Baladek terrane 

(cratonal) 

(Northern part of Russian Southeast)

Consists chiefly of a crystalline basement complex and younger stratified units. Basement complex consists 
of anorthosite, gabbro-anorthosite, gabbro, gabbro-norite and pyroxenite (Malotokhikansk and 
Tokhikansk complexes). Anorthosite intruded by granite and granodiorite with preliminary U-Pb 
ages ranging between 2.2 and 2.6 Ga and K-Ar ages ranging between 964 and 365 Ma. 
Unconformably overlying stratified units are: (1) Lower Cambrian red conglomerate, sandstone, 
siltstone, basalt, and limestone (Shevlinsk and Usttimptonsk suites); (2) Upper Cambrian 
limestone, sandstone and siltstone; (3) thick units of sandstone, siltstone, conglomerate, limestone, 
and marl that contain Early Ordovician algae and yield K-Ar glauconite ages of 491 and 495 Ma.; 
(4) Mississippian sandstone; and (5) Triassic and Early to Middle Jurassic marine clastic rocks 
that are unconformably overlie older rocks and are interpreted as a forearc basin of the Uda 
volcanic-plutonic belt (Mongol-Okhotsk active continental margin) which occurs along the 
Stanovoy block of the North Asian craton. Unconformably overlapped by Late Jurassic marine 
clastic deposits and Early Cretaceous nonmarine clastic deposits (Uda-Zeya sedimentary basin) 
that links the Baladek terrane and the Siberian Platform. Early Cambrian archaeocyatheans of 
terrane are similar to those of Siberian Platform and differ from archaeocyatheans in limestone 
olistoliths in nearby Galam terrane. Baladek terrane bounded to south by Uligdansk dextral-slip 
fault and is interpreted as a fragment of the Siberian Platform. REFERENCES: Kirillova and 
Turbin, 1979; Karsakov and others, 1987; Belyayeva, 1988.