Marco Ligi

Verified

Marco verified their affiliation via an institutional email.

Learn more

Verified

Marco verified their affiliation via an institutional email.

Learn more

• Laurea in Scienze Geologiche
• Research Director at Italian National Research Council

The role of magmatism in continental rupture at the birth of a new ocean is poorly understood. Continental rupture can take place with voluminous volcanism, as in the southern Red Sea, or in a relatively non-volcanic mode, as in the northern Red Sea. We report geophysical, geochemical and geochronological evidence suggesting that continental ruptur...

Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults, and, along transforms, by transtension due to changes in ridge/transform geometry. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic. Here we show, using high...

Although water is only present in trace amounts in the suboceanic upper mantle, it is thought to play a significant role in affecting mantle viscosity, melting and the generation of crust at mid-ocean ridges. The concentration of water in oceanic basalts has been observed to stay below 0.2 wt%, except for water-rich basalts sampled near hotspots an...

A 20-Myr record of creation of oceanic lithosphere is exposed along a segment of the central Mid-Atlantic Ridge on an uplifted sliver of lithosphere. The degree of melting of the mantle that is upwelling below the ridge, estimated from the chemistry of the exposed mantle rocks, as well as crustal thickness inferred from gravity measurements, show o...

Three major lithospheric plates—Antarctic, South American, and African—meet in the South Atlantic near Bouvet Island where the Mid-Atlantic Ridge (MAR), the Southwest Indian Ridge (SWIR), and the American Antarctic Ridge converge toward a fast evolving triple junction. A major magmatic pulse has recently built a new, swollen segment of the SWIR (Sp...

Shaban Deep (ShD) is one of several axial depressions discovered in the northern Red Sea, some considered sites of incipient seafloor spreading. Understanding the evolutionary history and salt tectonics of ShD is essential for constraining the rift-to-drift transition. This study integrates 2D seismic reflection profiles, gravity, magnetic, and bat...

Mid-ocean ridges serve as key sites for understanding the composition of the mantle, but extensive melting usually masks its lithological diversity. This study explores how cold mid-ocean ridge segments, such as the eastern Romanche ridge-transform intersection (ERRTI), provide unique insights into mantle heterogeneity. Here, a thick cold lithosphe...

Eastern Sicily is characterised by fast tectonic uplift, intricate GPS-derived velocity fields, and significant seismic activity. Mount Etna, the largest subaerial active volcano in Europe, dominates the landscape, influencing the development of large-scale instability processes on the facing continental margin. South of Etna, the Malta Escarpment...

Seafloor anomalies along mid-ocean ridges with exceptionally thick and compositionally distinct basaltic crust, for example, at Iceland, suggest that the underlying mantle is hotter and chemically different from the adjacent subridge mantle. Here we present hafnium and neodymium isotope ratios of peridotites from the Charlie Gibbs Transform Zone, w...

Red Sea Deep Water is presently slow-moving, but was this true of the earlier Plio-Pleistocene (PP)? In seismic reflection records, the PP deposits are distorted by halokinetic deformation of their underlying Miocene evaporites. However, if reflections are flattened to a prominent reflector representing the top of the Miocene, they reveal mounded d...

Voluminous Cenozoic lava fields are widespread in the western Arabian Peninsula, covering an area of 180,000 km2 from Yemen through Saudi Arabia, Jordan, Syria and Israel. Although most studies agree on a genetic link between the western Arabia alkaline magmatism with the plume head impingement beneath the Afar depression and the subsequent lithosp...

The Doldrums transform system, located in the Equatorial Atlantic at 7 – 8 ◦ N, is a 110 km-wide multi-fault shear zone, with five active transform faults separated by four short intra-transform ridge segments (ITRs). The two central ITRs, ITR-2 and ITR-3, are significantly deeper than the peripheral ridge segments, suggesting differences in the...

Several volcanic buildups have been documented using gravity and magnetic data at specific locations in the Northern Red Sea (NRS). Most of these volcanoes were never sampled, and only a few were imaged by seismic or bathymetry data. Furthermore, the confidentiality of commercial datasets does not allow adequate knowledge of these structures and th...

