No abstract

Recently published models for deep marine slopes provide a framework for understanding the sedimentary architecture and geometries of major correlative surfaces in this environment. These models use concepts which include: (i) the development of erosional and unconformable onlapping relationships in a slope-to-basin setting by processes other than changes in relative sea-level (e.g. earthquake induced gravity flows), (ii) the definition of genetic facies associations and (iii) the development of base-of-slope systems by repeated mass-wasting in order to establish an equilibrium slope profile. These models are based primarily on seismic data from present-day slopes or numerical simulation, and have not been tested in the field. An example from Turkey of a progradational Eocene basin-to-slope transition is presented to test these models. We found that most mass-wasting occurs at the top and not base of the slope, that this is likely to be earthquake-induced rather than related to changes in relative sea-level, and that seafloor topography continues to control sand transportation pathways and mass-wasting throughout slope apron deposition.

A series of deep-water channel deposits are exposed near Baskil, 50 km west of Elazi~ in eastern Turkey. The use of correlation panels, sedimentary logs, biostratigraphy and mapping revealed that all of the channel elements are found within much larger features. One series of channels from the southern margin of the basin lie, within an entrenched deep-water slope channel complex, over 3 km wide, called the Nohut Channel Complex. This channel complex has three main fill packages. The lower package is a highly disturbed, slumped interval that directly overlies the erosional base of the main channel complex. The slumped interval is interpreted as a series of mass transport complexes, derived from shallow marine or upper slope facies. The second package comprises a mixed carbonate-siliciclastic series, principally of interbedded calcarenites, marls and mudstones. Locally, outer shelf/upper slope offset-stacked channels with calcarenite fills occur. The upper package comprises isolated conglomerate and sandstone filled deep-water channels that are incised into laterally extensive depositional lobes. The coarse-grained fills are dominated by tabular beds. The lobes are comprised of fine-medium grained sandstones. Some of these channels have low aspect ratios (25:1), and are asymmetric in cross-section, suggesting sinuosity. The upper part of this fill package is either incised into by pro-fan delta conglomerate filled channels, or downlapped onto by shelfal calcarenites. A separate series of channels come from the northern margin of the basin, but are interpreted to have developed on an open, deep-water slope or ramp, rather than as an entrenched channel complex. These channels occur in two main sets, collectively referred to as the Aydinlar Channel Complexes. The lower set is characterized by syn-sedimentary foundering of the sand-filled channels within slumped enveloping finer-grained slope sediments. The upper set of channels, dominated by one large sand and gravel-filled fairway, is characterized by large bedforms at the base, passing upwards into stacked conglomerates, mud chip breccias and sandstones. The conglomerate facies is locally injected upwards into the fill or laterally into finer-grained marginal facies. The channel is capped by finer-grained facies, including graded sandstones and siltstones with complete Bouma sequences.

This study was carried out to determine the sedimentary provenance of Upper Cretaceous turbidites of Tanjero Formation. The sandstone portion of the unit has been examined based on field and laboratory studies. Seven sections were measured and described in detail on the perfectly cropped out part of the unit at the southern limb of the Sulaimaniyah Syncline. The thickness of the measured sections varies from 120 m to 192 m. The measured sections start from the top of the underlying Shiranish Formation to the syncline axis in the Tanjero Formation. For petrographic analysis sixty-nine representative rock samples were collected. Modal analysis and ternary diagrams point out that, the sandstones are calclithite (litharenite), very fine to medium grained in size consisting of chert, siltstone, mudstone, radiolarian chert and radiolarian mudstone fragments, angular to subangular in shape, very poorly to moderately sorted, transported over short distances and represent submature stage. Grain contact types and high contact index (4,7) indicate moderate to tightly packing, moderate compaction. Transported broken neritic fossil shells, moderately rounded glauconite grains, and undefinable fossils in the altered carbonate rock fragments indicate that the tectonic provenance, lithic recycle category, composed of not only the clastics as interpreted in previous studies derived from Lower Cretaceous Qulqula (radiolarian) Formation which represents deep marine, but also it revealed that a sedimentary formation must also exist in the source area, which is the Lower Cretaceous Balambo Formation.

Introduction The northern part of Iraq is an oil field area and there are many studies summarized in this part of the paper. The majority of them about the reservoir were done on carbonates and some on clastic rocks, excluding provenance analysis. The Tanjero Formation is the only turbidite formation cropped out in the area that can supply us with valuable petrographic data to establish a correct provenance and the related tectonic setting of the Cretaceous basin in the northeastern Iraq area.