Mid-ocean ridge interactions with hotspots strongly affect mantle flow processes. This study analyses the anomalies produced as a result of the interaction between a hotspot and an oceanic ridge-ridge-ridge triple junction, in close proximity to one another. The complex three dimensional (3D) nature of the Azores Triple Junction (ATJ), in which two near-collinear faster-spreading ridges are joined orthogonally with a slower-spreading ridge, provides an excellent opportunity to quantify the effect of triple junction geometry on along-axis magmatic accretion and mantle dynamic processes as a result of the interaction with a hotspot. For the ATJ, the faster-spreading ridges are two branches of the Mid-Atlantic Ridge (MAR), and the slower-spreading ridge is the Terceira Rift (TR). Using shipboard bathymetry and satellite free-air gravity, we obtain mantle Bouguer anomaly (MBA) by eliminating from free-air gravity the attractions of seafloor topography and a reference crust. Along the TR, the Azores hotspot has a maximum MBA axial gravity low of -100 mGal, suggesting localized crustal thickening, elevated mantle temperatures and/or low density mantle. The entire Azores plateau along the TR is associated with a large (~80 mGal) broad low. Dispersion of plume material along the TR, a distance in the range of 550 km, is likely minimized by the rift system's obliqueness, immature nature and hyper-slow spreading rate, as well as the presence of the Gloria Fracture Zone. Further, along-axis profiles along the TR suggest that MBA shows a strong dependence on the tectonic segmentation of the ridge axis. / A Thesis Submitted to the Department of Geological Sciences in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2009. / March 6, 2009. / Lithosphere, Geochemical, Crust, Compositional, Oceanic, Continental, Volcanism, Tomographic / Includes bibliographical references. / Jennifer Georgen, Professor Co-Directing Thesis; Jim Tull, Professor Co-Directing Thesis; Vincent Salters, Committee Member; William Parker, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_180329 |
| Contributors | Sankar, Ravi Darwin (authoraut), Georgen, Jennifer (professor co-directing thesis), Tull, Jim (professor co-directing thesis), Salters, Vincent (committee member), Parker, William (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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