STRATIGRAPHY AND PALEOMAGNETISM OF A 3-KM-THICK MIOCENE LAVA PILE IN THE MJOIFJORDUR AREA, EASTERN ICELAND

We have carried out stratigraphic mapping in the Upper Miocene basalt lava pile around the fjords Mjoifjordur and Seydisfjordur, eastern Ice land. The mapping is based on conventional methods including the use o f interbasaltic elastic horizons and petrographically distinct lava gr oups. These units are also used to provide correlations with the Nordf jordur area south of Mjoifjordur. We present a 3-km composite stratigr aphic column for the area between Mjoifjordur and Seydisfjordur. The g eology of this area shows some differences from the classical model of Walker for the structure of eastern Iceland partly due to the fact th at most of Mjoifjordur is not in the vicinity of central volcanoes. De tailed laboratory measurements of remanent magnetization were carried out on oriented core samples from 363 lavas in 10 selected profiles. T he local paleomagnetic polarity stratigraphy supports correlations mad e on the basis of other criteria. Over 20 geomagnetic reversals are re corded in the eastern Iceland lava pile in a period approximately 13-1 0 Ma ago. The geomagnetic field during this period averages to a centr al axial dipole field, and its overall statistical properties resemble those obtained in earlier surveys in Iceland.