We observed cycles presented in a luminescent solar insolation proxy record from a speleothem from Jewel Cave, South Dakota, US. We found cycles of orbital precession with periods of 23 and 19 ka and of obliquity of 41 ka and many others from non-orbital origin in this sample. We determined the Solar origin of the cycles with durations of 11500, 4400, 3950, 2770, 2500, 2090, 1960, 1670, 1460, 1280, 1195, 1145, 1034, 935, 835, 750 and 610 years. It was done by their detection both in proxy records of speleothem luminescence, Δ14C and the intensity of the geomagnetic dipole. It is well known that the main variations in the last two records are produced by the solar wind. The most intensive cycle discovered in this record has duration of 11.5 ka. It is not of orbital origin. It was found previously to be the most intensive cycle in the Δ14C calibration record and has been interpreted to be of terrestrial origin because “it is too strong to be of solar origin”. Our studies suggest that it should be a solar cycle modulating the geomagnetic field and 14C reversed production as the other solar cycles do.
Shopov, Y.; D. Stoykova; L. Tsankov; M. Sanabria; D. Georgieva; D. Ford; and L. Georgiev.
Influence of solar luminosity over geomagnetic and climatic cycles as derived from speleothems.
International Journal of Speleology,
Available at: http://scholarcommons.usf.edu/ijs/vol33/iss1/2