Dolomites of the Boat Harbour Formation in the Northern Peninsula, western Newfoundland, Canada: Implications for dolomitization history and porosity control

Olanipekun, Babatunde-John; Azmy, Karem; Brand, Uwe

doi:10.1306/08281312141

Cited by 24 publications

(66 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such a high water : rock ratio is several orders of magnitude higher than that applicable to dolomitization at the local microenvironment reaction site of the studied dolomite crystals. In addition, a wholesale change in bulk pore fluid composition was not documented for the diagenetic setting of the studied dolomites (Olanipekun et al ., ). Therefore, it is highly unlikely that the core to rim depletion in REEs of the zoned dolomite crystal facies of Main Brook (DZC and IZC) was caused by an equilibration with bulk pore fluids of different REE compositions during precipitation of individual dolomite crystals.…”

Section: Discussionmentioning

confidence: 99%

“…Mid‐stage burial dolomite (hereafter referred to as ‘burial dolomite’) samples P‐154 (depth of 154 m) and P‐158 (depth of 158 m) were taken from drill hole 12P/1‐12 at Main Brook and 6‐172 (depth of 172 m) from drill hole 12i/6‐121 at Daniel's Harbour of the Boat Harbour Formation (Fig. ; Olanipekun et al ., ). The formation contains approximately 40% dolomite (by volume) at Main Brook, while it is completely dolomitized at Daniel's Harbour.…”

Section: Methodsmentioning

confidence: 97%

“…For SIMS analyses, SEM‐CL examination was used as a guide to select core to rim crystal traverses of the representative burial dolomite (Olanipekun et al ., ) crystals from both localities (see Appendix S1 to S3 for indexed beam spots). It was found that core and rim sections of the dolomite crystals from Daniel's Harbour were not distinctively delineated in SEM‐CL.…”

Section: Methodsmentioning

confidence: 99%

“…Locality map of the Boat Harbour Formation and the studied drill holes in western Newfoundland, Canada (modified from Olanipekun et al ., ). Cores from two drill holes were investigated from Main Brook (12P/1‐12; 51°08′23″N; 56°10′54″W) and Daniel's Harbour (12i/6 121; 51°17′46″N; 57°27′22″W) on the Northern Peninsula.…”

Section: Dolomitization Of St George Group Carbonatesmentioning

confidence: 97%

“…This resulted in texturally and compositionally distinct (for example, Table ; Olanipekun et al ., ) dolomites. Dolomitization commenced at the near surface and continued through burial (Azmy et al ., , ; Olanipekun et al ., ).…”

Section: Dolomitization Of St George Group Carbonatesmentioning

confidence: 99%

See 4 more Smart Citations

In situ characterization of dolomite crystals: Evaluation of dolomitization process and its effect on zoning

Olanipekun

Azmy

2017

Sedimentology

Self Cite

View full text Add to dashboard Cite

Dolomitization is a dissolution–re‐precipitation process which proceeds via micrometre‐scale interface reaction horizons. However, the effect 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 (Newfoundland, Canada) from Main Brook and Daniel's Harbour (about 150 km apart) were studied. The investigation used high‐resolution approaches to carry out imaging and elemental analyses of individual dolomite crystals, including scanning electron microscopy, scanning electron microscopy‐based cathodoluminescence, secondary ion mass spectrometry and electron microprobe analysis. The purpose was to better understand geochemical variations across the crystal traverses and their association with dolomite replacement processes and conditions. The scanning electron microscopy‐based cathodoluminescence‐zoning character reveals three major crystal facies. Distinctly (planar boundaries) zoned core and indistinctly zoned core are zoned dolomite crystal facies in burial dolomite from Main Brook. Relatively unzoned crystal facies was identified in that of Daniel's Harbour. Compositionally zoned dolomite crystals are characterized by decreasing Sr, Na, Y and ∑REE but increasing Mn and Fe from core to rim sections. ‘Core to rim’ zoning was not found for major (Mg and Ca) elements. The zoning exhibited by the replacive dolomite crystals is interpreted to be, principally, a result of limited exchange between solutes of the bulk pore fluid and those of dissolving precursor marine carbonate. In tandem with petrographic features, the systematic compositional zoning character demonstrates that the effectiveness of the dolomitization process grades from indistinctly zoned core to relatively unzoned crystal facies via interface reaction horizons. Homogenization of major elements of core and rim sections, seen in distinctly zoned core crystal facies and to a much greater extent in relatively unzoned crystal facies, via a secondary reaction interface, is the first recognized stage of the ‘maturation process’ followed by homogenization of the trace elements seen largely in relatively unzoned crystal facies.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Dolomitization Of St George Group Carbonatesmentioning

confidence: 97%

Section: Dolomitization Of St George Group Carbonatesmentioning

confidence: 99%

See 3 more Smart Citations

In situ characterization of dolomite crystals: Evaluation of dolomitization process and its effect on zoning

