioneering biostratigraphic data. Recently, calcareous nannoflora allowed refining of the biostratigraphy in the lower to middle part of the studied Amizmiz sequence (western MHA) with calcareous nannofossil Zones (correlated to the fo...

Emerging evidence suggests that U-Pb and Lu-Hf ages of sedimentary apatite group minerals are often younger than their biostratigraphic ages. However, U-Pb dating of exquisitely preserved carbonate fluorapatite (CFA) is rare. The Upper Cretaceous/Paleogene marine sedimentary rocks of the Moroccan High Atlas host phosphate-rich sediments bracketed b...

The Anti-Atlas belt of Morocco preserves exceptional record of an Ediacaran microbial biosphere. The Amane Tazgart Formation of the Ouarzazate Group consist of an Ediacaran volcanic alkaline lake depositional system (ca. 571 Ma) were microbial buildups accreted in an extreme environment. These microbial accumulations are exceptional not only for th...

Accelerated precipitation of Mn-rich rocks in the early Paleoproterozoic ocean is considered to reflect the irreversible rise of oxygen in the atmosphere during the Great Oxidation Event (GOE), 2.501–2.220 billion years ago. But the precipitation conditions, pathways, mechanisms, and linkages to ocean redox, broadly remain unresolved. The Lagoa do...

Competition shapes evolution. Toxic metals and metalloids have exerted selective pressure on life since the rise of the first organisms on the Earth, which has led to the evolution and acquisition of resistance mechanisms against them, as well as mechanisms to weaponize them. Microorganisms exploit antimicrobial metals and metalloids to gain compet...

Talk is available here -> https://www.youtube.com/watch?v=2e2sf7-dzcY

Coming soon

EAG blog for June 2021

The Paleoproterozoic Lagoa do Riacho manganese deposit in the Borborema Province is central to unravelling the genesis of Paleoproterozoic manganese deposits, Paleoproterozoic redox evolution and genetic relationship to the West African Craton. With manganese contents averaging 35 wt%, the Lagoa do Riacho manganese unit is lithologically subdivided...

Emerging evidence suggests widespread ferruginous marine conditions promoted global seawater phosphate depletion and the maintenance of a low oxygen world at the start of the Neoproterozoic Era. However, the large-scale deposition of marine sedimentary Fe formations, as observed in the Paleoproterozoic, is rare in the early Neoproterozoic Era. We s...

The coexistence of motile macroorganisms and mat-building cyanobacteria in the Paleoproterozoic FB 2 Member of the Franceville sub-basin, Gabon, points to the possible emergence of multi-trophic-level biological interaction by 2.1 billion years (Ga) ago. However, it is uncertain how these shallow-marine communities acquired and cycled nitrogen, a k...

Find here - https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Paper/7356

The Ediacaran period coincides with the emergence of ancestral animal lineages and cyanobacteria capable of thriving in nutrient deficient oceans which together with photosynthetic eukaryotic dominance, culminated in the rapid oxygenation of the Ediacaran atmosphere. However, ecological evidence for the colonization of the Ediacaran terrestrial bio...

Hydro-geochemical data are required for understanding of water quality, provenance, and chemical composition for the 2,117,700 km2 Niger River Basin. This study presents hydro-geochemical analysis of the Benue River Basin, a major tributary of the Niger River. The distribution of major ions, Si, δD, and δ18O, trace and rare-earth elements (TE and R...

The proposed Special Issue emphasizes the powerful role of microbial biomineralization in low-temperature ore genesis. It highlights crucial questions to enable a wide and truly interdisciplinary viewpoint, by combining concepts and new high-resolution methods from different areas, e.g., geochemistry, mineralogy, biology, to build a comprehensive p...

Understanding microbial mediation in sediment-hosted Mn deposition has gained importance in low-temperature ore genesis research. Here we report Mn oxide ores dominated by todorokite, vernadite, hollandite, and manjiroite, which cement Quaternary microbially induced sedimentary structures (MISS) developed along bedding planes of shallow-marine to t...

