A Late Miocene plate boundary reorganization along the westernmost Pacific-Antarctic ridge

Lodolo, Emanuele; Coren, F.

doi:10.1016/s0040-1951(97)00005-x

Cited by 11 publications

(9 citation statements)

References 19 publications

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“…We also determined five spreading rates from isolated magnetic profiles of the sparsely surveyed ridge axis between the Macquarie triple junction and 180°E, four from transit tracks of the R/V Nathaniel B. Palmer (shown in Figs 9 and 40) and one from an isolated magnetic profile (AB08 in Fig. 40) collected during an Italian cruise (Lodolo & Coren 1997).…”

Section: Data and Results: Best‐fitting And Morvel Plate Motion Estmentioning

confidence: 99%

Geologically current plate motions

DeMets¹,

Gordon

Argus

2010

Geophysical Journal International

2,230

1,664

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S U M M A R YWe describe best-fitting angular velocities and MORVEL, a new closure-enforced set of angular velocities for the geologically current motions of 25 tectonic plates that collectively occupy 97 per cent of Earth's surface. Seafloor spreading rates and fault azimuths are used to determine the motions of 19 plates bordered by mid-ocean ridges, including all the major plates. Six smaller plates with little or no connection to the mid-ocean ridges are linked to MORVEL with GPS station velocities and azimuthal data. By design, almost no kinematic information is exchanged between the geologically determined and geodetically constrained subsets of the global circuit-MORVEL thus averages motion over geological intervals for all the major plates. Plate geometry changes relative to NUVEL-1A include the incorporation of Nubia, Lwandle and Somalia plates for the former Africa plate, Capricorn, Australia and Macquarie plates for the former Australia plate, and Sur and South America plates for the former South America plate. MORVEL also includes Amur, Philippine Sea, Sundaland and Yangtze plates, making it more useful than NUVEL-1A for studies of deformation in Asia and the western Pacific. Seafloor spreading rates are estimated over the past 0.78 Myr for intermediate and fast spreading centres and since 3.16 Ma for slow and ultraslow spreading centres. Rates are adjusted downward by 0.6-2.6 mm yr −1 to compensate for the several kilometre width of magnetic reversal zones. Nearly all the NUVEL-1A angular velocities differ significantly from the MORVEL angular velocities. The many new data, revised plate geometries, and correction for outward displacement thus significantly modify our knowledge of geologically current plate motions. MORVEL indicates significantly slower 0.78-Myr-average motion across the Nazca-Antarctic and Nazca-Pacific boundaries than does NUVEL-1A, consistent with a progressive slowdown in the eastward component of Nazca plate motion since 3.16 Ma. It also indicates that motions across the Caribbean-North America and Caribbean-South America plate boundaries are twice as fast as given by NUVEL-1A. Summed, least-squares differences between angular velocities estimated from GPS and those for MORVEL, NUVEL-1 and NUVEL-1A are, respectively, 260 per cent larger for NUVEL-1 and 50 per cent larger for NUVEL-1A than for MORVEL, suggesting that MORVEL more accurately describes historically current plate motions. Significant differences between geological and GPS estimates of Nazca plate motion and Arabia-Eurasia and India-Eurasia motion are reduced but not eliminated when using MORVEL instead of NUVEL-1A, possibly indicating that changes have occurred in those plate motions since 3.16 Ma. The MORVEL and GPS estimates of Pacific-North America plate motion in western North America differ by only 2.6 ± 1.7 mm yr −1 , ≈25 per cent smaller than for NUVEL-1A. The remaining difference for this plate pair, assuming there are no unrecognized systematic errors and no measurable change in Pacific-North America motion ...

