Lithofacies distribution and depositional environment of Tanjero formation (upper cretaceous) east of Darbandikhan, north eastern part of Iraq

This thesis is aimed to examine the depositional environment of perfectly cropped out Campanian- Maastrichtian deep marine turbidities of Tanjero Formation near eastern part of Darbandikhan, to the northeastern part of Iraq. For this aim total 1333 m thick sedimentary measured section was logged in detail located near Iranian border at Sirwan valley nearby Sarshata village, to the East of the Darbandikhan town. The log starts from lower contact of the formation underling Campanian- Maastrichtian Shiranish Formation and finishes at the upper contact overlying Paleocene-middle Eocene Kolosh Formation. From lithofacies analysis of the Tanjero Formation in Sirwan Valley section, nine lithofacies (LF) and eight sub lithofacies (SLF) have been distinguished: LF-1: Conglomerate; SLF-1a: Pebbly to sandy matrix supported conglomerate; SLF-1b: Sandy matrix supported conglomerate; SLF-1c: Muddy matrix supported conglomerate; LF-2: Structureless sandstone beds; SLF-2a: Fine-coarse structureless sandstone; SLF-2b: Very coarse-pebbly structureless sandstone; SLF-2c: Amalgamated structureless sandstone; LF-3: Deformed sandstone beds; LF-4: Normal graded sandstone beds; SLF-4a: Pebbly to fine normal graded sandstone beds; SLF-4b: Coarse-medium to fine normal graded sandstone beds; LF-5: Reverse (inversely) graded sandstone beds-coarse to pebbly grained; LF-6: Laminated sandstone beds; LF-7: Siltstone beds; LF-8: Mudstone beds; LF-9: Chaotic-distorted lithofacies. All facies are grouped into five facies associations based on standard models of deep-marine environment: FA-1: Slope; FA-2: Inner fan; FA-3: Middle fan; FA-4: Outer Fan; FA-5: Debrite deposits. Palaeoflow data measured from flute marks and clast imbrications and analyised on a rose diagram show that the flow direction was toward the SW. This means the source area of the formation was located to the NE. In this study from the interpretation of these facies and facies associations, it is concluded that the turbidites of Tanjero Formation in Sirwan Valley deposited in a slope fan with NE-SW axis. Keywords: Tanjero Formation, turbidite sandstones, facies analysis, deep marine slope fan, Sirwan valley, northeastern Iraq.