Publikationsdatum:
2022-05-25
Beschreibung:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 1999
Beschreibung:
Changes in morphology of the Marquesas Fracture Zone are correlated with small changes in Pacific-Farallon relative motion. The
simple flexural signal of a locked fracture zone may be obscured by
tectonic effects, and there is no evidence for the release of shear stress
on the fracture zone by vertical slip after leaving the active transform.
One such small change in plate motion is documented in the South
ern Austral Island region of the South Pacific. A twelve degree clock
wise change in Pacific-Farallon relative motion occurred around fifty
million years ago. This Eocene change in spreading direction and rate
is locally constrained with observations of magnetic anomalies and
spreading fabric orientation.
At the southeastern end of the Cook-Austral Island chain, multiple
episodes of volcanism have left a diverse population of seamounts.
Volume estimates from geophysical data and modeling show that one-half
to two-thirds of the volcanic material is over thirty million years
old, while the remainder is less than five million years old.
Seismic and bathymetric data imply the presence of abyssal basalt
flows in the flexural moat of the Austral Islands, probably associated
with Austral Islands volcanism, which may contribute a significant
amount of material to the archipelagic apron.
Beschreibung:
The research presented in Chapter 2 was supported by National Science Founda
tion grants OCE-9012949 and OCE-9012529. Chapters 3, 4 and 5 were supported
by National Science Foundation grant OCE-9415930. A National Science Foundation
graduate fellowship supported my first three years of graduate study.
Schlagwort(e):
Structural geology
;
Plate tectonics
;
Volcanism
;
Maurice Ewing (Ship) Cruise EW9109
;
Maurice Ewing (Ship) Cruise EW9602
;
Roger Revelle (Ship) Cruise KIWI03
Repository-Name:
Woods Hole Open Access Server
Materialart:
Thesis
Format:
application/pdf
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