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Section: Data and Results: Best‐fitting And Morvel Plate Motion Estmentioning

confidence: 99%

Geologically current plate motions

DeMets¹,

Gordon

Argus

2010

Geophysical Journal International

2,230

1,664

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“…Finally, the southern PAR (Figure 3e) has no left‐stepping offsets; all are right‐stepping and those surveyed in detail show evidence of magmatic leaking [e.g., Macario et al , 1994]. The westernmost portion of the boundary is a large extensional transform system which began to open ∼6 Ma [e.g., Lodolo and Coren , 1997; Marks and Stock , 1994]; prior to that time it was simply a large single transform. These dramatic changes are also reflected in the PAR spreading history [e.g., Cande et al , 1995].…”

Section: Pacific Plate Spreading Centersmentioning

confidence: 99%

Reconciling late Neogene Pacific absolute and relative plate motion changes

Wessel

Kroenke

2007

Geochem Geophys Geosyst

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[1] New models of Pacific absolute plate motion relative to hot spots and models of relative plate motion involving the Pacific plate all agree there was a significant change in the late Neogene (Chron 3A, $5.89 Ma), reflecting a more northerly absolute motion than previously determined. As Pacific absolute plate motion became slightly more northerly, left-stepping transform segments came under compression. Some left-stepping segments became microplates with clockwise rotation; others show clear evidence of compressional deformation. Conversely, right-stepping transforms came under tension, and many developed intratransform spreading centers or show similar evidence for transform magmatism. Several large left-stepping transform offsets represent portions of the Nazca plate protruding into the Pacific and as such act as obstacles to the more northerly Pacific absolute plate motion. We suggest these obstructions act to enhance the generally tensile equatorial Pacific stress regime caused by distant slab pull. As a consequence, the greater French Polynesia region has experienced diffuse volcanism that increased considerably following the Chron 3A plate motion change. We propose that since the Hawaii-Emperor Bend time, the distant Pacific slab pull and the friction between the large, buoyant Ontong Java plateau and the northern margin of the Australia plate have produced episodes of increased tensile stresses in the equatorial Pacific. We believe these stress excursions are responsible for much of the intraplate volcanism observed in a wide triangular region from Samoa to the East Pacific and Pacific-Antarctic Rises.Components: 7224 words, 5 figures.

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“…Changes in spreading direction at chrons C13o and C6C (33.5 and 24.1 Ma) are observed at FZs along the entire PAR. We then use these rotations to investigate the tectonic evolution of the southwesternmost section of the PAR, a region which underwent a significant clockwise change in spreading direction during the Late Miocene [ Cande et al , 1995; Lodolo and Coren , 1997]. Being close to the rotation poles, this area is ideal for testing the predictive quality of the new rotation parameters for changes in plate motion and observed tectonic features related to these changes.…”

Section: Introductionmentioning

confidence: 99%

Revised Pacific‐Antarctic plate motions and geophysics of the Menard Fracture Zone

Croon

Cande

Stock

2008

Geochem Geophys Geosyst

127

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A reconnaissance survey of multibeam bathymetry and magnetic anomaly data of the Menard Fracture Zone allows for significant refinement of plate motion history of the South Pacific over the last 44 million years. The right‐stepping Menard Fracture Zone developed at the northern end of the Pacific‐Antarctic Ridge within a propagating rift system that generated the Hudson microplate and formed the conjugate Henry and Hudson Troughs as a response to a major plate reorganization ∼45 million years ago. Two splays, originally about 30 to 35 km apart, narrowed gradually to a corridor of 5 to 10 km width, while lineation azimuths experienced an 8° counterclockwise reorientation owing to changes in spreading direction between chrons C13o and C6C (33 to 24 million years ago). We use the improved Pacific‐Antarctic plate motions to analyze the development of the southwest end of the Pacific‐Antarctic Ridge. Owing to a 45° counterclockwise reorientation between chrons C27 and C20 (61 to 44 million years ago) this section of the ridge became a long transform fault connected to the Macquarie Triple Junction. Following a clockwise change starting around chron C13o (33 million years ago), the transform fault opened. A counterclockwise change starting around chron C10y (28 millions years ago) again led to a long transform fault between chrons C6C and C5y (24 to 10 million years ago). A second period of clockwise reorientation starting around chron C5y (10 million years ago) put the transform fault into extension, forming an array of 15 en echelon transform faults and short linking spreading centers.

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A Late Miocene plate boundary reorganization along the westernmost Pacific-Antarctic ridge

Cited by 11 publications

References 19 publications

Geologically current plate motions

Geologically current plate motions

Reconciling late Neogene Pacific absolute and relative plate motion changes

Revised Pacific‐Antarctic plate motions and geophysics of the Menard Fracture Zone

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