Abstract

A surface section of the Gercus Formation (Middle-Late Eocene) was studied in Berafat area, Dohuk Governorate, Northern Iraq. The Gercus Formation consists of a mixed siliciclastic sediments, evaporates and carbonate sequences in the studied region, predominantly in the upper and middle parts. Nevertheless, it usually consists of upward-fining carbonate-rich sandstone cyclothems, marl, conglomerate and siltstone along with a gypsum lens and thin micrite carbonate beds. The Gercus Formation was deposited in delta and delta front of occasionally depositional environment which is represented by red-brown claystone and reddish-brown mudstone lithofacies. Cross bedded pebbly sandstone, trough cross-bedded sandstone and laminated cross-bedded sandstone lithofacies are deposited in braided delta environment. Marl lithofacies and gypsum lithofacies are deposited in intertidal and supratidal environments. The sea level fluctuation caused the river base level to occasionally rise and fall. In addition, the process changed from erosion to deposition, while the grain size also changed at different environments from gravel to sand and clays. The Gercus succession of northern Iraq was developed during the Middle-Late Eocene in an active margin basin, where the last stage closure of the New-Tethys and its collision with the Eurasian plate took place between the northeastern Arabian plate. It caused major episodes of uplifts and subsidence along with base level variations due to eustatic ups and downs. Within Gercus Formation, several fourth order cycles can be recognized, reflecting generally asymmetrical cycles, as well as the difference between sediment supply and accommodation space.

Highlights

  • Gercus Formation is a Middle to Late Eocene group based on stratigraphy of the location cultivated in northern Iraq's High Folded Area

  • The present study aims to identify the depositional environment based on the facies assessment of the segment selected within the study area

  • Sea level fall is accompanied with decreases of sea water influx and evaporation. This is associated with dilution of the lake by fresh water from source areas, which deposits red claystone or gypsarenite, which represents the transgressive systems tract (TST), and reddish brown mudstone lithofacies which represents highstand systems tract (HST)

Read more

Summary

Introduction

Gercus Formation is a Middle to Late Eocene group based on stratigraphy of the location cultivated in northern Iraq's High Folded Area It extends as a narrow NW-SE belt from Dohuk to the Darbandikhan region [1]. Middle-Late Eocene Gercus Formation was formed to the SW of an increasing plateau in a highly subsidizing area It occurs through a very narrow NW-SE trending belt, extending from eastern Iran to northwestern wards, through northeastern and northern Iraq to southeastern Turkey. It was formed in the last stage of the Neo-Tethys Ocean subduction and closing, in a relatively wide trough (Foredeep) along the northeastern edge of the Middle Eocene Basin, from the north and northeast uplifted regions [1]. These sediments are believed to represent a Middle-Late Eocene cycle fluvio-deltaic facies of northeastern Iraq [6, 12, 15]

Methodology and Study Area
Conclusions
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call