A sequence of marine terraces near Latina (Agro Pontino, central Italy) (original) (raw)
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Soil genesis in a marine terrace sequence of Sicily, Italy
Revista mexicana de …, 2007
Knowledge about the rates of pedogenic processes is essential to understand landscape development and history. It can be attained by the quantitative investigation of soil chronosequences. In this work, the development of Chromic Luvisols in the Mediterranean is addressed. The soils investigated are located on fi ve uplifted Pleistocene marine terraces in south-western Sicily, and have developed on calcareous marine and fl uvial sediments. The soil on the highest terrace is a Ferri-Profondic Luvisol, while soils on the lower terraces represent a Chromi-Profondic Luvisol (Bathifragic), a Chromi-Profondic Luvisol and two Bathicalci-Chromic Luvisols. The soils on the 1st (lowest) and 2nd terrace are 100 cm thick, the one on the 3rd terrace, 160 cm and those on the 4th and 6th (highest) terrace more than 200 cm. All soils are decalcifi ed, while greater CaCO 3 contents in the Ap horizons of the soils on the three lower terraces are due to deposition of younger calcareous fl uvial sediments. Soil pH (water) drops from pH 7. 7-8.9 in the soils on the three lower terraces to values below pH 7 in the soils on the two higher terraces. In general, the chemical alteration and the leaching of silicic acid increase with elevation, and are most pronounced on the 4th and 6th terrace. Clay illuviation and associated translocation of Fe, Al and K is pronounced in all soils. The clay minerals include kaolinite, illite and expandable three-layer silicates. Irregularly interstratifi ed clay minerals are composed of illite, vermiculite, smectite and chlorite, and usually constitute 20-40 % of all clay minerals, indicating proceeding soil development. The comparatively more advanced weathering and the high kaolinite content on the most elevated terrace point to soil development under warmer and wetter climate, that is early Pleistocene or earlier. The soil on the 4th terrace is more developed than the soils on the less elevated terraces.
Quaternary international, 2006
Two soil chronosequences, representative of four orders of marine terraces from Early to Late Pleistocene, have been studied along the Tyrrhenian coast of northern Calabria, in Southern Italy. All soil profiles show a high degree of weathering, although the degree of soil evolution varies according to the age of each terrace. The soils are characterized by reddish to reddish brown colors, clayey textures, abundant clay coatings, slickensides, Fe-Mn features or calcium carbonate concretions. The dominance of kaolinite and illite among phyllosilicate clay minerals in all soil horizons, the intense depletion in CaCO 3 , Na and K, and the severe etching of quartz crystals in the older soils all record a highly leached pedogenic environment that is progressively more intense from younger to older soils. Despite the carbonate bedrock, quartz, feldspar and mica minerals also occur, suggesting a partly allochthonous, eolian origin of the parent material. The major pedogenic features and their formative processes occurred polycyclically on the different orders of marine terraces, and we interpret the soils to have mainly developed during repeated Quaternary interglacials. Some surface A and Bw horizons show quite different features, suggesting a clear change in pedogenetic processes and possibly in climate and duration of soil formation. These horizons have the typical field appearance of volcanic soils with andic properties (brown colors, loamy textures, high porosity, low bulk density, high water retention, thixotropy). The occurrence of very small volcanic glass fragments and the possible presence of short-range order aluminosilicate minerals confirmed some pyroclastic supply during soil formation. r
Quaternary International, 1998
Two very deep, red soils on a loess-mantled fluvial terrace of the Trebbia River in northern Italy were sampled and analyzed to determine their history and pedologic significance. Magnetostratigraphy confirms that the upper part of the terrace gravel and all of the 4-m-thick loess cover is normally magnetized and therefore less than about 780,000 yr. Artifacts collected from the oldest loess suggest an age of about 400,000 yr for the inception of loess deposition in this area. The soil horizons in loess dominantly have argillic or albic character, with redoximorphic features that include mottles, glossic tongues, and zones of ferromanganese concretions. Soil colors become progressively redder with depth in the loess cover and are most red, a 2.5 YR color hue, in the top of the terrace gravel. The upper horizons in gravel have abundant ghosts of completely weathered marl and sandstone. Rubification and weathering of stones diminishes with depth to fresh, slightly carbonate enriched parent material at 12 m. The heavy mineral composition of the sand fraction suggests minor discontinuities in loess-derived horizons. Abundance of opaque heavy minerals and picotite, which are resistant to weathering, increases from the soil surface to the base of the loess, is highest in the upper part of the terrace gravel, and decreases from there to the C horizon in gravel. Depth functions of major elements to Si in the medium silt fraction (10–30 μm) indicate a downward increase in degree of decalcification and of dissolution of primary minerals. Micromorphology adds detail to the interpretation of these complex soils: yellow complex ferriargillans are present in almost all horizons; they are rare at the top of the sequence in loess and become progressively more abundant with depth, reaching a maximum in the upper 3 m of the gravel and then decreasing with further depth to 12 m. We interpret this peak in abundance of yellow cutans to result from long continued clay illuviation to this depth from a succession of eluvial zones in the aggrading loessial sequence above. Distinctive red, hematite-rich argillans are abundant only in the upper horizons in the gravel. The red argillans relate to initial development of the soil in gravel, because they are included as pedorelicts in the deepest loess layer, where they are embedded in the yellow argillans. Stratigraphic and pedologic evidence indicates that these soils began forming in terrace gravel for perhaps 300,000 yr during the early middle Pleistocene. From this relict core these soils continued developing, both downward by continuing deep decalcification and argilluviation and upward as a sequence of wet Alfisols developed in a succession of loess layers that began aggrading about 400,000 yr ago. A paleoclimatic record can be perceived weakly in these soils, mainly by thick horizons of FeMn nodules that mark boundaries between episodes of loess deposition that took place during glacial cold phases. Paleofeatures from one unit to another are similar in kind and intensity, indicating a degree of continuity of a basic set of pedogenic processes, principally declcification, argilluviation, and redoximorphism. These soils can be regarded as Vetusols because a single dominant set of pedogenic features are represented in all parts of these soils and deeper parts of these aggrading super profiles have never been isolated from continuing pedogenic change to the present.
