Rapid pluton emplacement via multiple discrete pulses, Lamarck Granodiorite, central Sierra Nevada batholith, California

New U-Pb geochronology and mapping indicate that emplacement of the Lamarck Granodiorite of the John Muir Intrusive Suite, Sierra Nevada batholith, California was punctuated by two intervals of high magma flux approx. 2 m.y. apart. Existing geochronology indicates that a significant volume of the Lamarck intruded at 92 Ma, yet nearly indistinguishable zircon ages from four mappable pulses within the Dusy Basin area define an earlier episode of rapid intrusion around 94 Ma. Preservation of steeply dipping internal contacts at both map and outcrop scales requires that the earlier flux of magmatism included multiple discrete pulses. A new zircon age of 95.4 +/- 0.3 Ma, along with textural and structural similarities, suggests that the Inconsolable Monzodiorite represents the oldest and most mafic member of the Muir suite. As a whole, the Muir suite was intruded episodically between 95 and 88 Ma.