The role of crustal and mantle sources in the genesis of granitoids of the Antarctic Peninsula and adjacent crustal blocks
Magmatic rocks from the Antarctic Peninsula show marked variations in isotope composition, which reflect changes in the geodynamic evolution of the peninsula through time. Most Antarctic Peninsula granitoids formed as a result of subduction: they fall on well‐defined trends on plots of ϵNd, 207Pb/204Pb and δ18O against 87Sr/86Sri, between a component derived from subduction‐modified mantle or juvenile basaltic underplate (ϵNdi>6, 207Pb/204Pb=15.61, δ18O=5.5‰, 87Sr/86Sr<0.704) and an end‐member interpreted as a melt of Proterozoic lower crust ( ϵNd=−7, 207Pb/204Pb=15.67, δ18O=10‰,87Sr/86Sr=0.709). A small group of granitoids, emplaced before or during Gondwana break‐up, plot on distinct trends towards high 87Sr/86Sri compositions, reflecting mixing between melts derived from Proterozoic lower crust and melts of middle–upper crustal rocks (ϵNdi=−9, 207Pb/204Pb=15.64, δ18O=10‰, 87Sr/86Sr=0.726), with little or no input of new material derived from the mantle or from juvenile basaltic underplate. These granitoids are thought to have formed as a result of crustal attenuation during the initial rifting phase of Gondwana break‐up. Similar trends are shown by data from granitoids of the adjacent crustal blocks of West Antarctica. The isotope data suggest that an enriched Ferrar/Karoo‐type lithosphere was not involved in the genesis of granitoids of the Antarctic Peninsula or of the Ellsworth–Whitmore Mountains crustal block.
This website uses cookies to improve your experience. We'll assume you're okay with this, but you can opt-out if you wish.AcceptRead more
Privacy & Cookies Policy
Privacy Overview
This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.