pillow lavas are locally conspicuous. A unit consisting of dark, thinly bedded sandstone and siltstone, lccally ranging to several hundred feet thick, is lowermost in the exposed section. The middle division consists of about 3,500 feet of mixed andesi.:e and basalt volcaniclastic rocks ~ lahar, tuff breccia, volcanic sandstone, and conglomeratic beds which rest on relatively thin, fossiliferou...

Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge. Depth horizons with functional...

Basement rocks in the 17,000-square-mile region of southern Oklahoma crop out in the Wichita and Arbuckle Mountains and have been studied in subsurface samples from 175 wells. The rocks are divided into two contrasting provinces, each completely different from the other in age and petrologic character. Each province has played a different role in guiding the stratigraphic and structural evoluti...

Samples of basalt were collected during the Rapid Response cruise to Loihi seamount from a breccia that was probably created by the July to August 1996 Loihi earthquake swarm, the largest swarm ever recorded from a Hawaiian volcano. Po–Pb dating of two fresh lava blocks from this breccia indicates that they were erupted during the first half of 1996, making this the first documented historical ...

A flinty, spherulitic dyke of peralkaiine trachyte in a Precambrian dyke-swarm consists mainly of albite and aegirine. Within this, euhedral crystals of narsarsukite, NadTi,Fe)Si401o(F), occur as short prisms elongate parallel to c. This distinguishes them from all previously described narsarsukites, which have tabular habits. Minor phases present include micas, apatite, quartz, pectolite, nord...

Introduction: In understanding the evolution of the Moon, a number of its fundamental magmatic characteristics must be explained in the context of other geophysical and geological observations. Volcanic activity subsequent to the formation of anorthositic crust was dominated by the eruption of mare basalt. (1) The main phase of mare volcanism began ~500 Myr after the crystallization of the anor...

Introduction: The lunar meteorites Miller Range 05035 (MIL) and Meteorite Hills 01210 (MET) were collected during the 2005 and 2001 ANSMET (Antarctic Meteorite Search) field seasons [1,2]. MET is a 22.8 g regolith breccia composed primarily of basaltic material [3-6]. MIL is a 142.2 g coarse-grained basalt [2]. The bulk composition, mineral assemblage, and texture of MIL is similar to lunar met...

Areas of exposed basalt along mid-ocean ridges and at seafloor outcrops serve as conduits of fluid flux into and out of a subsurface ocean, and microbe-mineral interactions can influence alteration reactions at the rock-water interface. Located on the eastern flank of the East Pacific Rise, Dorado Outcrop is a site of low-temperature (<20°C) hydrothermal venting and represents a new end-member ...

Introduction: Olivine vitrophyres are impact melts, consisting of Lunar highlands and KREEP-rich materials, that are primarily composed of olivines in an opaque glass, sometimes with lath-like plagioclase crystals [e.g. 0-2]. Petrographically, these are similar to vitrophyric Apollo 14 high-Al basalts [11]. The purpose of this study was to use olivine chemistry and petrographic evidence in orde...