The formation and growth mechanisms of young back-arc spreading ridges from high-resolution bathymetry:The Marsili Seamount(Tyrrhenian Sea,Italy)  

作　　者：Eugenio Nicotra Salvatore Passaro Guido Ventura 

机构地区：[1]Dipartimento di Biologia Ecologia e Scienze della Terra,Universitàdella Calabria,87036 Arcavacata di Rende,Cosenza,Italy [2]Istituto di Scienze Marine CNR,80133 Napoli,Italy [3]Istituto Nazionale di Geofisica e Vulcanologia,00143 Roma,Italy [4]Istituto per lo Studio degli impatti Antropici e Sostenibilitáin ambiente marino CNR,91026 Capo Granitola,Trapani,Italy

出　　处：《Geoscience Frontiers》2024年第1期325-338,共14页地学前缘（英文版）

基　　金：funded by the Marine Hazard CNR Project.

摘　　要：The formation and growth mechanisms of Mid-Ocean Ridges(MOR)are relatively well known,whereas those of back-arc spreading ridges are comparatively less known because geophysical,geochemical,and morphological data are scarce and of low density.Here we present a high-resolution bathymetry of the Marsili Seamount(MS;1 Ma-3 ka),which represents the inflated spreading ridge of the 2 Ma old Marsili back-arc basin associated to the subduction of the Ionian Sea below the Calabrian Arc and Tyrrhenian Sea.MS is 70 km long,30 km wide,and its height reaches about 3000 m from surrounding seafloor.Our new digital bathymetric model has a 5 m grid cell size resolution and covers the MS bathymetry from-1670 mbsl to the top at-491 mbsl.We conduct morphometric and morphological analyses of the bathymetry and recognize landforms due to volcanic,tectonic,hydrothermal and gravity processes.MS consists of volcanoes related to fissural and central-type activity,this latter located at the northern and southern tips of the main dike swarms.Dike swarms represent the surface expression of different ridge segments whose strikes are controlled by the larger scale back-arc spreading processes and by the local occurrence of an active hydrothermal field.This latter develops in a flat area between two partly overlapping ridge segments where historical volcanism and extensional processes concentrate.Such ridges represent the embryonic stage of the formation of transform-like faults.Central volcanoes,the northern of which is characterized by a caldera,form at the tips of MS because the decrease in width of the major volcanic fissures promotes vent localization associated with the formation of sill-like reservoirs from which central-type vents may develop.Gravity processes affecting the MS flanks are due to shallow seafloor sliding.Caldera collapses affecting the northernmost central-type polygenic volcano must be included in the evaluation of the hazard related to potential tsunami.Inward dipping faults characterize the MS eastern flank suggesting

关 键 词：Back-arc spreading ridge Morphology TECTONICS VOLCANISM Marsili seamount 

分 类 号：P597.3[天文地球—地球化学] P548[天文地球—地质学]