Conodont? 18O palaeothermometry from conjugated margins of the southern Iapetus Ocean during the Ordovician Period: a story of drifting?

S. M. BERGSTRÖM; G. L. ALBANESI; I. S. WILLIAMS; C. R. BARNES; J. A. TROTTER

FOURTH INTERNATIONAL CONODONT SYMPOSIUM. ICOS IV ?PROGRESS ON CONODONT INVESTIGATION?

INSTITUTO GEOLÓGICO Y MINERO DE ESPAÑA

Año: 2017; p. 55 - 57

The shelly faunas of several fossil groups of the upper Cambrian-Lower Ordovician from the Argentine Precordillera are of Laurentian affinity in general, which evolved to have a paleogeographically mixed character during the Dapingian-Darriwilian, with an increasing number of colder-water taxa typical of Avalonia and Baltica. These paleontological records have allowed palaeobiogeographic interpretations of different contrasting models proposing either that a) the Precordillera rifted from the southwestern margin of Laurentia in low latitudes during the Cambrian, then migrated across the Iapetus Ocean, to collide with the Gondwanan margin in the late Middle Ordovician, and received glaciogenic sediments in the Later Ordovician (e.g., Astini et al., 1995), or b) alternative models proposing that the Precordillera originated as a low-latitude segment of Gondwana then migrated southward through episodes of major transform faulting toward high latitudes in the late Middle Ordovician to reach its present position in the Devonian (e.g., Finney, 2007).Oxygen isotope composition (δ18Ophos) were determined from conodonts from Precordilleran and Laurentian carbonate successions, to track changes in sea surface temperatures and investigate the hypothesized drift of the Precordillera, thereby testing the Laurentian-Gondwana palaeogeographic model.