Field investigation, Microfacies analysis, and biostratigraphy have been carried out in the central parts of the Ionian Basin (Aetoloakarnania area, Western Greece) in order to decipher the depositional environments that developed during the accumulation of the Upper Cretaceous to Eocene carbonate succession. Three different Standard Microfacies types (SMF) have been observed, corresponding to two different depositional environments (Facies Zones or FZ) of a platform progradation. The three SMF types which occur in the study area during the Upper Cretaceous to Eocene are: 1. SMF 3 that includes mudstone/wackestone with planktic foraminifera and radiolaria, corresponding to toe-of-slope (FZ: 3), 2. SMF 4, which can be classified as polymict clast-supported microbreccia, indicating a toe-of-slope-slope environment (FZ: 4) and 3. SMF 5 which is characterized by allochthonous bioclastic breccia and components deriving from adjacent platforms and which reflects a slope environment. Microfacies analysis provided evidence of a change in the origin of sedimentary components and biota showing the transition from toe-of-slope to slope, as well as a change in organism distribution.
This study integrates sedimentological and stratigraphic insights into the Upper Permian sedimentary rocks of the Wittingham, Tomago and Newcastle Coal Measures in the Northern Sydney Basin, Australia. Facies analysis documented fifteen facies that belong to seven facies associations. These facies associations correspond to different depositional environments and sub-environments including prodelta, delta-front, upper, lower delta-plain and fluvial. The stratigraphic development points to a shallowing upward trend and is reflected with fluvial deposits sitting on top of the deltaic deposits. The fluvio-deltaic contact is represented by an unconformity and displays an upward increase in sediment caliber. The delta front is mainly controlled by wave, storms- and/or river currents, even though the contribution of tides also occurs in the form of sedimentary structures that suggest tidal influence. In contrast, prodelta and delta-plain are significantly modulated by tidal currents. The impact of tides in the delta plain is fading away upward and therefore, the upper delta plain is much less impacted compared to the lower delta plain. The low abundance of wave ripples suggests that the wave action was not very important in the delta plain. Steep topographic gradients and increased sediment input are suggested, based on the limited or absent evidence of tides in the fluvial realm, related to the growing New England Orogen. In sequence stratigraphic terms, the deltaic system accumulated during highstand normal regression, while the deposition of the overlying fluvial system occurred during lowstand normal regression. The two systems are separated by a subaerial unconformity developed during an intervening forced regression. Short periods of transgression are inferred from the presence of higher frequency cycles in the delta-front.
This study provides a sedimentological, stratigraphic and palaeocurrent investigation of Upper Eocene to Lower Oligocene deep‐sea fan deposits found in the central part of the Pindos foreland basin in western Greece. According to facies analysis, the examined succession at Amfilochia area has 13 sedimentary facies and 10 facies and sub‐facies associations. Depositional elements include abyssal plain pelagics, outer fan, inner fan, and slope deposits. Outer fan sediments are classified as lobe‐axis, lobe‐off‐axis, lobe‐fringe, and distant lobe‐fringe deposits, while inner fan sediments are classified as channel‐fill, crevasse‐splay, internal and external levee deposits. The stratigraphic study shows an upward shift from abyssal plain pelagics to outer, inner fan, and finally slope deposits, implying submarine fan system progradation and progressive infilling of a deep‐water sediment depocentre. The sediments were deposited in the foredeep of the Pindos foreland system and correspond to the system's underfilled stage, when sedimentation was unable to exceed the accommodation provided by lithospheric flexure. They point to deposition near the onset of the Pindos orogen, after the closure of the Pindos basin because of the collision of the Apulian with the Pelagonian microplate during the Cretaceous‐Palaeogene period. Palaeocurrent data from sole marks show bipolar directions associated with two distinct spreading sub‐marine fan deposits. As a result, the study region was split into Upper (major SE‐direction flow) and Lower (major NW‐direction flow) parts, indicating that axial flows were predominant during sediment deposition. However, as the deposition of the elements continued, the progradation of both systems constrained the space accommodation because of the increased basin sediment supply and forced an increase in the degree of basin confinement that changed the compensational to aggradational stacking pattern. The goals of this research are to develop an updated facies model for these deep‐sea fans as well as a robust correlation framework for the various stratigraphic units in the central Pindos foreland basin. This research also connects the stratigraphic development of deep‐sea fan deposits to the evolutionary phases of the Pindos foreland system, providing fresh insights into the palaeogeographic circumstances in the Pindos foreland basin.
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