Ages (U-Pb SHRIMP and LA ICPMS) and stratigraphic evolution of the Neoproterozoic volcano-sedimentary successions from the extensional Camaqua Basin, Southern Brazil

作者：Janikian Liliane^*; de Almeida Renato Paes; Santos Fragoso Cesar Antonio Romalino; de Souza Martins Veridiana Teixeira; Dantas Elton Luiz; Tohver Eric; McReath Ian; D' Agrella Filho Manoel Souza

来源：Gondwana Research, 2012, 21(2-3): 466-482.

DOI：10.1016/j.gr.2011.04.010

• Ediacaran
• Camaqua Basin
• Born Jardim Group
• Acampamento Velho Formation
• Depositional system
• Stratigraphic evolution

During the Ediacaran, southern Brazil was the site of multiple episodes of volcanism and sedimentation, which are best preserved in the 3000 km(2) Camaqua Basin. The interlayered sedimentary and volcanic rocks record tectonic events and paleoenvironmental changes in a more than 10 km-thick succession. In this contribution, we report new U-Pb and Sm-Nd geochronological constraints for the 605 to 580 Ma Born Jardim Group, the 570 Ma Acampamento Velho Formation, and a newly-recognized 544 Ma volcanism. Depositional patterns of these units reveal the transition from a restricted, fault-bounded basin into a wide, shallow basin. The expansion of the basin and diminished subsidence rates are demonstrated by increasing areal distribution and compressed isopachs and increasing onlap of sediments onto the basement to the west. The Sm-Nd isotopic composition of the volcanic rocks indicates mixed sources, including crustal rocks from the adjacent basement. Both Neoproterozoic and Paleoproterozoic sources are indicated for the western part of the basin, whereas only the older Paleoproterozoic signature can be discerned in the eastern part of the basin.

• 出版日期2012-3