By Sergey M. Rodionov1, Alexander A. Obolenskiy2

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Uchur Metallogenic Belt of

Phlogopite Skarn Deposits

(Belt UH) (Russia, Aldan-Stanovoy Shield)

This Paleoproterozoic metallogenic belt is hosted in the Uchur granulite-paragneiss terrane in the northeastern Timpton-Uchur granulite-paragneiss terrane in the East Aldan superterrane. The age of the belt is interpreted as Paleoproterozoic (about 2000 Ma). Phlogopite skarn, and W and Mo skarn deposits and occurrences extend over a 50 by 70 km area and are hosted in diopside gneiss, marble, with ages of 2.3 to 2.1 Ga. Deposits occur in diopside and phlogopite-diopside schist, marble, and calciphyre that are metasomatized into coarse-grained phlogopite-diopside skarn. Some deposits are controlled by synforms and fold hinges, and cores of superposed transverse folds that were favorable for phlogopite. Deposits consist of phlogopite, diopside, hornblende, scapolite, apatite, and actinolite. Phlogopite generally occurs in masses and rarely as thin veins. Almost all phlogopite deposits are associated diopside-magnetite metasomatite. The major deposit is at Megyuskan.

Megyuskan Phlogopite Skarn Deposit

This deposit (Biryul’kin and others, 1990) consists of phlogopite skarn that occurs on the limbs of the Bas-Muguskan synform. The skarn forms lenticular bodies that are concordant with the host phlogopite-diopside and scapolite-diopside metasomatite. Several deposits vary from 4 to 12 m thick and extend up to 250 m length. Phlogopite forms veins and nests, and the size of phlogopite crystals is 30 to 40 cm. Most common defects are undulation, cracks, and intergrowths The phlogopite is low Fe with a light color. The deposit is large with resources of 7.5 thousand tonnes phlogopite with average content of 46 to 79 kg/m³ phlogopite.

Origin and Tectonic Controls for

Uchur Metallogenic Belt

The belt is interpreted as forming during a late-stage or post-collisional tectonic event as a result of collision between the Central Aldan and East Aldan superterranes. The reason for the collision is unclear.

REFERENCES: Parfenov and others, 1999, 2001.

Kavakta Metallogenic Belt of

Magmatic and Metasomatic Apatite(?)

(Belt KV) (Russia, Aldan-Stanovoy Shield)

This Paleoproterozoic(?) metallogenic belt occurs in the Amga tectonic melange zone. The belt extends latitudinally for 25 km and is 25 km wide. The belt contains apatite-Ti magnetite deposits that are hosted in Paleoproterozoic zoned mafic and ultramafic plutons. The age of the belt is interpreted as Paleoproterozoic. The major deposit is at Kavakta.

Kavakta Mafic-Ultramafic Related Ti-Fe (V) Deposit

This deposit (Stogniy and others, 1992) consists of apatite and Ti-magnetite hosted in the central part of a pluton with a core of dunite, peridotite, troctolite, and anorthosite, and a margin of of norite, magnetite-bearing gabbro and norite, and gabbro. The ultramafic rock contains sulphides, including pyrite, chalcopyrite, pyrrhotine, minor pentlandite, and rare mackinawite, cubanite, valleriite, violarite, and bornite. The pluton intrudes biotite and amphibole-biotite gneiss with bands and lenses of amphibolite. The host rocks are metamorphosed to amphibolite facies. The pluton contains two deposits. The first apatite and Ti magnetite body occurs in the northeastern part of the pluton and is 4.5 km long and about 1.5 km wide. The other deposit occurs in the western and southwestern parts of the pluton and is 0.5 to 10 km wide and extends for 5.25 km. The deposit is large with reserves of apatite & Ti magnetite ores are 5 billion tonnes grading 15% Fe, 3.6% TiO₂, 2.3% P₂O₅ , 0.06% V₂O₅.

Origin and Tectonic Controls for

Kavakta Metalogenic Belt

The belt is interpreted forming during rifting related to break up of a hypothetical Late Archean continent at 2.5 to 2.3 Ga.

REFERENCES: Stogniy and others, 1992; Kislyi and Utrobin, 1994; Parfenov and others, 1999, 2001.

Baladek Metallogenic Belt of

Anorthosite Apatite-Ti-Fe-P Deposits

(Belt Bal) (Russia, Far East)

This early Paleoproterozoic metallogenic belt is hosted in Baladek cratonal terrane that consists chiefly of a crystalline basement complex and younger stratified units. The basement complex consists of anorthosite, gabbro and anorthosite, gabbro, gabbro and norite and pyroxenite. The anorthosite is intruded by granite and granodiorite. U-Pb isotopic age for igneous host rocks is about 1,700 Ma. Ti-P occurrences are related to anorthosite intrusions. No economic deposits are known. The major deposits are at Bogidenskoe and Gayumskoe.

