H2020Индивидуална стипендия2018–2021

Crater Chron · Understanding the role of impact cratering in Earth's evolution through state-of-the-art geochronology

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2018-07-01 → 2021-02-28
Финансиране от ЕС: 173 857 €
Участници: 1
Схема: MSCA-IF-EF-ST

Линиите свързват координатора с партньорите.

Накратко на български

Времето на образуване на импактните кратери от астероиди и комети се определя чрез анализ на минерала циркон. Това помага да се разбере как тези сблъсъци са повлияли на развитието на живота, тектониката и минералните находища на Земята.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Understanding the role of impact cratering in Earth's evolution through state-of-the-art geochronology

Impact cratering – the collision of asteroids or comets with planetary bodies such as the Moon and Earth – is a fundamental geological process that has played a primary role in the evolution of the inner Solar System. However, a major impediment to fully understanding the role of impacts in Earth’s history has been the poor geochronological constraints on most of Earth’s impact structures. Of the approximately 200 known impact structures on Earth – that range from less than 1 km to over 300 km in diameter – only about 15% are accurately and precisely dated. Simply put, we don’t know when most of Earth’s impact structures formed. The overall objectives of this project were to (i) take advantage of recent advances in our understanding of how rocks and minerals record impact ages and the analytical techniques used to determine such ages to refine existing, and develop new, techniques for dating impact structures; (ii) apply these newly developed protocols to dating impact structures whose precise formation age may have broad scientific significance, such as impact structures that have been proposed as having contributed to mass extinctions. Impacts hold a rare position in science in that they capture the imagination of the general public while also being scientifically important. The project, and our broad understanding of the role of impacts in Earth’s history, is important to society given the proposed role that impacts have played in, for example, the development of life on Earth (both its origin and its fate in mass extinctions), the onset of tectonic processes, and the formation of economic mineral deposits. The project focused on dating impact structures with a mineral that is almost ubiquitous in the Earth’s crust – zircon. Zircon can form when molten rock cools and solidifies, and it can thus be used to date this process (see image on left in attached figure). Zircon can also be affected by a hypervelocity impact and this project explored how disturbed zircon grains can record the age of the impact event (see image on right in attached figure). A standard protocol for dating impact structures with state-of-the-art analysis of so-called “shocked zircon” was developed at the host institution. This was applied to an impact structure that had previous been dating using another technique (Ar/Ar analysis), offering one of the first insights into how the different techniques complement each other and record the cooling of an impact structure over hundreds of thousands of years after the initial impact event. After demonstrating the utility of the method in dating impact structures, it was applied to other impact structures in collaboration with researchers around the world. Some of these ages have already been published in peer-reviewed journals with several more publications expected.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

The role of impact cratering in the evolution of Earth’s geosphere and biosphere is greatly underappreciated in the field of modern geoscience. Although years of research on terrestrial impact craters have contributed greatly to our knowledge of impact cratering processes and products, the available geochronological data represents a major and fundamental gap in our knowledge. Of the ca. 190 confirmed impact craters on Earth only ca. 10 % are considered to be accurately and precisely dated. Consequently, the vast majority of terrestrial craters cannot be correlated with each other or with other geological events such as mass extinctions. Here we propose to take timely advantage of recent advances both in our understanding of how the mineral zircon (ZrSiO4) can record the age of an impact event and in the analytical techniques used to determine such U-Pb ages to significantly and efficiently grow our database of accurately and precisely dated terrestrial impact craters. Specifically, this project will focus on craters whose precise formation age may have broad implications for Earth’s history. Among others, these include the Siljan impact crater, Sweden, which has been proposed as a contributing factor to the late Devonian mass extinction event, one of the largest mass extinctions in the Phanerozoic, and the Suavjärvi impact crater, northwest Russia. The latter has a very poorly constrained age of between 2.7 and 2.2 Ga but is likely to be the oldest impact crater on Earth with confirmation of an impact age in this study. This innovative action will couple recent advances in microstructural characterisation of shocked zircon (EBSD analysis and Raman mapping) with cutting-edge U-Pb analytical techniques not previously applied to shocked grains (including high resolution, fully quantitative U-Pb age mapping by SIMS and high precision multiple step leaching CA-ID-TIMS) and establish efficient protocols for future dating of craters on Earth and other planetary bodies.

Оригинален текст от CORDIS (на английски).

Участници

NATURHISTORISKA RIKSMUSEET · StockholmКоординаторШвеция