The Montesbelos mass-flow (southern Amazonian craton, Brazil): a Paleoproterozoic volcanic debris avalanche deposit?

Abstract

The present contribution documents the extremely well-preserved Paleoproterozoic architecture of the Montesbelos breccia (named here for the first time), which is interpreted as a rare example of a subaerial paleoproterozoic (>1.85 Ga) granular-dominated mass-flow deposit, few of which are recorded in the literature. Montesbelos deposit is part of the andesitic Sobreiro Formation located in the São Felix do Xingu region, southern Amazonian craton, northern Brazil. The large volume, high variability of textural features, presence of broken clasts, angular low sphericity fragments, mono-to heterolithic character, and the size of the outcrops point to a volcanic debris avalanche flow. Fluviatile sandy material and debris flows are associated with the deposit as a result of post-depositional reworking processes.

Stratigraphy and geochronological constraints of the Serra Sul Formation (Carajás Basin, Amazonian Craton, Brazil)

“…Age constraints obtained on volcanic and plutonic rocks and dykes indicate that the Uatumã SLIP was emplaced during a short period of time, between ca. 1.89 and 1.86 Ga (Antonio et al, 2017;Dall'Agnol et al, 2005;Machado et al, 1991;Roverato, 2016;Silva et al, 2016;Teixeira et al, 2019).…”

“…To the west, the Carajás Domain is overlain by volcanic and volcaniclastic rocks of the Uatumã Supergroup (Fig. 3A; Roverato, 2016;Roverato et al, 2017). These units belong to the Uatumã Silicic Large Igneous Province (SLIP; Antonio et al, 2017), which also includes A-type granitoids intrusive into the basement of the Carajás and Rio Maria domains (Teixeira et al, 2019).…”

Textural analysis and emplacement conditions of well-preserved Orosirian felsic volcanic rocks of Northern Amazon Craton, Brazil

“…The designation of Iricoumé Group is used for volcanic rocks outcropping in the Erepecuru-Trombetas and Uatumã-Anauá domains to the north of the Amazon Basin. To the south of this basin, correlated volcanic rocks occur in the Iriri-Xingu Domain under the designations of Sobreiro and Santa Rosa formations (Fernandes et al, 2006(Fernandes et al, , 2011Roverato, 2016;Roverato et al, 2017). In the Tapajós Domain, the correlated volcanic rocks are grouped in the Moraes Almeida Formation of the Iriri Group (Klein and Vasquez, 2000;Lamarão et al, 2002;Juliani et al, 2005).…”

Differences in the occurrence of debris flows in tropical and temperate environments: field observations and geomorphologic characteristics in Serra do Mar (Brazil) and British Columbia (Canada)

“…These events caused social damage (more than 3,000 deaths) and economic losses (at least $3 billion (USD)) (World Bank 2014, Kanji et al 2017). Nevertheless, debris flow research and practice in the country still lags behind other affected areas worldwide, with few local papers published about this issue (Kanji et al 2008, Gomes et al 2008, Jackson 2011, Dias et al 2016, Campos and Galindo 2016, Roverato 2016, Facuri and Picanço 2020, Cabral et al 2021. In comparison, debris flows are one of the most common and well-documented landslide processes in some parts of Canada, particularly in the province of British Columbia on the west coast (Thurber Consultants LTD. 1983, VanDine 1985, Slaymaker 1990, Scally et al 2001.…”