Glen J.M.G.,U.S. Geological Survey |
Schmidt J.M.,U.S. Geological Survey |
Connard G.G.,Geosoft Inc.
Geochemistry, Geophysics, Geosystems
The Amphitheater Mountains and southern central Alaska Range expose a thick sequence of Triassic Nikolai basalts that is underlain by several mafic-ultramafic complexes, the largest and best exposed being the Fish Lake and Tangle (FL-T) mafic-ultramafic sills that flank the Amphitheater Mountains synform. Three-dimensional (3-D) modeling of gravity and magnetic data reveals details of the structure of the Amphitheater Mountains, such as the orientation and thickness of Nikolai basalts, and the geometry of the FL-T intrusions. The 3-D model (50 × 70 km) includes the full geographic extent of the FL-T complexes and consists of 11 layers. Layer surfaces and properties (density and magnetic susceptibility) were modified by forward and inverse methods to reduce differences between the observed and calculated gravity and magnetic grids. The model suggests that the outcropping FL-T sills are apparently connected and traceable at depth and reveals variations in thickness, shape, and orientation of the ultramafic bodies that may identify paths of magma flow. The model shows that a significant volume (2000 km3) of ultramafic material occurs in the subsurface, gradually thickening and plunging westward to depths exceeding 4 km. This deep ultramafic material is interpreted as the top of a keel or root system that supplied magma to the Nikolai lavas and controlled emplacement of related magmatic intrusions. The presence of this deep, keel-like structure, and asymmetry of the synform, supports a sag basin model for development of the Amphitheater Mountains structure and reveals that the feeders to the Nikolai are much more extensive than previously known. Copyright 2011 by the American Geophysical Union. Source
Connard G.G.,Geosoft Inc. |
Glen J.M.,U.S. Geological Survey |
Schmidt J.M.,U.S. Geological Survey
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010
The Amphitheater Mountains synform on the southern flank of the Alaska Range in south-central Alaska provides one of the most complete sections of a Large Igneous Province worldwide, revealing, in near continuous section: basal mafic and ultramafic sill complexes, associated mafic and ultramafic rocks, lower submarine lavas, and overlying subaerial lavas. Three-dimensional (3D) modeling of gravity and magnetic data shows details of the Amphitheater Mountains structure, flood basalt thickness, and geometry of ultramafic sills. Modeling is based on a compilation of existing regional and newly-acquired high-resolution profile gravity data, a compilation of regional and high-resolution aeromagnetic surveys, and numerous rock-property data (including density, susceptibility, and magnetic remanence measurements of outcrops, hand samples, and drill cores). The final 3D model includes 12 layers with up to 2 km of Nikolai basalts in the center of the asymmetric, west-plunging, 50 km long Amphitheater synform. The western end of the synform appears to be terminated by a steep N-S structure. The outcropping Fish Lake and Tangle ultramafic sills, apparently connected beneath the surface, are traceable to 5 km depth, and modeling indicates variations in thickness (1 to 3 km), shape, and orientation which may identify paths of magma flow within the system. © 2010, European Association of Geoscientists and Engineers. Source
Geosoft Inc. | Date: 2011-06-14
Computer servers; and computer software for mapping, data processing, 3D modeling and analysis in earth science applications. Technical support services, namely, troubleshooting of computer software problems; computer programming services; technical consulting services in the field of earth science.
Geosoft Inc. | Date: 2014-09-05
computer software enabling provision of cloud hosting, cloud infrastructure and infrastructure-as-a-service services in the area of cloud computing and the field of earth science. electronic storage of computer data in the field of earth science; remote computer back-up services; computer hosting services for others; providing computer resource and network access for the transfer and dissemination of information in the field of earth science by means of a global computer network; computer services, namely, providing access to a computer server for users in the field of cloud computing; technical support services in the field of cloud computing; and software as a service (SaaS) for 2D and 3D visualization and 2D and 3D analysis for use in the field of earth science.
Geosoft Inc. | Date: 2001-02-06
data processing and analysis software for earth science applications. computer software support services; computer programming services; consulting services in the field of earth sciences.