Open AccessLonar Lake: palaeomagnetic evidence of shock origin
Author(s) -
Rao G. V. S. Poornachandra,
Bhalla M. S.
Publication year - 1984
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1984.tb02225.x
Subject(s) - meteorite , geology , impact crater , geophysics , natural remanent magnetization , shock (circulatory) , demagnetizing field , magnetization , magnetic field , astrobiology , physics , medicine , quantum mechanics
Summary Palaeomagnetic and rock magnetic investigations were carried out on oriented rock samples collected from the inner walls of Lonar Lake, which is believed to be a meteorite crater. These studies show systematic variation in some magnetic parameters ( Q n , J n , K and declination) whereas at surrounding localities these parameters show random variation. A soft secondary shock component, acquired in the present field, of D = 9°, I =+47° ( K = 47.6, α 95 = 6.4°) has been successfully isolated by vector difference analysis, whereas the stable primary vector is similar to that of Lower Tertiary period reverse magnetization. NRM and IRM s of the upper and lower flows respond differently to AF demagnetization as a function of their H cr . It is shown that the NRM carried by the lower flows is similar to that of IRM probably reset by the meteorite impact because of their low H cr carriers. It is suggested that such magnetic property variations are characteristic of shock origin and hence we propose an impact origin for Lonar Lake.