Quaternary Magnetic Stratigraphy of Deep‐Sea Sediments in the Western North Pacific: Influences of Paleomagnetic Recording Efficiency and Lock‐In Delay
Quaternary Magnetic Stratigraphy of Deep‐Sea Sediments in the Western North Pacific: Influences of Paleomagnetic Recording Efficiency and Lock‐In Delay
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北太平洋西部深海沉积物第四纪磁地层学：古地磁记录效率和锁定延迟的影响
DOI：
10.1029/2022jb025490
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
J. Shin;Wonnyon Kim;Y. Seong;Liao Chang
中科院分区：
文献类型：
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作者：
J. Shin;Wonnyon Kim;Y. Seong;Liao Chang
由于缺乏碳酸盐的远洋粘土沉积物的可靠年代学，对北太平洋西部过去环境变化的理解相当有限。本文提出了一种新的马里亚纳盆地北部第四纪深海沉积物磁地层学。综合古地磁、岩磁和显微结果表明，古地磁信号主要由亚洲风沙和火山碎屑磁性矿物携带。火山物质很可能来自马里亚纳弧，其特征是低矫顽力（~ 30 mT）相互作用的单畴（SD）和伪SD颗粒，并伴有丰富的枝晶磁性晶体/包裹体。这种火山成分是一种合适的剩磁载体，但在记录地磁强度方面不如高矫顽力风成成分有效。用最小岩石磁性人工制品得到的相对古强度记录显示出与全球模板相似的模式。在Matuyama - Brunhes过渡带，从铍同位素记录中确定了~ 2 cm的剩余物锁深偏移，并且估计的磁地层年龄延迟很小（~ 8 kyr）。我们的研究结果提高了对碳酸盐岩贫乏的深海粘土中剩余物记录过程的理解，并证明了磁地层学在北太平洋西部地区是一种有价值的年代学。
Understanding past environmental changes in the western North Pacific is rather limited due to the general paucity of robust chronology for carbonate‐lacking pelagic clay sediments. Here, we present a new magnetostratigraphy of Quaternary deep‐sea sediments in the northern Mariana Basin. A comprehensive set of paleomagnetic, rock magnetic, and microscopic results reveal that paleomagnetic signals are mainly carried by detrital magnetic minerals of Asian eolian dust and volcanic origins. The volcanic materials, most likely from the Mariana Arc, are characterized by low coercivity (∼30 mT) interacting single domain (SD) and pseudo‐SD grains, associated with abundant dendritic magnetic crystals/inclusions. This volcanic component is a suitable remanence carrier but is less efficient in recording geomagnetic intensity than the higher coercivity eolian component. The relative paleointensity record derived with minimum rock magnetic artifacts shows comparable patterns with global templates. At the Matuyama‐Brunhes transition, a ∼2‐cm remanence lock‐in depth offset is identified from beryllium isotope records, and the estimated magnetostratigraphic age delay is small (∼8 kyr). Our results provide an improved understanding of remanence recording processes in carbonate‐poor deep‐sea clays and demonstrate magnetic stratigraphy as a valuable chronology in the western North Pacific region.