TY - BOOK

T1 - Seismic Investigation of the Prospective Drilling Site for the DIVE Phase 2 Project

AU - Pasiecznik, Damian

N1 - no embargo

PY - 2024

Y1 - 2024

N2 - The Ivrea Verbano Zone (IVZ) in Italy presents one of the most complete crust-upper mantle geological references globally, featuring lower-crustal rocks and upper mantle fragments exposed adjacent to the Insubric Line. The Drilling the Ivrea-Verbano Zone (DIVE) project aims to deepen the understanding of this complex region by drilling a 4 km deep borehole intended to reach and study the top of the Ivrea Geophysical Body (IGB), which is considered a shallow expression of the crust-mantle transition. This thesis focuses on the geophysical characterization of the prospective drill site, located at the top of an outcropping ultramafic body known as the Balmuccia Peridotite. A high-resolution seismic survey was conducted across the Balmuccia Peridotite to delineate its structure and relationship with surrounding geological formations. The survey employed a fixed spread of 200 vertical geophones and 160 3C-sensors, spaced approximately 10-11 meters along three sub-parallel lines. Vibroseis source points were positioned at 22-meter intervals along a 2.2 km line, using a 12-140 Hz 10-second linear sweep with a 3-second listening time. The P-wave traveltime tomography reveals that the seismic velocities within the peridotite vary between 6 and 8 km/s, with an average velocity of 7 km/s. These differences highlight the heterogeneous nature of the peridotite, which is affected by the presence of fractures and faults. Notably, the higher velocities observed are consistent with laboratory results obtained from small-scale samples of the region. Reflection seismic analysis identified subvertical reflectors that coincide with the peridotite boundaries converging at a depth of around 0.175 km b.s.l. (ca. 875 m from the surface), suggesting a lens-like structure for the peridotite body. Although the survey's limited aperture impeded detailed imaging below the lens-shaped body, a prominent reflector at approximately 1.3 km depth b.s.l. potentially marks the top of the IGB, consistent with previous geophysical estimates. These findings provide critical insights into the seismic characteristics of the IVZ, laying the groundwork for future in situ geophysical measurements and advancing our understanding on the crust-mantle transition.

AB - The Ivrea Verbano Zone (IVZ) in Italy presents one of the most complete crust-upper mantle geological references globally, featuring lower-crustal rocks and upper mantle fragments exposed adjacent to the Insubric Line. The Drilling the Ivrea-Verbano Zone (DIVE) project aims to deepen the understanding of this complex region by drilling a 4 km deep borehole intended to reach and study the top of the Ivrea Geophysical Body (IGB), which is considered a shallow expression of the crust-mantle transition. This thesis focuses on the geophysical characterization of the prospective drill site, located at the top of an outcropping ultramafic body known as the Balmuccia Peridotite. A high-resolution seismic survey was conducted across the Balmuccia Peridotite to delineate its structure and relationship with surrounding geological formations. The survey employed a fixed spread of 200 vertical geophones and 160 3C-sensors, spaced approximately 10-11 meters along three sub-parallel lines. Vibroseis source points were positioned at 22-meter intervals along a 2.2 km line, using a 12-140 Hz 10-second linear sweep with a 3-second listening time. The P-wave traveltime tomography reveals that the seismic velocities within the peridotite vary between 6 and 8 km/s, with an average velocity of 7 km/s. These differences highlight the heterogeneous nature of the peridotite, which is affected by the presence of fractures and faults. Notably, the higher velocities observed are consistent with laboratory results obtained from small-scale samples of the region. Reflection seismic analysis identified subvertical reflectors that coincide with the peridotite boundaries converging at a depth of around 0.175 km b.s.l. (ca. 875 m from the surface), suggesting a lens-like structure for the peridotite body. Although the survey's limited aperture impeded detailed imaging below the lens-shaped body, a prominent reflector at approximately 1.3 km depth b.s.l. potentially marks the top of the IGB, consistent with previous geophysical estimates. These findings provide critical insights into the seismic characteristics of the IVZ, laying the groundwork for future in situ geophysical measurements and advancing our understanding on the crust-mantle transition.

KW - Geophysics

KW - Seismic Reflection

KW - Tomography

KW - Europe

KW - Alps

KW - Ivrea Verbano Zone

KW - Geophysik

KW - Seismische Reflexion

KW - Tomographie

KW - Europa

KW - Alpen

KW - Ivrea Verbano Zone

U2 - 10.34901/mul.pub.2024.212

DO - 10.34901/mul.pub.2024.212

M3 - Doctoral Thesis

ER -