Thermal alteration of terrestrial palynomorphs in mid-Cretaceous organic-rich mudstones intruded by an igneous sill (Newfoundland Margin, ODP Hole 1276A)

Pross, Jörg; Pletsch, Thomas; Shillington, D. J.; Ligouis, Bertrand; Schellenberg, Franziska; J, Kuś

doi:10.1016/j.coal.2006.06.005

Cited by 29 publications

(40 citation statements)

References 21 publications

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“…Vitrinite reflectance and palynomorph data from Site 1276 indicate that thermal alteration affected the sediments only within about 20 m of the sills (Pross et al 2007). However, Peron-Pinvidic et al (2010) found evidence from borehole and seismic reflection data that hydrothermal venting affected more than 500 m of the overlying succession, raising the possibility that fluid flow and heat advection accelerated chemical compaction processes without substantially altering other indicators of thermal maturity.…”

Section: Associations With Geothermal Heat Flow and Crustal Typementioning

confidence: 99%

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Shimeld¹,

Li²,

Chian³

et al. 2015

Geophysical Journal International

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S U M M A R YThe Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity-depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km 2 . The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity-depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity-depth profiles for each seismic trace. A thickness of 12-13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity-depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares favourably with borehole data for Miocene turbidites in the eastern Gulf of Mexico. The station-specific results also indicate that Quaternary sediments coarsen towards the Beaufort-Mackenzie and Banks Island margins in a manner that is consistent with the variable history of Laurentide Ice Sheet advance documented for these margins. Lithological factors do not fully account for the elevated velocity-depth trends that are associated with the southwestern Canada Basin and the Alpha-Mendeleev magnetic domain. Accelerated porosity reduction due to elevated palaeo-heat flow is inferred for these regions, which may be related to the underlying crustal types or possibly volcanic

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Section: Associations With Geothermal Heat Flow and Crustal Typementioning

confidence: 99%

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Shimeld¹,

Li²,

Chian³

et al. 2015

Geophysical Journal International

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“…From the analysis made, four sporomorph groups have been established based on the demonstration in Pross et al (2007). The representative sporomorphs in each group comprised stratigraphically long ranging forms that occurred in high numbers, with high consistency in the samples and are morphologically closely related (similar sporoderm thickness) taxa.…”

Section: Palynologymentioning

confidence: 99%

“…Subsequent to each chemical preparation step, the residues were sieved through a 6 μm nylon mesh using distilled water. To avoid processing-induced bleaching of the sporomorphs, no oxidation was performed (Pross et al,2007). If large amounts of clay minerals were present, sieving and separation in ZnBr was jgg.ccsenet.org…”

Section: Palynologymentioning

confidence: 99%

“…Visual colour analysis were later carried out on the sporomorphs recovered based on a visual comparison with the Munsell colour standards as suggested by Pearson (1984) in Pross et al, (2007).…”

Section: Palynologymentioning

confidence: 99%

“…To do this, we compared our sporomorphs data with and guided by the methods outlined in Pross et al(2007) to show that this method is applicable as it corroborates with calculated Vitrinite Reflectance from Rock-Eval Pyrolysis analyses carried earlier on these sediments.…”

Section: Introductionmentioning

confidence: 99%

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Spores and Pollen Colour Changes and Thermal Maturation of Mid-Cretaceous Lacustrine Organic-rich Sediments in the Mamfe Basin, S.W. Cameroon

Njoh¹,

Atud²

2017

JGG

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Repeated palynological analyses of samples collected from lacustrine black organic rich shales and carbonate rocks which are abound in the Mamfe Basin have consistently yielded extremely low count of palynomorphs. Geochemical analysis of the same rocks revealed very high Total Organic Carbon (TOC) content of up to 16.10wt%, whereas similar rocks elsewhere as expected, yielded high abundance and diversity of palynomorphs. Several geologic factors involved in the burial history of sedimentary rocks may account for this low sporomorphs count, however, microscopic analyses of the changes in their colour, provides a quick and relatively cheap approach by which the thermal alteration of the sediments can be reconstructed. Palynomorphs data from this and previous studies of the same sediments were compared and confirmed to be very poor in abundance however, the few recognizable species undoubtedly permitted the assignment of an Albian-Turonian age to these sediments under study. Spore-pollen colour variation (Munsell colour standards) has proven to have a positive correlation with thermal alteration hence, sediments and organic matter maturation. Using a three sporomorph group (SG) that include: (1) leiotrilete spores of the genera Cyathidites, Deltoidospora, Dictyophyllidites, Gleicheniidites, and Leiotriletes (SG-1) with sporoderm thicknesses <1μm, 1-1.5μm and >1.5μm, respectively); (2) trilete, regulate spores of the genus Lycopodiacidites (SG-2); (3) trilete, striate spores of the genus Cicatricosisporites (SG-3); and (4) the gymnosperm-pollen taxon Classopollis torosus (SG-4). Results show here that the colour index varied from 2.5 to 5.0, indicating low to high maturity with Kerogen types I, II and III corresponding to a paloetemparature range of 60 to 140 o C for an estimated stratigraphic interval of 1000 to 3000m in the Mamfe Basin.

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Ligouis

2017

Archaeological Soil and Sediment Micromorphology

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Thermal alteration of terrestrial palynomorphs in mid-Cretaceous organic-rich mudstones intruded by an igneous sill (Newfoundland Margin, ODP Hole 1276A)

Cited by 29 publications

References 21 publications

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

Spores and Pollen Colour Changes and Thermal Maturation of Mid-Cretaceous Lacustrine Organic-rich Sediments in the Mamfe Basin, S.W. Cameroon

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