Correlation of Mississippian (Upper Viséan) foraminiferan, conodont, miospore and ammonoid zonal schemes, and correlation with the Asbian–Brigantian boundary in northwest Ireland

Cózar, Pedro; Somerville, Ian D.; Mitchell, W. I.; Medina-Varea, Paula

doi:10.1002/gj.1036

Cited by 25 publications

(29 citation statements)

References 35 publications

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“…venusta (Figure 8.27) in the lowest sample (2744) could be a significant datum when compared to its stratigraphic record in Britain and Ireland, where it is usually recorded close to the Asbian-Brigantian boundary, (as Koktjubina sp. 1 in Cózar et al 2006b) and is widespread in the Brigantian (as Biseriammina; Cózar and Somerville 2005a;Somerville and Cózar 2005). However, the stratigraphic range of this genus is not well established due to the paucity of records.…”

Section: Tizra Formationmentioning

confidence: 97%

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Cózar¹,

Vachard

Somerville

et al. 2008

Geological Journal

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Three Upper Viséan to Serpukhovian limestone formations from the Adarouch region (central Morocco), North Africa, have been dated precisely using foraminiferans and calcareous algae. The lower and middle part of the oldest formation, the Tizra Formation (Fm), is assigned to the latest Asbian (upper Cf6g Subzone), and its upper part to the Early Brigantian (lower Cf6d Subzone). The topmost beds of this formation are assigned to the Late Brigantian (upper Cf6d Subzone). The lower part of the succeeding Mouarhaz Fm is also assigned to the Late Brigantian (upper Cf6d Subzone). The Akerchi Fm is younger than the other formations within the region, ranging from the latest Brigantian (uppermost Cf6d Subzone) up to the Serpukhovian (E 1 -E 2 ). The base of the Serpukhovian (Pendleian Substage, E 1 ) is repositioned, to coincide with the appearance of a suite of foraminiferans including Archaediscus at tenuis stage, Endothyranopsis plana, Eostaffella pseudostruvei, Loeblichia ukrainica, Loeblichia aff. minima and Biseriella? sp. 1. The upper Serpukhovian (Arnsbergian Substage, E 2 ) is marked by the first appearance of Eostaffellina ex. gr. paraprotvae and Globoomphalotis aff. pseudosamarica. The biostratigraphical scheme used for the reassessment of the foraminiferal zones and subzones in the Adarouch area closely compares with that for the British succession in northern England (Pennine Region), where the stratotypes of the Upper Viséan (Asbian and Brigantian) and Early Serpukhovian (Pendleian) substages are located. Thus, a succession equivalent to an interval from the Melmerby Scar Limestone to the Great (or Little) Limestone is recognized. These assemblages are also compared to other foraminiferal zones proposed in other regions of Morocco. Several foraminiferans have been identified that are proposed as potential Serpukhovian markers for other basins in Western Europe, and compared to sequences in Russia and the Donets Basin, Ukraine.

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Section: Tizra Formationmentioning

confidence: 97%

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Cózar¹,

Vachard

Somerville

et al. 2008

Geological Journal

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“…The Lugasnaghta Section exposes strata spanning three conodont biozones, ranging through much of the Brigantian (or possibly even all of this regional sub‐stage: currently, there is some debate about the placement of the Asbian–Brigantian boundary in the succession based on conflicting biostratigraphical schemes; see Cózar et al . ) and a significant portion of the Serpukhovian. The first ornamented Lochriea conodont species recorded in the section was L. nodosa , whose FAD is in the Ardvarney Limestone Member (CNLG13; located approximately 55 m above the base of the measured section) of the Carraun Shale Formation (Fig.…”

Section: Resultsmentioning

confidence: 99%

Conodonts of the genus Lochriea in Ireland and the recognition of the Viséan–Serpukhovian (Carboniferous) boundary

Barham

Murray

Sevastopulo

et al. 2015

LET

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Conodonts of the genus Lochriea offer high‐resolution biostratigraphical differentiation of the upper Mississippian (Carboniferous). In particular, L. ziegleri is regarded as the most suitable index taxon for recognition of a revised Viséan–Serpukhovian boundary and selection of a Global Stratotype Section and Point. Mixed carbonate‐siliciclastic Carboniferous sections from western Ireland demonstrate that gradual morphological evolution is expressed within the Lochriea lineage, evidenced by P1‐elements with progressively more complex ornament appearing in a pulsed fashion in the Late Viséan. Significant diversification of the Lochriea conodonts occurs below the currently recognized base of the Namurian (identified by ammonoids), with which the basal Serpukhovian has been correlated in the past. The First Appearance Datum (FAD) of L. ziegleri in the Lugasnaghta Section of western Ireland is apparently coincident with the FAD's of other complexly ornamented Lochriea species (e.g. L. cruciformis) and corresponds with the Irish and British P2a ammonoid biozone and the lower part of the upper Cf6δ (MFZ15) foraminiferal biozone. The FAD of L. ziegleri in Ireland is closely related to other Lochriea morphotypes with complex ornament, which are difficult to identify to species level using current species definitions. These forms, recorded from the three sections examined (St Brendan's Well, Kilnamona and Lugasnaghta), may partly be explained as abnormal growth histories, evolutionary intermediate forms, etc. In some instances, however, the apparently consistent and novel morphotypes suggest that current Lochriea taxonomy needs to be re‐examined. Furthermore, given the close association of the morphologies with asymmetric complex ornament and L. ziegleri, these taxa may hold significance as biostratigraphical tools in their own right.

