A Paleomagnetic Study of the Blake Event in Chinese Loess-Paleosol Sequences

9903074范德沃布莱克事件是布伦斯时区的一个短暂的反向间歇。它被认为发生在公元前125,000年左右，尽管它的年龄没有得到很好的限制。它可能包括多次逆转(据报道，最多有三个逆转间隔)。PI打算从兰州附近的中国黄土和古土壤中获得多达7个平行记录，此前在兰州附近的几个地方观察到了布莱克事件。目标是(1)限制事件的开始和结束日期，(2)验证事件是否包括多次逆转，以及(3)确定一些黄土-古土壤序列是否在显著延迟的情况下获得了剩余磁化作用。这一延迟时间反过来对修正黄土中较老的反转边界(如松山-布鲁内斯边界)的推断年龄至关重要。在文献中，中国黄土(冷期)记录的古气候阶段与深海层序(暖期)记录的古气候阶段之间存在不匹配。一旦延迟时间(如果有的话)被量化，PI将尝试将这些因素与环境参数相关联，如通过对磁性矿物的岩石磁学研究所揭示的降水、沉积速率或成土程度。这种相关性对于评估磁参数作为古气候指标的使用很重要，特别是对于亚洲和印度季风型的演变。

9903074 Van der VooThe Blake Event is a short-duration reversed interval in the Brunhes Chron. It is thought to have occurred about 125,000 years B.P, although its age is poorly constrained. It possibly included multiple reversals (up to three reversed intervals have been reported). The PI intends to obtain up to seven parallel records from Chinese loesses and paleosols near Lanzhou, where the Blake Event has previously been observed in a few places. The goals are (1) to constrain the beginning and end dates of the Event, (2) to verify whether the Event consists of multiple reversals or not, and (3) to determine whether some of the loess-paleosol sequences acquired their remanent magnetizations with a significant delay. This delay time, in turn, is critical to correct inferred ages for older reversal boundaries in the loess, such as the Matuyama-Brunhes boundary. A mismatch exists in the literature between the paleoclimatic stage in which this reversal is recorded in the Chinese loess (a cold interval) and that recorded in deep-marine sequences (a warm interval). Once delay times (if any) have been quantified, the PI will attempt to correlate these factors with environmental parameters, such as precipitation, sedimentation rates, or degree of pedogenesis, as revealed through rock magnetic studies of the magnetic minerals. This correlation is important to assess the use of magnetic parameters as paleoclimatic proxies, particularly for the evolution of Asian and Indian monsoonal patterns.