The Upper Miocene Injana (Upper Fars) Formation of Iraq: insights on provenance history

Abstract

Petrographic, geochemical, and scanning electron microscope analyses of the sandstone and mudstone units of the Upper Miocene Injana Formation are presented. Furthermore, microprobe analysis for amphiboles, pyroxenes, garnet, and chromian spinels as common heavy mineral species present is done to support other results for better understanding of the provenance history of the Injana Formation. The sandstones of the Injana Formation consist of terrigenous carbonate lithic fragments as common type of sedimentary rock fragments in addition to chert, argillaceous, and rare sandstone fragments. They also include metamorphic and igneous lithic fragments, quartz, feldspars, and mica and generally, the sandstones are lithic arenites and immature. Scanning electron microscopic analysis for the heavy minerals shows that they have been affected by dissolution due to chemical etching and mechanical abrasion through several surface texture generated either in arid and semihumid environment or in diagenetic environment. Clay mineralogy of the mudstone units indicates the presence of illite, chlorite, kaolinite, palygorskite, and illite-smectite mixed layers. Bulk-rock and mineral phase geochemistry in addition to petrographic data suggest the derivation of the Injana Formation from a nearby sources with contribution from igneous, metamorphic, and sedimentary provenance mainly from the high lands in the northeastern parts of Iraq which comprise mainly the Zagros mountains and the older sedimentary formations.

The Euphrates-Tigris-Karun river system: Provenance, recycling and dispersal of quartz-poor foreland-basin sediments in arid climate

“…The Neogene succession, gently folded and exposed in the foothills at the front of the range, consists of fluvio-deltaic red sandstones and mudrocks (Fat'ha or Lower Fars Formation; Al-Juboury and McCann, 2008) and 3 km-thick, coarse-grained fluvio-deltaic sediments (Injana or Upper Fars and Bakhtiari fFormations; Al-Juboury, 2009). …”

“…Amphibole and pyroxene correlate positively (r 0.3-0.6), and are virtually absent in epidote-dominated recycled sands of the Adhaim-Aqsu River. However, even unstable ferromagnesian minerals can be recycled, because they resisted diagenetic dissolution to some degree (Al-Juboury, 2009) and are quite common in upper Miocene foreland strata drained by the Euphrates (Philip, 1968). This points to decreasing intensity of diagenetic dissolution from more deeply buried internal units of the foothills, containing dominant epidote because ferromagnesian minerals have been selectively dissolved, to foreland strata where diagenetic effects are least extensive and ferromagnesian minerals largely preserved.…”

“…Neogene deposits are patchily exposed along the northeastern margin of the Arabian foreland from Syria to the Gulf (Jassim and Goff, 2006 p.181-183;Al-Juboury, 2009). Additionally, fine-grained quartzose sediment with K-feldspar, zircon and tourmaline is blown during major dust storms from Arabian deserts to reach the Mesopotamian plain, the Gulf and beyond ( Fig.…”

“…0.1%) and poorly negative for apatite, garnet and staurolite (r ≈ -0.3). Unstable Aamphibole and pyroxene correlate positively (r 0.3-0.6), and but may occur in Neogene molasses (Philip, 1968), and thus resisted diagenetic dissolution to some degree (Al-Juboury, 2009). Ferromagnesian minerals are virtually absent in epidote-dominated recycled sands of the Adhaim-Aqsu River.…”

Identification of facies‐controlled eogenetic karstification in the Upper Cretaceous of the Halfaya oilfield and its impact on reservoir capacity

“…(a) Regional structure and location of the study area in Iraq (modified from Al‐Juboury, ). (b) Enlarged of the study area in (a).…”