Sedimentology and Palynology of Late Pliocene-Early Pleistocene Syn-Rift Succession, Corinth Rift, Greece

Abstract

Rift basins have proven economically significant as hydrocarbon provinces and, furthermore, record the structural, sedimentary and climatic evolution of the basins and associated catchment areas. The aim of the study is to contribute to the understanding depositional processes of fine-grained sediment in an active deep-water rift setting combined with palynological analysis to understand palaeoenvironmental conditions and its influence on hydrocarbon potential.

This study addresses the currently active Corinth Rift, Greece. Subaqueous syn-rift deposits of Late Pliocene to Early Pleistocene age are exposed on the northern Peloponnese peninsula. Existing literature addresses mainly the western portion of the exposed basin-fill whereas the central and eastern part of the Pliocene – Pleistocene basin-fill have received significantly less attention. The study area is the northern Sythas Valley where deep-water deposits of the Rethio-Dendro Formation (RDF) are exposed in extensive cliff sections. The coarse-grained siliciclastic sediment of the RDF was emplaced as mass transport deposits, channel complexes and channelized lobes. The finer grained intervals consist of thinly bedded turbidites and pelagic sediment (marl).

The fine-grained intervals of the RDF are studied using digital outcrop data (LiDAR) combined with traditional field methods. Moreover, three drill-cores have been retrieved from the studied interval that together cover c. 750m of stratigraphy. The integrated dataset allows detailed sedimentological observations to be correlated with confidence over several kilometers. Palynological analysis was performed on samples from both core and outcrop. The resulting slides yield moderate to good palynomorph concentrations and preservation. The pollen and spore assemblage imply a strong sedimentary facies dependence related to changes in sediment supply and erosion rates of the catchment. Furthermore, the findings of marine dinoflagellate cysts suggest periods of ocean connectivity between the proto-Gulf of Corinth and the Mediterranean Sea. The results may prove vital for understanding the structural evolution of the basin as they imply that by Late Pliocene time the northern margin of the rift had already migrated close to its present location. It is our hope that the presented study will further enhance our understanding of fine-grained sedimentation in rift settings and their potential as source rocks of hydrocarbon systems.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018