Cretaceous anoxic events: from continents to oceans

Abstract

Pelagic Cretaceous sediments, deposited in a range of palaeotectonic and palaeogeographic settings, from continents to oceans, are commonly black and bituminous. 3 particular time-envelopes define the major occurrences of such facies: late Barremian-Aptian-Albian, the Cenomanian-Turonian boundary and, to a lesser extent, the Coniacian-Santonian. These intervals define the duration of so-called Oceanic Anoxic Events during which global marine waters were relatively depleted in oxygen, and deposition of organic matter, derived from both terrestrial and planktonic sources, was widespread. Cretaceous OAEs correlate closely with transgressions, and such a correlation exists throughout the stratigraphical column. Flooding of land-masses is thought to have transported much terrestrial plant material seawards; the progressive increase in shelf-sea area is thought to have stimulated production of marine plankton. Bacterial consumption of this organic matter favoured the development of poorly oxygenated mid-to late Cretaceous waters in which many of the characteristic facies of the Period, including glauconitic sandstones and phosphatic chalks, were deposited.

Secular variation in Late Cretaceous carbon isotopes: a new δ13C carbonate reference curve for the Cenomanian–Campanian (99.6–70.6 Ma)

“…3) is one of the largest and best documented carbon-isotope events in the geological record (Jenkyns, 1980(Jenkyns, , 1985Scholle & Arthur, 1980;Schlanger et al 1987). This event is conventionally interpreted as being related to accelerated burial of marine organic matter, particularly in the Atlantic, but also in other ocean basins (Herbin et al 1986;Arthur et al 1990;Kuypers et al 2002Kuypers et al , 2004.…”

A biomarker study of depositional paleoenvironments and source inputs for the massive formation of Upper Cretaceous lacustrine source rocks in the Songliao Basin, China

“…This succession of lacustrine sediments preserves abundant information regarding the paleoclimate and depositional environments, which are very important for the understanding of the regional continental climate and the massive formation of lacustrine petroleum-prone source rocks within the Cretaceous greenhouse climatic conditions. There have been numerous studies regarding Cretaceous climate and paleoenvironments based on marine sediments (Jenkyns, 1980;Barron, 1983;Arthur et al, 1988;Arthur and Sageman, 1994;Huber et al, 2002;Wagner et al, 2008;Wagreich et al, 2011, and references therein), but there are few published studies on Cretaceous terrestrial organic matter and related environments (Hasegawa, 1997;Hasegawa et al, 2003). In the Songliao Basin two major sets of organic rich source rocks developed during the Upper Cretaceous, the Qingshankou (K 2 q 1+2 ) and Nenjiang (K 2 n 1+2 ) formations.…”

Demise of the northern Tethyan Urgonian carbonate platform and subsequent transition towards pelagic conditions: The sedimentary record of the Col de la Plaine Morte area, central Switzerland

“…The Late Early to Early Late Cretaceous witnessed a suite of recurrent oceanic anoxic episodes, which was unique for the entire Mesozoic and Cenozoic if one considers its frequency and multiple impact on the environment (e.g., Schlanger and Jenkyns, 1976;Arthur and Schlanger, 1979;Jenkyns, 1980;Leckie et al, 2002). The "mid"-Cretaceous anoxic episodes are an expression of major environmental change during this period, for which its manifestation was not limited to ocean basins, but extended also onto the adjacent shelves and continents (e.g., Schlager and Philip, 1990;Gröcke et al, 1999).…”