Carbonaceous chondrite meteorites experienced fluid flow within the past million years

Science ◽  
2021 ◽  
Vol 371 (6525) ◽  
pp. 164-167
Author(s):  
Simon Turner ◽  
Lucy McGee ◽  
Munir Humayun ◽  
John Creech ◽  
Brigitte Zanda

Carbonaceous chondritic meteorites are primordial Solar System materials and a source of water delivery to Earth. Fluid flow on the parent bodies of these meteorites is known to have occurred very early in Solar System history (first <4 million years). We analyze short-lived uranium isotopes in carbonaceous chondrites, finding excesses of 234-uranium over 238-uranium and 238-uranium over 230-thorium. These indicate that the fluid-mobile uranium ion U6+ moved within the past few 100,000 years. In some meteorites, this time scale is less than the cosmic-ray exposure age, which measures when they were ejected from their parent body into space. Fluid flow occurred after melting of ice, potentially by impact heating, solar heating, or atmospheric ablation. We favor the impact heating hypothesis, which implies that the parent bodies still contain ice.

Antiquity ◽  
1963 ◽  
Vol 37 (147) ◽  
pp. 213-219 ◽  
Author(s):  
W. F. Libby

The first test of the accuracy of dates obtained by the radiocarbon technique was made by determining whether dates so obtained agreed with the historical dates for materials of known age (n. 1). The validity of the radiocarbon method continues to be an important question, especially in the light of the numerous results that have been accumulated and the greater precision of the technique during the past few years (n. 2).The radiocarbon content of the biosphere depends on three supposedly independent geophysical quantities: (i) the average cosmic ray intensity over a period of 8000 years (the average life of radiocarbon) as measured in our solar system but outside the earth's magnetic field (n. 1); (ii) the magnitude (but not the orientation, because of the relatively rapid mixing over the earth's surface) of the magnetic field in the vicinity of the earth, averaged over the same period (n. 1,3); and (iii) the degree of mixing of the oceans during the same period (n. 1). The question of the accuracy of radiocarbon dates therefore is of interest to geophysicists in general as well as to the archaeologists, geologists and historians who use the dates.Previous workers in this area (n. 1, 2) have reported some discrepancies, and it is the purpose here to consider the matter further.


2013 ◽  
Vol 50 (1) ◽  
pp. 14-25 ◽  
Author(s):  
Christopher D.K. Herd ◽  
Jon M. Friedrich ◽  
Richard C. Greenwood ◽  
Ian A. Franchi

The mineralogy, petrology, and geochemistry of an igneous-textured clast in the Peace River L6 chondrite meteorite was examined to determine the roles of nebular processes, accretion, and parent-body metamorphism in its origin. The centimetre-scale clast is grey and fine grained and is in sharp contact with the host chondrite. Two sub-millimetre veins cut across both the clast and host, indicating that the clast formed prior to the impact (shock) event(s) that produced the numerous veins present in the Peace River meteorite. The clast and host are indistinguishable in terms of mineral compositions. In contrast, there are differences in modal mineralogy, texture, as well as trace element and oxygen isotope composition between the clast and host. These differences strongly suggest that the clast was formed by impact melting of LL-group chondritic material involving loss of Fe–FeS and phosphate components, followed by relatively rapid cooling and incorporation into the Peace River host meteorite. Subsequent metamorphism on the Peace River parent body caused recrystallization of the clast and homogenization of mineral compositions and thermally labile element abundances between the clast and host. Shock metamorphism, including formation of shock melt veins, occurred post-metamorphism, during fragmentation of the L chondrite parent body. The results suggest that the formation of the Peace River parent asteroid included the incorporation of material from other asteroids and that the pre-metamorphic protolith was a breccia. Accordingly, we propose that the Peace River meteorite be reclassified as a polymict breccia.


Science ◽  
2020 ◽  
Vol 370 (6517) ◽  
pp. eabc3557 ◽  
Author(s):  
H. H. Kaplan ◽  
D. S. Lauretta ◽  
A. A. Simon ◽  
V. E. Hamilton ◽  
D. N. DellaGiustina ◽  
...  

The composition of asteroids and their connection to meteorites provide insight into geologic processes that occurred in the early Solar System. We present spectra of the Nightingale crater region on near-Earth asteroid Bennu with a distinct infrared absorption around 3.4 micrometers. Corresponding images of boulders show centimeters-thick, roughly meter-long bright veins. We interpret the veins as being composed of carbonates, similar to those found in aqueously altered carbonaceous chondrite meteorites. If the veins on Bennu are carbonates, fluid flow and hydrothermal deposition on Bennu’s parent body would have occurred on kilometer scales for thousands to millions of years. This suggests large-scale, open-system hydrothermal alteration of carbonaceous asteroids in the early Solar System.


