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Ciarcia, Sabatino
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Ciarcia, Sabatino
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- PublicationRestrictedBrittle vs. ductile strain during the synorogenic exhumation of HP-LT rocks: An example from the Lungro-Verbicaro Unit mylonites (northern Calabria, Italy)(2020-04)
; ; ; ; ; ; ; We present a study on the mylonites exposed in the Cirella area along the Tyrrhenian coast of northern Calabria(southern Italy), in order to understand the role of ductile and brittle deformation on the exhumation process ofthese rocks. The analyzed shear zone is located in the footwall of a regional tectonic contact between metao-phiolites (Ligurian Complex) on the top, and the continental Lungro-Verbicaro Unit (Adria plate) at the bottom.The latter consists of a metasedimentary succession with Triassic shallow-water carbonates at the base of it,evolving upward to Jurassic-lower Miocene slope to deep basin carbonates and foredeep siliciclastic rocks. Bothoceanic and continental successions are characterized by high-pressure and low-temperature (HP-LT) meta-morphism. The analyzed mylonites show different degrees of strain, ranging from protomylonites to ultra-mylonites, the latter characterized by well-marked foliation and stretching lineations. Several micro- and me-soscale progressive deformation structures, including two fold sets, S-C’structures are present in these rocks, anda late oblique foliation, indicating a NW sense of shear. A successive shortening stage produced thrust faults andrelated folds, indicating a tectonic transport toward SE. We associate the mylonitic deformation with the activityof the overlying detachment fault, which is responsible for the synorogenic exhumation of the Lungro-VerbicaroUnit during the Miocene time. However, the ductile strain, recorded by the studied mylonites, accounted for asmall displacement during the exhumation of this tectonic slice. In fact, the calculated displacement achieved bythe Lungro-Verbicaro Unit, during exhumation, is much larger than the one estimated considering only theductile zones activity. This evidence suggests that, synchronously with ductile strain, brittle deformation oc-curred along the detachment fault located at the top of the thrust sheet. In addition, a severe erosion due to thetectonic exhumation of the HP-LT rocks (in the late Miocene) produced a large amount of clastic sediment thatfilled the extensional basins widespread in northern Calabria.59 4 - PublicationOpen AccessLate miocene-early pliocene out-of-sequence thrusting in the Southern Apennines (Italy)(2020-08-06)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We present a structural study on late Miocene-early Pliocene out-of-sequence thrusts affecting the southern Apennine orogenic belt. The analyzed structures are exposed in the Campania region (southern Italy). Here, thrusts bound the N-NE side of the carbonate ridges that form the regional mountain backbone. In several outcrops, the Mesozoic carbonates are superposed onto the unconformable wedge-top basin deposits of the upper Miocene Castelvetere Group, providing constraints to the age of the activity of this thrusting event. Moreover, a 4-km-long N-S oriented electrical resistivity tomography profile, carried out along the Caserta mountains, sheds light on the structure of this thrust system in an area where it is not exposed. Further information was carried out from a tunnel excavation that allowed us to study some secondary fault splays. The kinematic analysis of out-of-sequence major and minor structures hosted both in the hanging wall (Apennine Platform carbonates) and footwall (Castelvetere Group deposits and Lagonegro-Molise Basin units) indicates the occurrence of two superposed shortening directions, about E-W and N-S, respectively. We associated these compressive structures to an out-of-sequence thrusting event defined by frontal thrusts verging to the east and lateral ramp thrusts verging to the north and south. We related the out-of-sequence thrusting episode to the positive inversion of inherited normal faults located in the Paleozoic basement. These envelopments thrust upward to crosscut the allochthonous wedge, including, in the western zone of the chain, the upper Miocene wedge-top basin deposits.60 42 - PublicationOpen AccessThe Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines(2023-07-20)
; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ;; The Roccamonfina volcano is located within the Garigliano Graben (southern Apennines, Italy) and has been active throughout the Middle-Late Pleistocene. Along its polyphase volcanic history (630–55 ka), including several caldera-forming eruptions (385–230 ka), several effusive/mildly explosive monogenetic events occurred along the volcano slopes, within the summit caldera, and along the graben-bounding carbonate reliefs. In this paper, we present a multidisciplinary study of a mafic magmatic feeder dike intruded within the Meso-Tertiary carbonates and overlying Lower Pleistocene breccias of Mt Cesima, northeast of the Roccamonfina volcano. We performed a stratigraphic and structural survey of the area and petrographic analyses on several samples of the dike. Results indicate that a ∼1 km long fissure fed an eruption that also emplaced a Strombolian pyroclastic sequence. Petrological data show that an open-system mafic recharge fueled the tephritic magma that fed the eruption, whereas no evidence of significant pre/syn-eruptive assimilation of carbonate has been identified. Stratigraphic and petrological data do not allow to firmly constrain the timing of the eruption, which could belong both to the pre-Brown Leucitic Tuff (>354 ka) and to the post-White Trachytic Tuffs (<230 ka) epochs of activity of the Roccamonfina volcano. Structural data show that the dike is broadly oriented E-W and changes direction toward NE-SW in correspondence with a pre-existing fault damage zone. We suggest that magma was intruded during an N-S trending extensional event in the Middle Pleistocene, whose prolonged activity resulted in regional uplift and exhumation of regional significance.30 14 - PublicationRestrictedHigh-resolution geological investigations to reconstruct the long-term ground movements in the last 15 kyr at Campi Flegrei caldera (southern Italy)(2019)
; ; ; ; ; ; ; ; ; ; ; ;; ;; Ground deformations are among the main volcanic phenomena occurring within the caldera system and pres- ently recorded at different volcanoes worldwide including the Campi Flegrei active caldera (southern Italy). A new stratigraphic, sedimentological and paleontological survey carried out in the central sector of the Campi Flegrei caldera both along the already known La Starza succession and through a new excavated tunnel provided new insights into the ground movement episodes occurred in the last 15 kyr. This study, which has also benefited of unpublished boreholes stratigraphic data, shows that the most uplifted sector of the Campi Flegrei caldera, presently marked by the morphological structure of the La Starza cliff close to the Pozzuoli coastline, was charac- terized by a complex sedimentary evolution. It results from different phases of alternating marine transgressions and regressions, the latter marked by both continental volcanic and/or palustrine/lacustrine sediments. These al- ternations result from the interplay between (i) subsidence and uplift episodes of the caldera floor and (ii) sea level variations during the Holocene. A rest period of volcanism accompanied by a sea level rise determined a sig- nificant submersion phase in about 3000 years between 8.59 and 5.5 ka. This phase was defined by a sea level with a maximum water depth value of 60–80 m and a late stage recording significant episodes of ground move- ments. Subsequently, between 5.5 and 3.5 ka, a ground uplift of about 100 m occurred, with short subsidence around 4.5 ka following the Plinian Agnano-Monte Spina eruption. The net vertical displacement represents the recorded deformation linked with a volcanism period in which ~2.5 km3 of magma were erupted by different vents within the caldera. It is worth to note as the general trend of ground movement through the time indicates a similarity in the pattern, beyond its scale.105 5 - PublicationOpen AccessEvidence of Seismic-Related Liquefaction Processes within the Volcanic Record of the Campi Flegrei Caldera (Italy)We report the occurrence of several sand liquefaction structures, such as sand dikes, in the stratigraphic record of the Campi Flegrei volcano, located both inside and outside the caldera. Five sites were analyzed within the caldera and two outside. The grain size analysis of the sand fillings indicates that these deposits are very fine-to-coarse sands generally poorly sorted. All of the granulometry curves fall within the field of the liquefiable, loose sediments. Frequently, dikes are characterized by two fillings: a rim showing poorly sorted finer sands and a core with extremely poorly sorted coarser sediments. We suggest that seismic-related liquefaction processes triggered the injection of these sand dikes during unrest episodes in the last 15 kyr. In particular, the sand dikes located outside the caldera, characterized by larger thicknesses and lengths, mark an important extensional episode, probably associated with the caldera formation during the Neapolitan Yellow Tuff eruption at 15 ka. Furthermore, liquefaction structures within the caldera are related to the seismic activity, probably occurring during the Agnano–Monte Spina caldera formation and the volcano-tectonic ground deformation, predating Epoch 3b (4.3 ka) and the Monte Nuovo (1538 CE) eruptions. This study highlights that these seismic-related liquefaction structures are common within the volcanic record of the Campi Flegrei, suggesting that the sand source can be both the widespread marine succession underlying the Epoch 3 deposits in the caldera central sector and the primary ash layers extensively present in the volcanic record.
