A wide variety of different rock types were dredged from the Tonga fore arc and trench between 8000 and 3000 m water depths by the 1996 Boomerang voyage. ⁴⁰Ar-³⁹Ar whole rock and U-Pb zircon dating suggest that these fore arc rocks were erupted episodically from the Cretaceous to the Pliocene...
New seafloor mapping and sampling demonstrates that the eruption of the high-Ca boninites is clearly associated with rifting of the northern Tonga ridge and the northern Lau Basin at the northern termination of the Tonga Trench. There is very strong evidence for OIB plume related mantle sources involved in the...
We report new geochemical data for boninites and backarc basin-type basalts recovered from the northern termination of the Tonga trench and Lau Basin. Boninitic pillow lavas, ranging from high-Mg compositions to andesites and dacites, have been erupted within large submarine volcanic edifices (calderas and volcanoes) associated with active rifting of...
The purpose of this study is to explore experiences of professional growth for mid-career community college faculty. The research question that guided the study is: How do community college faculty members experience professional growth at mid- career? The research design included an interpretive social science methodology and phenomenological method. Nine...
Turbulence measurements from the central equatorial Pacific in February 1982 have been analyzed and compared to synoptic CTD and current velocity profiles and current meter data. These suggest considerably more time (if not space) variability than had previously been anticipated. Above 300 m at the equator the turbulence levels were...
Reading through this issue of Oceanography, it will become
apparent that researchers in different disciplines see their
seamounts in quite different ways. The term seamount has been
defined many times (e.g., Menard, 1964; Wessel, 2001; Schmidt and
Schmincke, 2000; Pitcher et al., 2007; International Hydrographic
Organization, 2008; Wessel et al.,...
Western rangelands are currently under severe threat from exotic annual grasses. To successfully manage rangelands that are either infested with or susceptible to exotic annual grasses, we must focus on increasing resilience to disturbance and resistance to exotic annual grass invasion. Here, we present a fuel-based model and research framework...
Crested wheatgrass (Agropyron cristatum [L] Gaertm) has been seeded on more than 5 million hectares in western North America because it establishes more readily than native bunchgrasses. Currently, there is substantial interest in reestablishing native species in sagebrush steppe, but efforts to reintroduce native grasses into crested wheatgrass stands have...
Declining greater sage-grouse populations are causing concern for the future of this species across the western United States. Major
ecosystem issues, including exotic annual grass invasion and conifer encroachment, threaten vast acreages of sagebrush rangeland
and are primary threats to sage-grouse. We discuss types of problems facing sage-grouse habitat and...
We present a new method developed for measuring radiocarbon of methane (¹⁴CH₄) in ancient air samples
extracted from glacial ice and dating 11,000–15,000 calendar years before present. The small size (~20 μg CH₄ carbon), low
CH₄ concentrations ([CH₄], 400–800 parts per billion [ppb]), high carbon monoxide concentrations ([CO]), and low...