Potassium argon dating problems
Solid triangles are basalt-andesite volcanoes.15 11 North-northeast-trending normal faults with throws up to 30 m cut the volcanoes within the graben.
1).12 Though not as well publicized as its neighbor, Mt.
Ruapehu (about 12 km to the south), Ngauruhoe is an imposing, almost perfect cone that rises more than 1000 m above the surrounding landscape.
Potassium-argon “dating” of five of these flows and deposits yielded K-Ar model “ages” from Ar* content.
A survey of anomalous K-Ar “dates” indicates they are common, particularly in basalts, xenoliths, and xenocrysts such as diamonds that are regarded as coming from the upper mantle.Activity decreased for two months after the last of the lava flows on September 26, but increased again during December 1954 and January 1955 with lava fountaining and many highly explosive pyroclastic (ash) eruptions.