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Duncan, Robert A (1991): 40Ar-39Ar plateau and isochron ages from the Ninetyeast and Broken Ridges (Table 1). PANGAEA, https://doi.org/10.1594/PANGAEA.761131, Supplement to: Duncan, RA (1991): Age distribution of volcanism along aseismic ridges in the eastern Indian Ocean. In: Weissel, J; Peirce, J; Taylor, E; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 121, 507-517, https://doi.org/10.2973/odp.proc.sr.121.162.1991

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Abstract:
Concordant plateau and isochron ages are obtained from 40Ar-39Ar incremental heating experiments on volcanic rocks recovered by drilling at three Leg 121 sites along the Ninetyeast Ridge and two dredge locations on the southern scarp of the Broken Ridge, eastern Indian Ocean. The new data confirm a northerly increase in the age of volcanism along the Ninetyeast Ridge, from 38 to 82 Ma; this lineament links current hotspot volcanism near the Kerguelen islands with the Rajmahal flood basalt eruptions at M0 time (117 ± 1 Ma). The Broken Ridge was formed over the same hotspot at 88-89 Ma, but later experienced rift-related volcanism in Paleocene time (63 Ma). The geometry and distribution of ages along these prominent volcanic ridges and the Mascarene-Chagos-Laccadive-Maldive ridge system in the western Indian Ocean are most compatible with plate motions over fixed hotspots near Kerguelen and Reunion islands, respectively.
Project(s):
Coverage:
Median Latitude: -12.997933 * Median Longitude: 88.712933 * South-bound Latitude: -27.355000 * West-bound Longitude: 87.597400 * North-bound Latitude: 5.384200 * East-bound Longitude: 90.361200
Date/Time Start: 1988-05-27T18:45:00 * Date/Time End: 1988-06-24T13:30:00
Minimum Elevation: -2935.0 m * Maximum Elevation: -1524.0 m
Event(s):
121-756D  * Latitude: -27.355000 * Longitude: 87.597400 * Date/Time Start: 1988-05-27T18:45:00 * Date/Time End: 1988-05-29T10:30:00 * Elevation: -1524.0 m * Penetration: 221 m * Recovery: 46.04 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg121 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 11 core; 101.2 m cored; 0 m drilled; 45.5 % recovery
121-757C  * Latitude: -17.023000 * Longitude: 88.180200 * Date/Time Start: 1988-06-04T06:15:00 * Date/Time End: 1988-06-05T18:10:00 * Elevation: -1655.0 m * Penetration: 420.7 m * Recovery: 67.78 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg121 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 11 core; 106.1 m cored; 0 m drilled; 63.9 % recovery
121-758A  * Latitude: 5.384200 * Longitude: 90.361200 * Date/Time Start: 1988-06-15T23:50:00 * Date/Time End: 1988-06-24T13:30:00 * Elevation: -2935.0 m * Penetration: 676.8 m * Recovery: 453.83 m * Location: Indian Ocean * Campaign: Leg121 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 73 cores; 676.8 m cored; 0 m drilled; 67.1 % recovery
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
Event labelEvent
Sample code/labelSample labelDuncan, Robert ADSDP/ODP/IODP sample designation
Age, datedAge datedkaDuncan, Robert Awt by 1/sigma**2
Age, dated standard deviationAge dated std dev±Duncan, Robert Awt by 1/sigma**2
Age, datedAge datedkaDuncan, Robert Awt by % 39Ar
Age, dated standard deviationAge dated std dev±Duncan, Robert Awt by % 39Ar
Argon-3939Ar%Duncan, Robert A
Age, datedAge datedkaDuncan, Robert Aintegrated age
Age, datedAge datedkaDuncan, Robert Aisochron age
10 Age, dated standard deviationAge dated std dev±Duncan, Robert Aisochron age
11 Sample amountN#Duncan, Robert A
12 ParameterParameterDuncan, Robert Agoodness of fit (SUMS)
13 Argon-40/Argon-3640Ar/36ArDuncan, Robert A
14 Argon-40/Argon-36, standard deviation40Ar/36Ar std dev±Duncan, Robert A
Size:
65 data points

Data

Download dataset as tab-delimited text — use the following character encoding:


Event

Sample label

Age dated [ka]
(wt by 1/sigma**2)

Age dated std dev [±]
(wt by 1/sigma**2)

Age dated [ka]
(wt by % 39Ar)

Age dated std dev [±]
(wt by % 39Ar)

39Ar [%]

Age dated [ka]
(integrated age)

Age dated [ka]
(isochron age)
10 
Age dated std dev [±]
(isochron age)
11 
N [#]
12 
Parameter
(goodness of fit (SUMS))
13 
40Ar/36Ar
14 
40Ar/36Ar std dev [±]
121-756D 121-756D-7R-2,144-1494200060041600130065.83240043300150051.8292.72.3
121-756D121-756D-12R-2,98-10244500700438001500100.0438004210070050.1299.93.4
121-757C 121-757C-12R-1,124-128556004005550070057.35780057900160031.5268.215.8
121-758A 121-758A-62R-1,135-138807003500843001250059.476300713007600610.7295.80.3
121-758A121-758A-69R-5,98-10283100390081400760086.87310083400240050.2295.50.3