The Maratea valley (Calabria) is characterized by deep gravitational movements involving Mesozoic calcareous-dolomitic formations ("Alburno-Cervati" and "Bulgheria-Verbicaro" tectonic units), interpreted as sackung-type phenomena (Guerricchio et al., 1987; 1994; Colantoni et al., 1995). The complex morphostructural setting of the area has been influenced by Pleistocene extensional tectonics, probably still active. Tectonic dislocations, probably characterized by regional transcurrent component, have allowed in the past the superimposition of the Bulgheria-Verbicaro unit on the "Crete Nere" Formation and the tectonic contact of the last formation with the Alburno-Cervati unit, cropping out at the right flank of the valley. Normal faulting, block rotations and structural widening of the valley are produced as an effect of differential velocity during transcurrent tectonics. The "Crete Nere " Flysch ("Liguride Units"), assuming a plastic behaviour due to high water contents assumes a flow-type, relatively deep process (30-50m) within the valley and near the see and constitutes a lubricant base for detrital covers and carbonatic units outcropping along its left flank and nearest relief, where deep gravitational movements are developed. The geologic framework of the Maratea valley on land is connected with the Late Pleistocene-Holocene evolution of the surrounding continental platform and slope and with the significant glacio-eustatic variations during the Late Quaternary. High-resolution seismic reflection profiles recorded during the cruise GMS00-05 (October-November 2000) onboard of the R/V Urania (CNR) by using a Watergun 15 c.i. seismic source and Stratavisor (Geometrics Inc.) acquisition system (Marsella et al., 2001) give new evidences on the offshore elongment of the Maratea valley. The deep gravitational movements influence the geologic setting of surrounding platform and slope, characterized by deformed slope sequences involved by NE-SW normal faulting and slumps. Normal faulting has also controlled the development of the Maratea canyon itself. The occurrence of the Maratea submarine canyon's head is relevant, since the canyon undermine the instable masses of the Maratea valley and induces sliding through regressive erosion. Late Pleistocene progradations and relative structurally-controlled shelf break, occurring at water depths of about -30m are evident on the Watergun profile SASA130bis (fig. 1), running in the Policastro Gulf with a NNW-SSE trending. At the foot of the slope is evident the offshore prolongation of the Maratea valley. Significant normal faulting involves the Late Pleistocene-Holocene slope sequences, together with slumps, evidenced also by rapid variation in thickness of seismic sequences. Basic references - Guerricchio A., Melidoro G., Rizzo V. - Boll. Soc. Geol. It., 106, 293-302. - Guerricchio A., Melidoro G., Rizzo V. - Proc. IAEG 7th Cong., Lisboa, II, 1075-1082. - Colantoni P., Gabbianelli G., Rizzo V. e Piergiovanni A. - Atti Cong. CNR "Grandi fenomeni gravitativi lenti nei centri abitati delle regioni Alpine e Appenniniche", Maratea, settembre 1995. - Marsella E., Aiello G., Pelosi N., Angelino A., Budillon F., Giordano F., Rapolla A., Di Fiore V., Siniscalchi A., D'Isanto C., Ruggieri S. - Istituto di Ricerca "Geomare Sud", CNR, Napoli, Rapporto Tecnico n. 11 (crociera GMS00-05).
Deep gravitational processes in the Maratea valley (Southern Italy): evidences from high resolution seismic reflection profiles
Ennio Marsella;Gemma Aiello;Nicola Pelosi;
2007
Abstract
The Maratea valley (Calabria) is characterized by deep gravitational movements involving Mesozoic calcareous-dolomitic formations ("Alburno-Cervati" and "Bulgheria-Verbicaro" tectonic units), interpreted as sackung-type phenomena (Guerricchio et al., 1987; 1994; Colantoni et al., 1995). The complex morphostructural setting of the area has been influenced by Pleistocene extensional tectonics, probably still active. Tectonic dislocations, probably characterized by regional transcurrent component, have allowed in the past the superimposition of the Bulgheria-Verbicaro unit on the "Crete Nere" Formation and the tectonic contact of the last formation with the Alburno-Cervati unit, cropping out at the right flank of the valley. Normal faulting, block rotations and structural widening of the valley are produced as an effect of differential velocity during transcurrent tectonics. The "Crete Nere " Flysch ("Liguride Units"), assuming a plastic behaviour due to high water contents assumes a flow-type, relatively deep process (30-50m) within the valley and near the see and constitutes a lubricant base for detrital covers and carbonatic units outcropping along its left flank and nearest relief, where deep gravitational movements are developed. The geologic framework of the Maratea valley on land is connected with the Late Pleistocene-Holocene evolution of the surrounding continental platform and slope and with the significant glacio-eustatic variations during the Late Quaternary. High-resolution seismic reflection profiles recorded during the cruise GMS00-05 (October-November 2000) onboard of the R/V Urania (CNR) by using a Watergun 15 c.i. seismic source and Stratavisor (Geometrics Inc.) acquisition system (Marsella et al., 2001) give new evidences on the offshore elongment of the Maratea valley. The deep gravitational movements influence the geologic setting of surrounding platform and slope, characterized by deformed slope sequences involved by NE-SW normal faulting and slumps. Normal faulting has also controlled the development of the Maratea canyon itself. The occurrence of the Maratea submarine canyon's head is relevant, since the canyon undermine the instable masses of the Maratea valley and induces sliding through regressive erosion. Late Pleistocene progradations and relative structurally-controlled shelf break, occurring at water depths of about -30m are evident on the Watergun profile SASA130bis (fig. 1), running in the Policastro Gulf with a NNW-SSE trending. At the foot of the slope is evident the offshore prolongation of the Maratea valley. Significant normal faulting involves the Late Pleistocene-Holocene slope sequences, together with slumps, evidenced also by rapid variation in thickness of seismic sequences. Basic references - Guerricchio A., Melidoro G., Rizzo V. - Boll. Soc. Geol. It., 106, 293-302. - Guerricchio A., Melidoro G., Rizzo V. - Proc. IAEG 7th Cong., Lisboa, II, 1075-1082. - Colantoni P., Gabbianelli G., Rizzo V. e Piergiovanni A. - Atti Cong. CNR "Grandi fenomeni gravitativi lenti nei centri abitati delle regioni Alpine e Appenniniche", Maratea, settembre 1995. - Marsella E., Aiello G., Pelosi N., Angelino A., Budillon F., Giordano F., Rapolla A., Di Fiore V., Siniscalchi A., D'Isanto C., Ruggieri S. - Istituto di Ricerca "Geomare Sud", CNR, Napoli, Rapporto Tecnico n. 11 (crociera GMS00-05).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
