Biostratigraphy and isotope stratigraphy of upper Eocene microtektites at Site 612; how many impacts?

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doi: 10.2307/3514951
Author(s): Miller, Kenneth G.; Berggren, W. A.; Zhang, Jijun; Palmer-Julson, Amanda A.
Author Affiliation(s): Primary:
Rutgers Univ., Dep. Geol. Sci., New Brunswick, NJ, United States
Other:
Woods Hole Oceanogr. Inst., United States
Am. Mus. Nat. Hist., United States
Tex. A&M Univ., United States
Volume Title: Palaios
Source: Palaios, 6(1), p.17-38. Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States. ISSN: 0883-1351
Note: In English. 102 refs.; illus. incl. 3 tables
Summary: In view of recent controversy over the number and timing of late Eocene impact events, we evaluated biostratigraphic correlations at Deep Sea Drilling Project (DSDP)Site 612, New Jersey continental slope. Site 612, Core 21, Section 5 contains a tektite horizon which includes distinct microkrystite and microtektite layers (Glass, 1989). Ranges of magnetostratigraphically calibrated marker taxa firmly constrain the biostratigraphic position of these layers, although planktonic foraminiferal zonal criteria are equivocal for the upper Eocene at Site 612. Radiolarian and foraminiferal biostratigraphy indicate that the tektite layer at Site 612 is biostratigraphically older than a microtektite layer in Barbados which has been correlated with the North American strewn field. The Site 612 tektites are approximately 0.5-1.0 m.y. older than the Barbados microtektites. This conclusion is supported by compositional and isotope differences between the Site 612 tektites and the Barbados microtektites (Koeberl, 1988; Glass, 1989; Stecher et al., 1989), and requires that there were 3 or 4 separate late Eocene impact events. An alternative interpretation correlates the Barbados microtektites with the Site 612 tektites using 40A-39 Ar age measurements and some compositional similarities; this requires that biostratigraphic first and last occurrences were diachronous by ∼0.7 m.y. or extremely high sedimentation rates at Site 612. Strontium and oxygen isotope stratigraphies are consistent with magnetobiostratigraphic correlations. The late Eocene impact events do not correlate with climate changes inferred from the marine isotope record.
Year of Publication: 1991
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 03 Geochronology; 12 Stratigraphy, Historical Geology and Paleoecology; Absolute age; Antilles; Ar/Ar; Atlantic Coastal Plain; Barbados; Biostratigraphy; Caribbean region; Cenozoic; Continental slope; Correlation; DSDP Site 612; Dates; Deep Sea Drilling Project; Eocene; Foraminifera; Geochronology; IPOD; Impacts; Invertebrata; Isotopes; Leg 95; Lesser Antilles; Microfossils; Microtektites; New Jersey; Oceanography; Paleogene; Protista; Review; Stable isotopes; Tektites; Tertiary; United States; Upper Eocene; West Indies
Coordinates: N384912 N384913 W0724625 W0724626
Record ID: 1991038264
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States