Karem Azmy

Memorial University of Newfoundland · Department of Earth Sciences

The Jurassic–Cretaceous boundary is the only Phanerozoic period-level boundary that lacks a golden spike on the geological timescale despite significant global geological and environmental change during this time related to the opening of the Atlantic Ocean. Paleoenvironmental proxy profiles (total organic carbon, δ³⁴S, δ¹⁵N, Fe, Mn, Ce/Ce*, Th/U,...

The CO2-gas reservoirs have been recorded in many petroliferous basins worldwide. However, the impact of deep inorganic CO2 influx on reservoir quality has received little attention. Here, a new set of mineralogical and geochemical data collected from the Lower Cretaceous Quantou Formation sandstones in the southern Songliao Basin are presented to...

The Archaeocyathid Extinction Carbon Isotope Excursion (AECE) and Mingxinsi Carbon Isotope Excursion (MICE) are major events in the Early Cambrian sedimentary records but controversially heterogeneous in their magnitudes, as well as local and global correlations. This paper presents a high-resolution δ13Ccarb profile from the Shiliu section in the...

The Green Point Formation in western Newfoundland, GSSP of the Cambrian-Ordovician (Є-O) boundary, is dominated by slope rhythmites of alternating lime mudstone and shale interbeds. This formation was deposited in a semi-restricted basin with varying connectivity to the open ocean. In the current study, we investigate textures and bulk δ34S signatu...

The main exploration targets for hydrocarbons in the Niger Delta Basin are within the Agbada sandstone reservoirs. The current study utilizes a multi-technical approach (SEM-MLA, SEM-EDS, XRD and LA-ICP-MS) to evaluate the roles of framework composition and diagenetic processes, particularly calcite cementation on reservoir quality in Miocene inter...

Abstract The lower part of the Martin Point section (∼ 110 m - rhythmites) spans the uppermost Shallow Bay and lowermost Green Point formations (uppermost Franconian–lowermost Trempealeauan) of the Cow Head Group (western Newfoundland, Canada). It records two post-SPICE (Steptoean Positive Carbon Isotope Excursion) events marked by negative δ13Cca...

The early Paleozoic witnessed two spectacular radiations of marine organisms—the Cambrian (Є) Explosion and the Great Ordovician (O) Biodiversification Event. However, the period between them was characterized by a marine biodiversity plateau attributed to recurring biocrises. In the current study, we present the I/Ca records from slope lime mudsto...

The 8# coal seam in the Benxi Formation of the southeastern margin of the Ordos Basin is a deep coal seam with abundant coalbed methane resources. Calcite veins are commonly developed within the 8# coal seam, and their formation processes and mechanisms have significant implications for the enrichment of deep coalbed methane. Genesis of the calcite...

The Middle−Upper Xixiangchi Formation of the Sichuan Basin consists of mixed carbonates and siliciclastics. The carbonates are dominated by dolomitized lime-mudstones and dolo–grainstones of shallow warm-water environments. Petrographic examination of carbonates reveals two types of dolomite: (i) fabric retentive dolomicrite (D1, micritic to near-m...

The SPICE (Steptoean Positive Carbon Isotope Excursion) is a significant event in the Late Cambrian, recording global carbon cycle perturbations. Its driving mechanism is still controversial, but mainly believed to be related to an increase of organic carbon burial caused by ocean anoxia. The shallow-water platform carbonates of the Upper Cambrian...

The Ben Nevis sandstones in the Jeanne d’Arc Basin in offshore eastern Newfoundland have abundant carbonate cements, and are the primary hydrocarbon reservoirs of the White Rose Oilfield. A multiapproach of petrographic, carbon and oxygen isotopic, and in situ geochemical analyses were applied to investigate the origin of the carbonate cements in t...

The composition of formation waters in the Dongying Depression provide important clues about regional water-rock interactions. Chemical analysis (181 samples) of formation waters form the Shahejie Fm (58 wells) in the Niuzhuang oilfield suggest two main geochemical facies, the chloride-magnesium (Cl–Mg) and bicarbonate-sodium (HCO3–Na) facies (pH =...

