The bent Hawaiian—Emper or. Because fracture zone and magnetic anomaly data are generally available from the Pacific plate but not from adjacent plates, a new method of analysis for onesided data was required. Musicians Ridges started at the same time as a series of major. Further details are ou tlined in the. Drilling and dredging samples suggest volcanic seamounts are widely distributed in the oceanic basin of the South China Sea, and most of them were formed after cessation of seafloor spreading. Die Erkundung der Erde — sei es an deren direkt zugänglicher Oberfläche oder im tiefen Untergrund, sei es im Labor oder bei der Beobachtung aus dem Weltraum — bringt ständig neue, erstaunliche Einsichten hervor.
Due to the consistency between the distribution of the seamount volume and the seafloor spreading features in the South China Sea basin, we propose the ridge jump may induce additional partial melting zones which account for the larger number of seamounts developed in the northern flank while the re-orientation of the extension during seafloor spreading dominated the distribution of post-spreading magmatism. Lett 306, 229—240 2011. In the ongoing exploration of Earth — be it at its easily accessible surface or deep below, be it in the lab or from space — new, astonishing findings are constantly being uncovered. Eruption, even above fertile mantle, may be stifled when the combination of lithospheric stresses is compressive, and fairly voluminous, even above refractory asthenosphere, when lithospheric stresses are extensional. An intriguing feature of our results is the overall trend of decreasing skew throughout the major Cenozoic platemantle reorganization of the Pacific domain [Steinberger et al.
Dietmar Müller 5 , Jason P. Plate boundaries are shown in white; hotspots are magenta stars and hotspot tracks are in dark blue; yellow circles delineate deformation volcanism: Y ellow circles in the top panel indicate the locations of SO142 expedition. This model predicts an age for the oldest Emperor Seamounts that matches published ages, implying that a linear age-distance relationship might extend back to at least 82 Ma.
Earth is an exceptional planet. After the seafloor spreading stopped, magmas that generated by spontaneous melting of the enriched mantle source migrated along the weak lithosphere due to the spreading re-orientation, and thus favored post-spreading seamounts clustered locally. A paleomagnetic investigation of the skewness of magnetic anomaly 12r o n the.
Revised age of Aleutian Island Arc formation implies high rate of magma production. For com plete information see. Kapitel 04 Georeaktor Sedimentbecken. For example, there is ext ensive geologic evidence indicating that. Chemically, the samples can be subdivided into plateau basalt-like tholeiites and trachytic to alkalic ocean-island basalt compositions, indicating at least two types of volcanic activity. Union Fa ll Meet.
Correspondence and requests for materials should be addressed to J. We inf er that the seamounts are. These trends can be attributed to lower degrees of melting either from lower mantle material during hotspot-related transition to plume tail or from less refractory shallow mantle components tapped during intermittent deformation-related volcanism induced by local tectonic extension between and after the main volcanic-edifice building episodes on Shatsky Rise. The best and most obvious explanation for this new type of.
The re-orientation of seafloor spreading stretched and thinned the crust along the transform faults and normal faults that reactivated preexisting structures. These studies, supported by dated magmatic samples [Koppers and Staudigel, 2005; Koppers et al. To nga fore arc and trench. Yet, this mechanism cannot explain many volcanic features on the Pacific Ocean floor1 and some might instead be caused by cracks in the oceanic crust linked to the reorganization of plate motions1—3. Comparing the seismic results to existing Pacific paleo strain reconstructions, the timing of increased strain and local deformation direction fits well to our findings.
Reconstruction of plates and plate boundaries around the Pacific Ocean Basin. All contributing authors of this book are also working at GFZ. Author content All content in this area was uploaded by Dietmar Müller on May 22, 2015. Two end-member scenarios can be considered where a high skewness exists between paleospreading direction and APM based on deep mantle reference frames.
Financial support was provided by the German Federal Ministry of Education. In a second phase a change of extensional force direction occurred from southwest to west-northwest, forming the southern part of the Suvarov Trough that extends onto the High Plateau. Previous works termed the location where a major spread- ing direction change occurred as bending line with a weak lithosphere, favoring the later formation of seamounts Naugler and Rea 1970;Rea 1970;Sharp and Clagua 2006; O'Connor et al. T rue polar wander since 32 Ma B.
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Implications for the scale of Eocene volcanism in the western P acific. Folgende Themen konnten so bearbeitet werden: A further change in the.
The results of this study emphasize the necessity of using incremental-heating and total-fusion isochron analysis, with its inherent internal concordance check, in choosing which ages from partially altered samples may be considered reliable. Zircon U—Pb ages obtained here for gabbros are 51. We thus suggest that the multiple strike directions of the Suvarov Trough represent an extensional structure that was caused by the major, stepwise Pacific Plate reorganization during the Paleocene.