关键词: 西南天山造山带, 阿万达金矿, 原岩恢复, 沉积环境, 沉积时限, 物源

Abstract: The Awanda gold deposit is located in the Southwestern Tianshan Orogenic Belt. On the basis of the geological
characteristics of the Awanda gold deposit, the authors applied petrological geochemistry and LA-ICP-MS detrital zircon U-Pb dating
of the siliceous schist wall rocks from the So-called Aksu Group, which is closely related to the mineralization of Awanda gold deposit,
with an aim to understand depositional environment, provenance and age of these rocks. The results of petrochemistrical analysis show
that the protoliths of the ore-hosting strata are possibly composed of mudstones and sandstones with low maturity. Most of the
provenances are quartzose sediments and the depsotional environment is likely related to depositional basin nearby the active continent
margin. LA-ICP-MS detrital zircon U-Pb date indicates that the zircon ages have peaks of weighted age of 405 or 406 Ma. The
youngest peak age of these concordant age data is 405 Ma which could be regarded as the maximum sedimentary age. Therefore, it was
considered that the sedimentary age of the so-called Aksu group ore-hosting strata is not older than the Early Devonian, rather than the
Changcheng period as previously reported. In addition, the provenances of the strata are multiform. Among the analytic data, the ~405
Ma detrital zircons occupy the principal part, which could be related to the magmatic activity in the northern rim of the Early Devonian
volcanic arc of the Haerke Mountain. The ~745 Ma detrital zircons suggest that small part of the material source comes from
Neoproterozoic rocks. Several ~2.50 Ga detrital zircons reflect that North China block makes few contributions of material sources to
the strata.

Key words: Southwestern Tianshan Orogenic Belt, Awanda gold deposit, reconstruction of protolith, sedimentary environment, sedimentary age, sedimentary provenance