Abstract
In the Ordovician limestone of the Thorsberg quarry (South Sweden), about 130 meteorites have been found. Among the extraterrestrial material, several terrestrial Cr-spinels and zircons have been found too. In particular, in the interval 416–447 cm above the Arkeologen bed, terrestrial Cr-spinels, compositionally different from previous studied Cr-spinels of the same sequence, are present. Previous studies on zircon provided depositional ages that range from 464.22 ± 0.37 Ma to 465.01 ± 0.26 Ma. The trace element content of zircons suggests different possible source rocks. In fact, zircons from the oldest ash layer resemble those from dolerite, while those in the youngest layers are similar to zircons commonly found in granitoids, with more than 65% wt. SiO2. The chemistry of Cr-spinels suggests a strong alteration, so that it is difficult to assign them to a specific area, however they recall the chemistry of altered spinels from ophiolitic occurrences (among other possibilities). The geological setting of the Laurentia and Baltica areas, including the description of basalts to rhyolite association and the presence of ophiolitic slices, makes us confident about the derivation of these zircons and Cr-spinels from those areas.
Highlights
About a quarter of all meteorites falling on Earth today originate from the breakup of the L-chondrite parent body ∼466 Ma ago, the largest documented breakup in the asteroid belt in the past ∼3 Ga
The Österplana 065 seems to be a fragment of the impactor that broke up the L-chondrite parent body that, according to [8], was shown to be the first documented example of a meteorite type that does not fall on Earth today, because its parent body has been consumed by collisions
Cr-Spinels usually high; more than 75% of the studied spinels present Cr2O3 higher than 30 analysed are essentially chromites in form, composition
Summary
About a quarter of all meteorites falling on Earth today originate from the breakup of the L-chondrite parent body ∼466 Ma ago, the largest documented breakup in the asteroid belt in the past ∼3 Ga. A systematic search for fossil meteorites was initiated in the Thorsberg quarry in southern Sweden in the 1990s [1,2]. The Österplana 065 seems to be a fragment of the impactor that broke up the L-chondrite parent body that, according to [8], was shown to be the first documented example of a meteorite type that does not fall on Earth today, because its parent body has been consumed by collisions. In the sediments containing fossil meteorites, there are abundant L-chondritic chromite grains [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
