Paleoclimatic control of biogeographic and sedimentary events in Tethyan and peri-Tethyan areas during the Oxfordian (Late Jurassic)

Abstract

The paleobiogeographical distribution of Oxfordian ammonites and coral reefs in northern and Central Europe, the Mediterranean area, North and East Africa, and the Middle East and Central Asia is compared with the distribution in time and space of the most important lithofacies. Interest in the Oxfordian is focused on changes in facies and in biogeographical patterns that can be interpreted as the results of climatic events. Paleotemperature trends inferred from oxygen isotopes and paleoclimatic simulations are tested against fossil and facies data. A Late Callovian-Early Oxfordian crisis in carbonate production is indicated by the widespread absence of Lower Oxfordian reefal formations. There is a gap (hiatus) in deposition on epicontinental platforms, with Middle Oxfordian deposits resting paraconformably on Upper Callovian, while shales accumulated in adjacent intracratonic basins. Simultaneously, in Mediterranean Tethys, radiolarites accumulated in deep troughs while Rosso Ammonitico facies formed on pelagic swells. However, deposition on swells was also discontinuous with numerous gaps (hiatuses) and sequences that are much reduced in thickness. Middle Callovian deposits are generally overlain by Middle Oxfordian limestones. The dearth of carbonates is consistent with a cooling event lasting about 1 My. By the middle Oxfordian a warming, leading to bgreenhouseQ type conditions, is suggested on the basis of both biogeographical (mostly coralreef distribution) and geochemical data. Carbonates spread onto an extensive European platform while radiolarites reached a maximum development in the Mediterranean Tethys. Two distinct latitudinal belts, with seemingly different accumulation regimes, are therefore inferred. Similar latitudinal belts were also present in the late Oxfordian, when carbonates were widespread. The distribution of reefal facies in the late Oxfordian-early Kimmeridgian fits relatively well with GCMs simulations that imply low rainfall in the Tethyan Mediterranean area and slightly higher precipitation in central and northern Europe. Local salinity variations, reflecting more arid or humid conditions, may bias the paleotemperature signal inferred from

Timing of sea level, tectonics and climate events during the uppermost Oxfordian (Planula zone) on the Iberian ramp (northeast Spain)

“…The palaeoclimatic results deduced from the study of the Ricla Barranco section are thus in accordance with the model of southward/northward moving atmospheric convective cells as suggested by Cecca et al (2005) and explained by Martin-Garin et al (2012).…”

“…7, 8). Cecca et al (2005) and Martin-Garin et al (2012) observed high coral abundance in the Tethyan and PeriTethyan realms during the late Oxfordian, highlighting a general warming. They also interpreted the higher coral diversity found at a more southerly position (when compared to the middle Oxfordian) as to be at least partly related to southward displacement of the anticyclonic zone to around 25° N latitude, which is the position of the Iberian ramp at this time (Osete et al, 2011in Bádenas et al, 2012.…”

A comparison between dinosaur footprints from the Middle Jurassic of the Isle of Skye, Scotland, UK, and Shell, Wyoming, USA

“…In Scotland, the palaeolatitude was probably between latitude 35 ( and 45(N (Callomon 2003;Cecca et al 2005).…”

Carbon cycle history through the Jurassic–Cretaceous boundary: A new global δ13C stack

“…Indeed through the Late JurassicEarly Cretaceous transition elevated rates of carbonate burial and preservation are observed (e.g., Mackenzie and Morse, 1992;Berner and Mackenzie, 2011). For example, during the Late Jurassic carbonate sedimentation became dominant over wide parts of the northern Tethys (Rais et al, 2007), with the expansion and development of new reef sites (Leinfelder et al, 2002;Cecca et al, 2005).…”