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The Statistics of Helium Isotopes Along the Global Spreading Ridge System and the Central Limit Theorem
Author(s) -
Anderson Don L.
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl008476
Subject(s) - geology , ridge , flood basalt , mid ocean ridge , seamount , volcano , basalt , standard deviation , plume , oceanic basin , seismology , tectonics , statistics , paleontology , physics , mathematics , meteorology , volcanism
An unbiased estimate of the arithmetic mean of the ³He/ 4 He ratio (R) of basalts from the global spreading ridge system is 9.14 ± 3.59 Ra (n=503), where Ra is the atmospheric ratio and n is the number of data points. The ± two standard deviation (2σ) range covers much of the oceanic island and continental flood basalt data that have been attributed to ‘plume’ or ‘lower mantle’ components. The highest R values along the ridge system are associated with new ridges, backarc basins and near‐ridge seamounts. Low values are associated with long‐lived or abandoned ridges. The median, a more robust measure of the average, is 8.51 Ra.