Abstract
Seamounts are ubiquitous topographic units in the global ocean, and their effects on local circulation have attracted great research attention in physical oceanography; however, fewer relevant efforts were made on geological timescales in previous studies. The Caiwei (Pako) Guyot in the Magellan Seamounts of the western Pacific is a typical seamount and oceanographic characteristics have been well documented. In this study, we investigate a sediment core by geochronological and geochemical studies to reveal a topography-induce surface-to-bottom linkage. The principal results are as follows: (1) Two magnetozones are recognized in core MABC–11, which can be correlated to the Brunhes and Matuyama chrons; (2) Elements Ca, Si, Cl, K, Mn, Ti, and Fe are seven elements with high intensities by geochemical scanning; (3) Ca intensity can be tuned to global ice volume to refine the age model on glacial-interglacial timescales; (4) The averaged sediment accumulation rate is ~0.73 mm/kyr, agreeing with the estimate of the excess 230Th data in the upper part. Based on these results, a proxy of element Mn is derived, whose variability can be correlated with changes in global ice volume and deep-water masses on glacial-interglacial timescales. This record is also characterized by an evident 23-kyr cycle, highlighting a direct influence of solar insolation on deep-sea sedimentary processes. Overall, sedimentary archives of the Caiwei Guyot not only record an intensified abyssal ventilation during interglaciations in the western Pacific, but also provide a unique window for investigating the topography-induced linkage between the upper and bottom ocean on orbital timescales.
Highlights
All specimens produced reliable Characteristic remanent magnetization (ChRM) directions with the criterion of six continuous alternating field (AF) steps and maximum angular deviation (MAD) ≤ 10◦ (Figure 3c,d). Based on these 47 ChRMs, two magnetozones are recognized in core MABC–11 (Figure 3e): one of reversed polarity (R1, 48–58 cm) and one of normal polarity (N1, 11–48 cm)
Matuyama chron; J, Jaramillo subchron; M/B, the Matuyama/Brunhes boundary (0.781 ka)
By integrating magnetostratigraphy and geochemical scanning of the sediments on the Caiwei Guyot, Magellan Seamounts of the Western Pacific, we have established a reliable chronology for a sedimentary sequence and produced a record of deep-sea ventilation during the middle Pleistocene
Summary
Seamounts on the ocean floor are the most abundant volcanoes on the Earth and their origination is geologically and geochemically similar to ocean island basalts [1]. Seamount evolution is directly associated with mantle dynamics [1,2]. Their existence can significantly shape abyssal topography and induce development of marine ferromanganese crusts and nodules [3,4,5], resulting in changing ocean currents, and likely playing an important role in global climate changes [6,7,8,9]. Documenting details of sedimentary evolution of seamounts is critical to understand the topography-induced processes and the formation and mechanism of mineral resources on the ocean floor
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