Deep Origin of the Dome‐Shaped Hyblean Plateau, Southeastern Sicily: A New Tectono‐Magmatic Model. Issue 12 (26th December 2019)

• Record Type: Journal Article
• Authors: Henriquet, Maxime; Dominguez, Stéphane; Barreca, Giovanni; Malavieille, Jacques; Cadio, Cécilia; Monaco, Carmelo
• Is Part Of: Tectonics. Volume 38:Issue 12(2019)
• Page Start: 4488
• Page End: 4515
• Publication Date: 2019-12-26
• Subjects: Hyblean -- Plateau -- mafic intrusions -- uplift -- gravity anomaly -- analogue modeling; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2019TC005548
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: Southeastern Sicily is characterized by a prominent topography known as the Hyblean Plateau. It is commonly considered as a flexural bulge formed by the northwest plunging of the Hyblean‐Malta platform beneath the Sicilian Fold and Thrust Belt. However its noncylindrical shape and multiphase uplift history correlated to the Late Miocene and Plio‐Pleistocene volcanism outline a possible magmatic control on the Hyblean Plateau topographic expression. We argue, using 2‐D flexural models, that the flexural bending alone is unlikely to explain the high anomalous elevation of the Hyblean Plateau. Moreover, topographic analysis show that the Hyblean Plateau has a dome shape composed of radially tilted preserved surfaces defining individual blocks. The block edges seem to be related to deep‐seated inherited faults. Using an analogue modeling approach, we show that magmatic intrusions beneath the thick Meso‐Cenozoic sedimentary cover can reproduce the first‐order morphology of the Hyblean Plateau when a structural inheritance is imposed. Accordingly, we propose a tectono‐magmatic model that favors mafic sill intrusions as the major uplift source for the topographic anomaly. However, to explain the strong positive Bouguer anomaly, a deeper high‐density intracrustal body is needed. Moho uprising related to Mesozoic rifting or mafic lower crust underplating/intraplating since the Late Cretaceous can be evoked. The small wavelength of the topography and the deep intracrustal mass anomaly makes the lithospheric elastic stresses sufficiently high to maintain a nonisostatic state over the geological time scales. Plain Language Summary: A prominent dome‐shaped topography known as the Hyblean Plateau overcomes southeastern Sicily. It is commonly considered as originated from foreland flexural bulging of the Hyblean‐Malta platform in response to the southeastward migrating Sicilian orogenic wedge. However, its nonlinear shape and its multiphase uplift history correlate to the Late Miocene and Plio‐Pleistocene volcanic activity and hence suggest a possible magmatic control on the formation of the Hyblean Plateau. We show that flexural bending alone is unlikely to explain the subcircular topography of the Hyblean Plateau using 2‐D flexural models. Moreover, subsurface analysis coupled to an analogue modeling approach shows that the subcircular pattern is subdivided into radially tilted blocks whose edges seem to be related to inherited fault zones. The tectono‐magmatic model proposed here minimizes the flexural component to the Hyblean rise and prefers mafic sill intrusions in the upper crust as the major uplift source. However, gravity anomalies suggest a deeper high‐density intracrustal body beneath the Hyblean Plateau which can be related to the Meso‐Cenozoic history. The lack of isostatic equilibrium in this region can be related to the small length scale of the topography and the inferred intracrustal high‐density body which makes the lithosphere rigid enough to support these anomalies. Key Points: The topographic anomaly of the Hyblean Plateau (Sicily) is associated to a major gravimetric and magnetic anomaly within the Mediterranean Plate flexure induced by the Sicilian orogeny is insufficient to explain the Hyblean Plateau domal topography and geophysical anomalies The Hyblean dome‐shape relief originated from Late Miocene and Plio‐Pleistocene mafic sheet intrusions in the upper crust