Testing a proposed "second continent" beneath eastern China using geoneutrino measurements

TL;DR

This paper explores the potential of geoneutrino measurements to detect or constrain the existence of hypothesized 'second continents' at the base of Earth's Transition Zone, which are difficult to image seismologically.

Contribution

It provides predictions of geoneutrino flux from second continents and discusses how current and future neutrino detectors can test their existence.

Findings

Predicted geoneutrino flux varies with different models.

Current detectors may have limited sensitivity to second continents.

Future detectors could potentially confirm or rule out these structures.

Abstract

Models that envisage successful subduction channel transport of upper crustal materials below 300 km depth, past a critical phase transition in buoyant crustal lithologies, are capable of accumulating and assembling these materials into so-called "second continents" that are gravitationally stabilized at the base of the Transition Zone, at some 600 to 700 km depth. Global scale, Pacific-type subduction (ocean-ocean and ocean-continent convergence), which lead to super continent assembly, were hypothesized to produce second continents that scale to about the size of Australia, with continental upper crustal concentration levels of radiogenic power. Seismological techniques are incapable of imaging these second continents because of their negligible difference in seismic wave velocities with the surrounding mantle. We can image the geoneutrino flux linked to the radioactive decays in these second continents with land and/or ocean-based detectors. We present predictions of the geoneutrino flux of second continents, assuming different scaled models and we discuss the potential of current and future neutrino experiments to discover or constrain second continents. The power emissions from second continents were proposed to be drivers of super continental cycles. Thus, testing models for the existence of second continents will place constraints on mantle and plate dynamics when using land and ocean-based geoneutrino detectors deployed at strategic locations.