Volatiles in pillow rim glasses from Loihi and Kilauea volcanoes,Hawaii

Volatiles and major elements in submarine glasses from Loihi seamount and Kilauea volcano. Hawaii were analyzed by high temperature mass spectrometry and the electron microprobe. Loihi glasses are subdivided into three groups: tholeiitic, transitional and alkali basalts. The glasses are evolved: Mg numbers range from 48–58. The alkalic lavas are the most evolved.Total volatiles range from 0.73 to 1.40 wt.%. H₂O shows a positive linear correlation with K₂O content [H₂O = 0.83 (± .09) K₂O + 0.08 (± .06)]. Concentrations of H₂O are higher in the alkalic lavas, but Cl and F abundances are highly variable. Variations in ratios of incompatible elements (K₂O, P₂O₅, H₂O) indicate that each group was derived from a distinct source. CO₂ contents range from 0.05 to 0.19 wt.% but show no systematic correlation with rock type or Mg #. A well-defined decrease in glass CO₂ content with increasing vesicularity is shown by the alkalic lavas. CO₂ may have been outgassed from the tholeiitic and transitional magmas prior to eruption during storage in a shallow magma chamber. Reduced carbon species (CO and CH₄) were found in small amounts in most of the alkalic samples. Although the redox histories of Hawaiian lavas are poorly known, these new data indicate the presence of a reduced source for Loihi magmas.The Kilauea tholeiitic glasses are evolved (Mg # 48.3 to 55) and have higher H₂O contents (av. 0.54 wt.%) than Loihi tholeiites (av. 0.42 wt.%) at the same Mg # (~55). Cl is distinctly lower in Kilauea glasses (0.01 wt.%) compared to Loihi glasses (0.09 wt.%). The data indicate significant source differences for the two volcanoes, consistent with results of other geochemical studies.Loihi tholeiites have distinctly higher ³He/⁴He ratios than Kilauea tholeiites and are the highest measured in submarine basalts (KURZ et al., 1983). These high ratios have been used to invoke a primitive source for Loihi basalts. The high Cl content of these basalts, the highest we have ever measured in submarine basalts, may be a fingerprint of this primitive source, as previously noted for Icelandic basalts (Schillinget al. 1980).     

Analysis of Conceptual Designs for Remedial Measures at Lipari Landfill, New Jersey

During the two-week period from March 12 through March 26, 1982, a preliminary conceptual design analysis on various remedial measures for the Lipari Landfill, New Jersey, was performed. This site is currently ranked at the top of the EPA's Superfund Cleanup List. This report demonstrates the practical benefits and limitations of applying models (both analytical and numerical) to a hazardous waste site in a restricted period of time. The numerical model was used to simulate current flow conditions at the site and provide initial conditions for a series of sensitivity simulations. These sensitivity simulations were designed to test (1) a slurry wall, (2) drain location, (3) drain depth, and (4) a clay cap. Analytical solutions were designed to analyze (1) water in place, (2) flow through an underlying layer, the lower Cohansey, (3) draining the lower Cohansey, (4) flushing the contaminated area using wells, and (5) convective arrival time of contaminants to drains. This analysis quantified discharge to drains, flow rates to a swamp downstream of the landfill, time required to drain the landfill, and contaminant travel times that would result from the implementation of each of the remedial measures that were suggested. The conclusions from this study were used by engineers and planners who incorporated, economics and engineering decisions for the various remedial measures considered.     

Seismicity trends and potential for large earthquakes in the Alaska-Aleutian region

The high likelihood of a gap-filling thrust earthquake in the Alaska subduction zone within this decade is indicated by two independent methods: analysis of historic earthquake recurrence data and time-to-failure analysis applied to recent decades of instrumental data. Recent (May 1993) earthquake activity in the Shumagin Islands gap is consistent with previous projections of increases in seismic release, indicating that this segment, along with the Alaska Peninsula segment, is approaching failure. Based on this pattern of accelerating seismic release, we project the occurrence of one or moreM7.3 earthquakes in the Shumagin-Alaska Peninsula region during 1994–1996. Different segments of the Alaska-Aleutian seismic zone behave differently in the decade or two preceding great earthquakes, some showing acceleration of seismic release (type A zones), while others show deceleration (type D zones). The largest Alaska-Aleutian earthquakes—in 1957, 1964, and 1965—originated in zones that exhibit type D behavior. Type A zones currently showing accelerating release are the Shumagin, Alaska Peninsula, Delarof, and Kommandorski segments. Time-to-failure analysis suggests that the large earthquakes could occur in these latter zones within the next few years.     

Surficial geology of the Chicxulub impact crater,Yucatan, Mexico

The Chicxulub impact crater in northwestern Yucatan, Mexico is the primary candidate for the proposed impact that caused mass extinctions at the end of the Cretaceous Period. The crater is buried by up to a kilometer of Tertiary sediment and the most prominent surface expression is a ring of sink holes, known locally as cenotes, mapped with Landsat imagery. This 165 ± 5 km diameter Cenote Ring demarcates a boundary between unfractured limestones inside the ring, and fractured limestones outside. The boundary forms a barrier to lateral ground water migration, resulting in increased flows, dissolution, and collapse thus forming the cenotes. The subsurface geology indicates that the fracturing that created the Cenote Ring is related to slumping in the rim of the buried crater, differential thicknesses in the rocks overlying the crater, or solution collapse within porous impact deposits. The Cenote Ring provides the most accurate position of the Chicxulub crater's center, and the associated faults, fractures, and stratigraphy indicate that the crater may be 240 km in diameter.     

The locations of newly formed stars in molecular clouds

Observations of very massive stars (M10M ) are suggestive of a star formation process which requires an external trigger. However, observations pertaining to the formation of stars of lower mass (M9M ) require no such triggering mechanism and are consistent with the idea that such stars form as a natural consequence of the evolution, gravitational collapse and fragmentation of a proto-stellar molecular cloud.Paper presented at the Conference on Protostars and Planets, held at the Planetary Science Institute, University of Arizona, Tucson, Arizona, between January 3 and 7, 1978.