Sr-Pb-Nd-Hf isotopes and 40Ar/39Ar ages reveal a Hawaii-Emperor-style bend in the Rurutu hotspot

Current Pacific absolute plate motion (APM) models include two major, long-lived hotspot tracks: the similar to 80 Ma Hawaii-Emperor and similar to 79 Ma Louisville seamount tracks. Prior to similar to 50 Ma, these two tracks show significant inter-hotspot drift, most likely due to a strong southern motion of the Hawaiian plume. With the addition of a third long-lived Pacific hotspot track, featuring a well-constrained hotspot location and a Hawaii-Emperor-style bend, we can achieve a more robust evaluation of the relationship between APM models and inter-hotspot drift. Such a candidate exists in the Rurutu hotspot track. The youngest volcanism (similar to 10 to 0.2 Ma) associated with the Rurutu hotspot is located in the Cook-Austral Islands and is known as the Atiu or Young Rurutu trend. Here we show with 40Ar/39Ar ages and Sr-Pb-Nd-Hf isotopic fingerprints that islands and seamounts ranging between similar to 70 to 40 Ma fit the compositional trend and APM model-predicted locations of the Rurutu hotspot. The Rurutu hotspot has a distinctive HIMU- to FOZO-like composition, characterized by high Pb-206/Pb-204 (>= 20.0) and low Sr-87/Sr-86 (<= 0.704) ratios. HIMU is a rare composition, found in only two other hotspots worldwide. Uniquely, elevated Rurutu Pb-208/Pb-204 ratios relative to Pb-206/Pb-204 define a steeper regression that more closely reproduces the Northern Hemisphere Reference Line than the shallower regression defined by traditional HIMU. Rurutu also is the only HIMU-type hotspot known to continue into the West Pacific, allowing its unique composition to effectively be used as a fingerprint. The Rurutu signature can be traced through non-Samoan interloper seamounts in the Samoan region, to a hotspot bend in the southern Tuvalu Islands, continuing through the 74 to 63 Ma Gilbert Ridge and the 120 to 78 Ma Wake seamounts. However, precisely locating the Hawaii-Emperor style bend in Rurutu is complicated by the younger Samoan hotspot partially overlapping the Rurutu hotspot track, and Cretaceous volcanic structures predating regional Rurutu volcanism. Therefore, we present a computational method that tests a range of preexisting APM models, all generating Hawaii-Emperor style bend locations for Rurutu within error of each other. Our results confirm the presence of a third major hotspot track in the Pacific as originally proposed by W.J. Morgan (1972), with a 50.5-49.0 Ma bend at 178.48 degrees E and 8.56 degrees S. Paleomagnetic data for Hawaii indicate that changes in southern hotspot motion may explain its bend, while negligible latitudinal motion in Louisville and an unchanging distance to Rurutu (Tarduno et al., 2003; Koppers et al., 2012; Konrad et al., 2018) are consistent with subduction-driven plume motion explaining the Hawaii-Emperor bend. The presence of a defined similar to 135 degrees bend in the Rurutu hotspot track, coupled with minimal inferred latitudinal motion at that time (Konrad et al., 2018), leaves room for a small change in Pacific plate motion at 50 Ma. (C) 2018 Elsevier B.V. All rights reserved. Current Pacific absolute plate motion (APM) models include two major, long-lived hotspot tracks: the similar to 80 Ma Hawaii-Emperor and similar to 79 Ma Louisville seamount tracks. Prior to similar to 50 Ma, these two tracks show significant inter-hotspot drift, most likely due to a strong southern motion of the Hawaiian plume. With the addition of a third long-lived Pacific hotspot track, featuring a well-constrained hotspot location and a Hawaii-Emperor-style bend, we can achieve a more robust evaluation of the relationship between APM models and inter-hotspot drift. Such a candidate exists in the Rurutu hotspot track. The youngest volcanism (similar to 10 to 0.2 Ma) associated with the Rurutu hotspot is located in the Cook-Austral Islands and is known as the Atiu or Young Rurutu trend. Here we show with 40Ar/39Ar ages and Sr-Pb-Nd-Hf isotopic fingerprints that islands and seamounts ranging between similar to 70 to 40 Ma fit the compositional trend and APM model-predicted locations of the Rurutu hotspot. The Rurutu hotspot has a distinctive HIMU- to FOZO-like composition, characterized by high Pb-206/Pb-204 (>= 20.0) and low Sr-87/Sr-86 (<= 0.704) ratios. HIMU is a rare composition, found in only two other hotspots worldwide. Uniquely, elevated Rurutu Pb-208/Pb-204 ratios relative to Pb-206/Pb-204 define a steeper regression that more closely reproduces the Northern Hemisphere Reference Line than the shallower regression defined by traditional HIMU. Rurutu also is the