The higher abundance of dolomite in the Neoproterozoic compared with that of the Phanerozoic has been linked to elevated marine Mg/Ca ratios, and a hypothesized ‘dolomite sea’ that promoted widespread syn‐sedimentary fibrous dolomite cement precipitation. This article provides new uranium–lead (U–Pb) chronology, clumped isotope thermometry (TΔ47),...

The mechanism of fault-controlled hydrothermal dolomitization has long been controversial due to its complicated tectonic and diagenetic conditions, especially for the source of dolomitizing fluids and its hydrological driving models. In the southeastern Sichuan Basin, fracture-related dolomite bodies are well developed in a Middle Permian carbonat...

The lacustrine mixed rocks, which are composed of detrital, carbonate, and volcanic materials, have increasingly attracted attention due to their association with significant oil and gas occurrences. Their complex compositions influence the diagenetic products and consequently reservoir quality. The current study critically reviews diagenesis of mi...

The Green Point Formation (GPF) of the Cow Head Group in western Newfoundland (Canada) includes the Global Boundary Stratotype Section and Point (GSSP) for the Cambrian-Ordovician (Є-O) boundary on Laurentia. This formation is composed primarily of thick, deep subtidal to slope deposits (rhythmites) of alternating lime mudstones and shale interbeds...

The Early-Middle Permian δ 13 C carb variations are recorded by the marine carbonates of the Luduba section in the northern margin of the South China Block. The investigated interval (~ 300 m) spans the Chihsia and Maokou formations. Preservation of the investigated micritic carbonates was evaluated by multiple petrographic and geochemical screenin...

The oil-bearing layer in the first member of the Upper Cretaceous Yaojia Formation (K2y¹) in the middle of the Changling Sag of the southern Songliao Basin, northeast China, has low-permeability and is deemed to be an unconventional reservoir. Therefore, better evaluation of reservoir quality and related controlling factors are crucial for the redu...

Diagenetic carbonate cements occur throughout Eocene turbidite lithic arkose in Niuzhuang sag, eastern China, displaying as sporad-ical siderite, dolomite, calcite 1, and massive ankerite and calcite 2. Petrographic and geochemical investigations suggest that the non-ferroan calcite 1 (d 13 C carbonate (carb) +3.1‰ to +4.7‰ Vienna Pee-dee belemnite...

Lithium has proven a powerful tracer of weathering processes and chemical seawater evolution. Skeletal components of marine calcifying organisms, and in particular brachiopods, present promising archives of Li signatures. However, Li incorporation mechanisms and potential influence from biological processes or environmental conditions require a car...

The investigated Middle–Upper Cambrian carbonates span, from bottom to top, the uppermost Hawke Bay (40 m), the March Point (∼83 m thick), and the lowermost Petit Jardin (∼47 m) formations of the Port au Port Group (western Newfoundland, Canada). A multi-technique evaluation of the preservation of carbonates was applied by using several petrographi...

The Bathonian-Callovian (Middle Jurassic) Dorgali Formation in eastern Sardinia (Italy) consists of dolomitized oolitic grainstone and records a complex diagenetic history. Petrographic examinations revealed three main phases of replacive (D1, D2) and fracture-filling (D3) dolomites with crystal-size ranges of <4–50 μm (dolomicrite to dolomicrospar...

Petrographic and in situ geochemical analyses were carried out on cores of the fluvial sandstone (<50 to >4 mm; sublithic quartz arenite) dominated Tithonian Jeanne d’Arc Formation interval from wells C-09 and E-79 of the Terra Nova oilfield to understand diagenetic control on reservoir quality of the formation. Lithic clasts are dominantly carbona...

The subsurface distribution of carbonate cements in sandstones is cornerstone in understanding the fluid regime and origin of cements to shed the light on hydrocarbon migration. Petrography, cuttings, cores, well logs, and seismic data were integrated to better understand the distribution of carbonate cements in the Eocene turbidite-delta sandstone...

The examined interval of the March Point and Petit Jardin formations (total thickness ∼130 m) spans the Middle−Upper Cambrian (lower Port au Port Group) at the Belle Isle Strait, western Newfoundland. The deposits consist of dolomitized shallow-water carbonates ranging from microbial mudstones to oolitic grainstones. A multi-technique evaluation pr...

