Dating lava flows for paleomagnetic datingonlinecourse com
Type C eruptions last for months to years and produce small lava shields and many flows consisting of all three types.Type D eruptions persist for decades to centuries and produce large lava shields and flow assemblages dominated by tube-fed pahoehoe.Key flows of unknown age are dated by comparison with the history of variation, and relative ages of other flows are determined from super position and vegetation development.Paleomagnetic dating precision varies with time and depends uponthe rate of secular variation and dispersion in the data.We report on the paleomagnetic dating of 25 sites from the Reykjanes Peninsula and the Tungnaá lava sequence of Iceland.The gathered paleomagnetic directions were compared with the available reference paleosecular variation curves of the Earth magnetic field to obtain the possible emplacement age intervals.
Rift activity waxed as summit activity waned, and in one example the waxing sequence resembles an evolutionary progression: Rift eruptions were at first brief and widely separated in time and space but gradually became frequent along a restricted segment of the rift zone and culminated in sustained activity at one locality.
Kilauea's past behavior has varied in space and time.
The chief spatial variation is a decrease in typical eruption duration at increasing distances away from the summit magma reservoir.