The Malpelo Plate Hypothesis and implications for nonclosure of the Cocos‐Nazca‐Pacific plate motion circuit

Abstract

Using global multiresolution topography, we estimate new transform‐fault azimuths along the Cocos‐Nazca plate boundary and show that the direction of relative plate motion is 3.3° ± 1.8° (95% confidence limits) clockwise of prior estimates. The new direction of Cocos‐Nazca plate motion is, moreover, 4.9° ± 2.7° (95% confidence limits) clockwise of the azimuth of the Panama transform fault. We infer that the plate east of the Panama transform fault is not the Nazca plate but instead is a microplate that we term the Malpelo plate. With the improved transform‐fault data, the nonclosure of the Nazca‐Cocos‐Pacific plate motion circuit is reduced from 15.0 mm a−1 ± 3.8 mm a−1 to 11.6 mm a−1 ± 3.8 mm a−1 (95% confidence limits). The nonclosure seems too large to be due entirely to horizontal thermal contraction of oceanic lithosphere and suggests that one or more additional plate boundaries remain to be discovered.

Emergence/Subsidence Histories Along the Carnegie and Cocos Ridges and Their Bearing Upon Biological Speciation in the Galápagos

“…Malpelo Ridge and Coiba Ridge are elevated bathymetric rises, localized regions of thickened crust with incomplete isostatic compensation, or slightly positive free‐air gravity anomalies. The tectonic histories of these ridges are complicated and may involve individual microplates with motions that are distinct from that of the Nazca plate, as proposed by Zhang et al (). These two ridges could represent additional products of the Galápagos hotspot track that were formed simultaneously with the Carnegie Ridge.…”

Spatial-temporal Distribution Characteristics of Global Seismic Clusters and Associated Spatial Factors

“…The northern Nazca plate interacts with the Cocos and Pacific Ocean plates. Therefore, the geological conditions of this region are highly active and complex (Zhang et al, 2017). For example, clusters that C3, C4, C7, and C8 all last for 22-38 yr.…”

Quantification of Pacific Plate Hotspot Tracks Since 80 Ma

“…This is a useful benchmark for ancient plate circuits tying the the motion of the Pacific plate relative to the continental plates. A second dramatic example of misfit is the non-closure about the Galapagos triple junction, which equals 15 mm/a ±4 mm/a (DeMets et al, 2010;Zhang et al, 2017). With the recognition of a previously unknown microplate, the Malpelo plate, Zhang et al (2017) reduced the nonclosure about the Galapagos triple junction to 12 mm/a ±4 mm/a, which remains a huge unexplained plate-circuit nonclosure.…”

“…A second dramatic example of misfit is the non-closure about the Galapagos triple junction, which equals 15 mm/a ±4 mm/a (DeMets et al, 2010;Zhang et al, 2017). With the recognition of a previously unknown microplate, the Malpelo plate, Zhang et al (2017) reduced the nonclosure about the Galapagos triple junction to 12 mm/a ±4 mm/a, which remains a huge unexplained plate-circuit nonclosure. Given these well-documented plate-circuit nonclosures for geologically current plate motion, we assert that it is likely that errors of similar magnitude occur in estimates of ancient plate motion for which we have much less information and very little redundancy.…”