Alkalic to tholeiitic magmatism near a mid-ocean ridge: petrogenesis of the KR1 Seamount Trail adjacent to the Australian-Antarctic Ridge

• Main Authors: Sang-Bong Yi, Lee, Mi Jung, Park, Sung-Hyun, Nagao, Keisuke, Seunghee Han, Yang, Yun Seok, Hakkyum Choi, Jongmin Baek, Hirochika Sumino
• Format: Dataset
• Language: unknown
• Published: Taylor & Francis 2020
• Subjects: Biophysics; Cell Biology; Genetics; FOS Biological sciences; Molecular Biology; Physiology; Evolutionary Biology; 59999 Environmental Sciences not elsewhere classified; FOS Earth and related environmental sciences; 39999 Chemical Sciences not elsewhere classified; FOS Chemical sciences; Ecology; 69999 Biological Sciences not elsewhere classified; Marine Biology; Cancer; Inorganic Chemistry; 110309 Infectious Diseases; FOS Health sciences; Antarctic; Australian Antarctic Ridge; Antarc*
• Online Access: https://dx.doi.org/10.6084/m9.figshare.12854102.v1; https://tandf.figshare.com/articles/dataset/Alkalic_to_tholeiitic_magmatism_near_a_mid-ocean_ridge_petrogenesis_of_the_KR1_Seamount_Trail_adjacent_to_the_Australian-Antarctic_Ridge/12854102/1

Coexisting alkalic and tholeiitic basalt lavas has been identified in a seamount chain located near the Australian–Antarctic spreading ridge. The KR1 Seamount Trail (KR1 ST) is a series of volcanic seamounts extending to the southeast in the spreading direction of the Australian–Antarctic Ridge (AAR). We herein report Sr, Nd and Pb isotopic compositions and (U–Th)/He and K–Ar geochronology for dredge samples from the KR1 ST in order to evaluate mantle processes and the role of enriched components for alkalic to tholeiitic magma generation in this region. The KR1 ST is a medium-sized seamount chain that extends for ~60 km, has a maximum height of ~1600 m above the seafloor, and consists of alkaline basalts and tholeiites with formation ages of ~0.4 Ma to ≤1.3 Ma. The isotopic characteristics of the alkaline basalts ( 206 Pb/ 204 Pb = 19.52–19.91; 87 Sr/ 86 Sr = 0.7030–0.7033; 143 Nd/ 144 Nd = 0.5128–0.5130) from the KR1 ST reflect a dominant ‘PREMA (or FOZO)’ mantle component represented by radiogenic Pb and mildly enriched Sr and Nd isotopic compositions. On the other hand, the weak PREMA (FOZO)-affinity ( 206 Pb/ 204 Pb = 18.89–18.93; 87 Sr/ 86 Sr = 0.7028–0.7029; 143 Nd/ 144 Nd = ~0.5130; 3 He/ 4 He = 7.64 ± 0.13 (R/R A )) coupled with their enriched mid-ocean ridge basalt (E-MORB) characteristics of tholeiites from the KR1 ST largely overlap with the KR1 MORB composition. The potential source materials for the alkaline basalts are considered to be ancient, recycled oceanic crust (i.e. eclogite) as well as sub-KR1 depleted MORB mantle (DMM). Whereas the main source materials for the KR1 ST tholeiites are presumed to be the DMM-dominant lithology with minor recycled material. We interpret the KR1 ST as a submarine hotspot chain that was formed by asthenospheric upwelling and spreading processes that delivered fertile blobs of recycled oceanic crust to the sub-KR1 region. The fundamental reason for sub-KR1 upper mantle enrichment might be attributed to a mantle plume event that possibly occurred prior to the formation of the KR1 ST.