The paper considers the structure of the Burakovskii-Aganozero layered complex, which was formed at 2449 Ma. Petrographic and geochemical characteristics of rocks making up the layered series of the Aganozero and Shalozero blocks were studied in detail. New isotopic and geochemical data are presented and previous results on isotopic characteristics are generalized. It was concluded that the Burakovskii-Aganozero layered intrusion was a polyphase complex. The main phases correspond to the emplacement of "Aganozero" (εNd = -0-4 to +0.9 and 87Sr/86Sr(T) = 0.7021-0.7035) and "Shalozero" (εNd = -3.31 and 87Sr/86Sr(T) = 0.7020) magmas, which formed the intrusion. There is evidence for the presence of other small-volume intrusion phases. The Aganozero and Burakovskii-Shalozero blocks are two subchambers. According to geophysical data, each of them has its magma conduit. The Aganozero portion of the layered complex was formed earlier as the first intrusion phase. The Aganozero magma of this phase differed from the magma of the second intrusion phase, which produced the Burakovskii-Shalozero portion of the layered complex, both in isotopic characteristics and chemical composition (lower silica and iron contents). This is suggested by the petrography of the layered series rocks, compositions of rock-forming minerals, and geochemical characteristics of rocks composing blocks of the layered complex. This allows us to suppose that the initial magmas of these blocks were genetically different and represented successive intrusions of evolving magmas from a single magma chamber or from two independent chambers. Our data provide a new insight into the problem of ore potential of the layered complex, in particular, its platinum-bearing capacity (Korneev et al., 1999a, 1999b).
|Number of pages||22|
|State||Published - 1 Nov 2000|
Scopus subject areas
- Geochemistry and Petrology