New aerogeophysical view of the Antarctic Peninsula: More pieces, less puzzle

Abstract

New airborne geophysical data reveal subglacial imprints of crustal growth of the Antarctic Peninsula by Mesozoic arc magmatism and terrane accretion along the paleo‐Pacific margin of Gondwana. Potential field signatures indicate that the Antarctic Peninsula batholith is a composite magmatic arc terrane comprising two distinct arcs, separated by a >1500 km‐long suture zone, similar to the Peninsular Ranges batholith in southern and Baja California. Aeromagnetic, aerogravity and geological data suggest that a mafic Early Cretaceous western arc was juxtaposed against a more felsic eastern arc which, in mid‐Cretaceous times, was intruded by highly magnetic tonalitic/granodioritic plutons of island arc affinity. Suturing of the two arcs against the Gondwana margin caused the mid‐Cretaceous Palmer Land orogenic event. Convergence and suturing may have been driven by two subduction zones or, alternatively, by a decrease in slab dip, leading to an inboard migration of the arc, as in California.

Autochthonous v. accreted terrane development of continental margins: a revised in situ tectonic history of the Antarctic Peninsula

“…These data ( Fig. 5; Vaughan et al 1998;Ferraccioli et al 2006) broadly agree with those of Wendt et al (2013), with the most extensive high magnetic susceptibilities being on the west of the Peninsula in the Central Domain. The highest magnetic anomalies are focused along a narrow linear feature (the Pacific Margin Anomaly, Fig.…”

“…Less extensive, shorter wavelength magnetic highs are found in the Eastern Domain of Palmer Land, but the Jurassic gabbroic intrusions producing them are clearly not as prevalent as the mafic bodies in the Central Domain and may be related to Gondwanan rifting rather than arc magmatism Wever & Storey 1992). Although the data of Ferraccioli et al (2006) were presented in support of the terrane accretion model, no extensive linear magnetic feature follows the trace of the Eastern Palmer Land Shear Zone; this finding argues against the presence of a major tectonic suture separating allochthonous or parautochthonous terranes. Instead, the most prominent linear feature abruptly bisects the Central Domain into a western zone of high magnetic susceptibility and an eastern zone of low susceptibility, reflecting the edge of Pacific Margin Anomaly related mafic magmatism not a terrane boundary.…”

“…5; Vaughan et al 1998) along the Central Domain's western margin. This anomaly also correlates with a Bouguer gravity high (Ferraccioli et al 2006). Mapping and dating samples from this region indicates that the anomaly is largely caused by highly magnetically susceptible Early Cretaceous (141-129 Ma) gabbroic and tonalitic-granodioritic extensional plutons produced during a peak in magmatic activity (Vaughan et al 1998).…”

Chrono- and lithostratigraphy of a Mesozoic–Tertiary fore- to intra-arc basin: Adelaide Island, Antarctic Peninsula

“…Ph.D. thesis, Univ. Birmingham, 1965;1970) and later by Griffiths & Oglethorpe (1998) who were not able to place too much chronological control on the stratigraphy they proposed, but they did assign a probable Late Jurassic Vaughan & Storey (2000) and Ferraccioli et al (2006). age to the stratified rocks of Adelaide Island based on similarities to rocks from elsewhere on the west coast of the Antarctic Peninsula.…”

“…The area forms part of the geophysically and geologically defined Western Zone of the Central Domain of the Antarctic Peninsula ( Fig. 1), a Mesozoic magmatic arc terrane that formed in response to subduction along the protoPacific margin of Gondwana (Vaughan & Storey, 2000;Ferraccioli et al 2006).…”