Geochemistry, Provenance and Tectonic Setting of Alumina- rich Shale of Baluti Formation in Two Selected Sections, Iraqi Kurdistan Region

Abstractthumbnail of Baran- MSc. Thesis

Baluti Formation is considered as an Upper Triassic formation. It
consists of shale interbedded with thin bedded limestone. Twenty seven shale
samples were collected from Sararu at Northern Thrust Zone (26km northwest
of Amedi Town) and Sarki at High Folded Zone (15km southeast of Amedi
Town).
The geochemical and mineralogical compositions of these shales were
investigated using X-ray Diffraction, X-ray Fluorescence, Inductively
Coupled Plasma-Mass Spectrometry techniques and Scanning Electron
Microscope.
Mineralogically, the clay mineral assemblages are dominated with the
kaolinite, illite, illite/smectite mixed layers at Sararu section, and illite>
smectite with traces of kaolinite at Sarki. Illite is within the zone of
diagenesis. The non-clay minerals are dominated by calcite with minor
amounts of quartz and muscovite in Sararu shale; and are dominated by
dolomite with amounts of calcite and quartz in Sarki shale.
Geochemically, Baluti Formation is enriched with Al2O3, Fe2O3, CaO,
MgO, K2O, V, Cr and Ni, and depleted with SiO2, Na2O MnO, TiO2, Rb, Sr,
Ba, Th, U, Y, Zr, Nb, Hf, Sc, Co, Cu, Zn and Mo in comparison with UCC.
Chondrite-normalized patterns are typical for shale in general, with an
enrichment of the LREEs, negative Eu anomalies, and flat HREEs.
Baluti shale is classified as Al-rich shale based on major and minor
elements. The Al enrichment is due to the presence of free alumina phases.
Major, trace and rare earth elements of the Baluti shale have been analysed to
constrain their provenance, tectonic setting, depositional redox condition and
paleoclimate. The geochemical parameters such as Al2O3/TiO2, TiO2- Zr,
Th/Sc, Zr/Sc, Eu/Eu*, Th/Co, Th/Cr, La/Sc, LREE enrichment, relatively flat
HREE and negative Eu anomaly; these reveal that the studied shales were
derived from felsic source rocks.
The discrimination diagrams, as well as trace and REE concentrations
and ratios imply the continental island arc tectonic setting for the shale of the
Baluti Formation. Paleoweathering indices CIA, CIW, PIA, MIA and ICV
values indicate that the source rocks have subjected to strong chemical
weathering. The U/Th, V/Cr, V/Sc, Cu/Zn ratios and V-Al2O3 diagram for the
shale samples suggest that these sediments were deposited in an oxic shallow
marine environment under warm and humid climate.

Leave a Reply