THE XIAOJIAO HIGH-GRADE ECLOGITE-TYPE RUTILE DEPOSIT IN JIANGSU, CHINA: GEOLOGY, GEOCHEMISTRY AND METALLOGENESIS

摘要

The Xiaojiao rutile deposit with stratiform, banded and lens-shaped rutile-bearing eclogite in the Sulu ultra-high pressure metamorphic zone represents the largest and richest primary rutile mineralization in the zone. Four kinds of rutile can be recognized. They are: (1) inclusions in garnet and omphacite; (2) intergranular infilling between garnet and omphacite; (3) altered remnant; and (4) hydrothermal infilling in veinlets. Electron microprobe data show that sodic metasomatism probably from metamorphic fluid could play an important role in rutile mineralization during high and ultra-high pressure metamorphism. The present paper concludes that according to geochemical characteristics, the eclogite originated from mafic and ultramafic rocks in the upper mantle and crust-mantle boundary and the Xiaojiao eclogite-type rutile deposit is genetically closely related to ultra-high pressure metamorphism.