Volcanic Ash and Pumice at Shatsky Rise: Sources, Mechanisms of Transport, and Bearing on Atmospheric Circulation

Natland, James H.

doi:10.2973/odp.proc.sr.132.301.1993

Cited by 12 publications

(20 citation statements)

References 23 publications

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“…Compositional studies on tephra from ODP drill sites on Shatsky Rise (Arculus et al 1995;Natland 1993), 1600 km downwind from the Kuriles arc and west of Central America (Cadet et al 1982a, b), confirmed this link. However, the origin of volcanic glasses in DSDP leg 54 and ODP leg 138 sites approximately 2000 km west of Central America remains questionable.…”

Section: Constraints From Spatial Distributionsupporting

confidence: 53%

Evaluating the tephra input into Pacific Ocean sediments: distribution in space and time

Straub¹,

Schmincke²

1998

Geologische Rundschau

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We studied the volcanic contribution to the global sediment budget in the Pacific Ocean basin. It is the world's oldest (174 m.y.) and largest (≈49% of Earth's surface area) ocean basin and has had a high and continuous tephra influx from intraplate and convergent margin volcanoes through time. Computerized shipboard data from 65 legs of the Deep Sea Drilling Project (DSDP) and the Ocean Drilling Program (ODP) were screened for the presence of volcaniclastic components. Tephra-bearing and tephra-free core sections (standard 1.5-and 0.30-m core catcher sections) were separated, regardless of the mass fraction of tephra present. The percentage of tephra-bearing core sections ("tephra frequency") per site and time span ("age unit") was calculated. The age units were the Quaternary, the subepochs of the Tertiary, and the stages of the Cretaceous. A total of 424 drill sites yielded 1433 usable stratigraphic units. Fifty percent are younger than 13 m.y., corresponding to only approximately 10% of the total interval studied (124.5 m.y.). The percentage of tephra-bearing age units is high throughout (83±6%) and correlates linearly with the total number of age units (R 2 =0.998; n=17). The average tephra frequency (30-50%) fluctuates, because the abundance of age units of different tephra frequency classes (0, 1-33, 34-67, 68-100% tephra frequency) varies with time. This indicates that the Cenozoic increase in tephra production results from increase in volcanicity and not spatial extension of volcanic source areas. The Cenozoic sediments that were recovered are dominated by distal tephra from explosive arc volcanism. Pulses of arc volcanism occurred in the Pliocene-Quaternary (since ≈5 m.y.) and midMiocene (≈12-15 m.y.). However, the record of explosive arc volcanism in Paleogene and Cretaceous sediments was either not drilled or has been destroyed by subduction. Except for the Cretaceous (≈70-110 m.y.) volcanic pulse, intraplate volcanism is poorly represented in the tephra record because the drill sites are outside the proximal range (>500-1000 km) of the sources. Thus, the tephra record drilled contains significant gaps that bias the estimate of tephra volume towards the less voluminous distal deposits. Most of the volcaniclastic volume accumulated by mass wasting as volcaniclastic aprons surrounding ocean island volcanoes. Volcaniclastic production rates range from 10,000 to 41,800 km 3 /m.y. for large intraplate volcanoes and approximately 10-13 km 3 /km arc length per million years for oceanic island arcs. Extrapolation over the lifetime of major Pacific arcs and hotspot chains, combined with a volume estimate of the distal tephra component, indicates a minimum of 9.3×10 6 km 3 of tephra, corresponding to 23 vol.% of the existing Pacific oceanic sediments. At least two thirds of the tephra volume was deposited in the proximal range and at least half of it is derived from intraplate sources. The large proportion of tephra, its composition, and its localized accumulation causes significant spatial and temporal variati...

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Section: Constraints From Spatial Distributionsupporting

confidence: 53%

Evaluating the tephra input into Pacific Ocean sediments: distribution in space and time

Straub¹,

Schmincke²

1998

Geologische Rundschau

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“…Typical respective clastic particle sizes for the central North Pacific are from (1) Rea [], (2) Natland [], and (3) Yamazaki and Ioka []. From the magnetic sources (1)–(4) above, we deduce that only (1) contributes to HIRM, (2) and, less, (1) contribute to IRM 20mT , and (3) plus submicrometer magnetic inclusions of all other fractions contribute to ARM.…”

Section: Proxy Records Of Core So202‐39‐3mentioning

confidence: 98%

“…Intercalated fine volcanic ash and pumice layers (mostly 1–2 cm, some 10 cm) are frequent in sediments from the Shatsky Rise area and have been backtracked to recently active volcanoes on Hokkaido and the Kuril Islands [ Natland , ]. According to Natland's estimates, the number of observable tephra layers per Myrs should decline from ~30 in the west to ~5 in the east of our core transect.…”

