Midlatitude shelf seas in the Cenomanian‐Turonian greenhouse world: Temperature evolution and North Atlantic circulation

Abstract

[1] An 8 million year record of subtropical and midlatitude shelf-sea temperatures, derived from oxygen isotopes of well-preserved brachiopods from a variety of European sections, demonstrates a long-term Cenomanian temperature rise (16-20°C, midlatitudes) that reached its maximum early in the late Turonian (23°C, midlatitudes). Superimposed on the long-term trend, shelf-sea temperatures vary at shorter timescales in relation to global carbon cycle perturbations. In the mid-Cenomanian and the late Turonian, two minor shelf-sea cooling events (2-3°C) coincide with carbon cycle perturbations and times of high-amplitude sea level falls. Although this evidence supports the hypothesis of potential glacioeustatic effects on Cretaceous sea level, the occurrence of minimum shelf-sea temperatures within transgressive beds argues for regional changes in shelf-sea circulation as the most plausible mechanism. The major carbon cycle event in the latest Cenomanian (oceanic anoxic event 2) is accompanied by a substantial increase in shelf-sea temperatures (4-5°C) that occurred $150 kyr after the commencement of the d 13 C excursion and is related to the spread of oceanic conditions in western European shelf-sea basins. Our oxygen isotope record and published d 18 O data of pristinely preserved foraminifera allow the consideration of North Atlantic surface water properties in the Cenomanian along a transect from the tropics to the midlatitudes. On the basis of fossil-derived d 18 O, estimated dw ranges, and modeled salinities, temperature-salinity-density ranges were estimated for tropical, subtropical, and midlatitude surface waters. Accordingly, the Cenomanian temperate shelf-seas waters have potentially the highest surface water density and could have contributed to North Atlantic intermediate to deep waters in the preopening stage of the equatorial Atlantic gateway.

Evidence for oxic conditions during oceanic anoxic event 2 in the northern Tethyan pelagic realm

“…Contrary to other places where a general warming is observed (Jenkyns et al, 1994;Norris et al, 2002;Wilson et al, 2002;Voigt et al, 2004;Forster et al, 2007;Sinninghe Damsté et al, 2010), at Chrummflueschlucht, the evolution of the d 18 O record suggests a change in the regional hydrological cycle related to a possible cooling and more contrasted climate or more arid period (Keller et al, 2008).…”

“…9). However, the magnitude of the temperature change based on bulk-rock oxygen-isotopes is difficult to constrain because of the diagenetic alteration of fossil carbonate (Gale and Christensen, 1996;Wilson et al, 2002;Voigt et al, 2004) and the uncertainty with regards to the isotopic composition of the Cretaceous seawater Keller and Pardo, 2004;Voigt et al, 2004;Kuhn et al, 2005). The CenomanianeTuronian transition corresponds to the onset of the interval of peak Cretaceous warmth, which reached its thermal maximum in the Late Turonian (Clarke and Jenkyns, 1999;Wilson et al, 2002).…”

“…During OAE 2, a brief cooling episode is recognized based on southward migrations of boreal fauna (Jefferies, 1962;Jenkyns et al, 1994;Gale and Christensen, 1996), on oxygen-isotope records and TEX 86 data Wilson et al, 2002;Voigt et al, 2004;Forster et al, 2007;Sinninghe Damsté et al, 2010). At Chrummflueschlucht, the small plateau of higher oxygen-isotope values at the onset of OAE 2 (peak "a") may relate to this cooling episode.…”

Ophthalmoplax (Decapoda: Brachyura: Portunoidea) from the late Campanian, Upper Cretaceous, of Colombia

“…Based on calcareous nannofossil abundance (Bice et al, 2006;Forster et al, 2007;Voigt et al, 2004;Wilson et al, 2002;Linnert et al, 2011), it is known that between Turonian to Maastrichtian times, there was a continuous cooling of seawater, preceded by one of the warmest periods of the Phanerozoic (early Cenomanian -Turonian). In this scenario, global temperatures decreased between 4 -6 °C during the late Campanian (73 -70 Ma) (Li and Keller, 1999).…”

Facies and integrated stratigraphy of the Upper Turonian (Upper Cretaceous) Großberg Formation south of Regensburg (Bavaria, southern Germany)

“…35°n orthern palaeo-latitudes at the northern margin of the Tethyan warm-water zone, separated from the warmtemperate Boreal shelf of northwestern Europe by the Mid-European Island. Voigt et al (2004) reconstructed contemporaneous brachiopod palaeo-temperatures of 15-20 °C in the mid-latitude shelf sea of northwestern Europe. Thus, sea-water temperatures of the Großberg Text- fig.…”