The calc-alkaline Great Bear continental arc in the Wopmay Orogen developed after a collision ca. 1890 Ma of the Archean Slave craton with the Paleoproterozoic Hottah terrane to the west. U–Pb zircon dating of three volcanic and six intrusive rocks from the southern part of the arc shows four stages of development: (i) intrusion of a few small sodic leucogranite plutons at 1873 ± 2 Ma into a previously folded metasedimentary sequence; (ii) abundant calc-alkaline felsic volcanism and subvolcanic intrusions during the period 1870–1866 Ma, bracketed by five ages; (iii) intrusion of large calc-alkaline granitic plutons, including the Marian River batholith, dated by zircon and titanite from two samples at 1866 +2–3 Ma; and (iv) emplacement of the potassic Faber Lake rapakivi granite at 1856 +2–3 Ma. The arc was developed on the Hottah terrane due to easterly subduction of an oceanic plate under the amalgamated Slave craton – Hottah terrane. The oldest exposed rocks in the southern part of the arc are remnants of a Paleoproterozoic platformal sequence. They were regarded previously as equivalents of the initial passive margin sequence on the Slave craton, but are interpreted here as part of the Hottah terrane. The ages reported here are comparable with earlier data from the northern part of the arc, which show an age range from 1875 to 1840 Ma and also identify two suites of compositionally and temporally distinct granites. The age constraints show that the Great Bear arc evolved rapidly in time from sodic through calc-alkaline, and then, with a pause, to potassic composition.

The crystallization kinetics in the glass system (100−x)LiBO2−xNb2O5 (5≤x≤20, in molar ratio) prepared via the conventional metal‐plate quenching technique have been studied by isothermal and non‐isothermal methods using differential thermal analyses. X‐ray powder diffraction studies carried out on heat‐treated (500°C) glasses reveal the evolution of lithium niobate crystalline phase along with a minor phase of LiBO2. The exponent n in the Jhonson–Mehl–Avrami (JMA) equation applied to the isothermal process is 2.62, which is in excellent agreement with that obtained under the non‐isothermal process (2.67). The activation energies for crystal growth obtained from JMA equation under isothermal condition, modified Ozawa and Kissinger equations under non‐isothermal conditions, are 293, 311, and 306 kJ/mol, respectively.

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