Olanipekun

Azmy

2017

Sedimentology

Self Cite

View full text Add to dashboard Cite

show abstract

Multistage dolomitization in the Qal'eh Dokhtar Formation (Middle‐Upper Jurassic), Central Iran: petrographic and geochemical evidence

et al. 2016

View full text Add to dashboard Cite

The late Jurassic Qal'eh Dokhtar Formation lithologically comprises three parts, from bottom to top, a lower sandstone unit, middle shale unit and an upper carbonate unit, which extend in a N–S direction over a wide area to the east of the Shotori Range and west of the Lut Block (Central Iran). This succession was deposited on a mixed carbonate–siliciclastic ramp. Carbonate rocks of the Qal'eh Dokhtar Formation vary from undolomitized, to partly dolomitized, to completely dolomitized. Field observations from two measured sections (the type section, 955 m thick, and the Sorond section, 639 m thick), combined with detailed petrographic and geochemical analyses, revealed the diverse types of dolomite in this formation. Five types of replacement dolomite and one type of dolomite cement were distinguished. Replacement dolomites (RD) consist of: (1) fine crystalline planar‐s (RD1); (2) medium crystalline planar‐s (RD2); (3) medium crystalline planar‐e (RD3); (4) coarse crystalline planar‐s (RD4); and (5) coarse crystalline planar‐e (RD5). Coarse crystalline planar dolomite cements (DC) were observed in low abundance and filling dissolution voids and fractures. Variation in dolomite types is mainly related to early to late diagenetic processes leading to changes in composition of the dolomitizing fluids. Replacement dolomites are non‐stoichiometric (Ca43‐56–Mg34‐45) with Sr, Mn and Fe concentrations of 41–138 ppm, 168–919 ppm and 5000–21000 ppm, respectively. These dolomites are characterized by δ18O values ranging from 0.0 to –11.8 ‰ VPDB and δ13C values of +1.1 to +3.2 ‰ VPDB. These values are depleted in δ18O relative to the postulated values for late Jurassic dolomites precipitated in equilibrium with seawater, while δ13C values are within the range of Jurassic seawater dolomite values. Fluid inclusion data of RD4, RD5 and DC yield homogenization temperatures of 72 to 118 °C. Based on petrographic, fluid inclusion microthermometric data and geochemical results, the replacement dolomites in the Qal'eh Dokhtar Formation are interpreted to have formed in the subsurface at shallow to intermediate burial depths. These dolomites were then recrystallized at increased burial depths and temperatures. Seawater was the major source of Mg2+ for early diagenetic dolomite (DR1), while Mg2+ for late diagenetic dolomites was provided from diagenesis of clay minerals in shales and mechanical compaction of mudstone in the Qal'eh Dokhtar Formation. The dolomite cement is postdated by coarsely crystalline mosaic calcite cement indicating that diagenetic fluids eventually became undersaturated with respect to dolomite and oversaturated with respect to calcite. Copyright © 2016 John Wiley & Sons, Ltd.

show abstract

Hydrocarbon gas leakage from high‐pressure system in the Yanan Sag, Qiongdongnan Basin, South China Sea

Chen

Yang

et al. 2021

Geological Journal

View full text Add to dashboard Cite

Despite high pressure being ubiquitous in the Yanan Sag of the Qiongdongnan Basin, South China Sea, its potential effect on gas migration-accumulation remains unclear.In this study, a series of geochemical indicators combined with the origin of high pressure were used to elucidate the cause of gas accumulation failure in the overpressured YC19-1 structure. Drill-stem tests, mud weights, and well-loggings reveal two vertical overpressure systems. Pore pressure in the deep Lingshui and Yacheng formations almost reaches a lithostatic magnitude, which was interpreted as a result of gas generation and disequilibrium compaction triggered by the Pliocene-Quaternary rapid subsidence. A thermal anomaly above the high-pressure system was evidenced by high homogenization temperature (Th) of fluid inclusion, abnormally high vitrinite reflectance, and a rapid transformation from kaolinite to illite. The high thermal field likely resulted from a cross-stratal fluid migration from the deep high-pressure system. Both methane-bearing inclusions in sandstones and abnormal Rock-Eval data of mudstones above the high-pressure surface suggest an influx of external hydrocarbons. Based on primary aqueous inclusion Th and salinity, carbon and oxygen isotope compositions, and petrographic observations, widespread silica and carbonate cements near the overpressure surface were interpreted to be derived from extraformational materials carried by deep-seated basinal fluids. Fluid inclusion Th coupled with burial model suggests that the gas leakage took place at circa 1.6 Ma, coinciding well with the stages of both gas generation and overpressure.These observations suggest an upward leakage of gas-bearing fluids induced by pressure release, thus leading to the existence of only non-commercial gas-bearing aquifers in the overpressured YC19-1 structure.

show abstract

Dolomites of the Boat Harbour Formation in the Northern Peninsula, western Newfoundland, Canada: Implications for dolomitization history and porosity control

Cited by 24 publications

References 57 publications

In situ characterization of dolomite crystals: Evaluation of dolomitization process and its effect on zoning

In situ characterization of dolomite crystals: Evaluation of dolomitization process and its effect on zoning

Multistage dolomitization in the Qal'eh Dokhtar Formation (Middle‐Upper Jurassic), Central Iran: petrographic and geochemical evidence

Hydrocarbon gas leakage from high‐pressure system in the Yanan Sag, Qiongdongnan Basin, South China Sea

Contact Info

Product

Resources

About