TY - JOUR

T1 - Geophysical analysis of an area affected by subsurface dissolution - case study of an inland salt marsh in northern Thuringia, Germany

AU - Wadas, Sonja H.

AU - Buness, Hermann

AU - Rochlitz, Raphael

AU - Skiba, Peter

AU - Günther, Thomas

AU - Grinat, Michael

AU - Tanner, David C.

AU - Polom, Ulrich

AU - Gabriel, Gerald

AU - Krawczyk, Charlotte M.

N1 - Funding Information: We thank our colleagues Jan Bayerle, Dieter Epping, Eckhardt Großmann, Siegfried Grüneberg, Robert Meyer, Frank Oppermann, Wolfgang Südekum, and Sven Wedig for their excellent work during the field surveys. Furthermore, we thank Lutz Katzschmann, Sven Schmidt, and Ina Pustal from the Thuringian State Institute for Environment, Mining and Conservation for supporting this work and providing the gravity data. Further thanks go to Ronny Stolz and Andreas Chwala from IPHT Jena and Supracon AG Jena for conducting the TEM survey, which was funded by the Federal Ministry of Education and Research (BMBF) as part of INFLUINS under BMBF grant 031S2091A. We thank Matthias Queitsch and Nina Kukowski from the University of Jena for their advice on TEM data processing and interpretation as well as Pritam Yogeshwar and Sascha Janser from the University of Cologne for providing the inversion code EMUPLUS. Furthermore, we also want to thank the editor Elias Lewi and the two referees, Alireza Malehmir and one anonymous, for their useful comments that helped to improve the paper. Finally, we would like to dedicate this paper to our co-author Peter Skiba, who, to our deepest regret, passed away after the paper was submitted.

PY - 2022/11/2

Y1 - 2022/11/2

N2 - The subsurface dissolution of soluble rocks can affect areas over a long period of time and pose a severe hazard. We show the benefits of a combined approach using P-wave and SH-wave reflection seismics, electrical resistivity tomography, transient electromagnetics, and gravimetry for a better understanding of the dissolution process. The study area, "Esperstedter Ried"in northern Thuringia, Germany, located south of the Kyffhäuser hills, is a large inland salt marsh that developed due to dissolution of soluble rocks at approximately 300 m depth. We were able to locate buried dissolution structures and zones, faults and fractures, and potential fluid pathways, aquifers, and aquitards based on seismic and electromagnetic surveys. Further improvement of the model was accomplished by analyzing gravimetry data that indicates dissolution-induced mass movement, as shown by local minima of the Bouguer anomaly for the Esperstedter Ried. Forward modeling of the gravimetry data, in combination with the seismic results, delivered a cross section through the inland salt marsh from north to south. We conclude that tectonic movements during the Tertiary, which led to the uplift of the Kyffhäuser hills and the formation of faults parallel and perpendicular to the low mountain range, were the initial trigger for subsurface dissolution. The faults and the fractured Triassic and lower Tertiary deposits serve as fluid pathways for groundwater to leach the deep Permian Zechstein deposits, since dissolution and erosional processes are more intense near faults. The artesian-confined saltwater rises towards the surface along the faults and fracture networks, and it formed the inland salt marsh over time. In the past, dissolution of the Zechstein formations formed several, now buried, sagging and collapse structures, and, since the entire region is affected by recent sinkhole development, dissolution is still ongoing. From the results of this study, we suggest that the combined geophysical investigation of areas prone to subsurface dissolution can improve the knowledge of control factors, hazardous areas, and thus local dissolution processes.

AB - The subsurface dissolution of soluble rocks can affect areas over a long period of time and pose a severe hazard. We show the benefits of a combined approach using P-wave and SH-wave reflection seismics, electrical resistivity tomography, transient electromagnetics, and gravimetry for a better understanding of the dissolution process. The study area, "Esperstedter Ried"in northern Thuringia, Germany, located south of the Kyffhäuser hills, is a large inland salt marsh that developed due to dissolution of soluble rocks at approximately 300 m depth. We were able to locate buried dissolution structures and zones, faults and fractures, and potential fluid pathways, aquifers, and aquitards based on seismic and electromagnetic surveys. Further improvement of the model was accomplished by analyzing gravimetry data that indicates dissolution-induced mass movement, as shown by local minima of the Bouguer anomaly for the Esperstedter Ried. Forward modeling of the gravimetry data, in combination with the seismic results, delivered a cross section through the inland salt marsh from north to south. We conclude that tectonic movements during the Tertiary, which led to the uplift of the Kyffhäuser hills and the formation of faults parallel and perpendicular to the low mountain range, were the initial trigger for subsurface dissolution. The faults and the fractured Triassic and lower Tertiary deposits serve as fluid pathways for groundwater to leach the deep Permian Zechstein deposits, since dissolution and erosional processes are more intense near faults. The artesian-confined saltwater rises towards the surface along the faults and fracture networks, and it formed the inland salt marsh over time. In the past, dissolution of the Zechstein formations formed several, now buried, sagging and collapse structures, and, since the entire region is affected by recent sinkhole development, dissolution is still ongoing. From the results of this study, we suggest that the combined geophysical investigation of areas prone to subsurface dissolution can improve the knowledge of control factors, hazardous areas, and thus local dissolution processes.

UR - http://www.scopus.com/inward/record.url?scp=85142659722&partnerID=8YFLogxK

U2 - 10.5194/egusphere-2022-164

DO - 10.5194/egusphere-2022-164

M3 - Article

AN - SCOPUS:85142659722

VL - 13

SP - 1673

EP - 1696

JO - Solid Earth

JF - Solid Earth

SN - 1869-9510

IS - 11

ER -