Partial melting of mantle peridotite from which considerable amounts of melt have been extracted during prior melting episodes generates melts characterized by low incompatible element contents and very low ratios of highly to moderately incompatible elements, so-called ‘ultra-depleted ’ melts. Reaction of peridotite with percolating ultra-deple...

The Red Sea basin includes a thick Middle to Late Miocene evaporitic succession that underwent halokinesis and caused intensive reshaping of the seafloor and the development of salt tectonic structures. However, the geometry and kinematics of these structures are still poorly understood. This study uses 2D and 3D seismic surveys and well data of th...

This article presents results of the structural and morphological analysis of the fracture zones that are part of Doldrums Megatransform System (DMS), located in the northern part of the Equatorial Atlantic (6.5°-9° N) that include Vernadskiy and Bogdanov transform faults and the Doldrums and Pushcharovskiy megatransforms. Bathymetric map, based on...

A combination of a high sediment input and intense bottom currents often leads to the formation of contourites (sediments deposited or significantly reworked by bottom currents). Both of these components are present in the Vema Fracture Zone valley which is the most important passageway for the distribution of the Antarctic Bottom Water from the We...

This article presents results of the structural and morphological analysis of the fracture zones which are part of Doldrums Megatransform System (MTS), located in the northern part of the Equatorial Atlantic (6.5°–9° N) that include Vernadskiy and Bogdanov transform faults and the Doldrums and Pushcharovskiy megatransforms. Bathymetric map, based o...

Accretionary processes at mid‐ocean ridge segments with low magma input have seldom been investigated over the long term. The evolution of such magma‐starved segments over time is still largely unknown. We present a study on the structure and evolution of the southernmost intra‐transform ridge segment of the St. Paul Transform Fault System in the E...

This study investigates crustal accretion processes along the northern stretch of the Mid-Atlantic Ridge (MAR) between the Charlie Gibbs (52°-53°N) and Bight (57°N) transforms. These long-lived transform systems, active for more than 40 Ma, bound a ~ 550 km-long MAR segment influenced to the South by the Azores and to the North by the Iceland man...

Southern and Central Red Sea oceanic crust formation is generally accepted to have started ∼5 Ma. However, the nature of the crust in the Northern Red Sea (NRS) is still debated. This paper describes the rift architecture, dynamics and evolution of the NRS and identifies domains that relate to first-order geodynamic processes. The proximal margin d...

The Pacific, Antarctic, and Macquarie lithospheric plates diverge from the Macquarie Triple Junction (MTJ) in the southwestern Pacific Ocean, south of Macquarie Island. Morphobathymetric, magnetic, and gravity data have been used to understand the evolution of the three accretionary/transform boundaries that meet at the MTJ. Plate velocities, estim...

Strong acceleration of abyssal flows in narrow deep‐water channels and fracture zones is a key feature of bottom circulation in the Atlantic Ocean. In the Equatorial Atlantic, these bottom currents transport Antarctic Bottom Water (AABW) over the Mid‐Atlantic Ridge from west to east. The main pathway for Antarctic waters in this region is the Roman...

Red Sea Deep Water is presently slow-moving, but was this true of the earlier Plio-Pleistocene (PP)? Seismic reflection records reveal mounded deposits within the earlier PP along both sides of the sea. Off Egypt, a plastered drift occurs along a salt wall. In the central Red Sea, they are mounded drifts. Seismic reflections from these deposits cha...

The Red Sea formed as a consequence of Cenozoic rifting between the African and Arabian plates. While continuous oceanic spreading is active in the southern and central sectors, in the northern Red Sea, exposure of oceanic crust is limited to a few along‐axis isolated deeps. However, several off‐axis magmatic edifices have been recognized in this s...

The Doldrums Megatransform System (~7-8°N, Mid-Atlantic Ridge) shows a complex architecture including four intra-transform ridge segments bounded by five active transform faults. Lower crustal rocks are exposed along the Doldrums and Vernadsky transform walls that bound the northernmost intra-transform ridge segment. The recovered gabbros are chara...

Based on morphobathymetric and seismic reflection data, we studied a large landslide body from the eastern Sea of Marmara (NW Turkey), along the main strand of the North Anatolian Fault, one of the most seismically active geological structures on Earth. Due to its location and dimensions, the sliding body may cause tsunamis in case of failure possi...

