Nevertheless, the extent to which the Late Eocene warming impacted low-latitude climates, in particular in remote continental areas, remains largely unknown. Very recently, a new sea-surface temperature (SST) record revealed that an unequivocal tropical warming at equatorial oceanic latitudes initiated 4 million years prior to Antarctic glaciation, leading to an increase of heat accumulation in the low latitudes and a prominent meridional ocean reorganization predating the EOT 6. This climatic deterioration was punctuated by abrupt and short-lived cooling and warming events in the time period referred as the Late Eocene « Doubthouse » (LED) 4, which has long been well-documented in oceanic records (e.g., refs 1, 5). Our findings thus highlight an important period of climatic upheaval in terrestrial Asian environments ~2–4 millions years prior to the EOT.Įarth’s climate gradually cooled from greenhouse to icehouse climatic conditions in the Late Eocene, leading to the Eocene–Oligocene Transition (EOT) at ~33.7 Ma and permanent polar glaciation in Antarctica 1– 3. ![]() We suggest that this moisture redistribution possibly reflects more northern and intensified ITCZ-induced tropical rainfall in monsoonal Asia around 35.5 Ma, in accordance with recent sea-surface temperature reconstructions from equatorial oceanic records. We show that the occurrence of flash-flood events in semi-arid to sub-humid palustrine-sublacustrine settings preceded the development of coal-bearing deposits in swampy-like environments, thus paving the way to a more humid climate in SE Tibet ahead from the EOT. Here we report new sedimentological data from the Jianchuan basin (SE Tibet) arguing for wetter climatic conditions in monsoonal Asia at ~35.5 Ma almost coevally to the aridification recognized northwards in the Xining basin. Yet archival constraints on Late Eocene atmospheric circulation are scarce in (tropical) monsoonal Asia, and the paucity of terrestrial records hampers a meaningful comparison of the long-term climatic trends between oceanic and continental realms. ![]() Cenozoic climate cooling at the advent of the Eocene-Oligocene transition (EOT), ~33.7 Ma ago, was stamped in the ocean by a series of climatic events albeit the impact of this global climatic transition on terrestrial environments is still fragmentary.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |