Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>The distribution of water in the Moon’s interior carries implications for the origin of the Moon<jats:sup>1</jats:sup>, the crystallization of the lunar magma ocean<jats:sup>2</jats:sup> and the duration of lunar volcanism<jats:sup>2</jats:sup>. The Chang’e-5 mission returned some of the youngest mare basalt samples reported so far, dated at 2.0 billion years ago (Ga)<jats:sup>3</jats:sup>, from the northwestern Procellarum KREEP Terrane, providing a probe into the spatiotemporal evolution of lunar water. Here we report the water abundances and hydrogen isotope compositions of apatite and ilmenite-hosted melt inclusions from the Chang’e-5 basalts. We derive a maximum water abundance of 283 ± 22 μg g<jats:sup>−1</jats:sup> and a deuterium/hydrogen ratio of (1.06 ± 0.25) × 10<jats:sup>–</jats:sup><jats:sup>4</jats:sup> for the parent magma. Accounting for low-degree partial melting of the depleted mantle followed by extensive magma fractional crystallization<jats:sup>4</jats:sup>, we estimate a maximum mantle water abundance of 1–5 μg g<jats:sup>−1</jats:sup>, suggesting that the Moon’s youngest volcanism was not driven by abundant water in its mantle source. Such a modest water content for the Chang’e-5 basalt mantle source region is at the low end of the range estimated from mare basalts that erupted from around 4.0 Ga to 2.8 Ga (refs. <jats:sup>5,6</jats:sup>), suggesting that the mantle source of the Chang’e-5 basalts had become dehydrated by 2.0 Ga through previous melt extraction from the Procellarum KREEP Terrane mantle during prolonged volcanic activity.</jats:p>

<jats:title>Abstract</jats:title><jats:p>The Moon has a magmatic and thermal history that is distinct from that of the terrestrial planets<jats:sup>1</jats:sup>. Radioisotope dating of lunar samples suggests that most lunar basaltic magmatism ceased by around 2.9–2.8 billion years ago (Ga)<jats:sup>2,3</jats:sup>, although younger basalts between 3 Ga and 1 Ga have been suggested by crater-counting chronology, which has large uncertainties owing to the lack of returned samples for calibration<jats:sup>4,5</jats:sup>. Here we report a precise lead–lead age of 2,030 ± 4 million years ago for basalt clasts returned by the Chang’e-5 mission, and a <jats:sup>238</jats:sup>U/<jats:sup>204</jats:sup>Pb ratio (<jats:italic>µ</jats:italic> value)<jats:sup>6</jats:sup> of about 680 for a source that evolved through two stages of differentiation. This is the youngest crystallization age reported so far for lunar basalts by radiometric dating, extending the duration of lunar volcanism by approximately 800–900 million years. The <jats:italic>µ</jats:italic> value of the Chang’e-5 basalt mantle source is within the range of low-titanium and high-titanium basalts from Apollo sites (<jats:italic>µ</jats:italic> value of about 300–1,000), but notably lower than those of potassium, rare-earth elements and phosphorus (KREEP) and high-aluminium basalts<jats:sup>7</jats:sup> (<jats:italic>µ</jats:italic> value of about 2,600–3,700), indicating that the Chang’e-5 basalts were produced by melting of a KREEP-poor source. This age provides a pivotal calibration point for crater-counting chronology in the inner Solar System and provides insight on the volcanic and thermal history of the Moon.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Mare volcanics on the Moon are the key record of thermo-chemical evolution throughout most of lunar history<jats:sup>1–3</jats:sup>. Young mare basalts—mainly distributed in a region rich in potassium, rare-earth elements and phosphorus (KREEP) in Oceanus Procellarum, called the Procellarum KREEP Terrane (PKT)<jats:sup>4</jats:sup>—were thought to be formed from KREEP-rich sources at depth<jats:sup>5–7</jats:sup>. However, this hypothesis has not been tested with young basalts from the PKT. Here we present a petrological and geochemical study of the basalt clasts from the PKT returned by the Chang’e-5 mission<jats:sup>8</jats:sup>. These two-billion-year-old basalts are the youngest lunar samples reported so far<jats:sup>9</jats:sup>. Bulk rock compositions have moderate titanium and high iron contents  with KREEP-like rare-earth-element and high thorium concentrations. However, strontium–neodymium isotopes indicate that these basalts were derived from a non-KREEP mantle source. To produce the high abundances of rare-earth elements and thorium, low-degree partial melting and extensive fractional crystallization are required. Our results indicate that the KREEP association may not be a prerequisite for young mare volcanism. Absolving the need to invoke heat-producing elements in their source implies a more sustained cooling history of the lunar interior to generate the Moon’s youngest melts.</jats:p>