27 35 - PublicationOpen AccessSeismically Induced Soft‐Sediment Deformation Phenomena During the Volcano‐Tectonic Activity of Campi Flegrei Caldera (Southern Italy) in the Last 15 kyr(2019-06)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We report, for the first time, evidence of seismically induced soft‐sediment deformations in the central area of the active Campi Flegrei caldera (southern Italy). We analyzed the marine‐transitional and continental sequences located along the coastal La Starza cliffs and several stratigraphic logs exposed during the excavation of a 1‐km‐long tunnel in the Pozzuoli area. The successions host several soft‐sediment structures including sand dikes and sand volcanoes, which are largely dated within the 4.55‐ to 4.28‐kyr BP interval. The volcano‐sedimentary sequence, deposited within the Campi Flegrei caldera in the last 15 kyr, is schematically formed by the superposition of three layers with different rheological behaviors; from the base progressing upward we recognize (1) a massive tuff, (2) marine‐transitional sands of the La Starza unit, and (3) a dominance of continental volcanoclastics. We envisage that during unrest episodes of the volcano, which included ground deformation and seismic activity, the whole volcano‐sedimentary pile was deformed through brittle mechanisms with the formation of normal faults. However, the intermediate layer, when subject to seismic shaking, behaved locally as a viscous material facilitating liquefaction processes and lateral spreading deformation. Furthermore, new geophysical, stratigraphic, and structural surveys allowed us to model the deformation evolution of this area over the last 15 kyr. The evidence of seismically induced soft‐sediment deformation within the volcano‐sedimentary record suggests that moderate earthquakes could occur during future volcano‐seismic unrests. Consequently, liquefaction and related gravitational mass movements must be considered as a hazard during these unrest and volcanic crises.90 55 - PublicationOpen AccessStructural and Stratigraphic Setting of Campagna and Giffoni Tectonic Windows: New Insights on the Orogenic Evolution of the Southern Apennines (Italy)(2020-10-10)
; ; ; ; ; ; ; ; ; We present a structural study on the tectonic windows of Giffoni and Campagna, located in the western sector of the southern Apennines (Italy). We analyzed thrusts, folds, and related minor deformation structures. Here, a major in-sequence E-verging thrust fault juxtaposes Meso-Cenozoic successions of the Apennine Platform (Picentini Mts unit) and the Lagonegro-Molise Basin (Frigento unit). However, out-of-sequence thrusts duplicated the tectonic pile with the interposition of the upper Miocene wedge-top basin deposits of the Castelvetere Group. We reconstructed the orogenic evolution of these two tectonic windows, including five deformation phases. The first (D1) was related to the in-sequence thrusting with minor thrusts and folds, widespread both in the footwall and the hanging wall. A subsequent extension (D2) has formed normal faults crosscutting the D1 thrusts and folds. All structures were subsequently affected by two shortening stages (D3 and D4), which also deformed the upper Miocene wedge top basin deposits of the Castelvetere Group. We interpreted the D3–D4 structures as related to an out-of-sequence thrust system defined by a main frontal E-verging thrust and lateral ramps characterized by N and S vergences. Low-angle normal faults were formed in the hanging wall of the major thrusts. Out-of-sequence thrusts are observed in the whole southern Apennines, recording a crustal shortening event that occurred in the late Messinian–early Pliocene. Finally, we suggest that the two tectonic windows are the result of the formation of an E–W trending regional antiform, associated with a late S-verging back-thrust, that has been eroded and crosscut by normal faults (D5) in the Early Pleistocene. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.57 68