Rock magnetic characteristics of surficial marine sediments from the California continental borderland
Rock magnetic characteristics of surficial marine sediments from the California continental borderland
复制标题
加利福尼亚大陆边境地表海洋沉积物的岩石磁特征
DOI：
10.1016/0012-821x(92)90062-z
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发表时间：
1992
影响因子：
5.3
通讯作者：
T. Henyey
中科院分区：
文献类型：
--
作者：
S. Lund;D. Gorsline;T. Henyey
描述了与南加州相邻的加利福尼亚大陆边界的浅层海相沉积物的岩石磁性变异性。数据来自对230个5.33岩心385个样本的自然（NRM）、非滞后（ARM）和等温（IRM）剩余磁化率和磁化率的测量。对选定样品进行的磁矿物学研究表明，碎屑磁铁矿在整个边界地带占主导地位，但局部也有碎屑和自生赤铁矿、蚀变海绿石和生物成因磁铁矿的重要贡献。各岩石磁性参数分布图显示：(1)海岸线向外的磁性物质比例由于有机物质和碳酸盐的稀释而降低；(2)海岸线向外的磁性粒度分布转向更细的平均粒度；(3)对沉积物磁性物质的重要局部贡献可能来自淹没岸顶或山脊的侵蚀；(4)岸顶富海绿石带可能变成强度和矫顽力异常强的残余磁性物质。(5)深盆内普遍存在成岩作用，导致磁性物质大规模溶解。ARM、χ和SIRM（饱和IRM）的比较表明，ARMχ对粒度变化非常敏感，数量（ARM2+ χ2）0.5和SIRM都是边界区剩余磁性物质体积的良好指标。
The rock magnetic variability of surficial marine sediments from the California continental borderland adjacent to southern California is described. The data were derived from measurement of the natural (NRM), anhysteretic (ARM), and isothermal (IRM) remanent magnetization and magnetic susceptibility of 385 samples from 230 ☐ cores. Magnetic mineralogy studies carried out on selected samples indicate that detrital magnetite predominates throughout the borderland, but there are also locally important contributions from detrital and authigenic hematite, altered glauconite, and biogenic magnetite. Maps of the distributions of various rock magnetic parameters show that: (1) the proportion of magnetic material decreases outward from the coastline through dilution by organic material and carbonate, (2) the magnetic grain size distribution shifts to finer average grain size outward from the coastline, (3) important local contributions to the sediment magnetic material can come from erosion of submerged bank tops or ridges, (4) glauconite-rich zones on bank tops can be altered to remanent magnetic material that is anomalously strong in intensity and coercivity, and (5) that diagenetic processes occur ubiquitously within the deep basins causing large scale dissolution of the magnetic material. Comparisons of ARM, χ , and SIRM (saturation IRM) indicate that ARMχ is very sensitive to grain-size changes and that both the quantity (ARM2+ χ2)0.5and SIRM are good indicators of volume of remanent magnetic material in the borderland.