Bituminous shales and oolitic ironstones as indicators of transgressions and regressions

Hallam, A.; Bradshaw, M. J.

doi:10.1144/gsjgs.136.2.0157

Cited by 198 publications

(87 citation statements)

References 21 publications

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“…Periods of oxygen deficiency and deposition of organic-rich layers are frequently associated with transgressive settings (e.g. Hallam and Bradshaw, 1979;Speijer and Wagner, 2002;Schulte et al, 2011). This link has also been proposed for the early Eocene Peri-Tethys sapropels (e.g.…”

Section: Paleoenvironmental Reconstructionmentioning

confidence: 80%

Early Eocene environmental development in the northern Peri-Tethys (Aktulagay, Kazakhstan) based on benthic foraminiferal assemblages and stable isotopes (O, C)

Deprez

Tesseur

Stassen

et al. 2015

Marine Micropaleontology

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Section: Paleoenvironmental Reconstructionmentioning

confidence: 80%

Early Eocene environmental development in the northern Peri-Tethys (Aktulagay, Kazakhstan) based on benthic foraminiferal assemblages and stable isotopes (O, C)

Deprez

Tesseur

Stassen

et al. 2015

Marine Micropaleontology

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“…[52] In discussing Early Toarcian events recorded in the Cleveland Basin, the focus of others has been largely on the 3 m interval in the lower exaratum Subzone where TOC concentrations are highest (the putative OAE in the strict sense), or the 7 m of the exaratum Subzone itself (the putative OAE in the wider sense). Here, we revisit older literature [e.g., Hallam and Bradshaw, 1979], and emphasizes more recent literature [e.g., Harries and Little, 1999;Wignall et al, 2005] and German literature that places the black shales deposition and restriction into a longer temporal context. In conjunction with the timescale of Suan et al [2008], our data confirm that restriction in the shallow shelf seas of NW Europe was presaged by organic-rich intervals in the tenuicostatum Zone of Germany and the United Kingdom (the Sulfur Bands in the latter), then developed in around 150 ka through the upper semicelatum Subzone, was extreme for around 750 ka, and persisted in intermittent, or lesser form over the ensuing 500 ka into mid bifrons time.…”

Section: Case For a Pycnoclinementioning

confidence: 99%

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

et al. 2008

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[1] Profiles of Mo/total organic carbon (TOC) through the Lower Toarcian black shales of the Cleveland Basin, Yorkshire, United Kingdom, and the Posidonia shale of Germany and Switzerland reveal water mass restriction during the interval from late tenuicostatum Zone times to early bifrons Zone times, times which include that of the putative Early Toarcian oceanic anoxic event. The degree of restriction is revealed by crossplots of Mo and TOC concentrations for the Cleveland Basin, which define two linear arrays with regression slopes (ppm/%) of 0.5 and 17. The slope of 0.5 applies to sediment from the upper semicelatum and exaratum Subzones. This value, which is one tenth of that for modern sediments from the Black Sea (Mo/TOC regression slope 4.5), reveals that water mass restriction during this interval was around 10 times more severe than in the modern Black Sea; the renewal frequency of the water mass was between 4 and 40 ka. The Mo/TOC regression slope of 17 applies to the overlying falciferum and commune subzones: the value shows that restriction in this interval was less severe and that the renewal frequency of the water mass was between 10 and 130 years. The more restricted of the two intervals has been termed the Early Toarcian oceanic anoxic event but is shown to be an event caused by basin restriction local to NW Europe. Crossplots of Re, Os, and Mo against TOC show similar trends of increasing element concentration with increase in TOC but with differing slopes. Together with modeling of 187 Os/ 188 Os and d 98 Mo, the element/TOC trends show that drawdown of Re, Os, and Mo was essentially complete during upper semicelatum and exaratum Subzone times (Mo/TOC regression slope of 0.5). Drawdown sensitized the restricted water mass to isotopic change forced by freshwater mixing so that continental inputs of Re, Os, and Mo, via a low-salinity surface layer, created isotopic excursions of up to 1.3% in d 98 Mo and up to 0.6% for 187 Os/ 188 Os. Restriction thereby compromises attempts to date Toarcian black shales, and possibly all black shales, using Re-Os chronology and introduces a confounding influence in the attempts to use d 98 Mo and initial 187 Os/ 188 Os for palaeo-oceanographic interpretation.