The proposed Special Issue emphasizes the powerful role of microbial biomineralization in low-temperature ore genesis. It highlights crucial questions to enable a wide and truly interdisciplinary viewpoint, by combining concepts and new high-resolution methods from different areas, e.g., geochemistry, mineralogy, biology, to build a comprehensive p...

Identification of terrestrial hydrothermal processes, as signals of volcanic unrest or causes of explosive volcanic behaviour, is crucial in volcanic hazard assessment. However, the role of hydrothermal processes in triggering volcanic hazards in the marine environment remain poorly understood, hindering effective assessment. Hydrothermal vents in...

The sedimentary fabrics of Precambrian mat-related structures (MRS) represent some of the oldest convincing evidence for early life on Earth. The ca. 2.1 billion-year (Ga) old MRS in the FB2 Member of the Francevillian basin in Gabon has received considerable attention not only because they contain remnants of microbial mats that colonized large ar...

Hydrogeochemical data are required for understanding of water quality, provenance and chemical composition for the 2,117,700 km2 Niger River Basin. This study presents hydrogeochemical analysis of the Benue River Basin, a major tributary of the Niger River. The distribution of, major ions, Si, δD and δ18O, Trace and Rare Earth Elements (TE and REEs...

The production of H2 in hydrothermal systems and subsurface settings is almost exclusively assumed a result of abiotic processes, particularly serpentinization of ultramafic rocks. The origin of H2 in environments not hosted in ultramafic rocks is, as a rule, unjustifiably linked to abiotic processes. Additionally, multiple microbiological processe...

1. Summary of Fluid Inclusion Microthermometry for the Cape Vani Fe-Ba-Mn deposit. 2. SIMS analyses of S isotopes in barite, Cape Vani ore deposit. 3. SIMS analyses of O isotopes in barite, Cape Vani ore deposit.

Copper (Cu) has two isotopes: 63Cu and 65Cu. Both are stable, with natural abundances of 69.174% and 30.826%, respectively (Albarède 2004). The distribution of these Cu isotopes in nature is defined by the equation: δ65Cu = [(65Cu/63Cu)sample/(65Cu/63Cu)standard − 1] × 1000.

With fluoride-rich groundwater causing a climatic-dependent fluorosis in Mayo-Tsanaga River Basin, the overall objective of this study was to reduce fluoride concentrations in drinking water to acceptable levels thereby improving the resilience of the population to this climate change induced pathology. The specific objectives were to: (1) assess w...

A combined study of major ions, δ18O, δD, 13C, 87Sr/86Sr isotopes, X-ray diffraction, scanning electron microscopy, and electron probe microanalyses on springs and spring mineral precipitates along the Cameroon Volcanic Line (CVL) was undertaken to understand water chemistry, and infer the type and origin of the precipitates. The waters are of evap...

The toxicity of arsenic (As) towards life on Earth is apparent in the dense distribution of genes associated with As detoxification across the tree of life. The ability to defend against As is particularly vital for survival in As-rich shallow submarine hydrothermal ecosystems along the Hellenic Volcanic Arc (HVA), where life is exposed to hydrothe...

The toxicity of arsenic (As) towards life on Earth is apparent in the dense distribution of genes associated with As detoxification across the tree of life. The ability to defend against As is particularly vital for survival in As-rich shallow submarine hydrothermal ecosystems along the Hellenic Volcanic Arc (HVA), where life is exposed to hydrothe...

Supplementary Material

The 2.1‐billion‐year‐old (Ga) Francevillian series in Gabon hosts some of the oldest reported macroscopic fossils of various sizes and shapes, stimulating new debates on the origin, evolution and organization of early complex life. Here, we document ten representative types of exceptionally well‐preserved mat‐related structures, comprising “elephan...

An early Quaternary shallow submarine hydrothermal iron formation (IF) in the Cape Vani sedimentary basin (CVSB) on Milos Island, Greece, displays banded rhythmicity similar to Precambrian banded iron formation (BIF). Field-wide stratigraphic and biogeochemical reconstructions show two temporal and spatially isolated iron deposits in the CVSB with...

