The Environmental Setting of Early Carboniferous Mud‐Mounds

Bridges, P. H.; Gutteridge, P.; Pickard, Neil A. H.

doi:10.1002/9781444304114.ch6

Cited by 50 publications

(48 citation statements)

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“…The mounds present within both the Monsal Dale and Eyam Limestone formations are the Type 3 build-ups (crinoid-brachiopod-fenestrate bryozoan) described by Bridges et al (1995). They are, therefore, not Waulsortian type mounds which were described in Dove Dale at the platform edge by Bridges & Chapman (1988).…”

Section: Stratigraphy and Lithofaciesmentioning

confidence: 99%

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Nolan

Angiolini

Jadoul

et al. 2017

PYGS

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A sedimentological study was conducted at two localities exposing the Mississippian Eyam Limestone Formation of the Derbyshire carbonate platform, UK. Ricklow Quarry comprises seven facies with diverse skeletal assemblages, representing deposition on the inner to middle ramp within open marine waters. Once-a-Week Quarry comprises four facies, dominated by crinoidal debris representing deposition on the inner ramp. Both localities expose Gigantoproductus shell beds. Palaeoecological analysis of a single shell bed from each locality enabled investigation of the rapid colonization and success of this taxon on the platform. At Ricklow Quarry, on the eastern side of a localized mud mound, both life (>72% of thin and thick-shelled brachiopods in life position) and neighbourhood assemblages are present. A low-moderate diversity community (<1.37 and <0.8 Shannon diversity index) rapidly established over relict Brigantian mud mounds. Shell beds are preluded by intervals of decreased energy that allowed larvae to settle. Once established, the dominance of thick-shelled individuals enabled baffling, potentially providing localized shelter for larvae and nearby individuals. At Once-a-Week Quarry, where no mud mound is present, only thick-shelled Gigantoproductus species and a low diversity community (<1.07 Shannon diversity index) exclusively comprising neighbourhood assemblages (37% in life position) is present. The presence of inactive mud mounds at Ricklow Quarry appears to have been the key to the success of Gigantoproductus species enabling the onset of stable communities in the shelter provided by the relict mound. Once the first palaeocommunities were established, larvae dispersed and colonized higher energy settings, such as at Once-a-Week Quarry.

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Section: Stratigraphy and Lithofaciesmentioning

confidence: 99%

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Nolan

Angiolini

Jadoul

et al. 2017

PYGS

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“…Although they consist mainly of fine-grained carbonate they have, however, represented a habitat for a large variety of sessile organisms. Impressive examples of mud mounds have been described from Ordovician (Ross et al, 1975;Vennin et al, 1998), Silurian (Bourque and Gignac, 1983;De Freitas and Dixon, 1995) and Devonian settings (Brachert et al, 1992;Wendt et al, 1997;Kaufmann, 1998), but this type of buildup is most widespread in the Early Carboniferous, in particular, in the Waulsortian facies of England, Ireland and Belgium (Bolton et al, 1982;Lees, 1988;Bridges et al, 1995). The name is derived from the village of Waulsort in the Dinant Syncline of southern Belgium and has subsequently been applied to similar constructions in other parts of the world, including the United States and Canada.…”

Section: Introductionmentioning

confidence: 99%

An exhumed Palaeozoic underwater scenery: the Visean mud mounds of the eastern Anti-Atlas (Morocco)

