Late Miocene to mid‐Pleistocene sedimentary proxy records reveal that northwest Australia underwent an abrupt transition from dry to humid climate conditions at 5.5 million years (Ma), likely receiving year‐round rainfall, but after ~3.3 Ma, climate shifted toward an increasingly seasonal precipitation regime. The progressive constriction of the Indonesian Throughflow likely decreased continental humidity and transferred control of northwest Australian climate from the Pacific to the Indian Ocean, leading to drier conditions punctuated by monsoonal precipitation. The northwest dust pathway and fully established seasonal and orbitally controlled precipitation were in place by ~2.4 Ma, well after the intensification of Northern Hemisphere glaciation. The transition from humid to arid conditions was driven by changes in Pacific and Indian Ocean circulation and regional atmospheric moisture transport, influenced by the emerging Maritime Continent. We conclude that the Maritime Continent is the switchboard modulating teleconnections between tropical and high‐latitude climate systems.

Global climate underwent a major reorganization when the Antarctic ice sheet expanded ~14 million years ago (Ma) (1). This event affected global atmospheric circulation, including the strength and position of the westerlies and the Intertropical Convergence Zone (ITCZ), and, therefore, precipitation patterns (2–5). We present new shallow-marine sediment records from the continental shelf of Australia (International Ocean Discovery Program Sites U1459 and U1464) providing the first empirical evidence linking high-latitude cooling around Antarctica to climate change in the (sub)tropics during the Miocene. We show that Western Australia was arid during most of the Middle Miocene. Southwest Australia became wetter during the Late Miocene, creating a climate gradient with the arid interior, whereas northwest Australia remained arid throughout. Precipitation and river runoff in southwest Australia gradually increased from 12 to 8 Ma, which we relate to a northward migration or intensification of the westerlies possibly due to increased sea ice in the Southern Ocean (5). Abrupt aridification indicates that the westerlies shifted back to a position south of Australia after 8 Ma. Our midlatitude Southern Hemisphere data are consistent with the inference that expansion of sea ice around Antarctica resulted in a northward movement of the westerlies. In turn, this may have pushed tropical atmospheric circulation and the ITCZ northward, shifting the main precipitation belt over large parts of Southeast Asia (4).

The Indonesian Throughflow (ITF) controls the oceanic flux of heat and salt between the Pacific and Indian Oceans and therewith plays an important role in modulating the meridional overturning circulation and low latitude hydrological cycle. Here, we report new sea surface temperature and aridity records from the west coast of Australia (IODP Site U1460), which allow us to assess the sensitivity of the eastern Indian Ocean to the major reorganization of Earth’s climate that occurred during the Mid-Pleistocene Transition. Our records indicate glacial coolings at 1.55 and 0.65 million years ago that are best explained by a weakening of the ITF as a consequence of global sea level and tectonic changes. These coincide with the development of pronounced gradients in the carbon isotope composition of the different ocean basins and with substantial changes in regional aridity, suggesting that the restrictions of the ITF influenced both the evolution of global ocean circulation and the development of the modern hydrological cycle in Western Australia.

In the South Oman Salt Basin (SOSB), the Ara carbonates form an extensively cored, deeply buried intra-salt hydrocarbon play. Six surface-piercing salt domes in the Ghaba Salt Basin (northern Oman) provide the only outcrop equivalents for carbonates and evaporites of the Ediacaran – Early Cambrian Ara Group (upper Huqf Supergroup). Based on fieldwork, satellite images and isotope analysis it is concluded that most of the carbonate bodies (so-called stringers) in the Ghaba salt domes are time-equivalent to the stratigraphically uppermost stringer intervals in the SOSB (A5–A6). Maturity analyses demonstrate that the carbonate stringers in the salt domes were transported with the rising Ara Salt from burial depths of c. 6 to 10 km to the surface. Petrographic and stable-isotope data show that their diagenetic evolution during shallow and deep burial was very similar to the Ara carbonate stringer play in the SOSB. However, during the retrograde pathway of salt diapir evolution, the carbonate stringers were exposed to strong deformation in the diapir stem and diagenetic alterations related to dedolomitisation. As the salt domes contain facies that are in all aspects identical to the deeply buried Ara play in the SOSB, this study provides substantial additional information for hydrocarbon exploration in southern Oman. Moreover, our work has implications for the hydrocarbon prospectivity of the Ghaba Salt Basin and possibly of other Ediacaran – Lower Cambrian evaporite basins in the Middle East, such as for the time-equivalent Hormuz salt basins.