Palaeoclimatic Events

Abstract

Neoproterozoic palaeoclimate in the Río de la Plata Craton (RPC) can be understood in terms of a warm, possibly tropical, “background” climate punctuated by several cold or even glacial events. Evidences of a dominantly tropical palaeoclimate are: (1) Thick carbonate deposits blanketed the marginal areas of the RPC in the Neoproterozoic, beginning in the late Mesoproterozoic-Tonian (Mina Verdún Group) and especially in the late Ediacaran-Early Cambrian (Sierras Bayas and Arroyo del Soldado groups). (2) Clay minerals derived from the granitic-metamorphic basement were predominantly kaolinitic during certain periods. (3) Preliminary palaeomagnetic data suggest a tropical latitude for the late Ediacaran and Early Cambrian. On the other hand, clear evidences of ice-rafting and glacially-influenced deposits were reported from the Playa Hermosa and Las Ventanas formations, which could be lateral equivalents. These evidences will be discussed in detail below.