Nuovi dati stratigrafici e cartografici delle unità quaternarie del Foglio 438 "BARI" (Puglia - Italia meridionale)

Abstract

Spalluto L. et al., New Stratigraphic and Cartographic data from the Quaternary Units of the 438 Sheet “Bari”. (IT ISSN
0394-3356, 2010).
A new geological survey was carried out in order to create the 438 Sheet “Bari”, which is part of the National CARG (Cartografia
Geologica) Project whose aim is to produce the Geological Map of Italy at the scale 1:50 000. The 438 Sheet “Bari" represents an area
located in a coastal sector of the Murge region in Apulia (southern Italy), and its stratigraphy is quite simple: on a Cretaceous bedrock,
made up of limestones belonging to a Mesozoic carbonate platform (not of interest for this work), Plio-Plestocene sedimentary covers
disconfomably and discontinuosly lie. As regards these sedimentary covers, obtained data led us to propose a new lithostratigraphic
subdivision which differs from the formal one utilized in the previous geological maps referred to the same area (177 Sheet “Bari" and
178 Sheet “Mola di Bari" at the scale 1:100 000). In greater detail, the Plio-Pleistocene deposits cropping out in the studied area were
formerly included and classified in two formations (Tufi delle Murge and Argille di Rutigliano fms), locally Pleistocene in age. Tufi delle
Murge fm. is here referred partly to the Calcarenite di Gravina Fm. (late Pliocene ? - early Pleistocene in age) and to 4 of the 5 terraced
synthems of the Murge supersynthem (middle-late Pleistocene in age). Argille di Rutigliano fm. is here referred partly to argille subappennine fm. (early Pleistocene) and to the Rutigliano synthem of the Murge supersynthem. Terraced alluvial deposits of the lame delle Murge supersynthem complete the stratigraphic framework of Quaternary units in the area of the map 438 Sheet “Bari”.
Calcarenite di Gravina Fm. and argille subappennine fm. represent the sedimentary succession conformably deposited during the wellknown regional tectonic subsidence phase occurred during late Pliocene-early Pleistocene times in the Bradanic Trough. This succession is locally marked by the gradual change from shallow-water carbonate sedimentation (Calcarenite di Gravina Fm.) to deep-water emipelagic sedimentation in outer shelf environments (argille subappennine fm.).
The five synthems of the Murge supersynthem mark the gradual emersion of this sector of the Apulian Foreland during the regional
tectonic uplifting. Synthems represent the sedimentary expression of the general regressive trend produced by the interaction between tectonic uplift and glacio-eustatic sea-level changes. The regressive trend is also suggested by the irregular deepening of main karstic canyons (locally named lame), recording alternating phases of linear incision and deposition resulting in the deposition of the alluvial terraced deposits, locally mapped as synthems, belonging to the lame delle Murge supersynthem.