Iraqi National Journal of Earth Sciences

Abstract

Rock magnetic properties have been investigated across the Paleocene/Eocene boundary in two distally separate sections of Paleogene marine sedimentary rocks from Iraq, namely the Sinjar and the Shaqlawa sections. The sediments at the studied sections belong to the Aaliji and the Kolosh formations respectively, which were previously examined for their biostratigraphy by the authors using planktonic and benthonic foraminifera to delineate the Paleocene/Eocene (P/E) transition. Measured magnetic properties include; bulk magnetic susceptibility, hysteresis cycles, isothermal remnant magnetization (IRM) acquisition, and thermomagnetic curves analysis. Rock-magnetic results (i.e. low magnetic coercivity component) indicate greigite as the main magnetic phase at Aaliji rocks, while a mixture of magnetite and greigite with high magnetic coercivity has been observed at Kolosh clastics. Magnetic susceptibility is induced by related to both biogenic minerals (mainly at Aaliji Formation) and transported terrigenous material sources. Multi varied magnitude phases of high bulk rock magnetic susceptibility observed in both formations along PETM lithosomes are attributed to two sources: greigite or biogenic iron oxides source and increase in terrigenous discharge source as inferred by anoxic to suboxic iron - sulfate-reducing conditions and lithological change respectively. Both sources referred to some of environmental conditions associated with Paleocene - Eocene thermal maximum events such as methane dissociation, water stratification, enhanced hydrological and weathering cycles..