| Two low-temperature and high-pressure eclogite zones, which are separated by the Tongbaishan high-grade complex, were recognized in the Tongbaishan area. In every eclogite zone there are abundant garnet amphibolites which look very like eclogites both in occurrence and minerals assemblage. The detailed petrological observation and P-T estimation on four eclogites and their retrograde equivalents (garnet amphibolites) indicate that the two zones were formed at different conditions, 530-610°C and 1.7-2.0GPa for the northern zone, and 470-520°C and 1.3-1.7GPa for the southern zone. This suggests that the two zones do not belong to the same high-pressure slice, and correspond to the Huwan eclogite zone (Zone I) and the Qijiaoshan eclogite zone (Zone V) from western Dabieshan, respectively. Garnet amphibolites seem to form at the same conditions with retrograde eclogites from the two zones. 525-595°C and 0.7-1.4GPa for the northern eclogite zone, and 580-591°C and 0.78-1.1GPa for the southern eclogite zone. Electron microprobe analyses reveal that all the garnets from eclogites show progressive chemical zoning. By contrast, the zonation of garnets from retrograde eclogites (garnet amphibolites) is more complicated. For a single garnet porphyroblast, an earlier prograssive recrystallization at increasing temperature is recorded in the core, a further replacement at lower temperature in the inner rim, and a later growth at higher temperature in the outer rim. If so, a"hairpin-type"P-T path could be deduced from the Tongbaishan eclogites. Such a path implies that the eclogites were slowly uplifted at decreasing temperature from the deep levels, which is different from the fast exhumation model established for the most high- and ultrahigh-pressure rocks. The later retrograde metamorphism of eclogites occurring at higher geothermal gradient in the medium crust. Garnet amphibolites in both zones are the retrograde equivalents of eclogites.
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