Millennial‐ to submillennial‐scale features of the Matuyama‐Brunhes geomagnetic polarity transition from Osaka Bay, southwestern Japan

Abstract

[1] A high-resolution magnetic record of the Matuyama-Brunhes (MB) reversal transition was obtained from homogeneous marine clay in a 1700-m core from Osaka Bay. The transition stretches over a core length of 6.4 m and yields four short reversal episodes. Two predate the main MB boundary (MBB), and two postdate it. We made diatom analyses of sediments to estimate relative sea level changes and constructed an age model by correlation with the astronomically calibrated marine oxygen isotope curve. The age model shows the short reversal episodes, with durations of <1 kyr, occurred at 4-5 kyr intervals within stage 19, and the MBB occurred about 5 kyr after the sea level highstand corresponding to isotopic event 19.3. It also shows the paleointensity minimum of 15-20% of the postreversal mean occurred at about 6 kyr before the MBB and another minimum at about 1 kyr after. Four virtual reverse-to-normal polarity boundaries found in this study suggest different ages for the MBB could be observed in lava flow studies. Some millennial-to submillennial-scale transition features found in this study are compatible with the previous numerical simulations of geomagnetic field reversal.

High-resolution record of the Matuyama–Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia

“…S4). Thus, the Sangiran MB transition spans 783-773 ka, consistent with the Osaka Bay core data (785-775 ka) (28). We can see a similar duration (783-770 ka) for a multiple polarity swing zone with low paleointensity in a North Atlantic deep-sea core record from Ocean Drilling Program (ODP) site 984 (39).…”

“…sediments (>50 cm/ka) have short reversal episodes similar to those observed here. In an Osaka Bay marine core, a 6-m long MB transition record lies within the low relative paleointensity zone (28). The transition has a short episode named "a" that is 4.56 m to 4.0 m below the main MBB, and short episodes, about 20 cm thick, named "b" and "c" lie at 1.1 m below and 0.4 m above the boundary (Fig.…”

Early and middle Matuyama geomagnetic excursions recorded in the Chinese loess-paleosol sediments

“…9(e)), suggesting that the ChRM directions are well-defined. Due to the weaker NRM intensity of the high-temperature fraction, some specimens around the polarity transitions and geomagnetic excursions have larger MAD values, as is often observed in marine sediment cores (e.g., Guyodo et al, 2001;Channell et al, 2002Channell et al, , 2003aHyodo et al, 2006). Channell et al (2003a) attributed this result to superposition of normal and reverse magnetization directions.…”

A marker tephra bed close to the Lower-Middle Pleistocene boundary: Distribution of the Ontake-Byakubi Tephra Bed in central Japan

“…The MatuyamaeBrunhes boundary occurs just above Byk-E at Chiba section (Kazaoka et al, 2015), and chronologically it is positioned at the boundary between marine oxygen-isotope substages (MIS) 19.3 and 19.2 (Hyodo et al, 2006;Hyodo, 2014). The Ku1 tephra, which occurs about 50 m above Byk-E, correlates with the widespread HakkodaeKokumoto tephra (Hkd-Ku: Suzuki et al, 2005), which has been correlated in turn with the Imakuma I tephra, Osaka Group (Itihara et al, 1975), and the Hakkoda first-stage pyroclastic flow deposits in northernmost Honshu (Muraoka and Takakura, 1988).…”