Zircon Xenocrysts From Easter Island (Rapa Nui) Reveal Hotspot Activity Since the Middle Jurassic DOI Creative Commons
Yamirka Rojas‐Agramonte, Natalia Pardo, Douwe J.J. van Hinsbergen

и другие.

AGU Advances, Год журнала: 2024, Номер 5(5)

Опубликована: Окт. 1, 2024

Abstract We report the finding of mantle‐derived zircon grains retrieved from red soils, regoliths, and beach sands Easter Island, that are much older than island volcanism (0–2.5 Ma) its underlying lithosphere (Pliocene, 3–4.8 Ma). A large population 0–165 Ma old zircons have coherent oxygen (δ 18 O 3.8–5.9‰) hafnium (εHf (t) +3.5–+12.5) mantle isotopic signatures. These results consistent with crystallization plume‐related melts. In addition, a chemically diverse ages Paleozoic to Archean was found. populations enigmatic but they could represent remnants ancient subducted sediments. Meanwhile, ∼0–165 is interpreted as plume‐derived, suggesting hotspot started at least ∼165 ago. spike ∼164–160 Large Igneous Province (LIP) stage upon first arrival plume. use plate reconstructions show such LIP would formed on Phoenix Plate below Antarctic Peninsula around 100–105 Ma. There, subduction offer solution for Palmer Land deformation event, previously proposed result collision an unknown indenter. The here‐reported “ghost” prolonged activity suggests fragments plume ambient sub‐lithospheric stored re‐sampled xenocrysts due convective (re)circulation scale head. Our study demonstrates how geochronology geochemistry provide novel insights into global‐scale geodynamics, offering new perspectives dynamics plumes activity.

Язык: Английский

Biogeography of the Juan Fernández Archipelago: vicariance versus long-distance dispersal? DOI
Jason R. Ali, Tod F. Stuessy

Biological Journal of the Linnean Society, Год журнала: 2025, Номер 145(1)

Опубликована: Май 1, 2025

Abstract The biota of the Juan Fernández Islands (SE Pacific) provides important information on key evolutionary and biogeographical phenomena. However, a long-standing matter contention concerns how archipelago’s various lineages arrived there. Was it via former landbridges/exotic terranes, or did involve long-distance dispersal? We address issue through two-pronged review-synthesis, one focusing geology, other biology (using 207 clades from four groups: angiosperms, ferns, landbirds, coastal fishes). Regarding first, critical observation relates to emergence history as only since c. 4.7 Mya has there been an uninterrupted sequence land-surfaces in region. reflects this with bulk having definitely last few million years. That said, 5% groups have ‘colonization intervals’ that extend back >20 Mya, but these are probably artefacts caused by loss intervening off-archipelago lineages, which results their notably old stem ages. Concerning sourcing, landbirds plants mainly South America, whereas fishes strong connections western insular Pacific. Collectively, geological biological evidence indicates ancestors colonized geologically recently, exclusively dispersal.

Язык: Английский

Процитировано

0
Zircon Xenocrysts From Easter Island (Rapa Nui) Reveal Hotspot Activity Since the Middle Jurassic DOI Creative Commons
Yamirka Rojas‐Agramonte, Natalia Pardo, Douwe J.J. van Hinsbergen

и другие.

AGU Advances, Год журнала: 2024, Номер 5(5)

Опубликована: Окт. 1, 2024

Abstract We report the finding of mantle‐derived zircon grains retrieved from red soils, regoliths, and beach sands Easter Island, that are much older than island volcanism (0–2.5 Ma) its underlying lithosphere (Pliocene, 3–4.8 Ma). A large population 0–165 Ma old zircons have coherent oxygen (δ 18 O 3.8–5.9‰) hafnium (εHf (t) +3.5–+12.5) mantle isotopic signatures. These results consistent with crystallization plume‐related melts. In addition, a chemically diverse ages Paleozoic to Archean was found. populations enigmatic but they could represent remnants ancient subducted sediments. Meanwhile, ∼0–165 is interpreted as plume‐derived, suggesting hotspot started at least ∼165 ago. spike ∼164–160 Large Igneous Province (LIP) stage upon first arrival plume. use plate reconstructions show such LIP would formed on Phoenix Plate below Antarctic Peninsula around 100–105 Ma. There, subduction offer solution for Palmer Land deformation event, previously proposed result collision an unknown indenter. The here‐reported “ghost” prolonged activity suggests fragments plume ambient sub‐lithospheric stored re‐sampled xenocrysts due convective (re)circulation scale head. Our study demonstrates how geochronology geochemistry provide novel insights into global‐scale geodynamics, offering new perspectives dynamics plumes activity.

Язык: Английский

Процитировано

0