Preliminary Data From the First Record of the Early Toarcian Oceanic Anoxic Event in the Sediments of the Pindos Zone (Greece)

Abstract

The Early Toarcian Oceanic Anoxic Event (ca 183 Ma)

Βιοστρωματογραφία Ιζηματολογία Σταθερά Ισότοπα Και Οργανικό Υλικό Των Ιουρασικών Ιζημάτων Της Δυτικής Ελλάδας

“…By contrast, pelagic sediments of the Pindos Zone originate from an elongated oceanic basin remnant that formed in mid-Triassic times along the north-east passive margin of Apulia between the extensive Gavrovo-Tripolis platform in the present west, and the Pelagonian continental block in the present east . Organic carbon contents in the Ionian Zone suggest a higher degree of organic matter accumulation relative to the Pindos Zone; this is in accordance with the more restricted geometry of the Ionian basin versus the deeper ocean basin of the Pindos Zone TSIKOS et al, 2004b;KAFOUSIA et al, 2010).…”

“…The observed geochemical characteristics of the early Toarcian OAE include increased organic carbon sequestration and a negative and/or positive excursion in carbon isotopes from both carbonate and organic matter. Maximum TOC values of black shales of the lower Toarcian range from~19 wt% to as low as 0.60 wt%; this variation is interpreted in each instance to be the result of variable redox conditions, water depth, degree of water-mass stratification and/or organic productivity KAFOUSIA et al, 2010). A negative carbon-isotope excursion is hitherto recorded in most studied sections, whereas a positive onethat otherwise characterizes most other OAEs -is not always present.…”

Geochemistry and Depositional Conditions of the Cretaceous Oceanic Red Beds (CORBs) within the Shiranish Formation in North of Iraq

“…Obviously an inverse relationship between the TOC % and C 13 based on the results of the GS-section are noted stratigraphically upwards increasing in TOC % Figure-9. The reverse is the case under normal oxic conditions according to [22] Galarraga et al 2008). …”

“…The Cross plot of vanadium versus nickel Figure-8, from GS and Ch red bed samples from studied area showing that the sediments had mixed marine and terrigenous source input and were deposited under oxic to dyoxic [22]. Figure 8-Cross plot of vanadium versus nickel of GS and Ch red beds samples from studied area [22].…”

“…Through the results above, the highest content of total organic content (TOC %) presence in marly limestone rock (TOC %=1.13), whereas the higher value of TOC % in marl rock samples is 0.92 % Table-8. Using the relevant ratios with TOC% such as V/Ni ratio Tables- (11, 12 and 13), when V/Ni ratio greater than 3 indicates that the TOC % was deposited in a reducing environment, and when V/Ni less than 3 suggested the TOC% was deposited in oxidizing condition [22].…”