| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Bollard, J., et al.
(författare)
-
Early formation of planetary building blocks inferred from Pb isotopic ages of chondrules.
- 2017
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The most abundant components of primitive meteorites (chondrites) are millimeter-sized glassy spherical chondrules formed by transient melting events in the solar protoplanetary disk. Using Pb-Pb dates of 22 individual chondrules, we show that primary production of chondrules in the early solar system was restricted to the first million years after the formation of the Sun and that these existing chondrules were recycled for the remaining lifetime of the protoplanetary disk. This finding is consistent with a primary chondrule formation episode during the early high-mass accretion phase of the protoplanetary disk that transitions into a longer period of chondrule reworking. An abundance of chondrules at early times provides the precursor material required to drive the efficient and rapid formation of planetary objects via chondrule accretion.
|
|
| 7. |
- Connelly, J. N., et al.
(författare)
-
Calibrating volatile loss from the Moon using the U-Pb system
- 2022
-
Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533. ; 324, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- Previous isotope studies of lunar samples have demonstrated that volatile loss was an important part of the early history of the Moon. The radiogenic U-Pb system, where Pb has a significantly lower T50% condensation temperature than U, has the capacity to both recognize and calibrate the extent of volatile loss but this approach has been hindered by terrestrial Pb contamination of samples. We employ a novel method that integrates analyses of individual samples by Ion Microprobe and Thermal Ionization mass spectrometry to correct for ubiquitous common Pb contamination, a method that results in significantly higher estimates for mu-values (238U/204Pb) than previously reported. Using this method, six of seven samples of low-Ti basaltic meteorites return mu-values between 1900 and 9600, values that are consistent with a re-evaluation of published results that return mu-values of 510-2900 for both low-and high-Ti basalts. While some degree of fractionation during partial melting may increase mu-values, we infer that the source region(s) for the basalts must also have had elevated mu-values by the time the lunar magma ocean solidified. Models to account for the available initial Pb isotopic compositions of lunar basalts in light of timing constraints from thermal modelling imply that their source regions had a mu-value of at least 280, consistent with the elevated mu-values of lunar basalts and that inferred for their sources. Such high mu-values are attributed to the preferential loss of more than 99% of the Pb over U relative to a precursor with a Mars-like composition in the aftermath of the giant impact. Such an extensive loss of Pb is consistent with previously reported losses of other elements with comparable volatility, namely Zn, Rb, Ga and CrO2. Finally, our modelling of highly-radiogenic lunar Pb isotopes assuming crystallization of the lunar magma ocean over 100s of millions of years shows that the elevated mu-values allows for, but does not require, a young Moon formation age.
|
|
| 8. |
|
|
| 9. |
- Lindskog, A., et al.
(författare)
-
Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification
- 2017
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- The catastrophic disruption of the L chondrite parent body in the asteroid belt c. 470 Ma initiated a prolonged meteorite bombardment of Earth that started in the Ordovician and continues today. Abundant L chondrite meteorites in Middle Ordovician strata have been interpreted to be the consequence of the asteroid breakup event. Here we report a zircon U-Pb date of 467.50±0.28 Ma from a distinct bed within the meteorite-bearing interval of southern Sweden that, combined with published cosmic-ray exposure ages of co-occurring meteoritic material, provides a precise age for the L chondrite breakup at 468.0±0.3 Ma. The new zircon date requires significant revision of the Ordovician timescale that has implications for the understanding of the astrogeobiologic development during this period. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated.
|
|
| 10. |
- Merle, Renaud E., 1976-, et al.
