New insights into the magnetic characteristics of high mountain loess in Central Asia and its paleoclimatic implications

摘要

The previous studies applied "wind intensity" model to explain the corresponding variations of magnetic susceptibility and particle size curves in Tienshan Mountain loess. Most of these studies focused on low altitude loess, due to their high deposit rate, and ignored the high-altitude loess. In this study, we investigated characteristics of lithological and pedogenic magnetic particles to systemically understand their paleoclimatic implications. The result suggested high mountain loess in Tienshan region exhibits that, not only lithologic magnetic particles, but also pedogenic present the variable contents. The magnetic susceptibility has a complex implication. In contrast, the fine-grained magnetite exhibits a close link with pedogenesis. Therefore, the relative parameters can be used to recover moisture variation. The evidences from particle size and their dependence of magnetic susceptibility suggested particle-size effect on lithological magnetic susceptibility is weak. The "wind intensity" model can be an important factor for variations of lithologic magnetic susceptibility of Tienshan Mountain loess rather than a dominant factor. It still needs more study to determine the implication of magnetic susceptibility of lithologic materials.