only HIMU-type hotspot known to continue into the West Pacific, allowing its unique composition to effectively be used as a fingerprint. The Rurutu signature can be traced through non-Samoan interloper seamounts in the Samoan region, to a hotspot bend in the southern Tuvalu Islands, continuing through the 74 to 63 Ma Gilbert Ridge and the 120 to 78 Ma Wake seamounts. However, precisely locating the Hawaii-Emperor style bend in Rurutu is complicated by the younger Samoan hotspot partially overlapping the Rurutu hotspot track, and Cretaceous volcanic structures predating regional Rurutu volcanism. Therefore, we present a computational method that tests a range of preexisting APM models, all generating Hawaii-Emperor style bend locations for Rurutu within error of each other. Our results confirm the presence of a third major hotspot track in the Pacific as originally proposed by W.J. Morgan (1972), with a 50.5-49.0 Ma bend at 178.48 degrees E and 8.56 degrees S. Paleomagnetic data for Hawaii indicate that changes in southern hotspot motion may explain its bend, while negligible latitudinal motion in Louisville and an unchanging distance to Rurutu (Tarduno et al., 2003; Koppers et al., 2012; Konrad et al., 2018) are consistent with subduction-driven plume motion explaining the Hawaii-Emperor bend. The presence of a defined similar to 135 degrees bend in the Rurutu hotspot track, coupled with minimal inferred latitudinal motion at that time (Konrad et al., 2018), leaves room for a small change in Pacific plate motion at 50 Ma. (C) 2018 Elsevier B.V. All rights reserved. Current Pacific absolute plate motion (APM) models include two major, long-lived hotspot tracks: the similar to 80 Ma Hawaii-Emperor and similar to 79 Ma Louisville seamount tracks. Prior to similar to 50 Ma, these two tracks show significant inter-hotspot drift, most likely due to a strong southern motion of the Hawaiian plume. With the addition of a third long-lived Pacific hotspot track, featuring a well-constrained hotspot location and a Hawaii-Emperor-style bend, we can achieve a more robust evaluation of the relationship between APM models and inter-hotspot drift. Such a candidate exists in the Rurutu hotspot track. The youngest volcanism (similar to 10 to 0.2 Ma) associated with the Rurutu hotspot is located in the Cook-Austral Islands and is known as the Atiu or Young Rurutu trend. Here we show with 40Ar/39Ar ages and Sr-Pb-Nd-Hf isotopic fingerprints that islands and seamounts ranging between similar to 70 to 40 Ma fit the compositional trend and APM model-predicted locations of the Rurutu hotspot. The Rurutu hotspot has a distinctive HIMU- to FOZO-like composition, characterized by high Pb-206/Pb-204 (>= 20.0) and low Sr-87/Sr-86 (<= 0.704) ratios. HIMU is a rare composition, found in only two other hotspots worldwide. Uniquely, elevated Rurutu Pb-208/Pb-204 ratios relative to Pb-206/Pb-204 define a steeper regression that more closely reproduces the Northern Hemisphere Reference Line than the shallower regression defined by traditional HIMU. Rurutu also is the only HIMU-type hotspot known to continue into the West Pacific, allowing its unique composition to effectively be used as a fingerprint. The Rurutu signature can be traced through non-Samoan interloper seamounts in the Samoan region, to a hotspot bend in the southern Tuvalu Islands, continuing through the 74 to 63 Ma Gilbert Ridge and the 120 to 78 Ma Wake seamounts. However, precisely locating the Hawaii-Emperor style bend in Rurutu is complicated by the younger Samoan hotspot partially overlapping the Rurutu hotspot track, and Cretaceous volcanic structures predating regional Rurutu volcanism. Therefore, we present a computational method that tests a range of preexisting APM models, all generating Hawaii-Emperor style bend locations for Rurutu within error of each other. Our results confirm the presence of a third major hotspot track in the Pacific as originally proposed by W.J. Morgan (1972), with a 50.5-49.0 Ma bend at 178.48 degrees E and 8.56 degrees S. Paleomagnetic data for Hawaii indicate that changes in southern hotspot motion may explain its bend, while negligible latitudinal motion in Louisville and an unchanging distance to Rurutu (Tarduno et al., 2003; Koppers et al., 2012; Konrad et al., 2018) are consistent with subduction-driven plume motion explaining the Hawaii-Emperor bend. The presence of a defined similar to 135 degrees bend in the Rurutu hotspot track, coupled with minimal inferred latitudinal motion at that time (Konrad et al., 2018), leaves room for a small change in Pacific plate motion at 50 Ma. (C) 2018 Elsevier B.V. All rights reserved.