Cenozoic History of the Indonesian Gateway

Abstract

The tectonically complex Indonesian Gateway is part of the global thermohaline circulation and exerts a major control on climate. Waters from the Pacific flow through the Indonesian Archipelago into the Indian Ocean via the Indonesian Throughflow. Much progress has been made toward understanding the near-modern history of the Indonesian Gateway. However, the longer-term climate and ocean consequences of Australia's progressive collision with the Eurasian Plate that created it are less known. The gateway initiated ∼23 Ma, when Australia collided with Southeast Asia. By ∼10 Ma the gateway was sufficiently restricted to create a proto–warm pool. During the Pliocene it alternated between more or less restricted conditions, until modern oceanic conditions were established by 2.7 Ma. Despite its tectonic complexity, climate modeling and Indian and Pacific scientific ocean drilling research continue to yield insights into the gateway's deep history. ▪The Indonesian Gateway is a key branch of global thermohaline oceanic circulation, exerting a major control on Earth's climate over the last 25 Myr.▪We find that a complex interplay of tectonics and sea level has controlled Indonesian Gateway restriction since 12 Myr, resulting in La Niña– and El Niño–like states in the equatorial Pacific.▪Long term Indonesian Gateway history is best determined from ocean drilling cores on the Indian and Pacific sides of the Indonesian Gateway, as records from within it are typically disrupted by tectonics.▪Model simulations show the global impact of the Indonesian Gateway. Further modeling with ocean drilling/tectonic research will enhance our understanding of Cenozoic Indonesian Gateway history.