Half a century ago, our view of the Earth shifted from that of a Planet with fixed con- tinents and ancient stable ocean basins to one with wandering continents and young, active ocean basins, reviving Wegener’s Continental Drift that had rested dormant for years. The lithosphere is the external, mostly solid and relatively rigid layer of the Earth,...

Rayleigh-Taylor models for diapirism predict that diapirs should develop with characteristic spacings, whereas other models predict varied spacings. The deep-water Miocene evaporites in the Red Sea provide a useful opportunity to quantify length scales of diapirism to compare with model predictions. We first review the stratigraphy of the uppermost...

The Red Sea formed at the beginning of the Late Oligocene by rifting of the Eastern Africa continental lithosphere. The Northern Red Sea (NRS) has been usually interpreted as the result of a magma-poor rift, but several recent magmatic additions have been reported. However, their description in terms of architectural features and relative age is st...

The Red Sea rift system represents a key case study of the transition from a continental to an oceanic rift. The Red Sea rifting initiated in Late Oligocene-Early Miocene (⁓24-23 Ma) and was accompanied by extensive magmatism throughout the rifted basin, from Afar and Yemen to northern Egypt. Here, we present a petrological and geochemical study of...

The increasing quality and resolution of marine seismic reflection data, as well as their availability in digital form within large data sets, require the development and testing of new techniques to improve their interpretation. In this work, we present a case study dealing with application of 3D techniques to a set of 2D shallow-water data, where...

Volcanism in the western part of the Arabian plate resulted in one of the largest alkali basalt provinces in the world, where lava fields with sub-alkaline to alkaline affinity are scattered from Syria and the Dead Sea Transform Zone through western Saudi Arabia to Yemen. After the Afar plume emplacement (∼30 Ma), volcanism took place in Yemen and...

The Red Sea is the closest active analog to the rifting and rupturing of continental lithosphere and provides an ideal natural setting to study the continental to oceanic rift transition. Currently, the Egyptian Red Sea margin is one of the most potential regions for hydrocarbon exploration. The success of oil exploration in the Egyptian Red Sea ha...

The geological and geophysical data obtained during the 50th cruise of R/V Akademik Nikolaj Strakhov on the Charlie Gibbs megatransform system structure in the North Atlantic are presented. The structure of the Charlie Gibbs Fracture Zone was examined in detail, considering previously published data. It has been shown that the northern and southern...

The Charlie Gibbs offsetting by ~ 340 km the Mid Atlantic Ridge (MAR) axis at 52°-53° N is one of the main transform systems of the North Atlantic. Located between long mid-ocean ridge segments influenced from the south by the Azores and from the north by the Iceland mantle plumes, this transform system has been active since the early phases of Nor...

The Palinuro volcanic chain (PVC) is located about 80 km offshore the Campania region (Italy) in the southern sector of the Tyrrhenian Sea. The chain consists of 15 volcanic edifices aligned in an E-W direction with two distinct major seamounts (Palinuro and Glabro). They cover a 90 km long and 20 km wide area, with a present-day volume of 2700 km³...

The Sea of Galilee in northeast Israel is a freshwater lake filling a morphological depression along the Dead Sea Fault. It is located in a tectonically complex area, where a N-S main fault system intersects secondary fault patterns non-univocally interpreted by previous reconstructions. A set of multiscale geophysical, geochemical and seismologica...

The Doldrums transform system offsets the Equatorial Mid Atlantic Ridge by ~630 km at 7–8° N. This transform system consists of four intra-transform spreading centers (ITRs) bounded by five transform faults. The northernmost ITR is linked to the MAR axis by a ~ 180 km-long transform. Here, during two R/V A. N. Strakhov expeditions (S06 and S09), ma...

The SEISMOFAULTS project (www.seismofaults.it) was set up in 2016 with the general plan of exploring the seismicity of marine areas using deep seafloor observatories. The activity of the first two years (Seismofaults 2017 and 2018) consisted of the installation of a geophysical-geochemical temporary monitoring network over the Ionian Sea floor. Ele...

Oxide gabbros are a minor but diffuse component of the lower oceanic crust. Their presence poses questions on lower crust exhumation processes and magma differentiation at mid ocean ridges because they are systematically associated with shear zones and are hardly explained by classical fractionation and melt migration models. Here, we report on a s...

