Bq. Zhu et al., Relation of isotope geochemical steep zones with geophysical fields and tectonics in the junction area of the Cathaysian, Yangtze and Indochina plates, ACT GEO S-E, 74(2), 2000, pp. 236-240
Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochem
ical steep zones (GSZ) have been established, which clearly reveal the junc
tion relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are
closely related to gravity Moho gradient zones and lithospheric thickness.
The GSZ between the Yangtze and Cathaysian plates is consistent with the S
hizong-Mile tectonic belt, where island are basalts are well developed. The
Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt i
n rift-island are environments. The evidence of geology, geophysics and geo
chemistry all indicates that Cathaysia was subducted towards the Yangtze pl
ate and that the Yangtze plate was underthrust beneath the Indo-China, whic
h took place from the Early Carboniferous to the Early Triassic.