2009
The ability to investigate meaningful geoarchaeological questions is driven by appropriate scale-process focus fundamentally informing sampling strategies. This in turn, is driven by site-specific characteristics such as topography, sedimentology, geochemistry and climate. The Laurentine Shore is the Roman-period palaeo-shoreline preserved up to 1 km inland of the modern coastline of the Tiber Delta at the southern distal end. Mid- to late-Holocene progradation of the Tiber Delta linked to sediment supply in the context of changing relative sea level drives the macro-scale (103+) development of the region. Archaeological remains preserved within the Presidential Estate of Castelporziano must be interpreted within this macro-scale context. Using a multiscale, transect-based approach, SAAD-IRSL luminescence dating of relict foredune ridges has provided an age model constraining the development of the Tiber delta during the late Holocene. Both radiocarbon (Giraudi et al., 2009) and luminescence chronologies of dune ridge phases are in good agreement. Due to the protected status of the Castelporziano Estate the Holocene coastal dune topography is better preserved than at the central delta area and two additional phases of dune ridge formation are observed. Four macro-scale phases of delta progradation are recorded by the dune ridge record with increased mean rates of progradation observed during the Roman period and within the last 500 years. On the meso-scale (102) the high-status villas on the Laurentine Shore, and the Vicus Augustanus that serviced the villas are specifically located on the Roman-period shoreline. The timing of settlement (from around 2050 BP, i.e., 1st century BC) occurs during a pronounced Tiber delta progradation phase. Within this macro-scale context issues of sediment supply, frequency of Tiber flooding and the expression of shoreline advance at the Laurentine Shore have important meso-scale consequences for the development of the archaeological sites. It is likely that during the 2-phase development of the Vicus Augustanus that shoreline progradation was an observable phenomenon on decadal to multi-decadal timescales. Indeed the second, major seaward construction phase of the Vicus Augustanus likely occurred upon land that did not exist during the first phase, directly linked to delta progradation and the macro-scale processes acting upon the development of the site including anthropogenic activity in the Tiber catchment during the Roman period.
Zerboni et al J Soils Sediments 2014 personal copy
Purpose At the northern fringe of the Po Plain (northern Italy), several isolated hills exist, corresponding to the top of Late Quaternary anticlines. These hills were thoroughly surveyed for their soils and surficial geology, furnishing detailed archives of the palaeoenvironmental evolution of the area. A new, thick and complex loess-paleosol sequence, resting upon fluvial/fluvioglacial deposits, exposed in a quarry at the top of the Monte Netto hill was studied in detail to elucidate its significance. Materials and methods Highly deformed fluvial and fluvioglacial deposits, probably of Middle Pleistocene age, are exposed in a clay pit at Monte Netto, underneath a 2-to 4-m-thick loess-paleosol sequence. A geopedological, sedimentological and micropedological investigation of the sequence shows a distinctive difference between the B horizons forming the sequence, while luminescence and radiocarbon age determinations and the occurrence of Palaeolithic lithic assemblages elucidate the chronology of the sequence. Results and discussion The pedosedimentary sequence consists of several loess layers showing different degrees of alteration; loess deposition and weathering occurred, according to optically stimulated luminescence (OSL) and AMS-14 C dating as well as archaeological materials, during the Upper Pleistocene. The lower part of the section consists of strongly weathered colluvial sediments overlying fluvial and fluvioglacial sediments. A tentative model of the exposed profiles involves the burial of the anticline, which forms the core of the hill, by loess strata since Marine Isotopic Stage (MIS) 4 and their subsequent weathering (and truncation) during subsequent interstadials. The degree of weathering of buried B horizons increases from the top of the sequence toward the bottom, suggesting a progressive decrease in the intensity of pedogenesis. Finally, the highly rubified paleosol at the top of the hill is regarded as a buried polygenetic soil or a vetusol, developed near the surface since the Middle Pleistocene. Conclusions The palaeopedological, geochronological and geoarchaeological analyses permit to define the phases and steps of development of the Monte Netto pedosedimentary sequence; the lower part of the sequence is dated to the Mid-Pleistocene, whereas loess accumulation occurred between MIS 4 and MIS 2. Moreover, analyses help to clarify the climatic and environmental context of alternating glacial and interstadial phases, during which the sediments where deposited, deformed and weathered.