Section: Hydrography and Sedimentology Of The Northwest Pacificmentioning

confidence: 99%

Cyclic magnetite dissolution in Pleistocene sediments of the abyssal northwest Pacific Ocean: Evidence for glacial oxygen depletion and carbon trapping

et al. 2016

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The carbonate-free abyss of the North Pacific defies most paleoceanographic proxy methods and hence remains a "blank spot" in ocean and climate history. Paleomagnetic and rock magnetic, geochemical, and sedimentological methods were combined to date and analyze seven middle to late Pleistocene northwest Pacific sediment cores from water depths of 5100 to 5700 m. Besides largely coherent tephra layers, the most striking features of these records are nearly magnetite-free zones corresponding to glacial marine isotope stages (MISs) 22, 12, 10, 8, 6, and 2. Magnetite depletion is correlated with organic carbon and quartz content and anticorrelated with biogenic barite and opal content. Within interglacial sections and mid-Pleistocene transition glacial stages MIS 20, 18, 16, and 14, magnetite fractions of detrital, volcanic, and bacterial origin are all well preserved. Such alternating successions of magnetic iron mineral preservation and depletion are known from sapropel-marl cycles, which accumulated under periodically changing bottom water oxygen and redox conditions. In the open central northwest Pacific Ocean, the only conceivable mechanism to cause such abrupt change is a modified glacial bottom water circulation. During all major glaciations since MIS 12, oxygen-depleted Antarctic Bottom Water (AABW)-sourced bottom water seems to have crept into the abyssal northwest Pacific below~5000 m depth, thereby changing redox conditions in the sediment, trapping and preserving dissolved and particulate organic matter and, in consequence, reducing and dissolving both, biogenic and detrital magnetite. At deglaciation, a downward progressing oxidation front apparently remineralized and released these sedimentary carbon reservoirs without replenishing the magnetite losses.

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“…A study of volcanic ash layers from ODP site 810C on the Shatsky Rise just south of station 40 (Fig. 1) indicates contributions from the Kurile Islands, Kamchatka and Hokkaido (Natland, 1993). Volcanic material from Hokkaido probably does not contribute to ODP site 881 off the Kurile Islands (Fig.…”

Section: Local Uncertainties In the Lithogenic Component Deconvolutionmentioning

confidence: 99%

“…These regions are characterized by an excess pool of macronutrients delivered to the euphotic zone by mixing that is incompletely consumed during the annual biogeochemical cycle (Falkowski et al, 1998). The incomplete consumption has been explained by a lack of dissolved iron for which eolian dust is suggested to be the primary source in the SNP (e.g., Bishop et al, 2002;Duce and Tindale, 1991;Martin and Fitzwater, 1988;Martin et al, 1989; (Natland, 1993) and 881-882 (Cao et al, 1995a). ODP site 887 (Cao et al, 1995b) and MD02-2489 (Gebhardt et al, 2008) are located near stations 26-28, RAMA 44PC (Keigwin et al, 1992) is located near station 5 and the site of core RC10-196 (Kohfeld and Chase, 2011) is located near station 13.…”

Section: Introductionmentioning

confidence: 99%

Eolian dust input to the Subarctic North Pacific

Serno

Winckler

Anderson

et al. 2014

Earth and Planetary Science Letters

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Eolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high nutrient-low chlorophyll status of the Subarctic North Pacific. We map the spatial distribution of dust input using three different geochemical tracers of eolian dust, 4 He, 232 Th and rare earth elements, in combination with grain size distribution data, from a set of core-top sediments covering the entire Subarctic North Pacific. Using the suite of geochemical proxies to fingerprint different lithogenic components, we deconvolve eolian dust input from other lithogenic inputs such as volcanic ash, ice-rafted debris, riverine and hemipelagic input. While the open ocean sites far away from the volcanic arcs are dominantly composed of pure eolian dust, lithogenic components other than eolian dust play a more crucial role along the arcs. In sites dominated by dust, eolian dust input appears to be characterized by a nearly uniform grain size mode at ∼4 μm.Applying the 230 Th-normalization technique, our proxies yield a consistent pattern of uniform dust fluxes of 1-2 g/m 2 /yr across the Subarctic North Pacific. Elevated eolian dust fluxes of 2-4 g/m 2 /yr characterize the westernmost region off Japan and the southern Kurile Islands south of 45 • N and west of 165 • E along the main pathway of the westerly winds. The core-top based dust flux reconstruction is consistent with recent estimates based on dissolved thorium isotope concentrations in seawater from the Subarctic North Pacific. The dust flux pattern compares well with state-of-the-art dust model predictions in the western and central Subarctic North Pacific, but we find that dust fluxes are higher than modeled fluxes by 0.5-1 g/m 2 /yr in the northwest, northeast and eastern Subarctic North Pacific. Our results provide an important benchmark for biogeochemical models and a robust approach for downcore studies testing dust-induced iron fertilization of past changes in biological productivity in the Subarctic North Pacific.

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Volcanic Ash and Pumice at Shatsky Rise: Sources, Mechanisms of Transport, and Bearing on Atmospheric Circulation

Cited by 12 publications

References 23 publications

Evaluating the tephra input into Pacific Ocean sediments: distribution in space and time

Evaluating the tephra input into Pacific Ocean sediments: distribution in space and time

Cyclic magnetite dissolution in Pleistocene sediments of the abyssal northwest Pacific Ocean: Evidence for glacial oxygen depletion and carbon trapping

Eolian dust input to the Subarctic North Pacific

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