New chronostratigraphic constraints on the Lower Jurassioc Pliensbachian-Toarcian Boundary at Chacay Melehue (Neuquén Basin, Argentina) and the relationship to Karoo Igneous Province

AL-SUWAIDI, A.; RUHL, M.; JENKYNS, H.; HESSELBO, S.; CONDON, D.; DAMBORENEA, S.E.; MANCEÑIDO, M.O.; ANGELOZZI, G.N.; KAMO, S.; RICCARDI, A.C

New Orleans

Congreso; AGU Fall Meeting 2021; 2021

AGU

The Pliensbachian?Toarcian boundary interval is characterized by a ~3? negative carbon-isotope excursion in organic and inorganic marine and terrestrial archives as well as a marine extinction event. A new high-resolution organic-carbon isotope record, illustrating the same chemostratigraphic feature, is presented from Arroyo Chacay Melehue, Chos Malal, Argentina, indicating the global signifi cance of this disturbance to the carbon cycle. The negative carbon-isotope excursion, mercury and organic-matter enrichment is accompanied by high-resolution biostratigraphy together with geochronology derived from intercalated volcanic ash beds. A new age of ~183.65 ± 0.78/-0.77 Ma for the Pliensbachian?Toarcian boundary, and 182.66+0.35/-0.411 for the tenuicostatum ? serpentinum boundary, is assigned based on high-precision U/Pb zircon geochronology and a Bayesian Markov chain Monte Carlo stratigraphic age model. An integrated global correlation of this new data with other well constrained successions, as well as radiometric ages from Karoo and Ferrar support a link between the Pliensbachian?Toarcian boundary event and the initiation of Karoo large igneous province activity.