Journal
LITHOSPHERE
Volume 2, Issue 6, Pages 423-446Publisher
GEOLOGICAL SOC AMER, INC
DOI: 10.1130/L105.1
Keywords
-
Categories
Funding
- National Science Foundation (NSF) [0809226]
- Two Stanford McGee Grants
- Geological Society of America (GSA)
- Burt and DeeDee McMurtry Fellowship
- Directorate For Geosciences
- Division Of Earth Sciences [0809226] Funding Source: National Science Foundation
Ask authors/readers for more resources
Detailed mapping and sensitive high-resolution ion microprobe (SHRIMP) U-Pb geochronology centered around the Nightingale and Sahwave Ranges, similar to 100 km northeast of Reno, Nevada, reveal that most of the Mesozoic basement in this area is composed of predominantly granodiorite-composition plutonic rocks intruded ca. 110-88.5 Ma. These rocks are similar in age, petrology, and composition to the mid-Cretaceous eastern part of the Sierra Nevada Batholith, and are likely related. The youngest plutonic rocks, ca. 93-88.5 Ma, form a large, compositionally zoned intrusive suite, referred to as the Sahwave intrusive suite. This suite is composed of a set of nested, inward-younging intrusions, varying between mafic, equigranular granodiorite around the periphery to more felsic, K-feldspar-megacrystic granodiorite in the center. The Sahwave intrusive suite is coeval with the Cathedral Range intrusive event along the crest of the Sierra Nevada, including the Tuolumne intrusive suite. The geochemistry and petrology of this intrusion also support similar magma genesis and emplacement. Intrusions of the Cathedral Range intrusive event in the Sierra Nevada were emplaced along the margin of North American continental crust, whereas the Sahwave intrusive suite was intruded into a thick package of basinal metasedimentary rocks that were likely underlain by transitional crust. More primitive initial Sr-87/Sr-86 and epsilon(Nd) values (ca. 0.7047 and -0.2, respectively) reflect this difference. In light of this likely fundamental difference in lower-crustal character, other factors, possibly related to subducted, water-rich material, must be responsible for creating similar melting conditions among the series of large intrusions that represent the last magmatic flare-up of the Cretaceous arc.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available