عنوان المقالة: Stable carbon and nitrogen isotopes and elemental composition and origin of organic matter from the Neogene Euphrates, Injana and Dibdibba formations in Iraq: discrimination between marine and terrestrial environments
Three Neo gene sed i men tary for ma tions re flect ing dif fer ent depositional en vi ron ments have been in ves ti gated for the pur -
pose of di ag nos ing the iso to pic source of the sed i men tary or ganic mat ter and their palaeoenvironmental sig nif i cance in dis -
crim i nat ing be tween ma rine and ter res trial en vi ron ments. One of these for ma tions is com posed of car bon ate and marl of a
shal low-ma rine en vi ron ment (Eu phra tes For ma tion), and the other for ma tions are com posed of a clastic ter res trial (fluviatile)
de pos its with some dif fer ences in the depositional con di tions (Injana and Dibdibba for ma tions). The iso to pic d13C%, d15N%
val ues, or ganic car bon (OC) and to tal ni tro gen con tents, and atomic C/N ra tios are used as ev i dence of depositional en vi ron -
ment. Av er age d13C val ues (in ‰) for the Dibdiba, Injana and Eu phra tes for ma tions are –25.4, –25.7 and –24.5, re spec tively;
av er age d15N val ues (in ‰) are 4.44, 5.24 and 7.24 and av er age OC (in wt.%) is 0.13, 0.3 and 1.1, re spec tively. A sig nif i cant
vari a tion in the sta ble car bon and ni tro gen iso tope com po si tions be tween flu vial and ma rine de pos its was re corded. The
d13C, d15N and C/N val ues in di cate that the or ganic mat ter in the Eu phra tes For ma tion is of ma rine or i gin, whereas it is of ter -
res trial or i gin (fluviatile) in the Injana and Dibdibba for ma tions. The C/Natomic val ues are mostly high in the Injana (37) and
Dibddiba for ma tions (51), sug gest ing greater in put and/or pres er va tion of ter res trial or ganic mat ter de rived from land plants;
the shal low-ma rine en vi ron ment (Eu phra tes For ma tion) was char ac ter ized by a low C/N ra tio (9) due to the al gal-de rived or -
ganic mat ter with lim ited in put of ter res trial or ganic mat ter.
صالح محمد عوض | Salih Muhammad Awadh | 11388