Mesozoic Zircon from Gabbronorites of the Axial Mid-Atlantic Ridge, 6° N, Markov Deep

摘要

According to the theory of plate tectonics, rocks forming within spreading ridge axis should be no older than several millions of years. However, isotopic dat-ings of these rocks are very scanty. Zircon dating on gabbroids from the core of ODP 153, which was drilled in the axial zone of the slow-spreading Mid-Atlantic Ridge (MAR) near the Kane transform fault, yielded unexpected results. The obtained zircon ages were 330 ± 17 and 1623 ± 12 Ma [1]. We carried out isotopic investigations of magmatic rocks from the Markov Deep of the MAR, 6° N (Fig. 1). This work presents the results of U-Pb isotopic dating of zircon from gab-bronorites.