_version_ 1867170990218280960
author Minshull, Tim A
Papenberg, Cord
Klaeschen, Dirk
author_facet Minshull, Tim A
Papenberg, Cord
Klaeschen, Dirk
collection Datos científicos de ciencias marinas y ambientales
contents Hyperextension of continental crust at the Deep Galicia rifted margin in the North Atlantic has been accommodated by the rotation of continental fault blocks, which are underlain by the S reflector, an interpreted detachment fault, along which exhumed and serpentinized mantle peridotite is observed. West of these features, the enigmatic Peridotite Ridge has been inferred to delimit the western extent of the continent‐ocean transition. An outstanding question at this margin is where oceanic crust begins, with little existing data to constrain this boundary and a lack of clear seafloor spreading magnetic anomalies. Here we present results from a 160 km long wide‐angle seismic profile (Western Extension 1). Travel time tomography models of the crustal compressional velocity structure reveal highly thinned and rotated crustal blocks separated from the underlying mantle by the S reflector. The S reflector correlates with the 6.0–7.0 km s−1 velocity contours, corresponding to peridotite serpentinization of 60–30%, respectively. West of the Peridotite Ridge, shallow and sparse Moho reflections indicate the earliest formation of an anomalously thin oceanic crustal layer, which increases in thickness from ~0.5 km at ~20 km west of the Peridotite Ridge to ~1.5 km, 35 km further west. P wave velocities increase smoothly and rapidly below top basement, to a depth of 2.8–3.5 km, with an average velocity gradient of 1.0 s−1. Below this, velocities slowly increase toward typical mantle velocities. Such a downward increase into mantle velocities is interpreted as decreasing serpentinization of mantle rock with depth.
format Dataset Open Access
id pangaea_https___doi_org_10_1594_PANGAEA_859069
institution PANGAEA
language en
publishDate 2016
publisher PANGAEA
record_format pangaea
spellingShingle Hydrophone component of Ocean bottom recording sgy-files of seismic refraction and wide angle data from profile 1172 and 2222 of expedition MGL1307 and POSEIDON cruise POS453 with links to data files
Minshull, Tim A
Papenberg, Cord
Klaeschen, Dirk
Date/Time of event; DEPTH, water; Event label; File name; File size; LATITUDE; Line ID; LONGITUDE; OBH; OBH 79; OBH 80; OBH 81; OBH 82; OBH 83; OBH 85; OBH 86; OBS; OBS 37; OBS 38; OBS 39; OBS 40; OBS 41; OBS 42; OBS 43; OBS 45; OBS 46; OBS 47; OBS 48; OBS 51; OBS 52; OBS 53; OBS 54; OBS 73; OBS 74; OBS 75; OBS 76; OBS 78; Ocean bottom hydrophone; Ocean bottom seismometer; Optional event label; POS453; POS453_723-3; POS453_724-1; POS453_725-1; POS453_726-1; POS453_728-1; POS453_729-1; POS453_730-1; POS453_731-1; POS453_740-1; POS453_741-1; POS453_742-1; POS453_743-1; POS453_746-1; POS453_747-1; POS453_748-1; POS453_749-1; POS453_751-1; POS453_752-1; POS453_753-1; POS453_754-1; POS453_782-1; POS453_783-1; POS453_785-1; POS453_786-1; POS453_787-1; POS453_788-1; POS453_789-1; Poseidon; Uniform resource locator/link to sgy data file
Hyperextension of continental crust at the Deep Galicia rifted margin in the North Atlantic has been accommodated by the rotation of continental fault blocks, which are underlain by the S reflector, an interpreted detachment fault, along which exhumed and serpentinized mantle peridotite is observed. West of these features, the enigmatic Peridotite Ridge has been inferred to delimit the western extent of the continent‐ocean transition. An outstanding question at this margin is where oceanic crust begins, with little existing data to constrain this boundary and a lack of clear seafloor spreading magnetic anomalies. Here we present results from a 160 km long wide‐angle seismic profile (Western Extension 1). Travel time tomography models of the crustal compressional velocity structure reveal highly thinned and rotated crustal blocks separated from the underlying mantle by the S reflector. The S reflector correlates with the 6.0–7.0 km s−1 velocity contours, corresponding to peridotite serpentinization of 60–30%, respectively. West of the Peridotite Ridge, shallow and sparse Moho reflections indicate the earliest formation of an anomalously thin oceanic crustal layer, which increases in thickness from ~0.5 km at ~20 km west of the Peridotite Ridge to ~1.5 km, 35 km further west. P wave velocities increase smoothly and rapidly below top basement, to a depth of 2.8–3.5 km, with an average velocity gradient of 1.0 s−1. Below this, velocities slowly increase toward typical mantle velocities. Such a downward increase into mantle velocities is interpreted as decreasing serpentinization of mantle rock with depth.
title Hydrophone component of Ocean bottom recording sgy-files of seismic refraction and wide angle data from profile 1172 and 2222 of expedition MGL1307 and POSEIDON cruise POS453 with links to data files
topic Date/Time of event; DEPTH, water; Event label; File name; File size; LATITUDE; Line ID; LONGITUDE; OBH; OBH 79; OBH 80; OBH 81; OBH 82; OBH 83; OBH 85; OBH 86; OBS; OBS 37; OBS 38; OBS 39; OBS 40; OBS 41; OBS 42; OBS 43; OBS 45; OBS 46; OBS 47; OBS 48; OBS 51; OBS 52; OBS 53; OBS 54; OBS 73; OBS 74; OBS 75; OBS 76; OBS 78; Ocean bottom hydrophone; Ocean bottom seismometer; Optional event label; POS453; POS453_723-3; POS453_724-1; POS453_725-1; POS453_726-1; POS453_728-1; POS453_729-1; POS453_730-1; POS453_731-1; POS453_740-1; POS453_741-1; POS453_742-1; POS453_743-1; POS453_746-1; POS453_747-1; POS453_748-1; POS453_749-1; POS453_751-1; POS453_752-1; POS453_753-1; POS453_754-1; POS453_782-1; POS453_783-1; POS453_785-1; POS453_786-1; POS453_787-1; POS453_788-1; POS453_789-1; Poseidon; Uniform resource locator/link to sgy data file
url https://doi.org/10.1594/PANGAEA.859069