Bogidenskoe Anorthosite Apatite Ti-P Deposit

This deposit (Panskikh and Gavrilov, 1984; Neimark and others, 1992) consists of densely disseminated, massive lenticular, and sheeted bodies that occur in strongly stratified, rhythmic layers in olivine gabbro, syenite, syenite, anorthosite, norite, and pyroxenite. The sheeted deposits extend over 10 km along strike. Ore minerals are alternating massive, spotted, and disseminated apatite-ilmenite, Ti-magnetite, and ilmenite. Apatite contains up to 2.4% F. Ti magnetite contains up to 21% TiO₂ and from 0.3 to 1.1% V₂O₅. Ilmenite contains up to 3.1% Fe₂O₃. U-Pb isotopic age for igneous host rocks is 1,700 Ma. Deposit occurs in the upper basins of the Bogide and Soroga Rivers. The deposit is large with apatite grade of 3 to 15% and average of 5.7% P₂O₅. Deposit contains an estimated 34.3 million tonnes P₂O₅and extends to depth of 400 m.

Gayumskoe Anorthosite Apatite Ti-P Deposit

This deposit (Panskikh and Gavrilov, 1984; Neimark and others, 1992) consists of a group of closely-spaced, veined and stock-like bodies (nelsonite) of apatite, ilmenite, titanomagnetite in anorthosite that occurs in lenticular and irregular bodies of olivine gabbro, gabbro and pyroxenite, pyroxenite, and dunite. Apatite is a hydroxyl-F-bearing variety and contains up to 2.75% H₂O. Titanomagnetite contains from 3.8 to 21% TiO₂. Ilmenite is fairly oxidized and contains up to 2.5% Fe₂O₃. U-Pb isotopic age for igneous host rocks is 1,700 Ma. Deposit occurs in the upper reaches of the Gayum River. The deposit is large, average grade is 8.7% P₂O₅, locally up to 31.6% P₂O₅, and contains an estimated 40 million tonnes P₂O₅.

Maimakanskoe Anorthosite Apatite Ti-P Deposit

This deposit (Panskikh and Gavrilov, 1984; Neimark and others, 1992) consists of sparsely to densely disseminated, sheeted and lenticular, apatite-ilmenite-Ti magnetite deposits in olivine gabbro, gabbro and norite, gabbro and pyroxenite, and pyroxenite. Ore minerals are massive apatite, apatite-ilmenite, ilmenite, and apatite-ilmenite-Ti magnetite in steeply dipping (50 to 60°) in nelsonite veins that are hosted in coarse-grained anorthosite. The main ore minerals are apatite, ilmenite, and Ti magnetite and comprise up to 80% the deposit. Apatite contains F. Ti magnetite averages 13.6% TiO₂ and 0.37% V₂O₅. Ilmenite contains 6 to 7% Fe₂O₃. Apatite content ranges up to 50 to 60% in masses, but averages 15 to 20%. U-Pb isotopic age for igneous host rocks is 1,700 Ma. Deposit occurs in the upper reaches of the Maimakan River near Kendeke Spring, and occurs over an area of approximately 30 km². The deposit is large, contains an estimated 63 million tons P₂O₅, and extends to 400 m depth.

Dzhaninskoe Anorthosite Apatite Ti-P Deposit

This deposit (Panskikh and Gavrilov, 1984; Neimark and others, 1992) consists of sparsely disseminated apatite, ilmenite, and Ti magnetite in melanocratic olivine gabbro and pyroxenite that form stock-like bodies in anorthosite. Apatite contains up to 1.14% F. Ti magnetite contains up to 10.7% TiO₂ and 0.28% V₂O₅. Ilmenite contains 7.8% Fe₂O₃. U-Pb isotopic age for igneous host rocks is 1,700 Ma. Deposit occurs on the right bank of the Dzhana River near the mouth of the Kurung River. The deposit is large, has a low grade of up to 4% P₂O₅, contain an estimated 78 million tons P₂O₅, and extends to a depth of 400 m.

Origin and Tectonic Controls for

Baladek Metallogenic belt

Anorthosite hosting the belt is interpreted as forming during interplate magmatism.

REFERENCES: Panskikh and Gavrilov, 1984; Neimark and others, 1992; Nokleberg and others, 1998, 1999, 2000, 2003; S.M. Rodionov, this study.

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