Some Middle Silurian Reefs of Gotland

Manten, A.A.

doi:10.1111/j.1365-3091.1962.tb00456.x

Cited by 16 publications

(15 citation statements)

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“…Thus the sea-level drop that promoted deposition of the shoaling upward Gannarve Mb, c. 30 km towards the SW, was at least as large as the erosional relief on eastern Gotland, i.e. 16 m. The Bara Mb coarsens upward, comprising thinand crossbedded, pure oolite grainstones and oolitic skeletal/peloidal grainstones, reaching a maximum preserved thickness of 5 m (at Bara 1; Manten, 1971). Three different oolite micro-facies were interpreted as representing both mobile bar and mixed bar/lagoonal deposits (Calner & Säll, 1999).…”

Section: C1 Bara Oolite Membermentioning

confidence: 99%

“…2a,b;Calner, 2002). Bioherms and biostromes occur in several facies associations throughout the interval (Manten, 1971;Riding, 1981;Kano, 1994), notably also in the distal slope to basin environment (Stel, 1978;Nield, 1982;Calner, Sandström & Mõtus, 2000).…”

Section: A Geological Settingmentioning

confidence: 99%

“…(a) Depositional rates calculated from stratal thickness per Homerian chronal unit (H.c.u.). The total maximum thickness is estimated at 105 m (based on data in Hede, 1960, Manten, 1971. The 2.5 m thick Svarvare Mb accumulated during 34 H.c.u.…”

Section: C Depositional Bias During the Mulde Eventmentioning

confidence: 99%

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Carbonate platform evolution and conodont stratigraphy during the middle Silurian Mulde Event, Gotland, Sweden

2003

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-Evidence from sedimentology and conodont biostratigraphy is used to reinterpret the mid-Homerian (Late Wenlock) succession on Gotland, Sweden. A new conodont zonation includes from below: the Ozarkodina bohemica longa Zone (including five subzones), the Kockelella ortus absidata Zone and the Ctenognathodus murchisoni Zone (two taxa are named, Ozarkodina bohemica longa and Pseudooneotodus linguicornis). These new zones are integrated with facies in order to correlate strata and infer the major depositional environments and the controls on deposition during the mid-Homerian Mulde Event. Reef-associated and skeletal carbonate deposition predominated before and after the event, i.e. during the uppermost O. s. sagitta Zone and, again, in the C. murchisoni Zone. These periods are characterized by the expansion of reefs and shoal facies across marls in the topmost Slite Group on eastern Gotland and in the lower parts of the Klinteberg Formation on western Gotland, respectively. The intervening O. b. longa and K. o. absidata zones are initially characterized by rapid facies changes, including siliciclastic deposition, and later stabilisation of a carbonate depositional system. The composition of sediments and depositional rates are closely related to the creation and destruction of accommodation space and reflects a classical case of depositional bias of the carbonate and siliciclastic depositional systems. Based on coastline migration, stratal boundaries, and the stratigraphic position of major reef belts, several facies associations can be fitted into a sequence stratigraphic model for platform evolution. A highstand systems tract (HST) situation prevailed prior to, and during the early part of the event; the upper Slite Group including the lower Fröjel Formation. This HST was characterized by prolific skeletal production and regional reef development except for during the latest stage when carbonate production declined at the onset of the Mulde Event. Platform growth was inhibited during a following regressive systems tract (RST) when regional siliciclastic deposition predominated; the Gannarve Member. The subsequent lowstand resulted in regional emersion and karstification, i.e. a complete termination of the platform. The postextinction transgressive systems tract (TST) is exclusively composed of non-skeletal carbonates; the Bara Member of the Halla Formation. Re-occurrence of reefs and a prolific skeletal production marks platform recovery during a second HST; the remaining Halla and the lower Klinteberg formations. Integration of high-resolution biostratigraphy and sequence stratigraphy reveals that the major physical control on platform evolution was a 5th order eustatic sea-level change during an early part of the Mulde Event, and that the bulk of the strata accumulated when the platform aggraded and prograded during the highstand systems tracts. Thus, Silurian oceanic events and associated sea-level changes had profound impact on the neritic carbonate system. The Gotland-based middle and late Homerian...