Wendt

Kaufmann

Bełka

2001

Sedimentary Geology

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About one hundred carbonate mud mounds, covering an area of 440 km 2 in the eastern Anti-Atlas of Morocco, constitute one of the largest mound agglomerations known so far from Lower Carboniferous settings. They occur within a 4000-m-thick succession of shales with intercalated bedded limestones, sandstones, and siltstones. According to conodont and goniatite biostratigraphy, mound formation started in the early Gnathodus texanus Zone and terminated during the G. bilineatus Zone of the Visean stage. Individual mounds are a few metres to 30 m high, have base diameters of up to 300 m and are concentrated in several parallel, WNW -ESE running belts. From their lithology and facies relationships, four types of mounds can be distinguished: (1) massive crinoidal wacke-or packstones without stromatactis; (2) massive crinoidal wacke-or packstones with rare stromatactis; (3) similar to (2), but allochthonous; and (4) biodetrital (skeletal) grainstone mounds. While carbonate deposition in types (1) to (3) was probably triggered by microbial precipitation, type (4) is the result of a predominantly mechanical accumulation of skeletal debris. Biota in the four types comprise a great variety of invertebrates, among which crinoids, sponges, and bryozoans are most common. Diagenesis of the mound carbonates was dominated by recrystallization of micritic matrix and organic remains and late burial cementation. Oxygen and carbon isotope data of brachiopod and crinoid ossicles, matrix, and early marine cements plot in a large field and do not allow definite conclusions about the composition of the ambient seawater. Microbial activity and the absence or scarcity of green algae, colonial corals and coralline sponges suggest deposition of the mounds in moderate water depth close to the lower limit of the photic zone. D

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“…This resulted in a configuration with carbonate build-ups developing on the footwall block, while hanging-wall blocks were filled by deeper water slope deposits ( Fig. 3; Fraser & Gawthorpe, 1990;Bridges et al, 1995;TO-TAL, 2007). These downthrown blocks adjacent to carbonatedominated highs were often intervening low areas, where more basinal fine-grained siliciclastic sediments, such as the Bowland Shale, were deposited.…”

Section: Early Carboniferous (Dinantian) Sedimentological Developmentmentioning

confidence: 99%

Seismic stratigraphy of Dinantian carbonates in the southern Netherlands and northern Belgium

Reijmer

Veen²,

Jaarsma

et al. 2017

Netherlands Journal of Geosciences

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Due to their potential as a petroleum or geothermal system, the Dinantian carbonates of the Netherlands have recently attracted renewed interest because of the identified presence of excellent reservoir properties. This notion contrasts with the general assumption that these carbonates are tight. Therefore, in order to give the current knowledge state, this paper re-examines the sparse publicly available well and seismic data and literature to assess the distribution and reservoir properties of the Dinantian carbonates.Dinantian carbonate deposition occurred throughout the study area (southern onshore and offshore of the Netherlands and northern Belgium), which is situated on the northern margin of the London-Brabant Massif, progressively onlapping the latter structure. This study confirms the presence of three carbonate facies types in the study area: a Tournaisian low-gradient carbonate ramp system, succeeded by a succession in which the carbonate ramp system evolved to a rimmed shelf setting. Subsidence of the northern margin of the London-Brabant Massif resulted in a landward shift of the shallow-marine facies belts, while the formation of normal faults resulted in a 'staircase'-shaped shallow-water platform-slope-basin profile, associated with large-scale resedimentation processes. After deposition, the limestone deposits were frequently exhumed and reburied. A first period of regional exhumation occurred at the end of the Dinantian, which seems to be associated with porosity-enhancing meteoric karstification, possibly limited to the palaeo-shelf edge. The most intense alterations seem to be present as a deep leached horizon below the Cretaceous unconformity at the top of the Dinantian sequences. In addition, clear evidence for hydrothermal fluid migration is found locally, enhancing reservoir properties at some places while occluding porosity at others. The timing of these phases of hydrothermal fluid circulation is poorly understood.Whereas in the United Kingdom hydrocarbons have been produced from karstified Dinantian carbonates, this petroleum play has received little attention in the Netherlands. This paper shows that, also for the Netherlands, a karstic reservoir probably existed before the start of hydrocarbon generation from the onlapping basal Namurian shales. The hydrocarbon prospectivity of these sediments, however, is primarily controlled by the presence of both a karst-related reservoir and migration routes from a decent-quality source rock. Two geothermal projects producing from this reservoir in the southern onshore Netherlands have shown the potential of the Dinantian carbonates for ultra-deep geothermal projects. To conclude, the findings presented herein are relevant for studies of the hydrocarbon prospectivity and studies of the geothermal potential of Dinantian carbonates in the Dutch on-and offshore.

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The Environmental Setting of Early Carboniferous Mud‐Mounds

Cited by 50 publications

References 0 publications

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England

An exhumed Palaeozoic underwater scenery: the Visean mud mounds of the eastern Anti-Atlas (Morocco)

Seismic stratigraphy of Dinantian carbonates in the southern Netherlands and northern Belgium

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