UNIFIED TREATMENT OF SOLAR AND ATMOSPHERIC NEUTRINO OSCILLATIONS

We present an ansatz for the quark and lepton mass matrices, derivable from SO(10) type GUTs, which accommodates a heavy (> 92 GeV) top quark and permits large mixings in the nu(mu)<-- -->nu(tau) sector (as suggested by the recent Kamiokande and IMB data on the atmospheric neutrinos). The well known asymptotic relations m(b) = m(tau), ms = 2/3m(mu) and m(d)m(s) = m(e)m(mu) all hold to a good approximation. Depending on nu(mu)<-- -->nu(tau) mixing which can even be maximal, the mixing angle relevant for solar neutrino oscillation lies in the range 7.8 X 10(-3) less than or similar sin2 2theta(emu), less than or similar 2.1 x 10(-2). For the Ga-71 experiment the event rate, normalized against the standard solar model prediction of 132 SNU, is estimated to be between 80 and 20 SNU.