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A recent study on deposits constituting the Paleocene Salamanca Fm., in the south-central area of the Chubut Province (Comer et al., 2015), established facies associations that reflect a strong affinity with estuarine and marine depositional systems, involving two sequences. The first starts with a TST, overlying continental Cretaceous rocks, and reaching the maximum flooding surface within shelf deposits, covered by tidal bars and channels deposits (HST). The second sequence developed on an erosional surface, covered by tidal and channels bars, sand flats and microdeltas deposits (LST). The final stages of the second sequence (TST-HST) would be represented by abandoned tidal channels and swamp deposits. The deposits in this area contain abundant fossil plants, mostly included in the tidal heterolithic and clayey facies. The revision of outcrops located around 200 km to the east, on the coastal area of the Chubut Province, allow to define the existence of most facies defined in the western area, proving the continuity of estuarine/marine depositional conditions in the eastern area; however significant differences in the fossil content were found. These would reflect different progradational conditions, as expected from different settings within the basin, but also more time for developing swamp deposits under a temperate climate.The Salamanca Fm. crop outs in the San Jorge Basin, Argentina and constitutes the record of the epeiric Cretaceous?Paleocene flooding that took place in South America (e.g., Uliana and Biddle, 1998). Although an epicontinental to coastal setting is generally accepted in previous contributions, do exist some alternative proposals regarding the depositional context, and a fluvial (Iglesias et al., 2007) or deltaic origin (e.g., Foix et al., 2012) has been proposed. The traditional scheme of Feruglio (1949) defines the Salamanca Fm. as containing four members: ?Lignitífero?, ?Glauconítico?, ?Fragmentosa?, and ?Banco Verde?, underlying the Banco Negro Inferior (BNI), then considered the basal bed of the ?Río Chico Fm.?. On the basis of the continuity of marine influence, and chronological/magnetostratigraphic evidence provided by Clyde et al. (2014) and Comer et al. (2015), we consider to the BNI as the top of the Salamanca Fm. Thus, the Salamanca Fm. unconformably overlies the upper Cretaceous continental beds, and underlies, also unconformably, the fluvial Peñas Coloradas Formation. A recent work (Comer et al., 2015), encompassed in the present-day coordinates 45°?46° S and 68°?69° W (herein the western area) defined 10 facies, interpreted as the record of estuarine and marine depositional systems, and two sequences (Figure 1A). In this contribution a new section (Punta Peligro Norte: PPN) (67° 14´ 00´´, 45° 32´ 00´´) and surrounding outcrops cropping out ~200 km to the E (herein the eastern area) are described (Figure 1B?C), to analyze the continuity of the depositional context defined by Comer et al. (2015).The composite section at PPN, from base to top, contains the facies Cwb, Swc, Swb, Sppl, SCt and Mbb, all of them previously recognized in the western area (Figure1). The facies Cwb, corresponding to the ?Fragmentosa? (Feruglio, 1949), is a wispy-bedded clay with Arenicolitesat top. These U-shaped burrows do not disturb the lamination and always display a sandy fill proceeding from the overlying sandy beds. Its base is not exposed. Abundant microfossils (i.e. benthic and planktonic foraminifera and palynomorphs) were recorded within this facies in the western area.The Cwb facies is interpreted as deposited within a muddy shelf under normal marine conditions. Abundant and well preserved plant remains are contained in the western area, but are absent in the eastern outcrops. The facies Swc is constituted by a glauconitic, cross-bedded sandstone, displaying bi-directional bedsets. Crustaceous burrows (i.e. Thalassinoides) are common, and in some cases obliterate the primary structure.In the middle part of the beds containing the Swc facies, abundant marine invertebrate remains deposited on an erosional surface are recognized (Figure 1B?C). It overlies unconformably the Cwb facies, and displays spring-neap tidal bundles and mud drapes. It was recorded also in the Sarmiento area and is equivalent to the ?Banco Verde? of Feruglio (1949). The main differences with the Swc facies in the western area reside in the nature of the fossil content. Whereas marine fossils characterize the eastern deposits, abundant plant impressions, logs and tree stumps are contained in the deposits of the western area. In the western area, the Swc facies was interpreted as the record of elongated sand bars deposited in open marine environments and in tidal channels under the influence of vigorous tidal currents. In the eastern area tidal channels, and storm deposits are also present, but open marine conditions (i.e. shoreface setting) seem to prevail over tidal ones. The facies Swb is characterized by heterolithic beds, displaying lenticular, wavy and flaser arrangements and a high content in glauconite. Fragments of marine invertebrates are also very common. The rhythmic alternation of sand and silt/mud reflects tidal influence, being possible to recognize neap and spring cycles, whereas high content of glauconite evidences a strong marine influence. These features suggest an intertidal flat setting. The facies Sppl composes of sandstone beds displaying a subhorizontal parallel lamination and is interpreted as sand flats deposits probably developed under upper plane-bed regime. The facies SCt is constituted by silty clay shales, and it always underlies conformably the facies Mbb. The facies Mbb represents the BNI, and is characterized by dark-medium gray, massive mudstone. Both facies contain common pedogenic features such as rhizoliths, slickensides and mottles. Both facies crop out in all of the studied sections, and always underlies to the Río Chico Group. In the eastern area they are characterized by bearing abundant mammal and reptile remains, commonly included inside carbonate concretions (Krause and Clyde, 2013). Such fossils are absent in the western area. The facies SCt probably developed in a supratidal or upper intertidal setting, under periodic wetting and drying and subaerial exposition, as suggested by the pedogenetic features, representing the transition from the tidal/marine influenced settings to swamp conditions (Mbb).The deposits of the Salamanca Fm. at PPN display a strong affinity with estuarine and marine depositional systems, as those interpreted in the western area by Comer et al. (2015).Thus all paleoenvironmental interpretations for the facies previously recognized in the western area are herein maintained.The absence in the eastern area of some facies (micro-deltas, Figure 1A) and non marine fossils (logs and leaves) suggests more continental conditions and more intense progradational deposition for the western area. The stronger marine affinity of the fossils contained in the ?Banco Verde? (Swc) at PPN suggests the deposition under open marine conditions, at least for the lower part of this bed. Abundant reptile remains in the BNI at PPN and surrounding outcrops suggests a swamp setting developed under temperate climate. The restriction of this fauna to the eastern area probably reflects the stronger marine influence on the sedimentation, but also more time of developing for the transitional beds.The comparison of depositional features recognized in both western and eastern areas also suggests a similar sequence-stratigraphic scheme to that proposed by Comer et al. (2015). The absence of the sandy facies assigned to the first HST in the western area (Figure 1A) is probably the product of the erosive event occurred between the ?Fragmentosa? (Cwb) and the ?Banco Verde? (Swc) intervals. This surface along with the presence of Arenicolites, are compatible with a fall of the relative sea level, and the developing of a firmground. In addition, the abundance of marine fossils along with the presence of an irregular, erosional surface in the middle part of the ?Banco Verde? (Figure 1C) suggests the start of the TST-HST system tracts within this bed.

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