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“…It usually derives from marine rocks or from rocks influenced by marine waters during early diagenesis (Hallam and Bradshaw, 1979). However, n o n -m a r i n e occurrences have also b e e n described.…”

Section: Introductionmentioning

confidence: 99%

Experimental Clay-Mineral Formation from a Subvolcanic Rock by Interaction with 1 M NaOH Solution at Room Temperature

Drief

Nieto

Navas

2001

Clays and clay miner.

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Abstract--The alteration process of a subvolcanic rock with calcic plagioclase, pyroxene, and olivine as major components was investigated by X-ray diffraction (XRD) and analytical and transmission electron microscopy (TEM/AEM). Experimental interaction with 1 M NaOH solution led to the formation of dioctahedral beidellite to Fe-rich montmorillonite after 1 and 3 d of reaction. This range of smectite composition is similar to that from natural subvolcanic-derived soil formed from the same parent material. After 14 d of reaction, a berthierine-smectite (B-S) interstratified clay had partially replaced the smectite. Although, the presence of smectite interlayers prevented analysis of pure berthierine, berthierine-rich B-S interstratifications have a composition similar to pure berthierine. After 40 d, the alteration process led to a 7-A S interstratification whose composition falls between greenalite and lizardite. A series of amorphous materials were also found in the 14 and 40-d experiments. The most abundant of these is a Si-CaFe-rich material, whose chemical composition approaches that of the starting rock. In contrast, two other amorphous materials had a smectitic composition.Key W o r d s~A E M Analysis, Berthierine, Interstratification, Lizardite, NaOH Solution, Smectite. I N T R O D U C T I O NClay minerals such as smectites are widely distributed over the earth's crust as the weathering products of volcanic glasses or rock-forming minerals. Smectites have been synthesized at low temperature using v a r i o u s starting materials. F a r m e r et al. (1991a, 1991b) found that saponite-and nontronite-like structures developed from aluminosilicate precipitates digested in solutions containing M g and Fe ions, respectively. Plee et al. (1987) and Schultz et aI. (1987) reported the synthesis of beidellite from aluminosilicate gel in N a O H solutions at 300-340~ Grauby et al. (1993) synthesized smectite in the beidellite-saponite series using synthetic gels at 200~On the basis of transmission electron microscopy (TEM) analysis, they concluded that the A1-Mg series was continuous b e t w e e n beidellite and montmorillonite end-members. T h e formation of beidellite using aluminosilicate gel as starting material was also investigated by Kloprogge et al. (1990), with experiments performed in N a O H solutions with pH ranging from 7.5 to 13.5 at a temperature of 350~According to these authors, the m o s t highly crystallized beidellite was obtained at 350~ 1 Kbar, 5 d of reaction, and a pH of 10 in the starting solution. K a w a n o and Tomita (1992) reported the formation of beidellite b y hydrothermal alteration of volcanic glass below 200~ M o r e recently, the same authors ( K a w a n o and Tomita, 1994) studied the growth of smectite from leached layers during the experimental alteration of albite in deionized-distilled water at temperatures ranging from 150 to 225~ Berthierine, less c o m m o n in nature than smectite, is an iron-rich aluminous trioctahedral 1:l-type phyllosilicate belonging to the ser...

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Bituminous shales and oolitic ironstones as indicators of transgressions and regressions

Cited by 198 publications

References 21 publications

Early Eocene environmental development in the northern Peri-Tethys (Aktulagay, Kazakhstan) based on benthic foraminiferal assemblages and stable isotopes (O, C)

Early Eocene environmental development in the northern Peri-Tethys (Aktulagay, Kazakhstan) based on benthic foraminiferal assemblages and stable isotopes (O, C)

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

Experimental Clay-Mineral Formation from a Subvolcanic Rock by Interaction with 1 M NaOH Solution at Room Temperature

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