New crustal and lithospheric mantle structure of Alaska from geoid, elevation and thermal inversion analysis further constrained by 3D gravity modelling

• Main Authors: Carballo, Alberto, Jadamec, Margarete, Torné, Montserrat, Jimenez-Munt, Ivone, Fernandez, Manel
• Format: Still Image
• Language: unknown
• Published: 2018
• Subjects: Yukon; alaska range; Brooks Range; Kuskokwim; Yakutat; Alaska
• Online Access: http://hdl.handle.net/10261/220796

EGU General Assembly 2018 We investigate the lithospheric structure of Alaska and the lateral crustal density variations using a two-stepapproach. First, we calculate the crustal and mantle lithosphere thicknesses from joint geoid and elevationmodeling combined with thermal analysis further constrained by available seismic data. We then compute the 3Dgravity effect of the resulting lithospheric structure to separate the measured Bouguer anomaly into its regionaland local components. The thickest crust (> than 40 km) is observed in the Brooks Range, Wrangell Mountainsand the Alaska Range, while thinnest crust is located in the Aleutian Range and Chugach Mountains (< 30 km).In addition, moderate crustal thickness (in the range of 32 to 36 km, in average) is obtained underneath theYukon-Tanana basin, the Kuskokwim Mountains, Ahklum Mountains, the Yukon-Kuskokwim Coastal Lowlandand in eastern Alaska. The LAB depth map shows that the deepest LAB is located in the western Brooks Range (>180 km) while the shallowest (∼80 km) is observed along the continental side of the Yakutat Block. The obtainedresidual gravity anomalies highlight lateral average crustal density variations which we discus in terms of crustalstructure. Positive residual anomalies delineate the high density crustal rocks of the accreted Wrangellia andComposite terrains while negative values are associated with the sedimentary rocks of the Sadlerochit Mountains. This research is supported by project SUBITOP (MSCA-ITN-2015-ETN-674899).