Purpose At the northern fringe of the Po Plain (northern Italy), several isolated hills exist, corresponding to the top of Late Quaternary anticlines. These hills were thoroughly surveyed for their soils and surficial geology, furnishing detailed archives of the palaeoenvironmental evolution of the area. A new, thick and complex loess-paleosol sequence, resting upon fluvial/fluvioglacial deposits, exposed in a quarry at the top of the Monte Netto hill was studied in detail to elucidate its significance. Materials and methods Highly deformed fluvial and fluvioglacial deposits, probably of Middle Pleistocene age, are exposed in a clay pit at Monte Netto, underneath a 2-to 4-m-thick loess-paleosol sequence. A geopedological, sedimentological and micropedological investigation of the sequence shows a distinctive difference between the B horizons forming the sequence, while luminescence and radiocarbon age determinations and the occurrence of Palaeolithic lithic assemblages elucidate the chronology of the sequence. Results and discussion The pedosedimentary sequence consists of several loess layers showing different degrees of alteration; loess deposition and weathering occurred, according to optically stimulated luminescence (OSL) and AMS-14 C dating as well as archaeological materials, during the Upper Pleistocene. The lower part of the section consists of strongly weathered colluvial sediments overlying fluvial and fluvioglacial sediments. A tentative model of the exposed profiles involves the burial of the anticline, which forms the core of the hill, by loess strata since Marine Isotopic Stage (MIS) 4 and their subsequent weathering (and truncation) during subsequent interstadials. The degree of weathering of buried B horizons increases from the top of the sequence toward the bottom, suggesting a progressive decrease in the intensity of pedogenesis. Finally, the highly rubified paleosol at the top of the hill is regarded as a buried polygenetic soil or a vetusol, developed near the surface since the Middle Pleistocene. Conclusions The palaeopedological, geochronological and geoarchaeological analyses permit to define the phases and steps of development of the Monte Netto pedosedimentary sequence; the lower part of the sequence is dated to the Mid-Pleistocene, whereas loess accumulation occurred between MIS 4 and MIS 2. Moreover, analyses help to clarify the climatic and environmental context of alternating glacial and interstadial phases, during which the sediments where deposited, deformed and weathered.
Quaternary International, 2010
Two major synthems have been recognised along the coasts of Sardinia. The older one is composed of two sub-synthems, the oldest of which was formed in high-energy boulder beaches, and is a thin condensed transgressive sequence usually located at the foot of a marine cliff. The overlying sub-synthem was generated by aeolian, slope, interdunal ponds and alluvial depositional environments. It is widespread, and terraces and relict dune fields are usually deeply dissected. Its deposition is associated with a cold and arid climate. The aeolian and alluvial deposition was interrupted by the evolution of steppe-prairie soils. A more evolved reddish brown Bt paleosol is locally found at the top of the sequence. The younger synthem is made of beach and coastal lagoon and swamps. It is more variable in thickness, rests unconformably over the older, one and has no sedimentary cover. It is laterally correlated to the present-day depositional environments such as alluvial plains and beaches. Unfortunately, because beach deposits of this synthem are found up to 6 m asl and a marine notch is present at 5-6 m (Capo San Marco), the widespread idea that Sardinia is a stable area and that marine sea level during the Holocene was never higher than nowadays led to their previous attribution to MIS 5e. However, all the stratigraphic, geomorphic and pedological evidence indicates that only the older sub-synthem can be correlated with the MIS 5e high stand. The younger sub-synthems made of aeolian lacustrine and alluvial deposits at Cala Gonone, Santa Reparata, Capo S.Marco and S.Giovanni di Sinis were deposited during the rest of the Late Pleistocene. The younger synthem evolved during the Holocene, and this is the chronological setting of the beach deposits at Is Arenas, Scala é Croccas, Santa Reparata, and Capo San Marco. Radiocarbon dating confirms these attributions. Unfortunately, OSL dating suggests an older chronology for these deposits, and therefore it seems that further investigations are needed.