Tektite-bearing sediment was recovered from the New Jersey continental slope (1123 m water depth) by the Ocean Drilling Program (ODP) at Site 904. The biostratigraphy, mineralogy, and geochemistry of Site 904 tektites and enclosing sediment permit us to interpret their source and the sequence of events that led to their deposition.
  The tektites of Site 904 occur within upper Eocene (Zones P15, NP19/20) biosiliceous chalks. The tektites are concentrated in three well-defined laminae that occur in a 5-cm-thick section (Interval 150-904A-45X-2, 84.5-89.5 cm). Tektites are abundant between the laminae and occur sporadically, above and below the layers, through a 24-cm-thick section (Interval 150-904A-45X-2, 79-103 cm). Small-sized tektites (<63 µm) occur rarely above the 24-cm-thick interval for another 19 cm (Interval 150-904A-45X-2, 60-79 cm). Grain-size distribution indicates that the tektites and associated detrital minerals fine upward. The coarse-grained fractions occur in the bottom and middle laminae and the fine-grained fractions are concentrated in the upper lamina. Because benthic foraminifer assemblages are bathyal, turbidity currents originating in shallow water could not have deposited the tektites and detrital minerals. The abundance of planktonic versus benthic foraminifers also argues against displacement of sediment from shallow water.
  Site 904 tektites, as at Deep Sea Drilling Project (DSDP) Site 612, are associated with shock metamorphosed minerals and are considered to be an impact ejecta. Gravity settling of the ejecta through the air and the water column is the proposed depositional process. The structures and deformation features contained in the sediment that yielded the tektites indicate that deposition of the ejecta on the New Jersey continental slope was influenced by mass-wasting and gravity-flow processes. These processes are interpreted to have occurred as a result of disturbances to the seafloor and water column by tsunami and possibly shock-generated waves. Biostratigraphic and major oxide analyses correlate the upper Eocene tektites of Site 904 to those of Site 612, to the Exmore breccia at Exmore, Virginia, and to the North American strewn field. The range in the major oxide composition suggest that the tektites originated from a single but heterogeneous source.

Date of initial receipt: 2 March 1995
Date of acceptance: 10 November 1995

Return to Contents of Leg 150
Return to Contents of Scientific Results