Composition and accretion rate of fossil micrometeorites recovered in Middle Triassic deep-sea deposits

Onoue, Tetsuji; Nakamura, Tomoki; Haranosono, T.; Yasuda, Chika

doi:10.1130/g31866.1

Cited by 31 publications

(45 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The etching of spherules appears to be much more effective under deep‐sea conditions; as the deposits encompass larger periods of time, the percentage of the metallic spherules which are more resistant appears to increase. I‐type spherules have phenomenal surviving capacities, and they have been found in large numbers even in tertiary deposits [ Onoue et al ., ]. In view of the proportions of the textural types being similar to those in younger unbiased collections, the present collection appears to be largely unbiased.…”

Section: Discussionmentioning

confidence: 67%

Micrometeorite flux on Earth during the last ~50,000 years

2013

View full text Add to dashboard Cite

[1] Flux of micrometeorites is estimated by using cosmic spherule counts from a seafloor area of 2.50 m 2 from the Indian Ocean. The spherules are recovered from sediment samples in close-spaced locations from the Indian Ocean after sieving 293 kg of sediment. The terrestrial age of the spherules has a range of 0-~50,000 years. The spherules have a size range of 57-750 μm (average size 265 ± 92 μm). The diameter of the spherules increases from scoriaceous-barred-cryptocrystalline-glassy types. The time-averaged flux of the spherules is 160 t/yr, a sizeable mass (>60%) resides in the >300 μm fraction; the slope of distribution is similar to that of Deep-Sea Spherules but significantly different from other collections which have lower average diameters. It is observed here, a significant population of cosmic dust resides in the larger sizes which can be recovered by sampling large areas in time and space. The spherule textures are similar to that of unbiased collections from the polar regions, indicating that the textural types of cosmic dust that have been raining on the Earth during the last 50 kyr have been constant regardless of size. Major element chemistry of a majority of the spherules show elemental ratios that are close to a CM or CI chondritic parent body; a single spherule (0.2% of the population) suggests an achondritic parent body. Unbiased collections spanning large areas temporally and spatially enlarge the inventory of the Earth-crossing meteoroid complex and provide valuable inputs for models on cosmic dust accretion.

show abstract

Section: Discussionmentioning

confidence: 67%

Micrometeorite flux on Earth during the last ~50,000 years

2013

View full text Add to dashboard Cite

show abstract

“… Scanning electron micrographs in the backscattered mode of polished section of cosmic spherules and unmelted micrometeorite from the Ajiro cherts. Stratigraphic levels of samples are shown in Onoue et al (2011). (a) G‐type spherule with dendritic magnetite from sample AJR583.…”

Section: Discussionmentioning

confidence: 99%

Palaeomagnetism of Middle Triassic red bedded cherts from southwest Japan: equatorial palaeolatitude of primary magnetization and widespread secondary magnetization

Uno

Onoue

Hamada

et al. 2012

Geophysical Journal International

Self Cite

View full text Add to dashboard Cite

SUMMARY Middle Triassic (Anisian) red bedded cherts were collected from the Ajiro area in Kyushu Island, southwest Japan, for a palaeomagnetic study. Thermal demagnetization showed five distinct remanent magnetization components from the cherts. The lowest temperature component below 200 °C (component A) is a present‐day viscous overprint. The second‐ (up to 420 °C, component B) and third‐demagnetized (up to 580 °C, component C) components are secondary magnetizations of thermoviscous and chemical origin, respectively, both of which reside in magnetite. The fourth‐removed component (component D) was demagnetized at 630 °C and is a secondary magnetization carried by haematite. Components B and C are considered to be a result of widespread remagnetization in southwest Japan during the Cretaceous; the basis of this consideration is that red chert remagnetizations from an area about 600 km away from the present study area, are of the same origins with unblocking spectra similar to those observed in this study. The last‐removed component during thermal demagnetization (up to 695 °C, component E) is a primary magnetization carried by haematite. The directions of this component, after correction for the inclination flattening, yielded a mean palaeolatitude of 2°S at the time of deposition in the Middle Triassic. The Ajiro cherts accreted as part of an accretionary complex to the eastern margin of the South China Block during the Middle Jurassic and were then translated northwards from the continental margin to their present position through a margin‐parallel translation process owing to the oblique convergence of the oceanic plate.

show abstract

“…The reconstruction of variations in atmospheric Δ' 17 O from fossil cosmic spherules430313233 would be a new paleo-CO 2 proxy. The only published Δ' 17 O data on I-type spherules by Clayton et al 4.…”

mentioning

confidence: 99%

Tracing the oxygen isotope composition of the upper Earth’s atmosphere using cosmic spherules

Pack¹,

Höweling

Hezel

et al. 2017

Nat Commun

View full text Add to dashboard Cite

Molten I-type cosmic spherules formed by heating, oxidation and melting of extraterrestrial Fe,Ni metal alloys. The entire oxygen in these spherules sources from the atmosphere. Therefore, I-type cosmic spherules are suitable tracers for the isotopic composition of the upper atmosphere at altitudes between 80 and 115 km. Here we present data on I-type cosmic spherules collected in Antarctica. Their composition is compared with the composition of tropospheric O2. Our data suggest that the Earth's atmospheric O2 is isotopically homogenous up to the thermosphere. This makes fossil I-type micrometeorites ideal proxies for ancient atmospheric CO2 levels.

show abstract

Composition and accretion rate of fossil micrometeorites recovered in Middle Triassic deep-sea deposits

Cited by 31 publications

References 23 publications

Micrometeorite flux on Earth during the last ~50,000 years

Micrometeorite flux on Earth during the last ~50,000 years

Palaeomagnetism of Middle Triassic red bedded cherts from southwest Japan: equatorial palaeolatitude of primary magnetization and widespread secondary magnetization

Tracing the oxygen isotope composition of the upper Earth’s atmosphere using cosmic spherules

Contact Info

Product

Resources

About