Abstract

An apatite fission-track age profile from the Scott Glacier region provides evidence of uplift and denudation of the Transantarctic Mountains in the Early and Late Cretaceous. Samples for fission-track analysis were collected over a vertical range of ∼2 km from the Mt. Griffith massif. Apatite ages from the upper 700 m of Mt. Griffith vary little with elevation, indicative of rapid cooling accompanying Early Cretaceous uplift and denudation. Ages from the northeast buttress of Mt. Griffith (the Fission Wall) define a steep gradient and are indicative of rapid cooling accompanying Late Cretaceous uplift and denudation. The two parts of the profile are separated by a fault. Subsequent uplift and denudation of the Mt. Griffith massif in the Cenozoic were required to elevate the massif (and the apatite age profile) to its present position. This younger uplift was most likely initiated in the early Cenozoic, penecontemporaneously with welldocumented early Cenozoic uplift in the Victoria Land region of the Transantarctic Mountains. These three periods of uplift coincide with periods of major plate reorganization in the southwest Pacific region: (1) initial rifting of Australia from Antarctica and impingement of the Pacific-Phoenix ridge with the subduction zone marginal to New Zealand in the Early Cretaceous, (2) separation of Australia, New Zealand, and Antarctica in the Late Cretaceous, and (3) cessation of spreading in the Tasman Sea ∼10 m.y. prior to accelerated spreading between Australia and Antarctica in the early Cenozoic.

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