First evidence of sinter and travertine in Cameroon: fault reactivation and geothermal implications

Abstract

The Laopanga hot spring deposits along the “Cameroon Volcanic Line” (CVL) are distinctive in being both siliceous sinter and travertine, made up of immature amorphous silica and mainly calcite, and associated with detrital deposits such as claystone, sandstone and conglomerate. Their age range from Plio-Pleistocene to Actual. Sr concentrations (17 to 2304 ppm) suggest an enrichment by epithermal outflows. <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>δ</mml:mi> <mml:mn>13</mml:mn> </mml:msup> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>δ</mml:mi> </mml:mrow> <mml:mn>18</mml:mn> </mml:msup> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> </mml:math> values, ranging respectively from 1.5‰ to 2.9‰ V-PDB and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>-</mml:mo> </mml:math> 10.1‰ to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>-</mml:mo> </mml:math> 6‰ V-PDB, reflect a high temperature of the parent solution (40 °C) related to an elevated geothermal gradient. The europium anomalies values (Eu/Eu*: 0.54–1.78) indicate the temperature variation of precipitated deposits related to distance of the deep hot water flow. The chemical compositions of the lithofacies show the diversity of the spring deposits related to complex phenomena of internal migration of mineralized hot water and the tectonic controls during the Precambrian fault reactivations.