FN Archimer Export Format PT J TI The internal structure and geodynamics of Mars inferred from a 4.2-Gyr zircon record BT AF COSTA, Maria M. JENSEN, Ninna K. BOUVIER, Laura C. CONNELLY, James N. MIKOUCHI, Takashi HORSTWOOD, Matthew S. A. SUURONEN, Jussi-Petteri MOYNIER, Frederic DENG, Zhengbin AGRANIER, Arnaud MARTIN, Laure A. J. JOHNSON, Tim E. NEMCHIN, Alexander A. BIZZARRO, Martin AS 1:1;2:1;3:1;4:1;5:2;6:3;7:4;8:5;9:5;10:6,7;11:8;12:9;13:9;14:1,5; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;13:;14:; C1 Univ Copenhagen, Globe Inst, Ctr Star & Planet Format, DK-1350 Copenhagen, Denmark. Univ Tokyo, Univ Museum, Tokyo 1180033, Japan. British Geol Survey, Geochronol & Tracers Facil, Nicker Hill, Nottingham NG12 5GG, England. European Synchrotron Radiat Facil, F-38000 Grenoble, France. Univ Paris, Inst Phys Globe Paris, F-75005 Paris, France. Univ Bretagne Occidentale, Lab Geosci Ocean UMR CNRS 6538, Pl Nicolas Copernic, F-29280 Plouzane, France. Univ Bretagne Occidentale, Inst Univ Europeen Mer, Pl Nicolas Copernic, F-29280 Plouzane, France. Univ Western Australia, Ctr Microscopy Characterizat & Anal, Perth, WA 6009, Australia. Curtin Univ, Sch Earth & Planetary Sci, Perth, WA 6845, Australia. C2 UNIV COPENHAGEN, DENMARK UNIV TOKYO, JAPAN BRITISH GEOL SURVEY, UK ESRF, FRANCE UNIV PARIS, FRANCE UBO, FRANCE UBO, FRANCE UNIV WESTERN AUSTRALIA, AUSTRALIA UNIV CURTIN, AUSTRALIA UM LGO IF 11.205 TC 31 UR https://archimer.ifremer.fr/doc/00686/79847/82677.pdf https://archimer.ifremer.fr/doc/00686/79847/82678.pdf https://archimer.ifremer.fr/doc/00686/79847/82679.xlsx LA English DT Article DE ;Mars;meteorites;zircon;geodynamics AB Combining U-Pb ages with Lu-Hf data in zircon provides insights into the magmatic history of rocky planets. The Northwest Africa (NWA) 7034/7533 meteorites are samples of the southern highlands of Mars containing zircon with ages as old as 4476.3 +/- 0.9 Ma, interpreted to reflect reworking of the primordial Martian crust by impacts. We extracted a statistically significant zircon population (n = 57) from NWA 7533 that defines a temporal record spanning 4.2 Gyr. Ancient zircons record ages from 4485.5 +/- 2.2 Ma to 4331.0 +/- 1.4 Ma, defining a bimodal distribution with groupings at 4474 +/- 10 Ma and 4442 +/- 17 Ma. We interpret these to represent intense bombardment episodes at the planet's surface, possibly triggered by the early migration of gas giant planets. The unradiogenic initial Hf-isotope composition of these zircons establishes that Mars's igneous activity prior to similar to 4.3 Ga was limited to impact-related reworking of a chemically enriched, primordial crust. A group of younger detrital zircons record ages from 1548.0 +/- 8.8 Ma to 299.5 +/- 0.6 Ma. The only plausible sources for these grains are the temporally associated Elysium and Tharsis volcanic provinces that are the expressions of deep-seated mantle plumes. The chondritic-like Hf-isotope compositions of these zircons require the existence of a primitive and convecting mantle reservoir, indicating that Mars has been in a stagnant-lid tectonic regime for most of its history. Our results imply that zircon is ubiquitous on the Martian surface, providing a faithful record of the planet's magmatic history. PY 2020 PD DEC SO Proceedings Of The National Academy Of Sciences Of The United States Of America SN 0027-8424 PU Natl Acad Sciences VL 117 IS 49 UT 000598977500021 BP 30973 EP 30979 DI 10.1073/pnas.2016326117 ID 79847 ER EF