A short, reverse polarity interval within the Jaramillo subchron: Evidence from the Jingbian section, northern Chinese Loess Plateau
A short, reverse polarity interval within the Jaramillo subchron: Evidence from the Jingbian section, northern Chinese Loess Plateau
复制标题
DOI：
10.1029/2001jb000706
复制
发表时间：
2002-06
影响因子：
--
通讯作者：
B. Guo;R. Zhu;F. Florindo;Z. Ding;Jimin Sun
中科院分区：
文献类型：
--
作者：
B. Guo;R. Zhu;F. Florindo;Z. Ding;Jimin Sun
对中国黄土高原北端靖边地区（37.4°N, 108.8°E）的黄土-古土壤序列进行了高分辨率的古地磁和岩石磁学研究，并结合扫描电镜、x射线衍射和各向异性磁化率分析。结果表明，磁性组合以伪单畴磁铁矿为主，伴生磁铁矿和高矫顽力相（可能为赤铁矿）。对brunes - matuyama和上Jaramillo的转变进行了仔细的记录，并获得了一个短的反极性间隔（SRI）的记录，该记录完全在Jaramillo正极性亚时内。在48厘米的地层间隔上记录的SRI持续时间为10.1 kyr（如果包括极性转变，则为29 kyr）。这些结果似乎排除了岩石磁性变化对记录过程的不利影响，并迫使我们重新考虑Jaramillo亚时线，其特征是一对正常极性间隔被一个短的反向极性间隔所打断。
[1] A high-resolution paleomagnetic and rock magnetic investigation supported by scanning electron microscopy observations, X-ray diffraction determinations, and anisotropy of magnetic susceptibility analyses has been carried out on a loess-paleosol sequence from Jingbian (37.4°N, 108.8°E), at the northern extremity of the Chinese Loess Plateau. The results indicate that the magnetic assemblage is dominated by pseudo-single-domain magnetite with associated maghemite and traces of a higher-coercivity phase, probably hematite. The Brunhes-Matuyama and upper Jaramillo transitions have been carefully documented and a record of a short reverse polarity interval (SRI), entirely within the Jaramillo normal polarity subchron, has been obtained. The duration of the SRI, recorded over a stratigraphic interval of 48 cm, is 10.1 kyr (29 kyr if the polarity transitions are included). These results seem to exclude that rock magnetic variations are adversely affecting the recording process and compel us to reconsider the Jaramillo subchron as characterized by a pair of normal polarity intervals interrupted by a short reverse polarity interval.