The Tyrrhenian Basin is a region created by Neogene extensional tectonics related to slab rollback of the east-southeast–migrating Apennine subduction system, commonly believed to be actively underthrusting the Calabrian arc. A compilation of >12,000 km of multichannel seismic profiles, much of them recently collected or reprocessed, provided close...

The Equatorial portion of the Mid Atlantic Ridge is displaced by a series of large offset oceanic transforms, also called “megatransforms”. These transform domains are characterized by a wide zone of deformation that may include different conjugated fault systems and intra-transform spreading centers (ITRs). Among these megatransforms, the Doldrums...

We examined the transport of sediments and their surficial pathways from the mouth of Neretva River, through the Neretva Channel, toward the Adriatic Sea. This research was based on twelve box-cores and five grab samples collected within the Neretva Channel. Sediment dynamics were evaluated using several proxies, such as organic matter, radiochemic...

Global correlations of mid-ocean-ridges basalt chemistry, axial depth and crustal thickness have been ascribed to mantle temperature variations affecting degree of melting. However, mantle H2O content and elemental composition may also play a role. How H2O is distributed in the oceanic upper mantle remains poorly constrained. We tackled this proble...

The Red Sea and Gulf of Aden constitute parts of the Afro-Arabian rift system that are in the most advanced stages of continental break-up. These basins have therefore received extensive scrutiny in the geoscientific literature, but several aspects of their evolution remain enigmatic. Many of their most important features lie beneath several kilome...

Understanding magmatic systems and deep hydrothermal circulation beneath arc-volcanoes provides insights into deep processes associated with slab-subduction and mantle-wedge partial melting. Here we analyze hydrothermal flow below a structural high (Capo Vaticano Ridge, CVR) located offshore Capo Vaticano (western Calabria) and affected by magmatic...

The Ionian Sea in southern Italy is at the center of active interaction and convergence between the Eurasian and African–Adriatic plates in the Mediterranean. This area is seismically active with instrumentally and/or historically recorded Mw>7.0 earthquakes, and it is affected by recently discovered long strike-slip faults across the active Calabr...

The onshore‐offshore correlation of sedimentary successions is a common problem in basin analysis, but it becomes critical for the full understanding of the Messinian salinity crisis (MSC), a complex array of palaeoenvironmental events which affected the Mediterranean basin at the end of the Miocene. The outcrop records show that the Messinian stra...

The Ionian Sea in southern Italy is at the center of active interaction and convergence between the Eurasian and African-Adriatic plates in the Mediterranean. This area is seismically active with instrumentally/historically-recorded Mw > 7.0 earthquakes and it is affected by recently-discovered long strike-slip faults across the active Calabrian ac...

The thickness of deep-water Plio-Pleistocene (PP) sediments in the Red Sea varies somewhat, as expected from increased biogenic pelagic production rates in the south and with input of aeolian and fluvial sediments through the Tokar Gap in the Sudanese hills. Otherwise, however, the sediment distribution does not obviously reflect the likely pattern...

This paper reports on a detailed geochemical study of rocks from Harrats Lunayyir and Khaybar, two large lava fields located in the central portion of the western Arabian Peninsula. Lavas from young flows north of Al Birk were also considered. Sample composition ranges from basanite to basalts with transitional to alkaline affinity. Their incompati...

We present here 3D seismic reflection and gravity data obtained from an off-axis area of the NW Red Sea, as well as results of a study of gabbroic rocks recovered in the same area both from an oil well below a thick evaporitic-sedimentary sequence, and from a layered mafic complex exposed on the Brothers Islets. These new data provide constraints o...

The eastern border of the Adriatic Sea shows several examples of transitional areas marked by fragmented coastlines, islands and coastal bays. Bays and estuaries interact with the main basin influencing it and being influenced by it in terms of circulation patterns and freshwater supply. Coastal and transitional areas represent highly dynamic, rapidl...

In contrast to oceanic islands produced by mantle melting anomalies or “hotspots” lying in mid-plate settings, the central and eastern Azores islands are distributed on the Nubia-Eurasia tectonic plate boundary and experience frequent tectonic earthquakes. As they lie in an extensional to trans-tensional tectonic environment, volcanism is organised...

