Conglomerados del Paleógeno en Tierra del Fuego: Evidencias de discordancia entre el Cretácico Superior-(Paleoceno) y el Eoceno de Cuenca Austral.

MARTINIONI, D.R.; OLIVERO, E. B.; SUSANA PALAMARCZUK

PUBLICACION ESPECIAL - ASOCIACION PALEONTOLOGICA ARGENTINA

ASOCIACIÓN PALEONTOLÓGICA ARGENTINA

Lugar: Buenos Aires; Año: 1998 vol. 5 p. 129 - 136

0328-347X

<!-- /* Font Definitions */ @font-face {font-family:"ＭＳ 明朝"; mso-font-charset:78; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:-536870145 1791491579 18 0 131231 0;} @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:-536870145 1107305727 0 0 415 0;} @font-face {font-family:Cambria; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:-536870145 1073743103 0 0 415 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"ＭＳ 明朝"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"ＭＳ 明朝"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} @page WordSection1 {size:595.0pt 842.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.WordSection1 {page:WordSection1;} --> A 40m thick Paleogene conglomerate marine succession located just northeast of Hito XIX is described for the first time. A faulted block of Aptian-Albian strata rests on a north vergent reverse fault above this succession which, in turn is thrusted against younger rocks on its northern front. Coarse polymictic orthoconglomerate is dominant, with minor interbedded pebbly sandstone, fine sandstone and mudstone. Conglomerate clast imbrication indicates northwest-directed paleocurrents. Prevalent clasts are black shale and acidic volcanics; less common are bluish-gray sandstone, calcareous concretions, quartz and granite.  Autochtonous Eocene and reworked Late Cretaceous (Santonian to Campanian) dinocust were recovered from the interbedded fine-grained facies. To the south-southeast, in the Sierra del Apen, similar rocks lay disconformably on basal Cenozoic and on uppermost Cretaceous rocks, suggesting an unconformity with a regional extension. To the east, near lago Yehuin, a conglomerate succession previously assigned to the Beauvoir Formation (Lower Cretaceous), also bears Paleogene microfossils. Lithofacies and fossil evidence suggest that these conglomerates correlate with the Chilean Ballena Formation (Eocene(. Based on subsurface data, the latter unit was interpreted as fan-delta deposits fed from an uplifted area located to the south. Stratigraphic relationships, clast composition, paleocurrents, and inferred correlation of these deposits wirh the Ballena Formation are all consistent and indicate that they represent a major break in the sedimentation of the Austral Basin following a marked tectonic uplift of Upper Mesozoic rocks.