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“…The presence of thick gypsum beds in the late-Asbian/Brigantian Meenymore Formation (Fig. 3) suggests evaporitic conditions were present within the Sligo Basin after the deposition of the host limestones (Philcox et al, 1992;Cózar et al, 2005Cózar et al, , 2006. The temperature difference between fluid types Ft1 and Ft3 in northwest Ireland (Figs.…”

Section: Origin and Timing Of Mineralizing Fluidsmentioning

confidence: 94%

“…Several earlier studies of the Sligo syncline region (Oswald, 1955;George et al, 1976;Philcox et al, 1992;MacDermot et al, 1996;Cózar et al, 2005Cózar et al, , 2006Somerville et al, 2009) focused on defining and correlating the Carboniferous strata that host sulfide mineral deposits in the Sligo area. The northwest was the last region of Ireland to be submerged by a northward-transgressing sea during the Late Devonian and Early Carboniferous.…”

Section: Carboniferous Stratigraphymentioning

confidence: 97%

“…During deposition of these latter two units, the region was a continuous carbonate shelf . The Brigantian Meenymore Formation was deposited discomformably over the Dartry Limestone to the east and southeast of the Sligo syncline (east of the Ox Mountains inlier), marking the base of the Leitrim Group siliciclastic succession (Cózar et al, 2005(Cózar et al, , 2006. The Meenymore Formation consists of thin-bedded carbonates, laminated shales, fluvial sandstones, and two distinct evaporite deposits (West et al, 1968;Philcox et al, 1992).…”

Section: Carboniferous Stratigraphymentioning

confidence: 97%

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Base Metal Sulfide Mineralization in Lower Carboniferous Strata, Northwest Ireland

Persellin

Gregg

Shelton

et al. 2010

Exploration and Mining Geology

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Zn-Pb sulfide mineralization at Abbeytown mine and Twigspark quarry comprise the only known carbonate-hosted base metal sulfide deposits in the Sligo syncline, northwest Ireland. Limestone sedimentation occurred uniformly throughout the region during the Early Carboniferous (Mississippian) as observed by field relationships and lithofacies; however, petrographic and stable isotope evidence indicate that host-rock dolomitization occurred under different conditions at localities to the west and east of the Ox Mountains inlier, suggesting significant uplift and geologic isolation of these areas prior to dolomitization. Localized fluid flow systems are thought to be responsible for sulfide mineralization and associated epigenetic carbonate cements. West of the Ox Mountains inlier at Abbeytown, evidence of three geochemically distinct fluids are observed: (1) a lower-temperature, lower-salinity fluid (70°-130-°C , 4-9 wt.% equiv. NaCl); (2) a lower-temperature, higher-salinity fluid (70°-140°C, 15-24 wt.% equiv. NaCl); and (3) a higher-temperature, moderate-salinity fluid (165°-220°C, 8-14 wt.% equiv. NaCl). Similar fluid types were observed at the Twigspark deposit. The source of the higher-salinity fluid is likely seawater evaporated to near the point of halite precipitation. The higher-temperature fluid is thought to have been derived from deep circulation of basinal brines. It is speculated that mixing of the higher-salinity fluid with the high-temperature fluid was vital for ore formation at Abbeytown because fluid inclusions in sphalerite have homogenization temperatures and salinity values that fall along a mixing trajectory of these end member fluids. Also, areas where the high-salinity end member fluid is absent are barren of sulfides. Less complex fluid systems are indicated for sites east of the Ox Mountains inlier where no sulfide mineralization was observed. Data from base metal sulfide prospects in northwest Ireland indicate no connection with the regionally extensive flow system thought to be responsible for Zn-Pb deposits throughout the Irish Midlands.Sommaire -Les minéralisations en sulfures de Zn-Pb de la mine Abbeytown et de la carrière Twigspark sont les seules gîtes de métaux usuels à encaissant carbonaté connus dans le synclinal de Sligo, au nord-ouest de l'Irlande. Ces carbonates se sont déposés d'une manière uniforme dans la région au Carbonifère inférieur (Mississippien) tel que l'indiquent les relations de terrain et les lithofaçiès; les données pétrographiques et d'isotopes stables indiquent toutefois que la dolomitisation de l'encaissant s'est faite sous des conditions différentes aux localités situées à l'ouest ou à l'est de la boutonnière des Ox Mountains, ce qui suggère un soulèvement et une isolation géologique significative de ces secteurs avant la dolomitisation. L'action de systèmes de circulation locaux sont considérés être à l'origine de la minéralisation sulfurée et des ciments carbonatés épigénétiques qui leur sont associés. À Abbeytown, à l'ouest de la boutonnière des Ox Mountai...

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Correlation of Mississippian (Upper Viséan) foraminiferan, conodont, miospore and ammonoid zonal schemes, and correlation with the Asbian–Brigantian boundary in northwest Ireland

Cited by 25 publications

References 35 publications

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Conodonts of the genus Lochriea in Ireland and the recognition of the Viséan–Serpukhovian (Carboniferous) boundary

Base Metal Sulfide Mineralization in Lower Carboniferous Strata, Northwest Ireland

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