Basaltic crust is present in the oceans and marginal seas. Oceanic accretion from inception to ending may be usefully recognized in small basin setting like the Tyrrhenian. Alternating episodes of strong and moderate extensional tectonics characterized the small Tyrrhenian opening. Hyperextension (drifting) of late-Miocene and latemost Pliocene age...

A seismological and geochemical experiment, also accompanied by a detailed bathymetric survey, is now ongoing in the Ionian Sea from May 2017. Eight Ocean Bottom Seismometers and Hydrophones (OBS/H) and two modules for geochemical monitoring (CH4, CO2 and O) were deployed on the sea bottom (www.seismofaults.it).

One of the most intriguing feature along the entire Adriatic coast is the bay of Boka Kotorska, where the sea enters inland for over 20 km. The Bay is located along the Montenegro margin and is part of a ria coastal system surrounded by high mountains that are part of the Dinaric range. The Bay is composed by three major basins, connected by two na...

The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. We analysed the structural style of the frontal accretionary wedge through a multi-scale geophysical approach. Pre-stack depth-migrated crustal-scale seismic profiles unravelled the overall geometry of the subduction complex; high-resolution mu...

We present here 3D seismic reflection and gravity data obtained from an off-axis area of the NW Red Sea, as well as results of a study of gabbroic rocks recovered in the same area both from an oil well below a thick evaporitic-sedimentary sequence, and from a layered mafic complex exposed on the Brothers islets. We show that magmatism can play an i...

Boka Kotorska Bay is an enclosed water body with a narrow and shallow connection to the Adriatic Sea; the shallowest point is only 37.6 m deep at present, limiting exchange of water with the Adriatic. The Bay is one of the most important transitional areas of the Adriatic from both an environmental and a socio-economic viewpoint. High resolution ge...

The deformational behaviour of “salt giants” during and shortly after their deposition is difficult to decipher in ocean margin settings where the original evaporites have beendeeply buried and strongly mobilized. Here, we examine seismic reflection data from the Red Sea, where evaporites deposited until the end of the Miocene (~5.3 Ma),are general...

New multichannel seismic reflection profiles were acquired to unravel the structure of a portion of the eastern margin of the Tyrrhenian basin. This extensional feature is part of an Oligocene to Present back-arc basin in the hangingwall of the W-directed Apennines subduction system. The basin provides excellent conditions to investigate the early...

Continental rifting and ocean basin formation is occurring today in the Red Sea, providing a possible modern analogue for the creation of mid-ocean ridges. Yet many of the seafloor features observed along the axis of the Red Sea appear anomalous compared to ancient and modern examples of mid-ocean ridges in other parts of the world, making it uncle...

New high-resolution geophysical data collected along the eastern margin of the Tyrrhenian backarc basin, in the Pontine Islands area, reveal a ~NW-SE elongated morphological high, the Ventotene Volcanic Ridge (VR), located on the northern edge of the Ventotene Basin. High-resolution multibeam bathymetry, combined with magnetic data, multi- and sing...

ADS is hiring! We are looking for a project scientist for planetary science; we also have openings for developers and a DevOps engineer. Read more and apply here. Oceanization starts from below during continental rupturing in the northern Red Sea Cai, Y. ; Ligi, M. ; Bonatti, E. ; Bosworth, W. ; Cipriani, A. ; Palmiotto, C. ; Rasul, N. M. ; Ronca,...

The rifting apart of continents involves interaction of tectonic and magmatic events, that reflect the strain-rate and temperature-dependent processes of solid state deformation and decompression melting within the Earth. The spatial and temporal scales over which these mechanisms localize extensional strain, allowing continental rifts to evolve to...

Text:

Near-bottom magnetic field data were collected using a towed magnetometer over selected parts of Palinuro and Marsili submarine volcanoes in the southern Tyrrhenian Sea, Italy. We obtained equivalent magnetizations maps at these sites by inverting the corresponding magnetic anomalies, highlighting the seafloor expression of hydrothermal alteration....

Hydrothermal alteration processes involve mineralogical, chemical and textural changes as a result of hot aqueous fluid-rock interaction under evolving boundary conditions. These changes affect the physico-chemical properties of the rocks, enabling high-resolution geophysical prospecting to be an important tool in the detection of seafloor hydrothe...