Lithium deposits in the Central Asian Metallogenic Domain: Metallogenic regularity and model

A series of lithium deposits occur in the Central Asian Metallogenic Domain ( CAMD). These lithium deposits are mainly located in the orogenic belts in the southern Siberian Craton, and their formation has multiple stages, including the Precambrian (1. 85 similar to 1. 83Ga), Late Cambrian -Early Ordovician (494 similar to 483Ma), Early Permian (294 similar to 272Ma), Late Triassic -Early Cretaceous (220 similar to 180Ma) and Cretaceous (139 similar to 121Ma). The main types of lithium deposits are pegmatite- and granite -type. On the basis of the metallogenic tectonic backgrounds and rare -metal mineralization characteristics, the CAMD can be subdivided into 2 provinces and 7 metallogenic belts according to the tectonic line coundaries: (1) The Altay-Eastern Sayan metallogenic province is located in the western part of the CAMD, which includes three lithium metallogenic belts: the Altay, the Sangilen Highlands and the Eastern Sayan. It is mainly composed of pegmatite -type Li deposits, with mineralization concentrated in first four peak periods. The formation of Li deposits is related to the Siberian Craton and the Paleo-Asian Ocean tectonic systems. ( 2) The Mongolian -Okhotsk metallogenic province is located in the eastern part of the CAMD, which includes the Eastern Transbaikalia Li metallogenic belt as well as the Gobi Ugtaal-Baruun Urt and Daxing'an Mountains Li prospective belts. It is mainly composed of Cretaceous (139 121Ma) granite -type Li deposits. The formation of these Li deposits is mainly related to the Mongolian -Okhotsk tectonic system. In addition, there is a prospective belt in the Eastern Tianshan Mountains of China in which the Late Triassic pegmatite -type Li deposits occurred. The formation of the deposit is related to the collision between the Kazakhstan -Junggar and Tarim plates. The rare -metal granites and most rare -metal pegmatites in the CAMD are the products of the high differentiation of granitic magma which is triggered by the thermal driven. The magmtic temperature is relatively low ( 650 C), and its pressure change is significant ( 500 similar to 170MPa). The mechanism of Li enrichment mainly includes magmatic crystallization differentiation and fluid immiscibility. This study proposes a metallogenic model of "crustal melting -> deep granite pluton -> shallow rare metal granite apophyse-pegmatite vein" for the pegmatite type Li deposit in the Altai belt and a "crustal melting >deep granite pluton*shallow granite -rare metal granite stock" model for the granite -type Li deposit in the Eastern Transbaikalia belt.