Unknown
PANGAEA
In:
Supplement to: McKenzie, Judith A; Palmer, Sarah C; Mueller, Paul A (1990): Strontium isotope stratigraphy of the Pliocene-Pleistocene ''Deep-Sea Type Section'' at ODP Hole 653A. In: Kastens, KA; Mascle, J; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 107, 401-404, https://doi.org/10.2973/odp.proc.sr.107.160.1990
Publication Date:
2024-01-09
Description:
Strontium isotopic determinations were made on samples from the Pliocene-Pleistocene sequence recovered at ODP Hole 653A, the proposed "deep-sea type section" for the Mediterranean region. Biostratigraphic correlations can be combined with the patterns of variations in the 87Sr/86Sr values to delineate the following: (1) the earliest Pliocene (MP11 to basal MP12 zones) is distinguished by fluctuations in the ratio, probably related to the unstable paleoceanographic conditions following the Zanclean flooding and initial in-filling of the Mediterranean after the Messinian desiccation, (2) during most of the Pliocene between approximately 4.5 and 2.4 Ma (MP12 to MP15 zones) the 87Sr/86Sr values remain relatively constant, producing a plateau in the strontium isotope-depth curve for this period, and (3) beginning at approximately 2.4 Ma (across the MP15/MP16 boundary) and continuing into the latest Pleistocene, the 7Sr/86Sr values increase significantly but show fluctuations that have both positive and negative slopes.
The presence of a plateau in the curve generated for the Mediterranean type section duplicates in greater detail the late Neogene results reported by DePaolo (1986, doi:10.1130/0091-7613(1986)14〈103:DROTNS〉2.0.CO;2). The virtual lack of change in the ratio between 4.5 and 2.4 Ma essentially eliminates strontium isotopes as a high-resolution correlation method for this period. The fluctuations in the ratio beginning at 2.4 Ma may be a reflection of major climatic changes occurring in the latest Pliocene-Pleistocene. The relationship between glacial-interglacial cycles and seawater 87Sr/86Sr values suggested by DePaolo (1986) and Capo and DePaolo (1987) is uncertain but should be tested as significant increases and decreases in 87Sr/86Sr of seawater have apparently occurred since 2.4 Ma.
Keywords:
107-653A; 107-653B; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Joides Resolution; Leg107; Mass spectrometer VG Instruments 354 triple collector; Ocean Drilling Program; ODP; Sample code/label; Strontium-87/Strontium-86 ratio; Strontium-87/Strontium-86 ratio, error; Tirreno Sea
Type:
Dataset
Format:
text/tab-separated-values, 90 data points
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