(författare)
-
Pb-Pb ages and initial Pb isotopic composition of lunar meteorites : NWA 773 clan, NWA 4734, and Dhofar 287
- 2020
-
Ingår i: Meteoritics and Planetary Science. - : John Wiley & Sons, Ltd. - 1086-9379 .- 1945-5100. ; 55:8
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Constraining the duration of magmatic activity on the Moon is essential to understand how the lunar mantle evolved chemically through time. Determining age and initial isotopic compositions of mafic lunar meteorites is a critical step in defining the periods of magmatic activity that occurred during the history of the Moon and to constrain the chemical characteristics of mantle components involved in the sources of the magmas. We have used the in situ Pb-Pb SIMS technique to investigate eight lunar gabbros and basalts, including six meteorites from the Northwest Africa (NWA) 773 clan (NWA 2727, NWA 2700, NWA 3333, NWA 2977, NWA 773, and NWA 3170), NWA 4734, and Dhofar 287A. These samples have been selected as there is no clear agreement on their age and they are all from the dominant low titanium chemical group. We have obtained ages of 2981 ± 12 Ma for NWA 4734 and 3208 ± 22 Ma for Dhofar 287. For the NWA 773 clan, four samples (the fine-grained basalt NWA 2727 and the three gabbros NWA 773, NWA 2977, NWA 3170) out of six yielded isochron-calculated ages that are identical within uncertainties and yielding an average age of 3086 ± 5 Ma. The age obtained for the fine-grained basalt NWA 2700 is not precise enough for comparison with the other samples. The gabbroic sample NWA 3333 yielded an age of 3038 ± 20 Ma suggesting that two distinct magmatic events may be recorded in the meteorites of the NWA 773 clan. The present study aims to identify and assess all potential issues that are associated with different ways to date lunar rocks using U-Pb?based methods. To achieve this, we have compared the new ages with the previously published data set. The entire age data set from lunar mafic meteorites was also screened to identify data showing analytical issues and evidence of resetting and terrestrial contamination. The data set combining the ages of mafic lunar meteorites and Apollo rocks suggests pulses of magmatic activity with two distinct phases between 3950 and 3575 Ma and between 3375 and 3075 Ma with the two phases separated by a gap of approximately 200 Ma. The evolution of the Pb initial ratios of the low-Ti mare basalts between approximately 3400 and 3100 Ma suggests that these rocks were progressively contaminated by a KREEP-like component.
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Aad, G., et al.
(författare)
-
- 2015
-
Tidskriftsartikel (refereegranskat)
|
|
| 15. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 74:6
-
Tidskriftsartikel (refereegranskat)
|
|
| 16. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 17. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 90:2
-
Tidskriftsartikel (refereegranskat)
|
|
| 18. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 19. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 20. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 21. |
- Aad, G., et al.
(författare)
-
- 2014
-
swepub:Mat__t
|
|
| 22. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 112:9
-
Tidskriftsartikel (refereegranskat)
|
|
| 23. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :5
-
Tidskriftsartikel (refereegranskat)
|
|
| 24. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 25. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Physical Review D. Particles and fields. - 0556-2821 .- 1089-4918. ; 89:9
-
Tidskriftsartikel (refereegranskat)
|
|
| 26. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 27. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 112:20
-
Tidskriftsartikel (refereegranskat)
|
|
| 28. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - : Springer. - 1029-8479 .- 1126-6708. ; :6
-
Tidskriftsartikel (refereegranskat)
|
|
| 29. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :6
-
Tidskriftsartikel (refereegranskat)
|
|
| 30. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :6
-
Tidskriftsartikel (refereegranskat)
|
|
| 31. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :5
-
Tidskriftsartikel (refereegranskat)
|
|
| 32. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 33. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 34. |
- Aad, G., et al.
(författare)
-
- 2014
-
Tidskriftsartikel (refereegranskat)
|
|
| 35. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :6
-
Tidskriftsartikel (refereegranskat)
|
|
| 36. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :4
-
Tidskriftsartikel (refereegranskat)
|
|
| 37. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :4
-
Tidskriftsartikel (refereegranskat)
|
|
| 38. |
- Aad, G., et al.
(författare)
-
- 2014
-
Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :5, s. 1-52
-
Tidskriftsartikel (refereegranskat)
|
|