Field Photographs and Lithostratigraphic Sections

Pyrite from ancient hydrothermal ore deposits commonly shows coupled geochemical behaviour of Au and As, and spatial decoupling between Au-As rich areas and Cu contents [1,2,3]. Both speciation (solid solution Au 1+ vs. native Au 0 nanoinclusions) and concentration of Au are thought to be strongly dependent on the incorporation of As into the pyrit...

Banded iron formations (BIF) are proxies of global dissolved inorganic phosphate (DIP) content in Precambrian marine waters. Estimates of Precambrian DIP rely on constraining the mechanisms by which Fe(III) (oxyhydr)oxides scavenge DIP in NaCl solutions mimicking elevated Precambrian marine Si and Fe(II) concentrations. The two DIP binding modes su...

Banded Iron Formations (BIF) with interlayered chert bands common in the Archean and Proterozoic stratigraphy can be used to investigate Precambrian oceanic conditions and Si isotope systematics. Constraining the sources of Si in the BIF-related chert bands (i.e. continentally weathered or hydrothermally supplied Si) and the mechanisms through whic...

An Early Quaternary shallow submarine hydrothermal iron formation (IF) in the Cape Vani sedimentary basin (CVSB) on Milos Island, Greece, displays banded rhythmicity similar to Precambrian banded iron formation (BIF). Sedimentary, stratigraphic reconstruction, biogeochemical analysis and micro-nanoscale mineralogical characterization confirms the M...

The seafloor sediments of Spathi Bay, Milos Island, Greece, are part of the largest arsenic-CO2-rich shallow submarine hydrothermal ecosystem on Earth. Here, white and brown deposits cap chemically distinct sediments with varying hydrothermal influence. All sediments contain abundant genes for autotrophic carbon fixation used in the Calvin-Benson-B...

Methane and nitrous oxide are potent greenhouse gases (GHGs) that contribute to climate change. Coastal sediments are important GHG producers, but the contribution of macrofauna (benthic invertebrates larger than 1 mm) inhabiting them is currently unknown. Through a combination of trace gas, isotope, and molecular analyses, we studied the direct an...

An Early Quaternary shallow submarine hydrothermal iron formation (IF) in the Cape Vani sedimentary basin (CVSB) on Milos Island, Greece, displays banded rhythmicity similar to Precambrian banded iron formation (BIF). Previously published data, together with new stratigraphic reconstruction, biogeochemical analysis and micro-nanoscale mineralogical...

A potential target setting for Europe to secure sustainable access to precious and modern technology metal resources is modern sea-floor massive sulfides (SMS) located on submarine arc-volcanoes. EPMA and LA-ICP-MS analyses of SMS from Kolumbo, the only known SMS deposits associated with thinned continental margin volcanism [1], show that pyrite, g...

Pyrite from ancient hydrothermal ore deposits commonly shows spatial decoupling between Au, Cu and As contents, however investigations into this process in modern sea-floor massive sulphides is lacking [1, 2]. LA-ICP-MS minor metal(loid) analysis of early primary colloform pyrite (Py1), recrystallized sub-to euhedral pyrite (Py2) and associated sul...

Climate and human-induced environmental change promote biological regime shifts between alternate stable states, with implications for ecosystem resilience, function, and services. While these effects have been shown for present-day ecosystems, the long-term response of microbial communities has not been investigated in detail. This study assessed...

Subaerial exposure and oxidation of organic carbon (Corg)-rich rocks is believed to be a key mechanism for the recycling of buried C and S back to Earth’s surface. Importantly, processes coupled to microbial Corg oxidation are expected to shift new biomass δ13Corg composition towards more negative values relative to source. However, there is scarci...

Quantitative PCR data, coupled to sediment geochemistry highlights a situation where arsenotrophy and arsenic detoxification covary with high affinity phosphate uptake genes as a function of the degree of hydrothermal influence, Spathi bay, Milos Island, Greece..

Arsenate and phosphate are chemically very similar and therefore tend to substitute each other in biological and non-biological molecules. However, the various chemical forms of arsenic are toxic to cells while phosphate is an essential nutrient. It is therefore important to understand the relationship between arsenic and phosphorus cycling in the...