Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa
Abstract P and S wave tomographic models have been developed for the northern Malawi rift and adjacent Rungwe Volcanic Province (RVP) using data from the Study of Extension and maGmatism in Malawi aNd Tanzania project and data from previous networks in the study area. The main features of the models...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2018-10-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Online Access: | https://doi.org/10.1029/2018GC007730 |
| _version_ | 1797685936841031680 |
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| author | Ashley Grijalva Andrew A. Nyblade Kyle Homman Natalie J. Accardo James B. Gaherty Cynthia J. Ebinger Donna J. Shillington Patrick R. N. Chindandali Gabriel Mbogoni Richard Wambura Ferdinand Gabriel Mulibo J. P. O'Donnell Marsella Kachingwe Gabrielle Tepp |
| author_facet | Ashley Grijalva Andrew A. Nyblade Kyle Homman Natalie J. Accardo James B. Gaherty Cynthia J. Ebinger Donna J. Shillington Patrick R. N. Chindandali Gabriel Mbogoni Richard Wambura Ferdinand Gabriel Mulibo J. P. O'Donnell Marsella Kachingwe Gabrielle Tepp |
| author_sort | Ashley Grijalva |
| collection | DOAJ |
| description | Abstract P and S wave tomographic models have been developed for the northern Malawi rift and adjacent Rungwe Volcanic Province (RVP) using data from the Study of Extension and maGmatism in Malawi aNd Tanzania project and data from previous networks in the study area. The main features of the models are a low‐velocity zone (LVZ) with δVp = ~−1.5–2.0% and δVs = ~−2–3% centered beneath the RVP, a lower‐amplitude LVZ (δVp = ~−1.0–1.3% and δVs = ~−0.7–1%) to the southeast of the RVP beneath the center and northeastern side of the northern Malawi rift, a shift of the lower‐amplitude anomaly at ~−10° to −11° to the west beneath the central basin and to the western side of the rift, and a fast anomaly at all depths beneath the Bangweulu Craton. The LVZ widens further at depths >~150–200 km and extends to the north beneath northwestern Malawi, wrapping around the fast anomaly beneath the craton. We attribute the LVZ beneath the RVP and the northern Malawi rift to the flow of warm, superplume mantle from the southwest, upwelling beneath and around the Bangweulu Craton lithosphere, consistent with high 3He/4He values from the RVP. The LVZ under the RVP and northern Malawi rift strongly indicates that the rifted lithosphere has been thermally perturbed. Given that volcanism in the RVP began about 10 million years earlier than the rift faulting, thermal and/or magmatic weakening of the lithosphere may have begun prior to the onset of rifting. |
| first_indexed | 2024-03-12T00:58:26Z |
| format | Article |
| id | doaj.art-bcef98f1784c4d2fa9a44da0c03a401b |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-12T00:58:26Z |
| publishDate | 2018-10-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-bcef98f1784c4d2fa9a44da0c03a401b2023-09-14T11:39:59ZengWileyGeochemistry, Geophysics, Geosystems1525-20272018-10-0119103980399410.1029/2018GC007730Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East AfricaAshley Grijalva0Andrew A. Nyblade1Kyle Homman2Natalie J. Accardo3James B. Gaherty4Cynthia J. Ebinger5Donna J. Shillington6Patrick R. N. Chindandali7Gabriel Mbogoni8Richard Wambura Ferdinand9Gabriel Mulibo10J. P. O'Donnell11Marsella Kachingwe12Gabrielle Tepp13Department of Geosciences The Pennsylvania State University State College PA USADepartment of Geosciences The Pennsylvania State University State College PA USADepartment of Geosciences The Pennsylvania State University State College PA USALamont‐Doherty Earth Observatory of Columbia University Palisades NY USALamont‐Doherty Earth Observatory of Columbia University Palisades NY USADepartment of Earth and Environmental Sciences Tulane University of Louisiana New Orleans LA USALamont‐Doherty Earth Observatory of Columbia University Palisades NY USAGeological Survey of Malawi Zomba MalawiGeological Survey of Tanzania Dodoma TanzaniaGeology Department University of Dar es Salaam Dar es Salaam TanzaniaGeology Department University of Dar es Salaam Dar es Salaam TanzaniaDepartment of Geosciences The Pennsylvania State University State College PA USADepartment of Geosciences The Pennsylvania State University State College PA USADepartment of Physics and Astronomy University of Rochester Rochester NY USAAbstract P and S wave tomographic models have been developed for the northern Malawi rift and adjacent Rungwe Volcanic Province (RVP) using data from the Study of Extension and maGmatism in Malawi aNd Tanzania project and data from previous networks in the study area. The main features of the models are a low‐velocity zone (LVZ) with δVp = ~−1.5–2.0% and δVs = ~−2–3% centered beneath the RVP, a lower‐amplitude LVZ (δVp = ~−1.0–1.3% and δVs = ~−0.7–1%) to the southeast of the RVP beneath the center and northeastern side of the northern Malawi rift, a shift of the lower‐amplitude anomaly at ~−10° to −11° to the west beneath the central basin and to the western side of the rift, and a fast anomaly at all depths beneath the Bangweulu Craton. The LVZ widens further at depths >~150–200 km and extends to the north beneath northwestern Malawi, wrapping around the fast anomaly beneath the craton. We attribute the LVZ beneath the RVP and the northern Malawi rift to the flow of warm, superplume mantle from the southwest, upwelling beneath and around the Bangweulu Craton lithosphere, consistent with high 3He/4He values from the RVP. The LVZ under the RVP and northern Malawi rift strongly indicates that the rifted lithosphere has been thermally perturbed. Given that volcanism in the RVP began about 10 million years earlier than the rift faulting, thermal and/or magmatic weakening of the lithosphere may have begun prior to the onset of rifting.https://doi.org/10.1029/2018GC007730 |
| spellingShingle | Ashley Grijalva Andrew A. Nyblade Kyle Homman Natalie J. Accardo James B. Gaherty Cynthia J. Ebinger Donna J. Shillington Patrick R. N. Chindandali Gabriel Mbogoni Richard Wambura Ferdinand Gabriel Mulibo J. P. O'Donnell Marsella Kachingwe Gabrielle Tepp Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa Geochemistry, Geophysics, Geosystems |
| title | Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa |
| title_full | Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa |
| title_fullStr | Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa |
| title_full_unstemmed | Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa |
| title_short | Seismic Evidence for Plume‐ and Craton‐Influenced Upper Mantle Structure Beneath the Northern Malawi Rift and the Rungwe Volcanic Province, East Africa |
| title_sort | seismic evidence for plume and craton influenced upper mantle structure beneath the northern malawi rift and the rungwe volcanic province east africa |
| url | https://doi.org/10.1029/2018GC007730 |
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