Papers by Nancy R Grindlay
Morphology and tectonics of the southern mid-Atlantic ridge: Implications for accretion of oceanic lithosphere
Erratum: ``Lithospheric stresses associated with nontransform offsets of the Mid-Atlantic Ridge: Implications from a finite element analysis'' [Tectonics, 12(4), 982-1003 (1993)]
Tectonics, 1994
Neotectonics of southern Puerto Rico and its offshore margin
Active Tectonics and …
Geological Society of America Special Paper 385 2005 Neotectonics of southern Puerto Rico and its... more Geological Society of America Special Paper 385 2005 Neotectonics of southern Puerto Rico and its offshore margin Paul Mann* Institute for Geophysics, Jackson School ofGeosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Building 600, Austin, Texas ...
Reconnaissance study of Late Quaternary faulting along Cerro Goden fault zone, …
Active Tectonics and …
Geological Society of America Special Paper 385 2005 Reconnaissance study of Late Quaternary faul... more Geological Society of America Special Paper 385 2005 Reconnaissance study of Late Quaternary faulting along Cerro Goden fault zone, western Puerto Rico Paul Mann* Institute for Geophysics, Jackson School of Geoscienences, University of Texas at Austin, Austin, ...
Triple Junction Reorganizations: A Mechanism for the Initiation of the Great Pacific Fractures Zones
There are two general explanations for the initiation of oceanic transform faults that eventually... more There are two general explanations for the initiation of oceanic transform faults that eventually evolve into fracture zones: transforms inherited from continental break-up and transforms acquired in response to a change in plate motions. These models are sufficient to explain the fracture zones in oceans formed by continental break-up. However, neither model accounts for the initiation of the large-offset, great
Seamount Characteristics and Abundance as Proxy for Volcanic Accretion Style, Magma Supply, and Lithospheric Strength at the Southwest Indian Ridge
Seamounts have been used as indicators of volcanic accretion style, magma supply, and lithospheri... more Seamounts have been used as indicators of volcanic accretion style, magma supply, and lithospheric strength because they are of significant size (>50 m in height), indicating a steady magma source at the time of formation, and require strong lithosphere to support them. Seamount size, height, and population density will be analyzed along six segments of the Southwest Indian Ridge (SWIR) between 15°E and 35°E. The segments are offset by the 750 km-long Andrew Bain megatransform fault. Two segments to the northeast of the fault, thermally influenced by the Marion hotspot 250 km to the east, display an accretion style indicative of robust magma supply (shallow axial depths <1600 m, muted rift valley), creating hot, thin, weak lithosphere. In this area, seamount abundance should increase due to increased magma supply, while characteristic seamount height decreases, as weak lithosphere cannot support tall volcanic structures. Two segments to the southwest, thermally influenced by t...
Journal of Geophysical Research, 1996
Along-axis profiles of three-dimensional magnetic inversions for the Mid-Atlantic Ridge (MAR) 31 ... more Along-axis profiles of three-dimensional magnetic inversions for the Mid-Atlantic Ridge (MAR) 31 ø-35øS show low magnetization near the middle of ridge segments and high magnetization at the segment tips for three adjacent spreading segments; thus there is an inverse relation between axial magnetization and axial topography. The ridge segment at 26øS on the MAR has the same inverse relationship between magnetization and topography. The common occurrence of this relationship suggests that it reflects a fundamental process of crustal accretion at the MAR. We analyze the rock magnetic properties from 42 locations within the four ridge segments in the South Atlantic to constrain the inherent trade-off between source intensity and source thickness in the magnetization model. The natural reinanent magnetization (NRM) intensities from the four ridge segments, averaged together, correlate with the magnetic inversion profiles. This finding implies that changes in the magnetization of the extrusives may account for much of the observed magnetic anomaly amplitude variation. A direct correlation of FeO content and magnetization suggests that magnetic anomaly amplitudes may be an indicator of FeTi-rich basalts at the slow spreading MAR, even though the iron content of the basalts from high magnetization areas is not as high as observed at Pacific spreading centers. Despite the different magma plumbing systematics of the Pacifid spreading centers and the MAR, it appears that the segment-scale magma system of the MAR also results in segment-scale crustal magnetization variations. Further evidence that the axial magnetic variations result from source intensity variations is that older isochrons have higher intensifies near the ridge-discontinuities, similar to the behavior onaxis. Between 0 and 5 Ma the decay in magnetization is -50% independent of location within a spreading segment.
standing ridges, Spec. Pap. Geol. Soc. Am., 385, 3160. Manaker, DM, E. Calais, AM Freed, ST Ali, P. Przybylski, G. Mattioli, P. Jansma, C. Prépetit, and JB de …
Eos, 2010
... San Fernando, Spain; J. L. GRANJA-BRUÑA, P. LLANES ESTRADA, and A. MUÑOZ-MARTÍN, UCM; and U. ... more ... San Fernando, Spain; J. L. GRANJA-BRUÑA, P. LLANES ESTRADA, and A. MUÑOZ-MARTÍN, UCM; and U. S. TEN BRINK, USGS, Woods ... Mary Lou Zoback, vice president of Risk Management Solutions in Newark, Calif., said on-the-ground information can be very useful. ...
Mapping and Monitoring Bedforms on the Mid-Continental Shelf : 23Mile Site, Onslow Bay, NC
ABSTRACT
Segmentation of the Southwest Indian Ridge 15°E-25°E: Implications for Crustal Accretion at Ultra-Slow Spreading Rates
Southwest Indian Ridge 15°E-35°E : a geophysical investigation of an ultra slow spreading Mid-Ocean Ridge system
Morphologic Characteristics of Ridge Segments Along the Southwest Indian Ridge, 15-35°E: Comparison Between No Major Offset vs. Transform Dominated Segments
Segmentation of ultra slow spreading Mid-Ocean Ridges : bathymetry and Mantle Bouguer anomaly patterns along the Southwest Indian Ridge 15.5 to 25 degrees East
Preliminary results of a high-resolution geophysical investigation of an ultra-slow spreading center : Southwest Indian Ridge between 15E and 35E
Three-dimensional Euler deconvolution and tectonic interpretation of marine magnetic anomaly data in the Puerto Rico Trench
Journal of Geophysical Research, 1999
ABSTRACT
Eos, Transactions American Geophysical Union, 1997
Landslide Deposits, Cookie Bites, and Crescentic Fracturing Along the Northern Puerto Rico-Virgin Islands Margin: Implications for Potential Tsunamigenesis
The seismogenic North America-Caribbean oblique-slip plate boundary forms the 8-km-deep Puerto Ri... more The seismogenic North America-Caribbean oblique-slip plate boundary forms the 8-km-deep Puerto Rico trench north of the densely populated islands of Puerto Rico and Virgin Islands (combined population of just over 4 million people). The southern slope of the Puerto Rico trench adjacent to the Puerto Rico-Virgin Islands (PRVI) carbonate platform is characterized by frequent seismicity, rapid trenchward tilting, oversteepened slopes,
Magnetic and kinematic study at the Southwest Indian Ridge between 15°E and 35°E
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Papers by Nancy R Grindlay