Timing and stratigraphic evolution of a Miocene foreland unroofing sequence in the Austral-Magallanes Basin during Southern Patagonian Andes uplift

ARAMENDÍA, I.; CUITIÑO, J.I.; GHIGLIONE, MATÍAS C.; BOUZA, P.

JOURNAL OF THE GEOLOGICAL SOCIETY

GEOLOGICAL SOC PUBL HOUSE

Lugar: Londres; Año: 2022

0016-7649

Detrital zircon U-Pbgeochronology is a widely used technique for interpreting sedimentaryprovenance in basin systems. This, combined with detailed sedimentaryfacies interpretation and stratigraphy evolution, has beenextensively applied in foreland basin settings to understand tectonicprocesses by tracking the exposure and erosion of distinct sedimentsource areas through time. We present a case of study in the Mioceneforeland sedimentary record of northwest Austral-Magallanes Basin(~47º 30’ S) which is associated with the main phase of Andeanuplift. We define three sedimentary units (SU) for paleoenvironmentalinterpretation from shallow marine deposits (SU-I) to mixed-loadfluvial deposits (SU-II) to an alluvial fan (SU-III). Also, weconstrain the timing of this synorogenic clastic wedge between ~20 to~12 Ma applying U-Pb zircon maximum depositional ages of 6 sandstonesand 1 tuff sample. From detrital zircon provenance analysis, wedocument a progressive upsection loss of contribution from youngerunits and an enrichment of older units derived from hinterlandsources, suggesting the development of an unroofing erosional processdue to coeval Andean uplift of the cordilleran sources.Tectonostratigraphic stages determine the initial stages of orogenicuplift (Stage 1), the subsequent advance of the orogenic belt andprogressive loss of accommodation space (Stage 2) until its clogging(Stage 3).p { margin-bottom: 2.47mm; direction: ltr; color: #000000; line-height: 115%; orphans: 2; widows: 2; background: transparent }p.western { font-family: "Times New Roman", serif; font-size: 12pt; so-language: en-US }p.cjk { font-family: "Calibri", sans-serif; font-size: 12pt; so-language: zh-CN }p.ctl { font-family: "DejaVu Sans", "Verdana", sans-serif; font-size: 11pt; so-language: ar-SA }a:visited { color: #800080; text-decoration: underline }a:link { color: #0000ff; text-decoration: underline }