2000 ◽  
Vol 197 ◽  
pp. 515-526
Author(s):  
J. D. Gilmour

Primitive meteorites have preserved material that was present in the presolar nebula and record processes that occurred as evolution proceeded from the earliest solids. The discovery of isotopic anomalies in these samples led to the isolation of presolar grains and allowed the presence of short-lived radionuclides in the early solar system to be inferred. Isotopic anomalies in oxygen may reflect non-linear chemical fractionation rather than a nuclear effect, but the theory is as yet insufficiently developed to be rigorously assessed.Analyses of individual SiC and refractory oxide presolar grains reveal that a large number of distinct nucleosynthetic sites contributed material to the solar nebula, and much progress has been made in identifying the various environments in which they formed. Isotopic anomalies associated with nanometre-size diamonds are best explained by supernova nucleosynthesis but it is clear that several sub-populations exist.The extinct nuclides 26Al, 53Mn and 129I have each been used to establish the relative timing of events in the formation of the solar system. Calibrations of the Mn-Cr and I-Xe systems against the Pb-Pb system (based on decay of uranium isotopes) have been proposed, and Al-Mg data can be included through a calibration with the I-Xe scheme. Assuming these calibrations to be valid allows a tentative chronology of the early solar system to be developed, the plausibility of which can be seen as a test of the calibrations. In this chronology, the first solids to form in the solar system were refractory inclusions. Chondrules (rapidly cooled silicate droplets) appear to have formed later than CAIs over a period of a few million years. Parent body processing began early in solar system history and was ongoing as chondrules formed.


2006 ◽  
Vol 2 (14) ◽  
pp. 295-296
Author(s):  
Ignasi Ribas

AbstractThe results of the Sun in Time program indicate that the X ray, far ultraviolet and ultraviolet fluxes of the young Sun were significantly higher than today. Similarly, the solar wind mayhave been much stronger in the past. Such environment of intense energy and particle emissions could have influenced the paleo-atmospheres of Solar System planets and, by extension, the habitability and stability of exoplanets.


2020 ◽  
Author(s):  
Ke Du ◽  
Shijie Li ◽  
Ingo Leya ◽  
Thomas Smith ◽  
Dongliang Zhang ◽  
...  

Abstract The Kumtag meteorite strewn field was found in the Kumtag desert, 132 kilometers south of Hami city in the Xinjiang province, China. It is an ellipse of 2.5×7.9 km, with a long axis extending along the northeast-southwest direction. The largest individual meteorite of the strewn field weights about 10 kg; the smallest individual has as mass of only 27 g. In total more than 100 individuals with a total mass of more than 180 kg were collected. The Kumtag meteoroid entered the atmosphere in the direction Northeast-Southwest. All meteorites collected in this strewn field are samples from the same unique meteorite shower. The Kumtag meteorite is an H5 ordinary chondrite with a shock stage S2, and a weathering grade W2. The cosmic ray exposure age of Kumtag is 6.7± 0.8 Ma, which is rather typical for H chondrites and which indicates that Kumtag was derived from the massive impact event on its parent body ~7 Ma ago. A significant He amount has been released during certain unknown processe(s) before the Kumtag meteorite was ejected from its parent body.


2020 ◽  
Vol 55 (5) ◽  
pp. 1031-1047
Author(s):  
Tomoya Obase ◽  
Daisuke Nakashima ◽  
Tomoki Nakamura ◽  
Keisuke Nagao

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Kosuke Kurosawa ◽  
Ryota Moriwaki ◽  
Hikaru Yabuta ◽  
Ko Ishibashi ◽  
Goro Komatsu ◽  
...  

AbstractCarbonaceous asteroids, including Ryugu and Bennu, which have been explored by the Hayabusa2 and OSIRIS-REx missions, were probably important carriers of volatiles to the inner Solar System. However, Ryugu has experienced significant volatile loss, possibly from hypervelocity impact heating. Here we present impact experiments at speeds comparable to those expected in the main asteroid belt (3.7 km s−1 and 5.8 km s−1) and with analogue target materials. We find that loss of volatiles from the target material due to impacts is not sufficient to account for the observed volatile depletion of Ryugu. We propose that mutual collisions in the main asteroid belt are unlikely to be solely responsible for the loss of volatiles from Ryugu or its parent body. Instead, we suggest that additional processes, for example associated with the diversity in mechanisms and timing of their formation, are necessary to account for the variable volatile contents of carbonaceous asteroids.


1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.


1962 ◽  
Vol 11 (02) ◽  
pp. 137-143
Author(s):  
M. Schwarzschild

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.


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