Mitchell, John G; Terrell, David J (1985): (Table 1) Downhole variation of potassium, apparent K-Ar age, and inert gas abundances at DSDP Holes 69-504B, 70-504B and 83-504B [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.805064, Supplement to: Mitchell, JG; Terrell, DJ (1985): Downhole variation of potassium, inert gas abundance, and apparent K-Ar age in basalts from the Costa Rica Rift, Hole 504B, Leg 83, Deep Sea Drilling Project. In: Anderson, RN; Honnorez, J; Becker, K; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 83, 305-312, https://doi.org/10.2973/dsdp.proc.83.114.1985
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Abstract:
Ne, Ar, Kr, Xe, and K2O were measured in representative samples of holocrystalline basalt from DSDP Hole 504B. No hiatus in inert gas abundance is recognized at the base of the "oxic" alteration zone and the extent rather than the nature of alteration appears to determine these abundances. When the inert gas abundances are separately plotted against K2O, two distinct trends of loss emerge, one for alteration involving K-gain, the other for K-loss.
Apparent whole-rock K-Ar ages are anomalous in the upper 50 m of basement, and below 300 m sub-basement. In the intervening zone of basement, celadonization adds sufficient potassium and eliminates enough "primary" 40Ar early in the history of the basalts for "excess" 40Ar to become subordinate to radiogenic 40Ar in basalts showing potassium enrichment greater than 0.2%. Stratigraphically correct K-Ar ages are obtained, therefore, from K-enriched basalts of the oxic alteration zone.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Median Latitude: 1.227133 * Median Longitude: -83.730133 * South-bound Latitude: 1.227000 * West-bound Longitude: -83.730200 * North-bound Latitude: 1.227200 * East-bound Longitude: -83.730000
Date/Time Start: 1979-10-07T00:00:00 * Date/Time End: 1982-01-02T00:00:00
Minimum DEPTH, sediment/rock: 11 m * Maximum DEPTH, sediment/rock: 1054 m
Event(s):
69-504B * Latitude: 1.227200 * Longitude: -83.730200 * Date/Time: 1979-10-07T00:00:00 * Elevation: -3460.0 m * Penetration: 489 m * Recovery: 262 m * Campaign: Leg69 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL)
70-504B * Latitude: 1.227000 * Longitude: -83.730000 * Date/Time: 1979-12-04T00:00:00 * Elevation: -3460.0 m * Penetration: 836.1 m * Recovery: 91.6 m * Campaign: Leg70 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 40 cores; 328.6 m cored; 18.5 m drilled; 27.9 % recovery
83-504B * Latitude: 1.227200 * Longitude: -83.730200 * Date/Time Start: 1981-11-22T00:00:00 * Date/Time End: 1982-01-02T00:00:00 * Elevation: -3460.0 m * Penetration: 1350 m * Recovery: 107.7 m * Campaign: Leg83 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: Leg 83 of DSDP was devoted entirely to coring and experiments in Hole 504B, the deepest borehole to date into the oceanic crust. Hole 504B now extends over a kilometer into basement, nearly twice as far as any other DSDP hole, and it is the only DSDP hole to have clearly penetrated into the intrusive sheeted dikes that underlie the extrusive pillow lavas of the upper oceanic crust. At Hole 504B, Leg 83 continued an ongoing DSDP effort that began during Legs 68, 69, and 70 in 1979, and also included part of Leg 92 in 1983. 71 cores; 514 m cored; 0 m drilled; 21 % recovery
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | ||||
| 2 | Sample code/label | Sample label | Mitchell, John G | DSDP/ODP/IODP sample designation | ||
| 3 | DEPTH, sediment/rock | Depth sed | m | Geocode – mbsf | ||
| 4 | Potassium oxide | K2O | % | Mitchell, John G | ||
| 5 | Argon-40 | 40Ar | 10-7 cm3/g | Mitchell, John G | Mass spectrometry | Apparent radiogenic |
| 6 | Age, dated | Age dated | ka | Mitchell, John G | Age, 40K/40Ar Potassium-Argon | Apparent K-Ar age calculated assuming an atmospheric nonradiogenic 40Ar/36Ar ratio and decay constants of Steiger and Jäger (1977; doi:10.1016/0012-821X(77)90060-7) |
| 7 | Age, dated standard deviation | Age dated std dev | ± | Mitchell, John G | ||
| 8 | Neon-20 | 20Ne | 10-10 cm3/g | Mitchell, John G | Mass spectrometry | |
| 9 | Argon-36 | 36Ar | 10-9 cm3/g | Mitchell, John G | Mass spectrometry | |
| 10 | Argon-40 | 40Ar | 10-7 cm3/g | Mitchell, John G | Mass spectrometry | Nonradiogenic 40Ar calculated as 40Ar_total - K2O x (2 *10**-7) |
| 11 | Krypton-84 | 84Kr | 10-14 cm3/g | Mitchell, John G | Mass spectrometry | |
| 12 | Xenon-132 | 132Xe | 10-12 cm3/g | Mitchell, John G | Mass spectrometry | #0 = BDL |
| 13 | Sulfur, total | TS | mg/kg | Mitchell, John G | Sulfur data from Hubberten et al., 1983. # indicates - data are from core sections adjacent to one analyzed here |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
236 data points