Corals not serpulids: mineralized colonial fossils in the Lower Jurassic marginal facies of South Wales

Simms, Michael J.; Little, Crispin T. S.; Rosen, Brian

doi:10.1016/s0016-7878(02)80004-9

Cited by 10 publications

(4 citation statements)

References 12 publications

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“…Jurassic data come from the present compilation. Hettangian data : (1): England from Duncan, 1865; Simms et al, 2002 (2): Belgium and Luxembourg from Terquem and Piette, 1865; Bock, 1989 (3): Ardèche from Elmi, 1990 and French Alps from Dumont, 1998 (4): Tadjikistan Hettangian or Sinemurian (true reefs ?) from Melnikova, 1975.…”

Section: Resultsmentioning

confidence: 99%

Extinction, survival and recovery of corals from the Triassic to Middle Jurassic time

Lathuilière

Marchal²

2009

Terra Nova

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Recognizing extinction events and determining their cause at the Triassic/Jurassic (T/J) transition and near the Pliensbachian–Toarcian (Lower Jurassic) boundary is a field of growing interest. We provide arguments for these events through a literature based new evaluation of coral diversity from Triassic to Dogger and a new palaeobiogeographical map. The T/J extinction of corals is clearly related to the breakdown of reef environments. Origination curves show that Hettangian (the lowest Jurassic stage) was not only a survival phase but already rather a recovery phase. Post‐extinction evolution of reefs and their survival only in the northernmost margin of the Tethys support the hothouse hypothesis for the T/J extinction event. During Pliensbachian, many new taxa appear, but mostly solitary corals, not really framebuilders. Many of these taxa do not occur anymore during the following stages. The new increase in diversity is related to the development of Bajocian (Middle Jurassic) reefs.

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Section: Resultsmentioning

confidence: 99%

Extinction, survival and recovery of corals from the Triassic to Middle Jurassic time

Lathuilière

Marchal²

2009

Terra Nova

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“…1a), the unconformity surface is exposed and consists of multiple wave-cut platforms overlain by associated successive breccia and conglomeratic and grainstone limestones of the Sutton Stone (Fletcher, 1988; Sheppard, 2006). Both the unconformity surface and Carboniferous Limestone lithoclasts in the overlying Sutton Stone have Trypanites borings and are encrusted by oysters and colonial corals (Johnson & McKerrow, 1995; Simms, Little & Rosen, 2002; Sheppard, 2006). Some lithoclasts in the Sutton Stone are imbricated (Wobber, 1963) and elongate bioclasts have been used as palaeocurrent indicators that indicate long-shore drift and complex current movements influenced by the local islands of Carboniferous rocks (Wobber, 1966).…”

Section: Variations In Whole-rock Compositionmentioning

confidence: 99%

Combined sea-level and climate controls on limestone formation, hiatuses and ammonite preservation in the Blue Lias Formation, South Britain (uppermost Triassic – Lower Jurassic)

2017

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Lithostratigraphic and magnetic-susceptibility logs for four sections in the Blue Lias Formation are combined with a re-assessment of the ammonite biostratigraphy. A Shaw plot correlating the West Somerset coast with the Devon/Dorset coast at Lyme Regis, based on 63 common biohorizon picks, together with field evidence, demonstrate that intra-formational hiatuses are common. Compared to laminated shale deposition, the climate associated with light marl is interpreted as both drier and stormier. Storm-related non-deposition favoured initiation of limestone formation near the sediment–water interface. Areas and time intervals with reduced water depths had lower net accumulation rates and developed a greater proportion of limestone. Many homogeneous limestone beds have no ammonites preserved, whereas others contain abundant fossils. Non-deposition encouraged shallow sub-sea-floor cementation which, if occurring after aragonite dissolution, generated limestones lacking ammonites. Abundant ammonite preservation in limestones required both rapid burial by light marl during storms as well as later storm-related non-deposition and near-surface carbonate cementation that occurred prior to aragonite dissolution. The limestones are dominated by a mixture of early framework-supporting cement that minimized compaction of fossils, plus a later micrograde cement infill. At Lyme Regis, the relatively low net accumulation rate ensured that final cementation of the limestones took place at relatively shallow burial depths. On the West Somerset coast, however, much higher accumulation rates led to deeper burial before final limestone cementation. Consequently, the oxygen-isotope ratios of the limestones on the West Somerset coast, recording precipitation of the later diagenetic calcite at higher temperatures, are lower than those at Lyme Regis.

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“…Facies codes: BR, breccia lithofacies; SHL, shelly limestone lithofacies; CONG, conglomerate lithofacies; CALC, calcarenite lithofacies; MCR, micrite lithofacies; MCS, micrite-shale lithofacies; BLS, Blue Lias lithofacies. growth of enigmatic colonial forms, previously considered to be serpulid worm colonies (Cope 1971;Johnson & McKerrow 1995), but considered by Simms et al (2002) to be colonial corals, assigned by those workers to the genus Phacelostylophyllum.…”

Section: Shelly Limestone Lithofaciesmentioning

confidence: 99%

Sequence architecture of ancient rocky shorelines and their response to sea-level change: an Early Jurassic example from South Wales, UK

Sheppard

2006

JGS

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The sea-cliffs of Ogmore-by-Sea in Glamorgan, South Wales, expose a succession of Early Jurassic nearshore carbonates that drape rocky palaeoplatforms. A sequence-stratigraphic interpretation allows the recognition of four retrogradationally stacked parasequences, the internal facies architecture of each of which is controlled by the bathymetry and geometry of the underlying shore platforms. Preserved facies are interpreted as representative of foreshore, shoreface and offshore environments. Supratidal facies are absent, but representative storm-terrace clast assemblages are preserved in all lithofacies as a result of the cannibalization of the backshore during periods of shoreline retreat driven by sea-level rise. Biostratigraphical calibration allows the reconstruction of sea-level history and the correlation of regionally important flooding surfaces in the Rhaetian-Sinemurian of Southern Britain with the position of the contemporary shoreline. This suggests that platform incision in South Wales occurred several million years before the onset of major deposition; superseding deposits above ancient rock shore platforms may therefore not be representative of the environment in which coastal incision took place. As one of the best examples of its kind, the rockshore at Ogmore acts as a deposystem model for ancient rocky shores worldwide.

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Corals not serpulids: mineralized colonial fossils in the Lower Jurassic marginal facies of South Wales

Cited by 10 publications

References 12 publications

Extinction, survival and recovery of corals from the Triassic to Middle Jurassic time

Extinction, survival and recovery of corals from the Triassic to Middle Jurassic time

Combined sea-level and climate controls on limestone formation, hiatuses and ammonite preservation in the Blue Lias Formation, South Britain (uppermost Triassic – Lower Jurassic)

Sequence architecture of ancient rocky shorelines and their response to sea-level change: an Early Jurassic example from South Wales, UK

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