Keuper magnetostratigraphy in the southern Mesozoic margin of the Holy Cross Mts. (southeastern edge of the German Basin)

Abstract

Magnetostratigraphy of the Keuper suc ces sion in the south ern Me so zoic mar gin of the Holy Cross Moun tains is pre sented based on in ves ti ga tions of two sec tions of Brzeziny and Wolica. They cut an ~60 m thick suc ces sion of var ie gated siltstones and claystones, which over lies the Reed Sand stone (Stuttgart For ma tion). The suc ces sion has been cor re lated with the Patoka Mem ber of the Grabowa For ma tion, de fined in the Up per Silesia re gion as an equiv a lent of the Steinmergelkeuper (Arnstadt For ma tion). The pri mary Late Tri as sic mag ne ti za tion was ob tained from com po nent B car ried by fine-grained haematite. Twelve mag netic po lar ity zones, six of nor mal and six of re versed po lar ity, have been de fined. The ob tained polar ity pat tern cor re sponds to the Norian (E13-E16 New ark zones) ac cord ing to the Long-Rhaetian op tion of the Late Tri as sic Mag netic Po lar ity Time Scale. The mean nor mal po lar ity char ac ter is tic di rec tion (N = 24, D/I = 31/62, k = 28.24, a95 = 6.04) dif fers sig nif i cantly from the re versed one (N = 18, D/I = 223/-25, k = 16.38, a95 = 8.65): the pri mary mag netic sig nal is partly over lapped by com po nent A car ried by mag ne tite of re cent viscuous remanent mag ne ti za tion. Some sam ples do con tain also coarse-grained haematite that, how ever, does not form any clus tered mag ne ti za tion. The palaeopole po si tion cal culated from the trans posed re versed and nor mal po lar ity di rec tions of com po nent B cor re sponds to the Late Tri as sic (Norian) seg ment of the ref er ence Baltica/Eu rope Ap par ent Po lar Wan der Path.