| |
 |
UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-24 21:15 |
 |
|
|
|
Conference: Bucharest University Faculty of Physics 2001 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Preliminary rock magnetic properties of the loess-paleosol deposits from Costineoti: paleoclimatic implications.
Authors:
Cristian Panaiotu (1), Cristian Necula (1), Cristina Panaiotu (2)
Affiliation:
(1) University of Bucharest, Faculty of Physics
(2) University of Bucharest, Faculty of Geology and Geophysics
E-mail
Keywords:
Abstract:
We present here a detailed record (247 samples) of mineral magnetic properties of a loess-paleosol profile from Costineoti (Black Sea coast, Romania). There is a strong contrast between the soil and loess magnetic susceptibility as well as between other magnetic parameters (isothermal remanent magnetization, IRM, at 200 mT, anhysteretic remanent magnetization, ARM, at 100 mT, frequency dependent susceptibility, Kd%). Magnetic properties resemble those of similar mid-latitude sections in Europe, Central Asia and China. The Kd% values of up to 11% in the paleosol horizons show the presence of large amount of superparamagnetic (SP) crystals. To remove the effect of concentration, the ARM values were normalized by the IRM value. The relative variation in the content of single domain (SD) and pseudo-single-domain grains (PSD) can be approximated by the normalized values, ARM/IRM. This ratio shows sharp increment in paleosols, confirming that not only SP grains but also SD and PSD grains are relatively enriched in these horizons. Pedogenetic susceptibility in the first and second paleosols suggests paleoprecipitation values for the last two interglacial intervals similar with the present-day annual rainfall. During the formation of the third, forth and fifth paleosols the rainfall value was probably higher with that the present-day value. The rock magnetic parameters point to an important climatic change around 0.3 Ma. The magnetic susceptibility profile compared to the astronomically tuned oxygen isotope record from ODP site 677 suggest a maximum age of the section around 0.6 Ma.
|
|
|
|