TY - JOUR

T1 - Seismological and Geophysical Signatures of the Deep Crustal Magma Systems of the Cenozoic Volcanic Fields Beneath the Eifel, Germany

AU - Dahm, Torsten

AU - Stiller, Manfred

AU - Mechie, James

AU - Heimann, Sebastian

AU - Hensch, Martin

AU - Woith, Heiko

AU - Schmidt, Bernd

AU - Gabriel, Gerald

AU - Weber, Michael

N1 - Funding information: The German Continental Seismic Reflection Program DEKORP (utsches ntinentales eflexionsseismisches rogramm) was carried out between 1984 and 1999 as the German national reflection seismic program funded by the Federal Ministry of Research and Technology. The aim of DEKORP in the western part of the RHM was to investigate the deep crustal structure of the Eifel with high?fold, high?resolution near?vertical incidence vibro?seismic acquisition (for field parameters see Table SC1 ), supplemented by wide?angle seismic and other target?oriented piggy?back experiments, all complemented by optimized methods of data processing and interpretation. The DEKORP?Atlas (Meissner & Bortfeld, 1990 ) gives a detailed overview of most of the different campaigns and results. The profiles 1A, 1B, and 1C (Figures 1 and 2a ) were recorded in 1987 and 1988 as part of DEKORP. DE KO R P We thank Karin Br?uer for discussion of isotope fluid components. TD thanks Susanne K?ster for help during the preparation of the manuscript and editing tables and Jan Bergmann Barrocas (LIAG) for help preparing plots. The constructive comments of three reviewers helped to improve the manuscript. We thank the DEKORP archive (DOI data publications via GFZ Data Services, Stiller et al.,?2020a, 2020b, 2020c) for access to the data of profiles and the Geological Survey of Rhineland-Palatinate for funding the reprocessing of the DEKORP 1B and 1C. We thank the Geological Survey of North Rhine-Westphalia and DMT GmbH & Co KG for the support and funding of the reprocessing of DEKORP 1A. The paper is related to activities in the PoF-IV programme Topic 3 of GFZ.

PY - 2020/8/25

Y1 - 2020/8/25

N2 - The Quaternary volcanic fields of the Eifel (Rhineland-Palatinate, Germany) had their last eruptions less than 13,000 years ago. Recently, deep low-frequency (DLF) earthquakes were detected beneath one of the volcanic fields showing evidence of ongoing magmatic activity in the lower crust and upper mantle. In this work, seismic wide- and steep-angle experiments from 1978/1979 and 1987/1988 are compiled, partially reprocessed and interpreted, together with other data to better determine the location, size, shape, and state of magmatic reservoirs in the Eifel region near the crust-mantle boundary. We discuss seismic evidence for a low-velocity gradient layer from 30–36 km depth, which has developed over a large region under all Quaternary volcanic fields of the Rhenish Massif and can be explained by the presence of partial melts. We show that the DLF earthquakes connect the postulated upper mantle reservoir with the upper crust at a depth of about 8 km, directly below one of the youngest phonolitic volcanic centers in the Eifel, where CO2 originating from the mantle is massively outgassing. A bright spot in the West Eifel between 6 and 10 km depth represents a Tertiary magma reservoir and is seen as a model for a differentiated reservoir beneath the young phonolitic center today. We find that the distribution of volcanic fields is controlled by the Variscan lithospheric structures and terrane boundaries as a whole, which is reflected by an offset of the Moho depth, a wedge-shaped transparent zone in the lower crust and the system of thrusts over about 120 km length.

AB - The Quaternary volcanic fields of the Eifel (Rhineland-Palatinate, Germany) had their last eruptions less than 13,000 years ago. Recently, deep low-frequency (DLF) earthquakes were detected beneath one of the volcanic fields showing evidence of ongoing magmatic activity in the lower crust and upper mantle. In this work, seismic wide- and steep-angle experiments from 1978/1979 and 1987/1988 are compiled, partially reprocessed and interpreted, together with other data to better determine the location, size, shape, and state of magmatic reservoirs in the Eifel region near the crust-mantle boundary. We discuss seismic evidence for a low-velocity gradient layer from 30–36 km depth, which has developed over a large region under all Quaternary volcanic fields of the Rhenish Massif and can be explained by the presence of partial melts. We show that the DLF earthquakes connect the postulated upper mantle reservoir with the upper crust at a depth of about 8 km, directly below one of the youngest phonolitic volcanic centers in the Eifel, where CO2 originating from the mantle is massively outgassing. A bright spot in the West Eifel between 6 and 10 km depth represents a Tertiary magma reservoir and is seen as a model for a differentiated reservoir beneath the young phonolitic center today. We find that the distribution of volcanic fields is controlled by the Variscan lithospheric structures and terrane boundaries as a whole, which is reflected by an offset of the Moho depth, a wedge-shaped transparent zone in the lower crust and the system of thrusts over about 120 km length.

KW - crustal magma chamber

KW - deep low-frequency earthquakes

KW - distributed volcanic fields

KW - low velocity zone

KW - magma reservoirs

KW - reflection seismic

UR - http://www.scopus.com/inward/record.url?scp=85091665634&partnerID=8YFLogxK

U2 - 10.1029/2020GC009062

DO - 10.1029/2020GC009062

M3 - Article

AN - SCOPUS:85091665634

VL - 21

JO - Geochemistry, Geophysics, Geosystems

JF - Geochemistry, Geophysics, Geosystems

SN - 1525-2027

IS - 9

M1 - e2020GC009062

ER -