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On the relation between P-wave travel time residuals and the age of continental plates

1979; Elsevier BV; Volume: 43; Issue: 1 Linguagem: Inglês

10.1016/0012-821x(79)90163-8

1385-013X

G. Poupinet,

Geological and Geochemical Analysis

A new set of P-station anomalies has been computed for 583 seismological observatories which sent their arrival times to the International Seismological Centre between 1964 and 1974. These P-residuals are used as a marker of the variations of the properties of the uppermost mantle. Important changes of P-residuals are observed within continents and particularly within Precambrian shields. It is shown that residuals tend to increase outwards from the centers of the North American and Scandinavian shields. As a first approximation, the P-residuals are a linear function of the root square of the age of the basement inside stable continental plates. For these stable plates, a P-residual is an indirect measurement of lithospheric thickness. The lithospheric thickness Z (in km) is related to its age t (in 109 years) by:z≃10+140t We then speculate on a possible use of P-residuals in the search of Archean nuclei inside Precambrian shields. Tiksi, in northern Siberia, is the "fastest" station on continents and could be the location of a very old continental nucleus.