Diagenetic sources of stable remanence in remagnetized paleozoic cratonic carbonates: A rock magnetic study

摘要: Hysteresis measurements, Lowrie-Fuller tests, Cisowski and low-temperature demagnetization experiments on samples of the Knox Dolomite, Trenton Limestone, Onondaga Limestone indicate that remanence in these remagnetized carbonate units resides principally single-domain magnetite, contrast to previous interpretations. Volumetrically, however, a significant fraction magnetite is coarser grained, as scanning electron microscopic work magnetic extracts has shown. These conclusions are based mainly characteristic “wasp-waisted” shape hysteresis loops anomalously high ratios remanent coercivity bulk coercivity, both which clearly bimodal distribution coercivities/grain sizes. The magnetization controlled by cubic magnetocrystalline anisotropy, consistent with spheroidal particles commonly observed extracts. trends show especially finest lack anisotropy. In view conclusions, two components natural rocks interpreted (1) late Paleozoic (Kiaman) chemical carried diagenetic (2) Cenozoic thermoviscous overprint residing coarser, pseudosingle domain multidomain also origin.