Assessing thermal effects on magnetic fabrics of sedimentary rocks: Results from synthetic and natural samples

作者：Li YX^*; Kodama KP

来源：Geophysical Research Letters, 2005, 32(4): L04314.

DOI：10.1029/2004GL022049

In order to examine thermal effects on magnetic fabrics, particularly remanence fabrics that test the accuracy of paleomagnetic records, the pre- and post- heating magnetic fabrics of synthetic(magnetite+CaF2) and natural samples were compared. The natural samples were collected from a thermally remagnetized, baked zone of the Triassic Passaic Fm. in southeastern Pennsylvania, USA and their magnetic fabrics were compared with those from the unremagnetized Passaic country rocks. The unheated synthetic and natural samples display predominantly oblate magnetic susceptibility and remanence fabrics. The heated synthetic samples yield oblate AMS and AAR fabrics; whereas the remagnetized Passaic rocks show random AMS fabrics, but exhibit depositional remanence fabrics. Apparently, natural samples we studied lost their initial AMS fabrics but inherited their initial depositional remanence fabrics during thermal remagnetization. Thus, the presence of oblate fabrics may not uniquely indicate a primary remanence. The disagreement between AMS and AAR fabrics could indicate a possible remagnetization.

• 出版日期2005-2-25