CONCLUSIONES Y RECOMENDACIONES

Fluvial input

A total of seven main distinct sedimentary packages were identified in the cores recovered from AL2 bar. They are numbered according to a chronological order of deposition, from the oldest (1) to the youngest (7) (Table 3A; Figure 8).

AL2 was deposited over a thick, extensive and massive muddy (clayey) deposit. This muddy deposit slightly thins in the landward direction and separates AL2 from an older point bar deposit (upper part reached by the cores 2, 3 and 5), which exhibits sedimentological

characteristics similar to the DUP bar. The upper part of this muddy deposit is formed by Packages 1 and 2. Package 1 was identified only at the seaward part of the bar, closer to the flood channel. It is a 40 centimetric thick package consisted of poorly sorted coarse to very coarse conglomerate lag4 in the base covered by thick massive sandy clay. Package 2 is found closer to the flood channel, from the middle toward the seaward part of the bar. It mostly

consists of muddy IHS (with mm-cm silty clay) intercalated with some massive sandy clay to clay deposits.

AL2 basal deposit erosionally overlies the muddy deposit. It is represented by Package 3, which was identified throughout the bar. It is a subhorizontal package formed by low angle accretion surfaces. It is predominantly consisted of poorly (at the base) to well sorted (at the top) mixed IHS (with mm-cm clayey to silty drapes).

Above the basal deposit, a series of vertically and laterally stacked upward-fining deposits delimited by erosional surfaces were deposited. These deposits are represented by Package 4. This package was subdivided in packages 4.1 (predominant), 4.2 and 4.3. Package 4.1 consists of poorly sorted conglomerate lag4 (with mm-cm mud clasts) at the base capped by

4

Conglomerate lag, as defined by Thomas et al. (1987), is a deposit characterized by an erosionally- based massive (structureless) sandy package with some well-rounded mud intraclasts located mostly at

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intercalations of muddy and mixed IHS (with mm-cm clayey to silty drapes) grading to massive or inclined laminated sandy to silty clay at the top. Packages 4.2 and 4.3 are similar to package 4.1, but with thicker muddy layers. Package 4.2 does not contain conglomerate lag4 deposits. These packages are predominantly composed of intermediate angle ebbward-seaward-dipping accretion surfaces. AL2 is mostly composed of Package 4, which also comprises the top of the bar in its middle part, both along the ebb and flood channels. At the lower part of the bar, these packages are poorly sorted with sandy particles ranging from fine to very coarse. Upwards, the sedimentary packages become well sorted and muddier, with sandy particles ranging from fine to medium.

The top of the bar, in its landward and seaward parts closer to the ebb channel is composed of a thick well sorted upward-coarsening section, represented by Packages 5 and 6. Package 5 is predominantly composed of sandy IHS (with mm-cm silty clay) with fine to medium sands and intermediate angle ebbward-seaward-dipping accretion surfaces. This package grades upward to Package 6, which is composed of massive sand. However, at the seaward part of the bar, closer to the flood channel, these upward-coarsening deposits are not present. At this part of the bar, a thick layer of massive silty clay (Package 7) is covering Package 4.

No fluvial input

A total of nine main distinct sedimentary packages were identified in the cores recovered from DUP bar. They are numbered according to a chronological order of deposition, from the oldest (1) to the youngest (9) (Table 3B; Figure 9).

The entire bar is composed of well sorted sedimentary packages. The base of the bar is delimited by an extensive erosive surface. It is consisted of two distinct upward-fining

sedimentary packages (Packages 1 and 2). Package 1 was identified at the most seaward part of the bar in a section longitudinal to the bar crest. It is formed by massive sand (predominant), its lower part. These deposits are abundant at the base channel-fill deposits but they can also be found at the base of point bars. For a more detailed description see item 3.3.1. in Chapter 3.

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with medium sands, intercalated with sandy and muddy IHS (with mm-cm silty drapes). Package 2 was found all over the bar, extending above and beside Package 1. It is mainly composed of thin-layered sandy IHS (with mm-cm silty drapes) with fine sands. Both packages are formed by ebbward-seaward-dipping accretion surfaces.

Package 3 is distributed all over the bar and it is erosionally overlaying the basal packages. This package is exclusively composed of thin-layered sandy IHS (with mm-cm silty drapes) with fine sands, showing no vertical grain size trend and formed by ebbward-seaward- oriented accretion surfaces, which exhibit less steep foresets than the foresets of the accretion surfaces that compose the basal Package 2.

Packages 4 and 5 are partially overlaying packages 2 and 3. They are well delimited mud-dominated IHS (with centimetric clayey drapes), with very fine to fine sands. These deposits show either no vertical grain size trend or upward-fining.

Packages 6 and 7 erosionally truncate the underlying mud-dominated deposits. From this point, the bar starts to exhibit a slight upward-coarsening (and also upward-sandier) grain size trend, with sand grain sizes increasing from fine to medium. Package 6 was found at the landward and middle parts of the bar while Package 7 was deposited throughout the upper part of the bar. These packages are mainly consisted of conglomerate lags4 (with mm-cm mud clasts) grading to sandy and mixed IHS (with mm-cm silty drapes) deposits, though package 6 is muddier. Package 7 is consisted of massive sands in its uppermost part. Both packages are mostly composed of ebbward-seaward-dipping accretion surfaces. However, floodward-

landward-dipping accretion surfaces were also observed.

Packages 8 and 9 are also upward-coarsening deposits. Package 8 is composed of massive sandy silt or sandy IHS intercalated with mixed and muddy IHS. It was found along the entire bar, except at its most landward part. Package 9 is composed of massive sand or

conglomerate lag4 (with centimetric mud clasts). It was not found at the middle part of the bar. It is important to note that as Boomer is a deep penetration seismic method, it loses resolution

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when closer to the bar surface, so the lateral extension of shallower deposits (Packages 7, 8 and 9) are difficult to be mapped.

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