On the origin of fore-arc basins: new evidence of formation by rifting from the Jurassic of Alexander Island, Antarctica
The Middle Jurassic–Lower Cretaceous Fossil Bluff Group of Alexander Island, Antarctica represents the fill of a fore-arc basin unconformably overlying an accretionary complex. Like most fore-arc basins, this example had been considered to have a passive origin, as a topographic hollow between the a...
| Published in: | Terra Nova |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Blackwell
1999
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| Subjects: | |
| Online Access: | http://nora.nerc.ac.uk/id/eprint/503581/ https://doi.org/10.1046/j.1365-3121.1999.00244.x |
| Summary: | The Middle Jurassic–Lower Cretaceous Fossil Bluff Group of Alexander Island, Antarctica represents the fill of a fore-arc basin unconformably overlying an accretionary complex. Like most fore-arc basins, this example had been considered to have a passive origin, as a topographic hollow between the arc 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 arc, it is concluded that a late Jurassic pause in subduction led to active rifting to form the fore-arc basin. |
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