The Emeishan large igneous province (ELIP) is known to have a relatively small-exposed
area with a radius no longer than 700 km. New zircon U-Pb and plagioclase and pyroxene
Ar-40/Ar-39 age determinations from mafic dykes in the nucleus of Yangtze Craton,
located more than 1000 km away from the inner zone of ELIP, reveal that they were
emplaced at similar to 260 Ma. This is synchronous with the ELIP. The zircon (epsilon
Hf)(t) values of the dolerite dyke vary between +5.4 and +8.9. These mafic dykes have
low Ti/Y ratios (299-413) and are enriched in light rare-earth elements (LREE) and
depleted in heavy rare-earth elements (HREE) and high field strength elements (HFSE).
These dykes bear similarities to the Emeishan high-Ti basalts despite their relatively
low Ti/Y ratios. Whole-rock Sr-Nd isotopes gave highly radiogenic initial Sr-87/Sr-86
(0.710033-0.710371) and extremely low initial Nd-143/Nd-144 (0.511515-0.511641) and
(epsilon Nd)(t) of -15.4 to -12.9. Electron microprobe analysis of concentric-zoned
pyroxenes yielded increasing Mg# and Cr2O3 from core to rim. Bulk rock geochemistry,
Sr-Nd isotopes, and mineral chemistry indicate that recharge of a new batch of ascending
plume-derived magma into an enriched lithosphere generated the mafic dykes. The synchronous
emplacement and geochemical and isotopic similarities between the examined Huangling
mafic dykes and Emeishan flood basalts, as well as the presence of titanaugite, all
point to the genetic link between the Huangling mafic dykes to the ELIP. The Emeishan-age
of the Huangling dykes permits a substantial increase of at least 3 x 10(5) km(2)
in the spatial extent of the ELIP.
