Palaeoenvironmental controls on late Cenomanian–early Turonian dinoflagellate cyst assemblages from Condemios (Central Spain)

Abstract

A detailed account of the organic-walled dinoflagellate cyst succession and geochemical data (δ13Corg, δ13Ccarb, δ18O, CaCO3 and Total Organic Carbon) from an outcrop section in Condemios (Province of Guadalajara, Central Spain) are presented and statistically correlated in order to identify the palaeoenvironmental conditions prevailing in this palaeogeographical area. The geochemical data revealed low TOC contents, and stable isotope values moderately (δ13Corg, δ13Ccarb) to strongly (δ18O) affected by diagenesis. The low organic content of the studied material, the diverse macropalaeontological fauna recovered and the absence of Cyclonephelium distinctum and prasinophytes in the palynological assemblages do not support the presence of anoxic conditions in this depositional setting. Two transgressive pulses centred in the upper part of the Spathites (Jeanrogericeras) subconciliatus Zone and in the Choffaticeras (Leoniceras) luciae Subzone are inferred by the presence of a high number of blade-shaped opaque phytoclasts and high diversity values in the corresponding palynofacies and dinoflagellate cyst assemblages, respectively.