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Characterization of Siliceous Nodules in Western Kefalonia Ιsland Greece: An Initial Approach to Their Formation and Diagenetic Characteristics

Authors :
Paraskevi Lampropoulou
Vayia Xanthopoulou
Małgorzata Wojtaszek-Kalaitzidi
Petros Petrounias
Elena Zoumpouli
George Iliopoulos
Stavros Kalaitzidis
Source :
Minerals, Vol 12, Iss 1, p 101 (2022)
Publication Year :
2022
Publisher :
MDPI AG, 2022.

Abstract

In this study, siliceous nodules from the world-famous Myrtos beach, as well as from Avithos beach, in the western flanks of Kefalonia Island in Greece are examined by means of petrographical, mineralogical, geochemical and micropaleontological methods. The objectives of this study are to characterize the textural and compositional features of the nodules, with the aim to provide an initial interpretation of their origin and their diagenetic evolution. The studied siliceous nodules are hosted within Lower Cretaceous thin-bedded limestones at Myrtos and Upper Eocene limestones at Avithos. Nodules from both areas display a characteristic concentric texture at a macroscopic and microscopic scale. They both have a dense fine-grained siliceous sedimentary fabric, composed mainly of microcrystalline or cryptocrystalline quartz and moganite with common residual calcite in the case of Avithos. These results, and in particular the shape of the nodules, along the textural and compositional characteristics, indicate different conditions of formation in the two localities, both during the early epigenetic stages, as well as later during the diagenetic processes. Myrtos nodules originated from Si-precursors deposited in a pelagic environment, going through intense Si-replacement. Avithos nodules were deposited in a more proximal environment, being influenced by a less intense silicification. Nevertheless, the higher degree of recrystallization of Avithos samples indicates a syn- or post-diagenetic tectonic activity that resulted in the circulation of geothermal fluids. The conclusions drawn from this work demonstrate the usefulness of thorough studies of siliceous nodules in order to get a more comprehensive understanding of the initial depositional conditions, as well as diagenetic pathways and processes.

Details

Language :
English
ISSN :
2075163X
Volume :
12
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Minerals
Publication Type :
Academic Journal
Accession number :
edsdoj.22d4a5f49314d468e4d398f3aa05adb
Document Type :
article
Full Text :
https://doi.org/10.3390/min12010101