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In the light of field investigation, microscopic study, X-ray phase analysis and mineral infrared spectral analysis, it is considered that laumontitization is of extensive occurrence in the Axi gold orefield. The development of laumontitization and its relationship to mineralization show that the laumontitization appeared mainly at the top of and in the periphery of orebodies, and occurred at the edge of the epithermal system or at the late stage of epithermal system evolution. Therefore, laumontitization can be used as an exploration indicator of epithermal gold deposits. The fluids responsible for laumontitization in the Axi gold orefield are similar to those producing hot spring-type gold deposits or those from modern geothermal fields. Epithermal mineralization of the Axi gold deposit was dated at Carboniferous, indicating that the West Tianshan of China is a region favorable to epithermal-type gold mineralization and preservation. Hence the West Tianshan of China is a target area for exploring epithermal gold deposits.

It is suggested in this paper that the famous Taylor’s model for the composition and evolution of the continental crust consists of three closely related key links. These links include an assumption that the surficial environment has no effect on the sedimentary REE patterns and the REE patterns in shales can reflect the composition of their provenance, a discovery about the discrepancy of sedimentary REE patterns between Archean and Proterozoic, and a deduction that there was a global scale K-granitoid event at the end of the Archean. Based on a detailed discussion, this paper substantially negates the rationality of the Taylor’s model and argues that its three critical links be three great errors indeed. Moreover, some other deficiencies or problems it confronts are described in this paper. The authors suggest that what led to the errors involved in the Taylor’s model is its wrongly neglecting the effect of the sedimentary environment on the chemical composition of sediments, and that the environment should be an important factor affecting the distribution patterns of trace elements in the sediments.

The supracrustal rocks of the Wuyang metamorphic terrain are divided into the Zhao ’anzhuang, Tieshanmiao and Yangshuwan Formations. These three Formations were dated at 3000–2550 Ma, 2550–2300 Ma and 2300–2200 Ma, respectively. ΣREE and La/Yb)n of the Zhao ’anzhuang Formation volcanic rocks are obviously higher than those of the Tieshanmiao Formation equivalents, suggesting a sedimentary gap (2550 Ma boundary) between these two formations. The Zhao ’anzhuang Formation is older than the Tieshanmiao Formation. The sediments of these two Formations show no obvious differences in REE and are generally characterized by low ΣREE and positive Eu anomalies. On the contrary, the sediments of the Yangshuwan Formation are characterized by high ΣREE and negative Eu anomalies. Detailed discussions demonstrate that the Yangshuwan Formation was deposited in an oxidizing environment whereas the other two formations were formed in a reducing environment. At the end of the evolution of the Tieshanmiao Formation about 2300 Ma ago, the sedimentary environment was transformed from reducing to oxidizing. On the basis of the SHAB (soft/hard acid and base) theory, an oxidation-reduction model for sedimentary REE evolution has been established. It is proposed that the mantle tends to become gradually depleted in REE, especially in LREE, and the indices ΣREE and La/Yb)n of mantle-derived volcanic rocks also tend to become lower and lower.