Graptolite biostratigraphy of the Lower Silurian 

(Llandovery) shelf deposits of the Western Iberian Cordillera, 

Spain

Gutiérrez-Marco, J. C.; Štorch, Petr

doi:10.1017/s0016756897007802

Cited by 31 publications

(17 citation statements)

References 18 publications

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“…Above the gemmatus Subzone in Saudi Ara bia the renaudi Subzone can be rec og nized and this is prob a bly an equiv a lent biostratigraphic level to the epon y mous subzone in Wales (Loydell, 1992). As the renaudi Subzone in Saudi Ara bia also con tains Parapetalolithus elongatus, this sug gests cor re lation with the palmeus Subzone of the linnaei Biozone in Spain (Gutiérrez-Marco and Štorch, 1998).…”

Section: Correlation Of the Early Telychianmentioning

confidence: 58%

“…This graptolite oc curs in strata suc ceeding those of a well-de fined halli Biozone that in di cate its cor re lation with the guerichi Biozone of Wales (see Loydell, 1991Loydell, , 1992Loydell, , 1993. Strata bear ing S. guerichi in Saudi Ara bia succeed those with the ear li est Rastrites linnaei, pro vid ing cor re lation with suc ces sions in con ti nen tal Eu rope that iden tify a linnaei Biozone at this strati graphic level (see Štorch and Loydell, 1992;Gutiérrez-Marco and Štorch, 1998). The low ermost part of the guerichi Biozone in Saudi Ara bia does not usually bear the subzonal in dex fos sil Paradiversograptus runcinatus (Lapworth).…”

Section: Correlation Of the Early Telychianmentioning

confidence: 99%

“…P. runcinatus has been found in low-diver sity as sem blages in lithofacies that seem to rep re sent more in shore con di tions. P. runcinatus is known from Wales (Loydell 1993), though Gutiérrez-Marco and Štorch (1998) noted the rar ity of this graptolite in the Span ish suc ces sion, and chose to iden tify a com bined runcinatus-gemmatus Subzone as the lower most in ter val of the linnaei Biozone. We sug gest that part of the low-di ver sity in ter val at the base of the guerichi Biozone in Saudi Ara bia may equate to the runcinatus Subzone in Wales; in both ar eas it is suc ceeded by rocks that bear abun dant Monograptus gemmatus, with this graptolite ef fect ing a clear subzonal cor re la tion be tween the Welsh and Ara bian suc cessions.…”

Section: Correlation Of the Early Telychianmentioning

confidence: 99%

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Early Silurian (Llandovery) graptolite assemblages of Saudi Arabia: biozonation, palaeoenvironmental significance and biogeography

Williams

Zalasiewicz

Boukhamsin

et al. 2016

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1 Uni ver sity of Leicester, De part ment of Ge ol ogy, Leicester LE1 7RH, UK 2 Saudi Aramco, Geo log i cal Tech ni cal Ser vices Di vi sion, Dhahran, Saudi Ara bia Wil liams, M., Zalasiewicz, J., Boukhamsin, H., Cesari, Ch., 2016. Early Si lu rian (Llandovery) graptolite as sem blages of Saudi Ara bia: biozonation, palaeoenvironmental sig nif i cance and biogeography. Geo log i cal Quar terly, 60 (1): 3-25, doi: 10.7306/gq.1270Anal y sis of Si lu rian graptolite as sem blages from 1017 sam ple ho ri zons in 132 cores (from 65 bore holes) through the Qusaiba Mem ber, Qalibah For ma tion of Saudi Ara bia, pro vides a re fined graptolite biostratigraphy for the Ara bian Pen in sula com pa ra ble in its res o lu tion to that from the Brit ish Isles and the Czech Re pub lic. Over 150 graptolite spe cies char ac ter ize 11 biozones from the low er most Rhuddanian lubricus Biozone to the lower Telychian guerichi Biozone, with sub-zonal res o lution for sev eral in ter vals. Graptolite biozonal bound aries and the Rhuddanian-Aeronian and Aeronian-Telychian stage bound aries can be placed with high pre ci sion. De tailed anal y sis of graptolite spa tial dis tri bu tion sug gests per sis tent depth-strat i fied ma rine as sem blages across the Si lu rian palaeo-Ara bian Plate. Near-sur face-dwell ing as sem blages prob ably oc cu pied the mixed-layer of Si lu rian oceans, en abling col o ni za tion of shal low shelf en vi ron ments. They are low-di ver sity (1-2 spe cies) as sem blages char ac ter ized by Neodiplograptus, Coronograptus, Neolagarograptus and Stimulograptus species and of ten are pre served in strata with ex ten sive shelly fau nas. Deeper ma rine as sem blages are of higher di ver sity (up to 15 spe cies per ho ri zon), and are char ac ter ized by dor sally curved or heli cally coiled spe cies of Spirograptus, Demirastrites, Lituigraptus, Rastrites and Torquigraptus. Rec og ni tion of depth-strat i fied graptolite as sem blages pro vides an im por tant tool for es tab lish ing palaeo-ba sin to pog ra phy and wa ter depth at the time of sed i men tary de po si tion. At the spe cies level, the graptolite as sem blages of Saudi Ara bia are re mark ably sim i lar to con tem po ra ne ous fau nas from peri-Gondwanan Eu rope and, from the mid dle Rhuddanian on wards, also to the Avalonian and Lau ren tian Llandovery graptolites of the UK.

