Abstract
The Middle Jurassic-Lower Cretaceous Fossil Bluff Group of Alexander Island, Antarctica represents the fill of a fore-are ba sin unconformably overlying an accretionary complex. Like most fore-are basins, this example had been considered to have a passive origin, as a topographic hollow between the are and the trench-slope break. Recent discoveries of igneous rock coeval with sedimentation have altered this view. Oxfordian-Kimmeridgian basaltic and rhyolitic sills and lava flows are found in a restricted area at the north of the basin, within a single formation. Chemically, most basalts are high-Nb types, which cannot have originated in a supra-subduction zone setting. Since the age of emplacement of these rocks coincides with a gap in the record of plutonism in the Antarctic Peninsula volcanic are, it is concluded that a late Jurassic pause in subduction led to active rifting to form the fore-are basin.
Original language | English |
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Pages (from-to) | 186-193 |
Number of pages | 8 |
Journal | Terra Nova |
Volume | 11 |
Publication status | Published - 1999 |
Keywords
- GONDWANA BREAK-UP
- ALKALINE MAGMAS
- MAFIC DYKES
- PENINSULA
- EVOLUTION
- BASALTS
- BATHOLITH
- MARGIN