Mesoproterozoic erg and sand sheet system: Architecture and controlling factors (Galho do Miguel Formation, SE Brazil)

Author(s)

Abrantes, Jr., Francisco R. ^[1] ; Basilici, Giorgio ^{[2, 1]} ; Theodoro Soares, Marcus Vinicius ^[1]

Affiliation

^[1] State Univ Campinas UNICAMP, Inst Geosci, Dept Geol & Nat Resources, BR-13083870 Campinas, SP - Brazil

^[2] Consejo Nacl Invest Cient & Tecn, CRILAR, Ctr Reg Invest Cient & Transferencia Tecnol, Entre Rios & Mendoza S-N, RA-5301 Anillaco, La Rioja - Argentina

• Document type: Journal article
• Source: Precambrian Research; v. 338, MAR 2020.
• Web of Science Citations: 0

Abstract

Aeolian systems of the Precambrian time were established in different palaeoclimatic and palaeogeographic conditions than the present. Different morphologies of dunes/draas, as linear, oblique and star forms, are widespread in the recent aeolian systems. However, the ancient aeolian deposits are rarely interpreted as these types of bedforms and usually referred to as transverse dunes. The nature and complexity of bedform morphology in Precambrian aeolian systems, as well as the factors that allow the construction, accumulation and preservation of these environments are still not well defined. Extensive exposures of Galho do Miguel Formation in southeastern Brazil represent a Mesoproterozoic Erg succession and exhibit a distinct facies architecture, which contributed to the understanding of these deposits. Three architectural elements were identified: (i) tangential cross-stratified sandstone with superimposed trough cross-bedded sandstone, (ii) planar-laminated sandstone, and (iii) extensive flat-bedded sandstone dominated by wrinkly laminae. These elements are organized into three succession groups representative of simple transverse dune, oblique compound draa and sand sheet systems. The simple to compound dune/draa system corresponds to the most central parts of the erg, associated with a higher sediment availability and lower water-table level. Conversely, the sand sheet system occurs under low sediment availability and higher water-table level in the marginal portions of the erg. Precambrian climatic oscillations may have changed the aeolian system morphology, allowing the alternation of simple and complex aeolian dunes, resulting in high-frequency changes in sand sheet system, and the remobilization of previously accumulated sediments over large geographic areas. (AU)

• FAPESP's process: 17/11091-8 - Architectural model and evolution of a Mesoproterozoic ERG: Galho do Miguel formation
• Grantee: Francisco Romério Abrantes Júnior
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 17/03649-9 - Sedimentary models of Precambrian ergs in Brazil and India
• Grantee: Giorgio Basilici
• Support type: Regular Research Grants