The transfer of chalcophile metals across the continental lithosphere has been traditionally
modeled based on their chemical equilibrium partitioning in sulfide liquids and silicate magmas.
Here, we report a suite of Ni-Fe-Cu sulfide droplets across a trans-lithospheric magmatic
network linking the subcontinental lithospheric mantle to the overlying continental crust.
Petrographic characteristics and numerical calculations both support that the sulfide droplets
were mechanically scavenged from the mantle source during partial melting and transported
upwards by alkalinemagmas rising through the continental lithosphere. Nanoscale investigation
by high-resolution transmission electron microscopy (HR-TEM) documents the presence of
galena (PbS) nanoinclusions within the sulfide droplets that are involved in the mantle-to-crust
magma route. The galena nanoinclusions show a range of microstructural features that are
inconsistent with a derivation of PbS by exsolution from the solid products of the Ni-Fe-Cu
sulfide liquid. It is argued that galena nanoinclusions crystallized from a precursor Pb(-Cu)-rich
nanomelt, which was originally immiscible within the sulfide liquid even at Pb concentrations
largely below those required for attaining galena saturation. We suggest that evidence of
immiscibility between metal-rich nanomelts and sulfide liquids during magma transport would
disrupt the classical way by which metal flux and ore genesis are interpreted, hinting for
mechanical transfer of nanophases as a key mechanism for sourcing the amounts of mantlederived
metals that can be concentrated in the crust.BES-2017-079949The Spanish
projects PID2019-111715GB-I00/AEI/10.13039/501100011033NANOMET PID2022-
138768OB-I00MECOBE ProyExcel_00705(FEG-ESEM), focused-ion beam (FIB)High-resolution transmission electron microscopy (HR-TEM)Australian Research Council through ARC Linkage Project
LP190100785European Social FundEuropean Regional Development Fun
