A major ductile fault zone, the eastern Palmer Land shear zone, has been identified east of the spine of the southern Antarctic Peninsula. This shear zone separates newly identified geological domains, and indicates that during Late Jurassic terrane accretion and collision, two and possibly three separate terranes collided, resulting in the Palmer Land orogeny. The orogeny is best developed in eastern Palmer Land and eastern Ellsworth Land. There, shallow-marine sedimentary rocks of the Latady Formation, and a metamorphic and igneous basement complex of possible Lower Palaeozoic to pre-Early Jurassic age, are thrust and folded. This forms an arcuate, east-directed, foreland, fold and thrust belt up to 100 km wide and 750 km long, parallel to the axis of the Antarctic Peninsula. The newly identified Antarctic Peninsula domains include: (1) a parautochthonous Eastern Domain that represents part of the margin of the Gondwana continent, comparable to the Western Province of New Zealand, the Ross Province superterrane of Marie Byrd Land, the Eastern Series of south-central Chile, the Pampa de Agnía and Tepuel rocks of north Patagonia, and the Cordillera Darwin rocks of Tierra del Fuego, (2) a suspect Central Domain that represents an allochthonous, microcontinental, magmatic arc terrane, comparable to the Median Tectonic Zone of New Zealand, the Amundsen Province superterrane of Marie Byrd Land, and Coastal Cordillera of north Chile and (3) a suspect Western Domain, with strong similarities to the Eastern Province of New Zealand, Western Series of south-central Chile, and Chonos metamorphic complex of north Patagonia, that represents either a subduction–accretion complex to the Central Domain, or another separate crustal fragment. Although an allochthonous terrane hypothesis for the Antarctic Peninsula remains to be fully tested, this has much in common with models for the New Zealand and South American parts of the Pacific margin of Gondwana. The identification of a potential allochthonous terrane–continent collision zone allows us to define the edge of the Gondwana continent in the Antarctic Peninsula sector of the supercontinent margin, which has implications for Mesozoic reconstructions of Gondwana.

GF is high and melt water is present under ice cover [11][12] Greenland to explain the origin of the observed melting beneath the ice cover (Figure 1). This are controlled by a combination of GF and non-GF influences, we build our calibration 137 strategy on estimating GF required to reproduce the observed thawed basal ice conditions, 138 discounting basal ice melt rates as a proxy for GF. This has the effect that GF estimates will 139 likely be biased downwards where basal melt is rapid; nevertheless, our strategy is 140 sufficiently effective to separate out the signal of a strong and spatially extensive geothermal 141 anomaly beneath the GIS and provides a hard lower bound for GF values at the observed 142 basal melt locations. 143The anomalous GF zone lies in the area with the highest density of direct measurements. 150One potential cause of elevated GF is illustrated by seismic data that link our west-to-east GF 151anomaly with a zone of low-seismic-velocity mantle, a "negative anomaly", beneath Iceland 6- Greenland may be the expression of Iceland hotspot history. The geothermal anomaly 237 provides evidence for a more northerly hotspot track than previously proposed and will offer 238 a useful test for existing paleoreconstructions of absolute plate motion. This study advocates 239 a previously undocumented strong coupling between Greenland's present-day ice dynamics, 240 subglacial hydrology, and the remote tectonothermal history of the North Atlantic region.

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.

Zircons gneisses and migmatites collected from the Antarctic Peninsula have different core-rim hafnium isotope ratio relationships depending on whether evidence for zircon dissolution is present or absent. Two samples contain inherited zircon that is partially dissolved. In these samples, the 176 Hf/ 177 Hf rations of the inherited zircon and new magmatic zircon rims are, on average, indistinguishable and consistent with in situ melting. In such cases the hafnium isotopic composition of the melt was probably strongly influenced by the dissolved zircon component at the source. Variation in 176 Hf/ 177 Hf within the magmatic zircon rims from grain to grain suggests that Hf isotopes were only partially homogenized during melt migration; alternatively, zircon growth may have taken place within small volumes of partial melt. Other samples do not preserve textural evidence for zircon dissolution during melt generation; in these samples the 176 Hf/ 177 Hf values of the inherited zircon and new magmatic zircon rims are different. The zircon rims apparently suggest a source of less evolved hafnium than that contained within the inherited zircon. Whether this relates to a separate juvenile source or, alternatively, is derived from minerals other than zircon at the source, cannot be resolved. Inherited zircon, irrespective of age, has been strongly influenced by the reworking of a juvenile Late Mesoproterozoic source, suggesting that such crust underlies the Antarctic Peninsula. Our results therefore suggest that Hf isotope analyses provide great potential for future studies investigating the source and processes involved in the generation of crustal melts.

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