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doi:10.14379/iodp.sp.355.2014

Introduction

The theory of plate tectonics has established that the solid Earth’s lithosphere interacts intimately with the asthenosphere, but more recently it has been revealed that the lithosphere also has significant interactions with the atmosphere and oceans, where it can influence circulation and thereby control Earth’s climate. These interactions between the solid Earth and the climate system can occur in at least two different ways. The opening and closure of deep-ocean gateways is believed to have caused large-scale climate change by affecting heat transport between ocean basins or between polar and tropical regions (Haug and Tiedemann, 1998; Cane and Molnar, 2001; von der Heydt and Dijkstra, 2006). In addition, mountain building is proposed to have perturbed planetary scale atmospheric circulation, influencing continental environments and even the oceanography of the surrounding basins. The suggestion that mountain building in Asia has intensified the Asian monsoon is the most dramatic proposed example of such interactions (Prell and Kutzbach, 1992; Molnar et al., 1993; An et al., 2001). Asia is the only continent that experiences such an intense monsoon, partly a reflection of the size of the landmass but also linked to its tectonic history and anomalous altitude. Therefore, understanding what controls the monsoon intensity is of great scientific interest and has substantive societal importance considering the large number of people whose livelihood depends on the summer rains and the increasing global economic importance of the region. If we can identify the various processes that control monsoon intensity over geologic timescales, we can establish an improved context for shorter term modeling of how future climate change may affect the densely populated environments of Asia. Specifically, we aim to answer the question of what are the links between the monsoon and the building of high topography in Asia and whether there are feedbacks?

The Arabian Sea in the northern Indian Ocean (Fig. F1) preserves regional sedimentary records of rifting and paleoceanographic history, as well as providing sedimentary archives of long term erosion of the Himalaya since the start of collision between India and Asia, which probably began in the Eocene (Rowley, 1996; Najman et al., 2010). Scientific drilling in the Eastern Arabian Sea is designed to reconstruct the evolution of the Indian monsoon system and define its role in controlling weathering and erosion in the Himalaya under the IODP Science Plan theme, “Climate and Ocean Change.”

As well as being a repository of information about climate and mountain building, the Arabian Sea also holds potentially illuminating records of continental rifting and break-up tectonics dating from the time of Gondwana fragmentation (Heine et al., 2004). Paleogeographic reconstructions, as well as similarities in the structural/tectonic elements, suggest a conjugate relationship between the western continental margin of India and the eastern continental margin of Madagascar and the Seychelles margin (Storey et al., 1995; Collier et al., 2008). In-depth studies on the conjugate margins in this region offer new data to complement our knowledge from other well-studied conjugate margins such as the Iberia-Newfoundland and Greenland-Norway margins of the Atlantic Ocean (Minshull et al., 2008). This secondary objective of the proposal addresses the “Earth Connections” theme of the IODP Science Plan.

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