Geochemical signatures of siliciclastic rocks constituting the sedimentary fill of a basin can provide useful clues for constraining sedimentary processes. The inorganic geochemical composition of interbedded sandstone and shale in hydrocarbon-producing zones of the Agbada Formation (Niger Delta Basin) were used as proxies to determine the provenan...

Middle Permian ⁸⁷Sr/⁸⁶Sr variations are recorded by the marine carbonates in the Qianfo section and the Yundadi3 well in the Sichuan Basin of the Yangtze Platform, China. Petrographic and geochemical examinations of micritic carbonates confirmed the preservation of near-primary ⁸⁷Sr/⁸⁶Sr signatures that can be utilized to construct a reliable high-...

The Middle and Upper Cambrian Port au Port Group of western Newfoundland consists mainly of mixed carbonates and siliciclastics and is composed of the March Point, Petit Jardin, and Berry Head formations. Samples were collected from the core NF-02 that spans the uppermost Hawke Bay (40 m), the March Point (∼83 m thick) and the lowermost Petit Jardi...

The Tithonian Vaca Muerta Formation (500 m-thick marine carbonates) in the Pampa de Tril area is a potential unconventional hydrocarbon reservoir but earlier studies rarely focused on its diagenetic history. It constitutes the upper part of the lower Mendoza Group in the Neuquén Basin, western Argentina. Petrographic examinations reveal four genera...

The Tithonian Vaca Muerta Formation (500 m-thick marine carbonates) in the Pampa de Tril area is a potential unconventional hydrocarbon reservoir but earlier studies rarely focused on its diagenetic history. It constitutes the upper part of the lower Mendoza Group in the Neuqu´en Basin, western Argentina. Petrographic examinations reveal four gener...

The radiogenic strontium isotope (⁸⁷Sr/⁸⁶Sr) system is a powerful tool for constraining sea‐level change and palaeoclimatic variations as well as tectonic activities. The Permian is a period that records the lowest seawater Sr‐isotopic ratios in the Earth's history. The near‐primary geochemical signatures retained in the micritic carbonates of the...

Geochemical signatures of sedimentary rocks provide reliable proxies that allow a better understanding of sedimentary processes. The geochemical compositions of Awgu Shale (southern Benue Trough) and Enugu Shale (Anambra Basin), south-eastern Nigeria, were investigated to appraise the degree of source area weathering and reconstruct the provenance...

The petrographic, cathodoluminescence (CL), stable isotope, and microthermometry investigation of inner platform facies of the pervasively dolomitized carbonate platform of the Norian (Upper Triassic) Dolomia Principale (Southern Alps, N Italy) identified two major dolomite phases. An early replacement fabric-retentive dolomite (D1 and D2, respecti...

A preliminary enhanced oil recovery (EOR) screening was completed for the Ben Nevis Formation, Hebron Field, offshore Canada. Polymer flooding was determined to be the most viable methodology, based on the oil and reservoir properties and known challenges with respect to sourcing potential injection gas. Digital image analysis and microscopic petro...

A succession of tight-oil mixed siliciclastic-volcaniclastic sandstones (MSVS) deposited in the Lower Cretaceous in the Erlian Basin has increasingly attracted attention for its significant discovery of oil and gas. The mixed compositions have a significant influence on diagenesis and reservoir properties. Understanding the relationship between lit...

In the early 1950’s, McCrea and Epstein and co-workers laid the foundation for the oxygen isotope-based thermometers. Many variations of the thermometer have been since formulated based on synthetic and biogenic carbonates. Overall, the use and application of oxygen isotope thermometers must consider and be specific as to the mineralogy, and whethe...

The Martin Point section (western Newfoundland, Canada) spans the uppermost Cambrian Broom Point and Martin Point members of the Green Point Formation (upper Furongian). The investigated interval (~90 m) consists of rhythmites of thinly‐bedded marine carbonates (lime mudstones) alternating with green and black shale and thin conglomerate beds. Samp...

The species of the brachiopod Gigantoproductus are giants within the Palaeozoic sedentary benthos. This presents a dilemma as living brachiopods have low‐energy lifestyles. Although brachiopod metabolic rates were probably higher during the Palaeozoic than today, the massive size reached by species of Gigantoproductus is nevertheless unusual. By ex...

