Book Chapters

No abstract available.

No abstract available.

The Devonian batholiths of western Tasmania represent a diverse assemblage of highly fractionated intrusions (70 to 77 percent SiO2) that are the products of different source materials. The Housetop batholith exhibits compositional affinities to a fluorine-rich I-type magma. The Meredith batholith also has characteristics indicative of I-type source materials. The Heemskirk batholith is composite,

Upper Paleozoic rocks of the northern Sierra and eastern Klamath terranes provide detailed stratigraphic records of ensimatic arc-related sedimentation and magmatism. Comparison of Paleozoic stratigraphic relations between the two terranes, however, suggests certain contrasts in depositional environments and the nature, volume, and timing of volcanism for given time intervals. Some lithologic and

No abstract available.

The upper Paleozoic Havallah sequence of central Nevada is a folded and thrust-faulted association of greenstone, siliceous marine sedimentary rocks, and deep-water clastic rocks. Microfossil assemblages (radiolarians, sponge spicules, and conodonts) are used as tools to unravel the stratigraphy and to interpret the paleoenvironments of the siliceous sedimentary rocks. Nine radiolarian assemblages

Biostratigraphic data, based mostly on radiolarian assemblages, establish synchronous deposition in the northern Sierra terrane and the Havallah basin beginning in the Late Devonian and extending into the early Late Permian. Lower Mississippian and mid-Permian arc-derived volcaniclastic debris was deposited in parts of the Havallah basin during episodes of arc volcanism in the northern Sierra terr

No abstract available.

Understanding of the crust has improved dramatically following the application of seismic reflection and refraction techniques to studies of the deep crust. This is particularly true in areas where the last tectonic event was extensional, such as the Basin and Range province of the western United States and much of western Europe. In these regions, a characteristic reflective pattern has emerged,

The Eastern Klamath and Northern Sierra terranes of northern California consist of Devonian to Jurassic arc-related rocks that structurally and/or stratigraphically overlie Devonian(?) or older complexes that consist of quartzite, quartzofeldspathic sandstone, chert, and mafic and ultramafic rocks. These terranes lie within a regional belt of Paleozoic arc-related rocks that can be recognized from

Approximately 90 Earth-crossing asteroids had been discovered through September 1989. Discovery is thought to be complete at absolute V magnitude (H) = 13.2 (the magnitude of the brightest known object, diameter ∼8.1 km), and about 6 percent complete at H = 17.7 (typical diameter about 1 km). The calculated mean probability of collision of Earth-crossing asteroids with Earth is (4.2 ± 1.7) × 10−9 

Middle Jurassic marine conglomeratic and debris-flow deposits in the Mt. Tallac roof pendant are interpreted to be syntectonic fault trough deposits. Similar deposits in similar stratigraphic successions throughout the northern Sierra Nevada demonstrate that the Middle Jurassic continental-margin arc north of latitude 39° was essentially marine, and possibly extensional or transtensional in nature