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Middle–late Holocene Caribbean aridity inferred from foraminifera and elemental data in sediment cores from two Cuban lagoons

Gregory, Braden R.B., Peros, Matthew, Reinhardt, Eduard G., Donnelly, Jeffrey P.
Palaeogeography, palaeoclimatology, palaeoecology 2015 v.426 pp. 229-241
Retaria, ammonia, basins, calcium, climate, climate change, coastal water, dry environmental conditions, drying, freshwater, iron, paleoclimatology, playas, potassium, sea level, sediments, titanium, Caribbean, Cuba
Coastal lagoons are rarely used as paleoclimate archives because of their complex geomorphic histories, which can be affected by both climate and sea-level change. Combined foraminiferal and XRF element analysis of sediment cores from Punta de Cartas and Playa Bailen, Cuba, isolated the effects of climate change (wet vs dry) on the lagoon environments. Foraminiferal assemblages from both Punta de Cartas and Playa Bailen show increasing diversity over the past 4000yrBP, with a prominent increase at ~1400–1100yrBP. Assemblages were initially dominated by Ammonia spp. (e.g., Ammonia tepida) and Elphidium spp. (e.g., Elphidium excavatum), indicating brackish conditions, but increased miliolid species (e.g., Triloculina spp. Quinqueloculina spp.), indicate a shift to more marine conditions up-core. Correspondingly, terrigenous input to the lagoon (Fe, Ti, Ti/Ca and K) declined over the past 4000yrBP with a flexion at ~1200–1100yrBP that is likely a consequence of decreasing precipitation. Fe, Ti and K have been used as proxies for detrital erosion and transport rates in tropical and sub-tropical basins, with greater input during wet periods, but have rarely been applied to shallow lagoon systems. Coincident changes in the XRF and foraminiferal data indicate decreased freshwater input to the lagoon and support an inference for the onset of drier climate conditions. Similar temporal patterns in the foraminifera and XRF records from the two lagoons, which are ~10km apart, suggest a regional climate influence, with increasingly arid conditions developing since the middle-Holocene (4kyrBP). A pronounced drying over the last ~1200years agrees with other climate records from the Caribbean.