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Section: C1 Bara Oolite Membermentioning

confidence: 99%

Section: A Geological Settingmentioning

confidence: 99%

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Carbonate platform evolution and conodont stratigraphy during the middle Silurian Mulde Event, Gotland, Sweden

2003

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“…According to Manten (1971), Gotland was located not far from the northwestern border of the Silurian sea, which covered parts of the present Baltic area. The course of the ancient shore line is assumed to have been parallel to the present-day southwest-northeast strike of the strata.…”

Section: Introductionmentioning

confidence: 99%

The Silurian of Gotland (Sweden): facies interpretation based on stable isotopes in brachiopod shells

et al. 1996

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The Silurian of Gotland, Sweden, consists of 440 m of carbonate deposits. Repeatedly, uniform sequences of micritic limestones and marls are interrupted by complex-structured reefs and by adjacent platform sediments. Generally, the alteration of facies is interpreted as the result of sea-level fluctuations caused by a gradual regression with superimposed minor transgressive pulses. The purpose of this study is a facies interpretation based on both field observations and stable isotope measurements of brachiopod shells. Approximately 700 samples from stratigraphically arranged localities in different facies areas have been investigated. The carbon and oxygen isotopes show principally parallel curves and a close relationship to the stratigraphic sequence. Lower values occur in periods dominated by deposition of marly sequences. Higher values are observed in periods dominated by reefs and extended carbonate platforms. The oxygen isotope ratios are interpreted to reflect paleosalinity changes due to varying freshwater input, rather than to paleotemperature. Carbon isotope ratios are believed to have been connected to global changes in the burial of organic carbon in black shales during periods of euxinic deep water conditions. Consequently, the facies succession on Gotland results from global paleoclimatic conditions. Changes in terrigenous input due to different rates of weathering and freshwater runoff, rather than sea-level fluctuations, control the carbonate formation of the Silurian on Gotland.

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“…The localities on Gotland yield numerous sedimentological data that allow tracing the evolution of the succession through time (Manten 1971;Laufeld and Bassett 1981;Cherns 1983;Samtleben et al 2000;Baarli et al 2003). However, in spite of good exposures, the Gotland sections do not enable study of the anatomy of a carbonate platform in detail and for a selected time horizon, and particularly give no opportunity to reconstruct lateral facies changes.…”

Section: Introductionmentioning

confidence: 99%

Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine)

Łuczyński¹,

Kozłowski²,

Skompski³

2015

Acta Geologica Polonica

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ABSTRACT:Łuczyński, P., Kozłowski, W. and Skompski, S. 2015. Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine). Acta Geologica Polonica, 65 (3), 297-318. Warszawa.The term "re-flooding window" was recently proposed as a time-interval connected with the transgressive stage of present day peri-reefal development. In the analysis presented here, a fossil record of a re-flooding window has been recognized. Nine Late Silurian carbonate sections exposed on the banks of the Dnister River in Podolia (Ukraine) have been correlated base on bed-by-bed microfacies analysis and spectral gamma ray (SGR) measurements. Correlated were sections representing settings ranging from the inner part of a shallow-water carbonate platform to its slope, through an organic buildup. The reconstructed depositional scenario has been divided into six development stages, with the first three representing a regressive interval and the latter three a transgressive interval of the basin's history. The re-flooding window has been identified at the beginning of a transgressive part of the succession. Surprisingly, it is characterized by an extremely fast growth of a shallow, tide-dominated platform and by deposition of calciturbiditic layers in a more basinal area. The interpreted succession is a small-scale model illustrating the reaction of carbonate depositional sub-environments to sea level changes and determining the facies position of the stromatoporoid buildups within the facies pattern on a Silurian shelf. The use of SGR analyses in shallow water, partly high-energy, carbonate facies, both for correlation purposes and for identifying depositional systems, is a relatively new method, and thus can serve as a reference for other studies of similar facies assortment.

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Some Middle Silurian Reefs of Gotland

Cited by 16 publications

References 1 publication

Carbonate platform evolution and conodont stratigraphy during the middle Silurian Mulde Event, Gotland, Sweden

Carbonate platform evolution and conodont stratigraphy during the middle Silurian Mulde Event, Gotland, Sweden

The Silurian of Gotland (Sweden): facies interpretation based on stable isotopes in brachiopod shells

Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine)

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