and in lower Paleozoic articulate brachiopods: Implications for the isotopic composition of seawater

Wadleigh, Moire A.; Veizer, Ján

doi:10.1016/0016-7037(92)90143-7

Cited by 99 publications

(48 citation statements)

References 30 publications

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“…Lowenstam, 1961;Veizer et al, 1986;Bates and Brand, 1991;Grossman et al, 1991;Wadleigh and Veizer, 1992;Wenzel and 18 13 measurements of NBS-19 (δ O= − 2.20‰ and δ C = + 1.95‰ vs. Joachimski, 1996;Azmy et al, 1998;Bruckschen et al, 1999;Mii et al, 18 13 VPDB) and L-SVECS (δ O = − 26.64‰ and δ C = − 46.48‰ vs. VPDB) as well as internal standards.…”

Section: Shell Preservationmentioning

confidence: 99%

Biochemostratigraphy of the Upper Frasnian in the Namur–Dinant Basin, Belgium: Implications for a global Frasnian–Famennian pre-event

Azmy

Poty

Mottequin

2012

Palaeogeography, Palaeoclimatology, Palaeoecology

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a b s t r a c tThe Upper Frasnian sequence of the Namur-Dinant Basin in southern Belgium consists of mixed siliclasticcarbonate succession of a ramp setting, where the sequence spans the rhenana-linguiformis conodont zones. Earlier studies investigated the chemostratigraphic variations during the Frasnian-Famennian event, but little has been yet known about the nature of the counterpart variations that immediately preceded that time interval. Despite the scarcity of well-preserved brachiopods, sixty-one calcitic shells were collected mainly from beds of the Neuville and Les Valisettes formations (Lower and Upper rhenana zones), to investigate biochemostratigraphic profiles of oxygen-, carbon-isotope and rare earth element (REE) variations of 18 13 Upper Frasnian Namur-Dinant Basin Belgium the time interval immediately before the Frasnian-Famennian boundary. The δ O and δ C values of the well-preserved shells range from − 9.5 to − 5.6‰ VPDB (− 7.7 ± 1.1, n = 33) and from − 1.8 to 3.8‰ VPDB (1.1 ± 1.7, n = 33), respectively, which are within the documented global values. The C-and O-isotope profiles exhibit parallel shifts, particularly at the top of the Neuville Formation (top of the Lower rhenana Zone), which are associated with a sea-level rise and shrinkage in the brachiopod community. Also, the Th/U (0.9 ± 0.6, n = 16) and Ce/Ce* (2.2 ± 0.5, n = 16) ratios suggest deposition under reducing conditions consistent with sea transgression.

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Section: Shell Preservationmentioning

confidence: 99%

Biochemostratigraphy of the Upper Frasnian in the Namur–Dinant Basin, Belgium: Implications for a global Frasnian–Famennian pre-event

Azmy

Poty

Mottequin

2012

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…In contrast to carbonate rock samples, which often show a diagenetic imprint on isotopic compositions, well-preserved brachiopods are assumed to reflect nearly unaltered isotopes related to paleoenvironmental conditions (Lowenstam 1961;Popp et al 1986;Veizer et al 1986;Grossman 1992;Wadleigh and Veizer 1992). Wenzel (1994) measured oxygen and carbon isotopes in brachiopod shells from the Silurian of Gotland and interpreted the repeated shifts of isotope values, which correlate with sea level, as affected mainly by changes of global water temperatures and polar glaciation.…”

Section: Introductionmentioning

confidence: 97%

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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“…This biotic event was recognized from the Lower Silurian faunal changes on the island of Gotland, Sweden (Wilde, 1991). The Niagara Gorge area is located between Ontario and New York State and locations of other studies are: 1) Nevada (Saltzman, 2001), 2) Oklahoma (Ruppel et al, 1996(Ruppel et al, , 1998Saltzman, 2001), 3) Anticosti Island (Wadleigh and Veizer, 1992;Ruppel et al, 1996Ruppel et al, , 1998Azmy et al, 1998Azmy et al, , 1999, 4) Britain (Azmy et al, 1998, 5) Gotland, Sweden (Wadleigh and Veizer, 1992;Wenzel and Joachimski, 1996;Azmy et al, 1998Azmy et al, , 1999Samtleben et al, 2001;Munnecke et al, 2003), and 6) Estonia/Lithuania (Azmy et al, 1998Heath et al, 1998). Arrows are the hypothetical track of currents, c -cold, w-warm (modified from Driese et al, 1991;Wilde et al, 1991;Brett et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Salinic I tectonic, Cancañiri glacial and Ireviken biotic events: Biochemostratigraphy of the Lower Siluriansuccession in the Niagara Gorge area, Canada and U.S.A.

Brand

Azmy

Veizer

2006

Palaeogeography, Palaeoclimatology, Palaeoecology

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Well-preserved brachiopods from the Niagara Gorge area, Anticosti Island, Britain, Gotland and Estonia were utilised to delineate a complex isotopic evolution for Llandovery-Wenlock seawater. The Sr-isotope record reflects the Salinic I tectophase of the Late Llandovery in the continuous increase in 87 Sr/ 86 Sr values from 0.708070 to 0.708346. The Salinic II tectophase is marked by relative constancy of Sr isotope values until the Late Wenlock when it rises from 0.708345 to 0.708430. The second tectonic phase was therefore likely only of a regional nature. The carbon isotopes during the Llandovery fall within a band of about − 1‰ to + 3‰, a range comparable to modern low-latitude brachiopods. A large positive δ 13 C excursion of about 3‰, identifies the Ireviken event/excursion, characterizes the Early Wenlock. The biotic crisis and the isotope excursion itself may be ultimately related to the onset and duration of the Cancañiri glaciation, although a direct causative scenario is as yet unknown. The oxygen isotopic trends of well-preserved brachiopods clearly reflect a warm climate interval during the latest Llandovery associated with the Silurian sea level highstand. Subsequently, in the Early Wenlock, the sea level fell with the onset of the Cancañiri glaciation in the southern hemisphere. This is reflected in a significant positive δ 18 O excursion, particularly in brachiopods from the Niagara Gorge area. Brachiopods from lower latitudes were awash in warm tropical currents and therefore exhibit somewhat more negative δ 18 O values, indicating a lesser cooling gradient.

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and in lower Paleozoic articulate brachiopods: Implications for the isotopic composition of seawater

Cited by 99 publications

References 30 publications

Biochemostratigraphy of the Upper Frasnian in the Namur–Dinant Basin, Belgium: Implications for a global Frasnian–Famennian pre-event

Biochemostratigraphy of the Upper Frasnian in the Namur–Dinant Basin, Belgium: Implications for a global Frasnian–Famennian pre-event

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

Evaluation of the Salinic I tectonic, Cancañiri glacial and Ireviken biotic events: Biochemostratigraphy of the Lower Siluriansuccession in the Niagara Gorge area, Canada and U.S.A.

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