The bedding-parallel fibrous calcite veins in black shales are common in sedimentary basins and retain significant information about shale diagenesis and organic matter evolution. However, the origin of the bedding-parallel fibrous calcite veins in black shales is still of great controversy. Carbonaceous black shales of Es4s–Es3x interval are the m...

Dalmanelloid brachiopod shells were collected from the Upper Ordovician Lexington Formation (lower Katian) of Kentucky, Sheguindah Shale (middle Katian) on Manitoulin Island, Ontario, and the Stony Mountain Formation (upper Katian) in the Winnipeg area, Manitoba. They were investigated to test the hypothesis of paleo-latitudinal zonation of the she...

The δ ¹³ C profile from the lower interval of the Martin Point section in western Newfoundland (Canada) spans the Upper Cambrian (uppermost Franconian – lowermost Trempealeauan). The investigated interval (∼110 m) is a part of the Green Point Formation of the Cow Head Group and consists of the upper part of the Tucker Cove Member (topmost part of t...

Carbon-isotope stratigraphy of the Furongian (stage 10; Upper Cambrian) and Tremadocian (lowermost Ordovician) reveals distinct variations from the carbonates of the Berry Head and Watts Bight formations of the East Isthmus Bay section that accumulated in a shallow-marine setting on the eastern Laurentian platform in a passive margin setting in wes...

The δ ¹³ C profile from an interval of the Martin Point section in western Newfoundland (Canada) spans the upper Furongian (uppermost Cambrian). The interval (~90 m) is a part of the Green Point Formation of the Cow Head Group and consists of the Martin Point (lower) and the Broom Point (upper) members. It is formed of slope marine carbonates alter...

Secondary ion mass spectrometry (SIMS) was used to measure the δ³⁴S of pyrite disseminated in burial dolomite matrix of Boat Harbour formation at Main Brook and Daniel’s Harbour (about 130 km apart). At Main Brook, δ³⁴S values for the pyrite grains show wide variation (–15 to +20‰ (n = 20)), but are mostly negative. Combined with a paucity of two-p...

Dolomitization is a dissolution–re-precipitation process which proceeds via micrometre scale interface reaction horizons. However, the effect(s) of this fundamental local medium of replacement process on precipitated dolomite crystals is rarely investigated. For this purpose, dolomite samples of Ordovician Boat Harbour Formation carbonates (Newfoun...

Widespread application of the novel clumped isotope paleothermometer (Δ47) using dolomite samples from shallow crustal settings has been hindered by a lack of adequate constraints on clumped isotope systematics in dolomites that formed at temperatures greater than 50 °C. Consequently, many high-temperature applications involving diagenetic dolomite...

The Upper Devonian Kettle Point Formation of southwestern Ontario is characterized by intervals of organic-rich interlaminated black shale interbedded with organic-poor greyish green mudstones and rare red beds, separated by metre-scale sequences of non-interlaminated black shale. The formation shows a largely consistent background value for the bl...

Variations in environmental physicochemical parameters result in corresponding changes in seawater rare earth element (REE) distributions. For an archive to be utilized in paleoceanographic and paleoenvironmental reconstructions, it should record these variations. Therefore, an archive's proxy potentiality should be assessed analogous to modern oce...

The cause for the end Permian mass extinction, the greatest challenge life on Earth faced in its geologic history, is still hotly debated by scientists. The most significant marker of this event is the negative δ13C shift and rebound recorded in marine carbonates with a duration ranging from 2000 to 19 000 years depending on localities and sediment...

The Lower Head Formation in the Parson’s Pond area (western Newfoundland, Canada) comprises siltstones with very fine grained to fine-grained sandstones. Petrography confirms that these sandstones are matrix rich, essentially wackes, with detrital minerals including quartz, feldspar, biotite, and numerous accessory minerals. Observed petrographic f...

The Kettle Point Formation of southwestern Ontario consists of intervals of organic-rich interlaminated black shale interbedded with organic-poor greyish green mudstones and rare red beds, separated by metre-scale sequences of noninterlaminated black shale. The formation shows a largely consistent background value for the black shales around −20‰ σ...

