Nearshore euxinia in the photic zone of an ancient sea: Part II – The bigger picture and implications for understanding ocean anoxia

Abstract

University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above.

Zechstein Main Dolomite oil characteristics in the Southern Permian Basin: I. Polish and German sectors

“…7) can be utilized to differentiate between oxic and reducing palaeodepositional environments, but the distributions can be affected by maturity 287 and secondary alteration (Peters and Moldowan, 1991). The distribution for oils from NE (Słowakiewicz et al, 2016a). 301 All oil samples are characterised by the dominance of C30 17α-hopane over lower or 302 higher homologues in many oil samples (Fig.…”

A new and working petroleum source rock on the UK Continental Shelf (Upper Permian, offshore Yorkshire)

“…In addition, comparisons are made in this paper to previously published and reported herein biomarker data from fourteen samples of KAF dolomite lagoonal facies (onshore equivalent of the Innes Carbonate Member of the NPB) of the Malton 4 well (Słowakiewicz et al, 2016), and typical carbon isotopic values for saturated and aromatic fractions of Jurassic, Permian and Devonian oil from the SPB and North Sea areas.…”

“…In addition, the Toarcian Whitby Mudstone Formation is in the early oil window (French et al, 2014), but the Carboniferous Bowland Shale-Hodder Mudstone shales are thermally mature for gas (Haarhoff et al, 2018). Higher thermal maturity (R o ~0.8-0.9 %) has also been noted in Lockton 2a KAF limestone slope facies, revealed by negative δ 18 O values (-2 to -14 ‰), the presence of saddle dolomite and increased abundance of tricyclic and tetracyclic terpenoids (Słowakiewicz et al, 2016). 4) from the roof of the Boulby Mine at workings (2000 West Salt) at a depth of 1100 m subsurface were collected by hand into pre-furnaced glass jars.…”

“…Clay-and microbial-rich lagoonal dolomites are, in addition to lower slope facies and chicken-wire anhydrites, regarded as source rocks for Zechstein oil in the central and eastern SPB (Słowakiewicz et al, 2018). Lagoonal carbonate facies in the Yorkshire area have TOC <2 wt.% and thickness ~25-35 m (Słowakiewicz et al, 2016). In addition, thinly-laminated basinal calcareous mudstone, named Stinkschiefer in the SPB, commonly regarded as a source rock for hydrocarbons, has previously been ruled out by Słowakiewicz and Gąsiewicz (2013) as an effective source rock.…”

Hydrocarbon habitat in the Zielin Late Permian isolated carbonate platform, western Poland

“…12), as well as the observed slightly marked unresolved complex mixture in the aliphatic compounds of one particular sample (not shown), are a reflection of the clay-minerals present at this depth (3229.5 m), where partial microbial reworking of the deposited algal OM took place. This is probably the result of episodic suboxic conditions in the shallow-water column (Słowakiewicz et al 2015(Słowakiewicz et al , 2016 around the Zielin-3Kbis well area. The cross-plot developed by Hughes et al (1995) for a wide maturity range of hydrocarbons, expressed as the dependence of dibenzothiophene/phenanthrene ratio (DBT/P) vs. Pr/Ph ratio, is useful in determining the depositional environment of a source rock and the lithology in which it was generated.…”