Early Holocene climate transitions, fossil dinoflagellate cyst assemblages in the southern Gulf of California: Insights from the DIPAL IV core

This work reports on the variability of fossil dinoflagellate cysts and their relationship with climatic and oceanographic changes during the Early Holocene in the Alfonso Basin in the southern Gulf of California. The integrated palynological and geochemical analysis of 100 sediment samples from the DIPAL IV core provides information from 12.7 to 10.8 ka BP. The laminated sediments were dated using C-14 analysis and examined for concentrations of dinoflagellate cysts and continental palynomorphs, as well as content of total organic carbon, iron, titanium, and biogenic opal. The appearance of thermophilic dinoflagellate cysts at the beginning of the Early Holocene implies a warming trend, while changes in terrigenous input indicate fluctuations in precipitation and nutrient availability. Multivariate analyses revealed two distinct dinoflagellate cyst ecological intervals, accounting for over 65 % of the observed variance across the Younger Dryas–Early Holocene. This study shows how climate influenced both land and marine ecosystems in the Gulf of California during the Early Holocene, and the results deepen our understanding of paleoceanographic changes in the region and provide a foundation for future modelling of ocean productivity and algal blooms under climate change.