Global ice losses will likely continue with ongoing climate warming, culminating in an almost ice-free planet analogous to that which persisted throughout much of the Cretaceous. Despite extensive research, Early Cretaceous cryosphere responses to temperature and atmospheric P CO ₂ fluctuations over short, human, timescales remain uncertain. Here, we show rapid late Valanginian (~133 million years ago) seasonal fluctuations in sea surface temperature (SST) and δ ¹⁸ O mainly driven by atmospheric P CO ₂ . Two distinctive features emerge: large seasonal variability of up to 15.9° ± 4.9°C in Southern Hemisphere mid-latitudes, comparable to that found today, a positive sea surface δ ¹⁸ O value related to evaporation (expressed as salinity increases), and the existence of polar ice. Model-predicted patterns of SST change match with high statistical confidence those derived from clumped isotopes in well-preserved oyster fossils from Madagascar and display consistent warm/cold seasonality. Given its relative coolness in a Cretaceous context, the late Valanginian is a valuable analog for Earth’s future climate.

The configuration and timing of the Arabia‐Eurasia continental collision, part of the broader Alpine‐Himalayan collisional system, remains controversial. We conducted sandstone petrology, detrital zircon U‐Pb‐Hf isotopic and trace element analysis, and Cr‐spinel electron microprobe geochemical analysis of samples from Paleocene to Miocene peripheral foreland strata in interior Fars, southern Iran. These data were used to test competing models for ophiolite obduction and Arabia‐Eurasia collision. In addition, we applied these data to compare the history of outward and upward growth of the Zagros and Himalayan‐Tibetan segments of the Alpine‐Himalayan collisional orogenic belt. The first appearance of radiolarian‐rich chert conglomerate, 100–90 Ma detrital zircons with positive ɛHf(t) values from +1 to +20 and midocean ridge geochemical affinity, and suprasubduction zone (SSZ) affinity Cr‐spinel is in the lower and middle Sachun Formation. These data indicate that obduction occurred before deposition of the upper Maastrichtian‐lower Paleocene Sachun Formation and developed in an intra‐oceanic setting rather than an Arabia‐Eurasia collision setting. Abundant continental‐arc affinity detrital zircon with 180–160 Ma and 50–27 Ma age‐probability peaks and varied ɛHf(t) values are present in the upper Oligocene‐lower Miocene Razak and Agha Jari formations, indicating sedimentary overlap with Eurasia. SSZ‐affinity Cr‐spinel in all samples indicates that ophiolitic rocks were a continual source of detritus in the foreland basin since Paleocene. The depositional age of the basal Razak Formation is between 25.7 and 21.5 Ma. Therefore, we interpret that collision between Arabia and Eurasia must have been initiated before deposition of the Razak Formation.

The forearc basin in Myanmar is significant in understanding the development of continental forearc basins. We present stratigraphic, sandstone petrographic, and U-Pb detrital data from Upper Cretaceous−Eocene strata of Chindwin and Minbu sub-basins in the Central Myanmar Depression. The Upper Cretaceous lower Kabaw Formation consists of turbiditic conglomerate, sandstone, and mudstone in the Minbu sub-basin. The composition of conglomerates are mainly schist and subordinate quartz. Prominent detrital zircon age probability peaks are between 260 and 223 Ma, similar with that of Upper Triassic Pane Chaung turbidites and Kanpetlet schist on the West Burma plate. In the upper Kabaw Formation, turbiditic volcanic-rich sandstones have major age populations ranging from 103 to 70 Ma in both Minbu and Chindwin sub-basins. The Paleocene slope environment Paunggyi Formation, which overlies the Kabaw Formation, mainly consists of conglomerate, sandstone, mudstone, and tuff beds in the Minbu sub-basin. In contrast, the Paunggyi Formation in the Chindwin sub-basin is composed of sandstone and mudstone; major detrital zircon age populations from the Paunggyi Formation are between 100 and 60 Ma. Eocene strata in both basins are composed mainly of shallow marine to delta sandstone and mudstone. Major detrital zircon age populations are 100−36 Ma and 600−500 Ma. The Late Cretaceous−Eocene ages from Upper Cretaceous−Eocene strata overlap with igneous crystallization ages from the Western Myanmar Arc. We propose that the Chindwin and Minbu sub-basins developed as parts of a forearc basin along the west flank of Western Myanmar Arc (present coordinate). The forearc basin initiated in Albian time atop the continental West Burma plate due to the formation of a structural high along the western margin of West Burma plate.