Struttura fisica della conoide alluvionale gigante del Fiume Taro e ricarica degli acquiferi della pianura parmense

Using a large set of stratigraphic data, numerous cross-sections of the sauthern margin of the Parma alluvial plain were drawn; they allowed the recognition of the architecture of the Taro al/uvia! fan and the water flow pattern from the sur1ace to the unconfined and confined aquifers. The middle (Medesano-Madregolo) and outer portion of the al/uvial fan system are separated by an anticline, named Madregolo high, which controls the groundflow pattern with its impermeable basement uplifted al about -70 m from ground level. In its outer portion the fan has giant dimensions extending up to 15 km axial/y and up to 20 km normal/y to the depositional strike. The sedimentation of the Middle-Late Pleistocene alluvium is strongly refated to clima tic changes. GeneraI and !oca! evidence permit the assignment of the tens of meter thick coarse fJuvial deposits to cold (glacia!) periods and of the meters thick fine al/uvium to warm (interglacial) periods. The base of the al/uvial fan rests on a lateral/y continuous confining layer dated 180.000 yr BP. At the intersection Taro RiverAutostrada A 1 this layer is encountered at -130 m from ground level; confining layers of lesser importance, internaI to the alluvial fan body, are encountered at -40 and -80 m from ground level. In front of the Madregolo high the coarse sedimentary units (aquifers) of the al/uvial fan body are amalgamated. Northwards these aquifers expand in lhickness and are put under pressure by the intervening confining fayers. This indicates that the groundwater f10w pattern is from the front of the Madregolo high northwards into the unconfined and confined aquifers of the thickest part of the fan.