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Section: Correlation Of the Early Telychianmentioning

confidence: 58%

Section: Correlation Of the Early Telychianmentioning

confidence: 99%

Section: Correlation Of the Early Telychianmentioning

confidence: 99%

See 1 more Smart Citation

Early Silurian (Llandovery) graptolite assemblages of Saudi Arabia: biozonation, palaeoenvironmental significance and biogeography

Williams

Zalasiewicz

Boukhamsin

et al. 2016

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“…in the western branch of the Iberian Range at the following geographical coordinates: N40°35′24.7″ W01°46′49.0″ elevation 1365 m (sample BSCH-7B), N40°28′26.2″ W01°38′47.1″ elevation 1571 m (sample CHECA-3B), and N40°27′44.2″ W01°37′58.1″ elevation 1447 m (sample CHECA-5B). Samples belong to the Pizarras de Checa Formation, Upper Aeronian to Lower Ludfordian (Gutiérrez-Marco and Storch, 1998). The coexistence of pyrophyllite, mixed-layer I-Sm, illite, kaolinite, and chlorite is due to the combination of sedimentary, lowgrade metamorphic-and low-temperature hydrothermal processes (Bauluz and Subías, 2010).…”

Section: Geological Settingmentioning

confidence: 99%

Mineral and textural transformations in aluminium-rich clays during ceramic firing

Laita

Bauluz

2018

Applied Clay Science

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The aim of this study has been to analyse the mineralogical and textural transformations of a set of aluminiumrich shales of interest for refractory and ceramic uses, fired from 800°C to 1300°C. To that end, raw and fired samples were analysed by X-ray diffraction, transmitted light microscopy, field emission scanning electron microscopy, and transmission electron microscopy. Raw samples comprise variable proportions of illite, pyrophyllite, orthoclase, quartz, kaolinite, mixed-layer I-Sm, and organic matter. At temperatures below 800°C, kaolinite, mixed-layer I-Sm, and organic matter are destabilized, indicating that they are the least stable phases in the firing process. Illite, pyrophyllite, and orthoclase remain until 1000°C and show a broader stability field during firing than in natural environments. Quartz persists throughout the entire firing process, although it is partly replaced by vitreous phase. Hematite crystallizes at 900°C. Vitrification begins at 1000°C, marking the first significant textural change. From 1000°C mullite starts to crystallize from the Si-and Al-rich vitreous phase. The mullite composition is not stoichiometric and probably as temperature increases Si is partially replaced by Al, Fe and Ti in the structure. Nevertheless, with the increase of the firing temperature, the mullite composition is closer to the theoretical composition and also to that of natural mullites. Furthermore its crystal thickness increases with temperature up to 70 nm. The samples analysed in this study were taken from a shale outcrop

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“…the 'Criadero Quartzite' and 'Los Puertos Quartzite') are overlain by black graptolitic shales of the guerichi Biozone (Garcia Palacios, Gutiérrez-Marco & Herranz Araújo, 1996;Gutiérrez-Marco & Štorch, 1998), indicating earliest Telychian transgression.…”

Section: D3 Gondwanan Peripherymentioning

confidence: 99%

Early Silurian sea-level changes

1998

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Of the various mechanisms suggested (Donovan & Jones, 1979), that most likely to be responsible for the eustatic sealevel changes in the early Silurian is variation in the amount of water incorporated in land-based ice-sheets. This conclusion is based first on the apparent rapidity of many of the sea-level changes (see, e.g. Loydell, 1994) and secondly on the direct evidence of glacial deposits present in the Silurian sequences of Brazil (Grahn & Caputo, 1992) and elsewhere in South America (see Hambrey, 1985).Obviously, the third (and possibly fourth) order cycles being discussed here are superimposed upon the longer term second order and first order cycles (Haq, Hardenbol & Vail, 1988) linked to global tectonic processes. It is likely, for example, that the particularly high sea-levels of the Telychian and early Sheinwoodian reflect the coincidence of interglacial 'greenhouse' conditions with an increase in the volume of oceanic ridges. Abstract -Global sea-level fluctuated markedly during the early Silurian, probably as a result of the waxing and waning of ice-sheets in the South American portion of Gondwana. The highest sea-levels of the Silurian are recorded by the Telychian upper crispus-lower griestoniensis and spiralis-lower lapworthi biozones. Other highstands occurred in the early Aeronian, during the convolutus Zone (mid Aeronian), guerichi Zone and late turriculatus Zone (early Telychian), and early Sheinwoodian. Low sea-levels characterized much of the argenteus and sedgwickii zones (Aeronian), the utilis Subzone (late guerichi-early turriculatus zones, early Telychian), the late Telychian (commencing in the mid lapworthi Zone) and, after a period of apparently only small amplitude sea-level fluctuations in the late Sheinwoodian and earliest Homerian, the mid-late Homerian, in particular the early nassa Zone. Facies (and faunal) changes in the Lower Silurian do not support the P and S model of Jeppsson and others, but are consistent with the sea-level changes proposed herein. Mid Telychian marine red beds appear to have been deposited during a minor sea-level fall immediately after a period of very high sea-levels, rather than during a transgressive episode as previously suggested. Comparison of the sea-level curve presented herein with those constructed in the past is hampered by the lack of precision currently possible in the correlation of early Silurian deep water (graptolitic) and shallow water (shelly) sequences. Improving the precision of this correlation should be a priority for future research.*

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Graptolite biostratigraphy of the Lower Silurian (Llandovery) shelf deposits of the Western Iberian Cordillera, Spain

Cited by 31 publications

References 18 publications

Early Silurian (Llandovery) graptolite assemblages of Saudi Arabia: biozonation, palaeoenvironmental significance and biogeography

Early Silurian (Llandovery) graptolite assemblages of Saudi Arabia: biozonation, palaeoenvironmental significance and biogeography

Mineral and textural transformations in aluminium-rich clays during ceramic firing

Early Silurian sea-level changes

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