Calcium carbonate, total and organic carbon and accumulation rate characteristics at DSDP Leg 78A Holes

Bulk sediment accumulation rates and carbonate and carbonate-free accumulation rates corrected for tectonic tilting have been calculated for Leg 78A sediments. These rates are uniformly low, ranging from 0.1 to 6.8 g/(cm**2 x 10**3 yr.), reflecting the pelagic-hemipelagic nature of all the sediments drilled in the northern Lesser Antilles forearc. Rates calculated for Sites 541 and 542 [0.6-6.8 g/(cm**2 x 10**3 yr.)], located on the lower slope of the accretionary prism, are significantly greater than the Neogene rates calculated for oceanic reference Site 543 [0.1-2.4 g/(cm**2 x 10**3)]. This difference could be the result of (1) tectonic thickening of accretionary prism sediments due to folding, small-scale faulting, and layer-parallel shortening; (2) deposition in shallower water farther above the CCD (carbonate compensation depth) resulting in preservation of a greater percentage of calcareous microfossils; or (3) a greater percentage of foraminiferal sediment gravity flows. Terrigenous turbidites are not documented in the Leg 78A area because of (1) great distance from South American sources; (2) damming effects of east-west trending tectonic elements; and (3) location on the Tiburon Rise (Site 543). This lack of terrigenous material, characteristic of intraoceanic convergent margins, suggests that published sedimentation models for active continental convergent margins with abundant terrigenous influxes are not applicable to intraoceanic convergent margin settings.

Description of sediments, epoch, calcium carbonate, orgnic carbon, geolipids and mass accumulation rate at DSDP Holes 92-597A, 92-600 and 92-601B

Low concentrations of organic carbon in slowly accumulating sediments from Sites 597, 600, and 601 reflect a history of low marine productivity in the subtropical South Pacific since late Oligocene times. The distributions of n-alkanes, n-alkanoic acids, and n-alkanols provide evidence of the microbial alteration of sediment organic matter. Landderived hydrocarbons, possibly from eolian transport, dominate n-alkane distributions in these samples.

(Table 1) Magnetozone boundaries, age and sedimentation rate at DSDP Hole 93-605

Natural Remanent Magnetization (NRM) was measured for regularly spaced samples from the 620-m-thick, lower middle Eocene to upper Maestrichtian section of DSDP Site 605. The total NRM of the Eocene chalks was too low (5-50 µA/m) to establish a reliable magnetic polarity stratigraphy. However, the results from the somewhat more clayrich Paleocene-upper Maestrichtian section are useful. A fourfold quality classification of the results of progressive demagnetization studies aided in determining the polarity of the original remanence. Two types (1 and 2a) showed a Characteristic Remanent Magnetization (ChRM) direction with reversed and normal polarity, respectively; the third type (2b) can be interpreted as having a reversed ChRM, which could not be cleaned, whereas the fourth type (3) is considered to be unreliable. The Site 605 magnetic polarity stratigraphy compares well with published sections, adding important detail to the correlation with planktonic microfossil zones and, hence, to the resolution of this portion of the time scale (C24-C32 on the Berggren et al., 1985, scale). The Cretaceous/Tertiary boundary occurs in a reversed polarity zone that has been correlated with Subchron C29r. We suspect the presence of an unconformity at the boundary between lithostratigraphic Units Va and IV a location which is also the level of Reflection Horizon A*.

Examination of DWI conviction rate procedures.

National Highway Traffic Safety Administration, Washington, D.C.

Blink rate as a measure of fatigue: a review.

Federal Aviation Administration, Washington, D.C.

Impact of discontinuing Idaho's periodic motor vehicle inspection program (a before and after outage rate study).

Mode of access: Internet.

Evaluation of Arizona's fatality rate. Final report.

Arizona Department of Transportation, Phoenix

Analysis of insurance premiums and payouts for 1983-1984 designated high theft rate passenger cars. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Effect of rate of change of slip on the peak braking coefficient of passenger car tires. Technical report.

Mode of access: Internet.