Asociaciones palinológicas del tránsito Rhaetiense-Hettangiense en Asturias (España)

Abstract

The palynological study of 49 successive samples collected from the Vilorteo and Cantavieyo Diamond Drill Holes, drilled in the La Camocha Mine area, near Gijón (Asturias), allowed the characterization of three palynological assemblages. The oldest assemblage (PA 1) is characteristic of the Rhaetian. A precise age for the middle assemblage (PA2) cannot be assigned, due to the scarce productivity of the samples. The youngest assemblage (PA3) is characteristic of the Hettangian. Consequently the Triassic-Jurassic boundary (TJB) is located within the upper part of the carbonate succession of the Solís Mb. Two pa/ynozones, Rhaetipollis germanicus one and Krausselisporites reissingeri Zone, have been established. Their boundary nearly coincides with the TJB. A quantitative analysis reveals an increase in the proportion of hygrophilous and warmer taxa near the TJB, compatible with a global climatic change probably related with the end-Triassic mass extinction.