Outline of the structural and tectonic history of the Ellsworth Mountains-Thiel Mountains Ridge, West Antarctica

The Ellsworth Mountains‐Thiel Mountains ridge and adjoining areas are divided into three tectonic provinces: (1) Haag Nunataks, (2) Thiel Mountains, and (3) Ellsworth‐Whitmore Mountains crustal block. Haag Nunataks are part of a Precambrian tectonic province the overall extent of which is not clearly known. The Thiel Mountains are part of a distinctive Transantarctic Mountains province that is separated by a major tectonic break from deformed sedimentary rocks of the Ellsworth‐Whitmore Mountains crustal block. The crustal block is divided, on the basis of a detailed structural analysis, into two domains: the Ellsworth and Marginal domains. The sedimentary rocks throughout the Ellsworth domain are correlated with parts of the Paleozoic succession forming the Ellsworth Mountains themselves. These rocks were all deformed by a single phase of northwest‐southeast trending structures, whereas in the Marginal domain the fold history is more complex and structures trend northeast‐southwest. The tectonic significance of the Marginal domain is discussed but is not clearly understood. Mount Woollard has a unique lithological association with the Ellsworth‐Whitmore Mountains crustal block; it consists of paragneiss and pegmatite of possible Middle Jurassic age and has a structural trend parallel to the Ellsworth domain structures.