The age and origin of the South Mountain Batholith (Nova Scotia, Canada) as constrained by zircon U–Pb geochronology, geochemistry, and O–Hf isotopes

The South Mountain Batholith (SMB; Nova Scotia, Canada) is the largest composite batholith exposed in Appalachians and lies entirely within most outboard Meguma terrane. In situ CA–TIMS U–Pb dating isotopes (Lu–Hf, O) geochemistry for zircon from all phases of SMB constrain its source as well evolution. CA–ID–TIMS yields emplacement (autocryst) ages, indicating a transition granodiorite (378.7 ± 1.2 to 375.4 0.8 Ma) leucogranite (375.4 371.8 over several million years. Furthermore, SHRIMP, LA–MC–ICP–MS, SIMS analyses distinct domains reveal: (1) abundant ancient xenocrysts (∼420 Ma 2.2 Ga); (2) antecryst ages ca. 3–15 years older than emplacement; (3) autocryst δ 18 O values between +7.3‰ +9.1‰ (V-SMOW); (4) similar isotopes, REE signatures, derived fO 2 among antecrysts autocrysts; (5) ε Hf Davis Lake Pluton (DLP) autocrysts that are higher (+1.74 +4.38) rest (−2.99 +1.68). Collectively, these data suggest protracted magmatic evolution with melt generation assembly ∼390 370 via melting metasomatized mantle followed by contamination, first structurally underlying Avalonian terrane later metasedimentary wall rocks southwesterly part (i.e., DLP) represents petrogenetically phase underwent less overall contamination SMB.