The Flemish Pass Basin is a deep-water basin located offshore on the continental passive margin of the Grand Banks, eastern Newfoundland, which is currently a hydrocarbon exploration target. The current study investigates the petrographic characteristics and origin of carbonate cements in the Ti-3 Member, a primary clastic reservoir interval of the...

The end of the Permian was a time of great death and massive upheaval in the biosphere, atmosphere and hydrosphere. Over the last decades, many causes have been suggested to be responsible for that catastrophe such as global warming, anoxia and acidification. The Gyanyima limestone block was an open ocean seamount in the southern Neotethys at subtr...

The Hebron Project is the fourth major offshore development in the province of Newfoundland and Labrador, with an estimated 2620 MBO in place and 800 MBO recoverable. Hebron Field oil and reservoir properties are similar to previous successful offshore polymer flooding projects. However, the formation water salinity, which is greater than 60,000 pp...

Despite the recent interest in black shales as alternative hydrocarbon reservoirs, the ancient depoformational environments of these rocks remains enigmatic due in large part to a lack of modern analogs. This study aims to help elucidate the mechanisms behind the deposition of black shales by using the Upper Devonian Kettle Point Formation, located...

The Green Point Formation of the Cow Head Group in western Newfoundland (Canada) represents the Global Stratotype Section and Point (GSSP) for the Cambrian–Ordovician boundary on Laurentia. The formation consists of the Martin Point (lower) and the Broom Point (upper) members, which constitute a thick (~ 170 m) deep subtidal to slope marine carbona...

Despite recent interest in black shales as hydrocarbon reservoirs, the depositional environments of these rocks remain enigmatic. This study aims to help elucidate the mechanisms and factors behind the deposition of black shales by conducting lithological and geochemical analyses on an Upper Devonian black shale in southwestern Ontario, the Kettle...

Dolomite rocks are very important hydrocarbon reservoirs. However, besides the fact that the mode of dolomite formation is not fully understood, the origin of porosity associated with dolomitization remains, to some extent, a matter of debate. Study of porosity in dolomites is commonly focused on micrometer (greater than tens of micrometer) scale i...

Dolomite is an important hydrocarbon reservoir but its origin and mechanism of formation remains a hot debate. Recrystallization to more stoichiometric dolomite is usually accompanied by characteristic textural and geochemical signatures.These factors are primarily studied using multiple populations of crystals, comparison of modern and ancient dol...

The Boat Harbour Formation constitutes the upper part of the Lower Ordovician St. George Group on the Northern Peninsula, western Newfoundland. It ranges in thickness from 140 m (459 ft) at Main Brook to 96 m (315 ft) at Daniel's Harbour. Dolomitization of the carbonate sequence is more pervasive in the lower 30 to 40 m (98 to 131 ft) at Main Brook...

The Carboniferous North Brook Formation (western Newfoundland, Canada) consisting of fluvial/lacustrine arkosic litharenites has undergone two cementation cycles. The first cycle comprises chlorite followed by minor quartz and calcite. Mono-phase aqueous fluid inclusions hosted in first-cycle calcite reflect precipitation in a near-surface meteoric...

A new Re–Os radiometric age date for an organic-rich shale horizon from the Vazante Group in Brazil, coupled with geological observations, provide evidence for late Mesoproterozoic glacial episodes, conflicting with the general view of greenhouse conditions marked by a eustatic high stand at this time. Field observations of a reverse fault juxtapos...

Diagenetic evaluation of the Pennsylvanian Bird Spring Formation, Arrow Canyon, Nevada (U.S.A.) involved the detailed petrographic and geochemical examination of its brachiopod and whole rock components. δ13C, δ18O and 87Sr/86Sr of whole rock (WR) statistically (p = 0.0001) do not agree with isotope values of coeval brachiopod low-Mg calcite (LMC)....

Isotope curves delineating δ13Ccarb and δ16O variations across the Cambrian–Ordovician boundary at Green Point, western Newfoundland (Canada) are presented. The δ13Ccarb profile of the section reveals a composite (three peaks) negative shift of ~6.0 ‰ and starts immediately at the base of bed 23 of the Broom Point Member. The 13Ccarb profile ties t...