Paleoclimatic and paleoenvironmental reconstruction at Tarfaya Atlantic coastal basin (Morocco) based on clay mineral records from Upper Cretaceous to Quaternary
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We generated clay mineral assemblage records on Late Cretaceous to Miocene-Pliocene rocks and on Holocene river sediments at Tarfaya Atlantic coastal basin in Morocco. Results show that illite, chlorite, kaolinite, smectite, and palygorskite originated from a continental source whereas corrensite formed within the basin. A very high kaolinite content and kaolinite/(illite+chlorite) ratio during the Turonian indicate a high chemical weathering which was coeval with a global weathering event during a warm and humid climate during that time. An increase in physical erosion during the Santonian as reflected by high (illite+chlorite) content and low kaolinite/(illite+chlorite) ratio was most likely associated with the early western Anti-Atlas uplift. Abundant (palygorskite+sepiolite) contents in Early Eocene rocks reflect the development of extremely dry and warm climatic conditions over the coastal regions of Tarfaya during that time. Dominant (illite+chlorite) and smectite clay minerals and a marked increase in sedimentation during the Miocene-Pliocene suggest an increase in physical erosion of the high-relief source region (western Anti-Atlas) which was mainly controlled by tectonic denudation. High kaolinite content and kaolinite/(illite+chlorite) ratio also occurred in the Holocene river sediments indicating warm and humid climate during that time. The abundant corrensite, however, indicates a basin depositional environment and suggests that oxic conditions were dominant in the Tarfaya basin during the Campanian and the Oligocene-Early Miocene.
KeywordsClay minerals Chemical weathering Physical erosion Late Cretaceous to Miocene Tarfaya basin Morocco
We thank ONHYM for supporting, organizing, and accompanying the field campaign in March–April 2009, and for drilling in September–December 2009. We also would like to thank many colleagues at the State Key Laboratory of Marine Geology, Tongji University, China, for measurement of clay minerals and suggestions to improve the manuscript. The authors are thankful to the AJGS Associate Editor for handling our manuscript. The authors are also grateful to two anonymous reviewers for critical reviews and constructive suggestions which have significantly improved the manuscript.
The authors received financial support from RWE Dea for this project.
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