FN Archimer Export Format PT J TI Assessing Origins of End-Triassic Tholeiites From Eastern North America Using Hafnium Isotopes BT AF ELKINS, Lynne J. MEYZEN, Christine M. CALLEGARO, Sara MARZOLI, Andrea BIZIMIS, Michael AS 1:1;2:2;3:3;4:2;5:4; FF 1:;2:;3:;4:;5:; C1 Univ Nebraska, Earth & Atmospher Sci, Lincoln, NE USA. Univ Padua, Dipartimento Geosci, Padua, Italy. Univ Oslo, Ctr Earth Evolut & Dynam, Oslo, Norway. Univ South Carolina, Sch Earth Ocean & Environm, Columbia, SC USA. C2 UNIV NEBRASKA, USA UNIV PADUA, ITALY UNIV OSLO, NORWAY UNIV SOUTH CAROLINA, USA IF 2.623 TC 6 UR https://archimer.ifremer.fr/doc/00687/79862/82716.pdf https://archimer.ifremer.fr/doc/00687/79862/82717.pdf https://archimer.ifremer.fr/doc/00687/79862/82718.xlsx LA English DT Article DE ;basalt;CAMP;hafnium;rift;LIP;isotope AB The driving processes responsible for producing the Central Atlantic Magmatic Province, the Large Igneous Province associated with end-Triassic rifting of Pangea, remain largely debated. Because their compositions encompass most of the Central Atlantic basalt spectrum, tholeiites from southern Eastern North America are considered pivotal for identifying magma origins. New(176)Hf/Hf-177 measurements for 201 Ma Eastern North American tholeiites dominantly record a local petrogenetic history. Their epsilon(Hf)ratios, corrected to an emplacement age of 201 Ma (-7.85 to +5.86), form a positive but shallowly sloped array slightly deviating from the terrestrial array on a epsilon(Hf)versus epsilon(Nd)diagram. Comparison of(176)Hf/Hf-177 to other isotope ratios and trace elements helps to rule out several petrogenetic scenarios, particularly mixing of melts from global depleted or enriched mantle components. In contrast, partial melting of subduction-metasomatized mantle can explain the parental magma composition for southern Eastern North America. Such metasomatism likely occurred during Paleozoic subduction around Pangea and may have been dominated by sediment-derived fluid reactions. The observed(176)Hf/Hf-177 versus(143)Nd/Nd-144 array may reflect subsequent assimilation of lower continental crust, perhaps together with limited direct melting of recycled continental crust in the asthenosphere. The proposed recycling scenario does not specifically support or preclude a mantle plume origin for the Central Atlantic Magmatic Province but instead points toward the presence of a distinct local mantle source and crustal assimilation processes during magma transport. Detailed understanding of these local effects is needed in order to more accurately understand the origins of Large Igneous Provinces. PY 2020 PD JUL SO Geochemistry Geophysics Geosystems SN 1525-2027 PU Amer Geophysical Union VL 21 IS 6 UT 000545699900021 DI 10.1029/2020GC008999 ID 79862 ER EF