Oligocene to Holocene erosion and glacial history in Marie Byrd Land, West Antarctica, inferred from exhumation of the Dorrel Rock intrusive complex and from volcano morphologies

Abstract

Research Article| July 01, 2006 Oligocene to Holocene erosion and glacial history in Marie Byrd Land, West Antarctica, inferred from exhumation of the Dorrel Rock intrusive complex and from volcano morphologies Sergio Rocchi; Sergio Rocchi 1Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, I56126 Pisa, Italy Search for other works by this author on: GSW Google Scholar Wesley E. LeMasurier; Wesley E. LeMasurier 2Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, Colorado 80309, USA Search for other works by this author on: GSW Google Scholar Gianfranco Di Vincenzo Gianfranco Di Vincenzo 3Istituto di Geoscienze e Georisorse (IGG), Consiglio Nazionale delle Ricerche (CNR), Via Moruzzi 1, I56124 Pisa, Italy Search for other works by this author on: GSW Google Scholar GSA Bulletin (2006) 118 (7-8): 991–1005. https://doi.org/10.1130/B25675.1 Article history received: 14 Jul 2004 rev-recd: 27 Jan 2006 accepted: 24 Mar 2006 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Sergio Rocchi, Wesley E. LeMasurier, Gianfranco Di Vincenzo; Oligocene to Holocene erosion and glacial history in Marie Byrd Land, West Antarctica, inferred from exhumation of the Dorrel Rock intrusive complex and from volcano morphologies. GSA Bulletin 2006;; 118 (7-8): 991–1005. doi: https://doi.org/10.1130/B25675.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Dorrel Rock intrusive complex in Marie Byrd Land, West Antarctica, consists of a coarse-grained gabbro cut by fine-grained benmoreite and trachyte dikes, all exposed in a single nunatak. It is the only exposed plutonic body related to late Cenozoic volcanism in this part of the West Antarctic rift system. Our 40Ar-39Ar age determinations indicate emplacement of the gabbro took place ca. 34 Ma, followed by dike injection at ca. 33.5 Ma. Marie Byrd Land volcanoes are all younger than ca. 27–29 Ma, and lie on a low-relief Late Cretaceous erosion surface that has been disrupted by block faulting and dome uplift since late Oligocene time. The erosion surface and overlying volcanoes are well preserved, but in contrast, we estimate that at least 3 km of overburden has been eroded away to expose the gabbro. This anomaly is most easily explained if most of the exhumation took place during a period of rapid erosion between ca. 34 Ma and 27–29 Ma and was followed by a pronounced decrease in erosion rate in the late Oligocene.Temporal anomalies in the degree of dissection of volcanic edifices, together with evidence from hydrovolcanic deposits, suggest there was an ice cap in Marie Byrd Land in the late Oligocene and that inland (200+ km) volcanoes were being actively eroded by glaciers until ca. 15 Ma. This is consistent with seismic and stratigraphic work in the Ross Sea, which documents at least two expansions of the West Antarctic Ice Sheet in the early mid-Miocene. We find that rates of glacial erosion in Marie Byrd Land increase significantly with nearness to the coast, and in nonresistant rock. Thus, the observation that inland volcanoes younger than ca. 15 Ma show no effects of glacial erosion, except for one with a basal section of weak tuffs, suggests that a transition from warm-based to cold-based glaciers took place around 15 Ma. These findings are similar to many of those reported from well-studied McMurdo Sound and Ross Sea localities, so they provide a wider regional picture of middle to late Cenozoic climatic and surficialgeologic events in Antarctica. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.