Publication Date:
2024-04-26
Description:
We present a continuous ∼6.2 Ma long record of explosive activity from the Northwest Pacific volcanic arcs based on a composite tephra sequence derived from Ocean Drilling Program Sites 882A and 884B, and core MD01‐2416 on the Detroit Seamount. Geochemical fingerprinting of tephra glass using major and trace element analyses and correlations of tephra layers between the three cores allowed the identification of 119 unique tephras, suggesting eruptions of magnitude (M) of 5.8–7.8. Age estimates for all the identified eruptions were obtained with the help of published and further refined age models for the studied cores, direct 40 Ar/ 39 Ar dating of four ash layers, and Bayesian age modeling. The glass compositions vary from low‐ to high‐K 2 O basaltic andesite to rhyolite and exhibit typical subduction‐related affinity. The majority of the tephras originated from Kamchatka, only a few tephras—from the neighboring Kuril and Aleutian arcs. The glass compositions revealed no temporal trends but made it possible to identify their source volcanic zones in Kamchatka and, in some cases, to determine their source eruptive centers. Our data indicates episodes of explosive activity recorded in the Detroit tephra sequence at ∼6,200, 5,600–5,000, 4,300–3,700 ka, and almost continuous activity since ∼3,000 ka. Within the latter episode, the most active intervals can be identified at 1,700–1,600, 1,150–1,050, and 600–50 ka. Geochemically fingerprinted and dated Detroit tephra sequence form a framework for dating and correlating diverse paleoenvironmental archives across the Northwest Pacific and for studies of geochemical evolution of the adjacent volcanic arcs.
Plain Language Summary
Explosive volcanic eruptions produce defragmented material named tephra, which can be spread over large distances and form layers in sediments on ocean floor and continents. Long continuous tephra sequences preserved in marine sediments provide one of the best chronicles of the explosive eruptions, and allow detailed evaluation of their timing relative to climatic changes. We studied one of such natural records of explosive volcanism preserved in the sediments covering the Detroit Seamount in the Northwest Pacific. We identified 119 tephra layers, which have been buried in the sediments during the last 6.2 Ma and represent volcanic eruptions with ≥7 km 3 tephra volume. We analyzed geochemical composition and determined age of each tephra. Most tephras were found to originate from volcanoes in Kamchatka, a few from the Kuril and Aleutian volcanoes. We found that the explosive activity recorded in the Detroit tephra sequence was not uniform over time. It peaked at ∼6,200, 5,600–5,000, 4,300–3,700, has continued since ∼3,000 thousand years ago until present. All tephra layers from our study can be used as unique isochrons for dating and correlating paleoenvironmental archives across the Northwest Pacific and for the reconstruction of the detailed volcanic record in the Earth history.
Key Points
We report age and composition for 119 tephras from sediment cores representing ∼6.2 Ma record of explosive volcanism in the NW Pacific
The tephras have subduction‐related origin and mostly originate from volcanic eruptions with magnitude (M) of 5.8–7.8 in Kamchatka
The data indicates episodes of explosive activity at ∼6,200, 5,600–5,000, 4,300–3,700 ka, and almost continuous activity since ∼3,000 ka
Type:
Article
,
PeerReviewed
Format:
text
Format:
text
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