A new study from Adelaide University suggests that the long-vanished Tethys Ocean played a decisive role in forming Central Asia’s mountainous landscapes during the Cretaceous period, long before the collision of India and Eurasia created the Himalayas.
“Instead, the dynamics of the distant Tethys Ocean can directly be correlated with short-lived periods of mountain building in Central Asia.”The Tethys Ocean, which once spanned much of the globe, gradually disappeared during the Meso-Cenozoic era, leaving only remnants like the modern Mediterranean Sea.
a Generalised tectonic map of Central Asia, showing distribution of major terranes, basins, locations of digitised thermal history models32, and fault systems88.
Pearson correlation coefficients (r) between cooling rate and both dynamic topography (b) and change in dynamic topography (c) are 0.000 across the full dataset.
“We analyzed a compilation of thermal history models in function of plate-tectonic models for the Tethys Ocean evolution, as well as deep-time precipitation and mantle-convection models,” Glorie explained.
A new study from Adelaide University suggests that the long-vanished Tethys Ocean played a decisive role in forming Central Asia’s mountainous landscapes during the Cretaceous period, long before the collision of India and Eurasia created the Himalayas. By analyzing decades of geological data, researchers have uncovered evidence that distant oceanic dynamics, rather than climate or mantle processes, drove episodes of mountain building in this region.
The Hidden Power of the Tethys Ocean
For years, scientists believed that the terrain of Central Asia was primarily shaped by tectonic collisions, mantle convection, and climate variations. However, recent findings published in Communications Earth, challenge this view.
“We found that climate change and mantle processes had only little influence on the Central Asian landscape, which persisted in an arid climate for much of the last 250 million years,” said Dr. Sam Boone, a post-doctoral researcher at Adelaide University when the study was conducted. “Instead, the dynamics of the distant Tethys Ocean can directly be correlated with short-lived periods of mountain building in Central Asia.”
The Tethys Ocean, which once spanned much of the globe, gradually disappeared during the Meso-Cenozoic era, leaving only remnants like the modern Mediterranean Sea. During its prime, the ocean influenced geological activity far inland, generating stress and movement along ancient suture zones that ultimately produced mountain ridges thousands of kilometers away from the main collision zones.
Tectonic framework and thermochronology of Central Asia.
a Generalised tectonic map of Central Asia, showing distribution of major terranes, basins, locations of digitised thermal history models32, and fault systems88. The distribution of (b) apatite fission-track (AFT) apparent ages and (c) mean confined track lengths (MTL), a proxy for the rate of cooling whereby longer MTLs record faster cooling through ~120–60 °C56,57, are illustrated by inverse distance weighted interpolations. Note, that these interpolations are for illustrative purposes only and are not used in any subsequent analyses. Rather, all correlation analysis between cooling rates, dynamic topography, plate kinematics and paleoprecipitation rates are performed only at the exact sample localities of the thermochronology-derived thermal history models. Below, four-dimensional plots illustrate spatiotemporal trends in Central Asian upper crustal cooling histories recorded by thermal history modelling of thermochronology data viewed from the southeast (d) and northwest (e). B Basin, F Fault, FB Fergana Basin, STSS South Tian Shan Suture, MTSZ Main Tian Shan Suture Zone, TFF Talas Fergana Fault, CTUSS Charysh-Terekta-Ulagan-Sayan Suture.
Dinosaur-Era Landscapes Reimagined
Associate Professor Stijn Glorie, co-author of the study, emphasizes the scale of these ancient mountain-building events:
“The present-day relief of Central Asia was largely built by the India-Eurasia collision and ongoing convergence. However, during the Cretaceous periods, dinosaurs would have seen a mountainous landscape as well, similar to the present-day Basin-and-Range Province in the western USA.”
Glorie explained that the mountains did not form solely from the movement of nearby plates.
“It is thought that the extension in the Tethys, due to roll-back of subducting slabs of ocean crust, reactivated old suture zones into a series of roughly parallel ridges in Central Asia, up to thousands of kilometers away from the Himalaya collision zone.”
This insight reframes our understanding of ancient mountain formation, revealing that distant oceanic activity could trigger uplift in otherwise stable continental interiors.
Temporal relationships between denudational cooling recorded by thermochronology in Central Asia and periods of major tectonism.
Mean and standard deviation cooling rates recorded by low-temperature thermochronology in the greater Tian Shan (a) and Altai (b) regions (see Fig. 1 for sample locations), with highlighted approximate periods of major tectonism documented in the two areas and discussed in the text. Plate tectonic reconstructions24 of wider Eurasia at 220 Ma (c), 160 Ma (d), 100 Ma (e), 45 Ma (f) and 20 Ma (g) showing the evolution of seafloor age and thermochronology-derived crustal cooling rates in an orthographic projection centred on 73 °E, 37 °N. Thick black lines indicate mid-oceanic ridge, transform, or orogenic plate boundaries, while toothed purple lines indicate subduction and the subduction polarity. Arrows indicate plate velocities in the mantle reference frame. EU Eurasia, MO Mongol-Okhotsk Ocean, F Farallon Plate, IZA Izanagi Plate, PT Paleo-Tethys Ocean, MT Meso-Tethys Ocean, SB Siberia, MB Mongolian Block, LH Lhasa Block, QI Qiangtang Block, T Tarim Block, P Pamir, K Karakoram, NT Neo-Tethys Ocean, PO Pacific Plate, I Indian Plate, BR Baikal Rift, TFF Talas Fergana Fault, SF Sayan Fault.
Decoding Earth’s Thermal History
The research team relied heavily on thermal history models, which track how rocks cooled as they were uplifted and eroded over millions of years.
“These models were constructed using thermochronology methods and reveal how rocks cooled down when they are brought towards the surface during mountain uplift and subsequent erosion,” said Associate Professor Glorie.
Spatiotemporal relationship between dynamic topography and denudational cooling.
Central Asia, shown here at four key time periods (a), has remained above a long wavelength region of negative dynamic topography for the last 230 Ma. Reconstructions are shown in an orthographic projection centred on 73 °E, 37 °N. Changes in denudational cooling rates recorded by thermochronology data across Central Asia do not correlate with either dynamic topography amplitudes, which have remained negative since the Triassic (b), or changes in dynamic topography (c). Pearson correlation coefficients (r) between cooling rate and both dynamic topography (b) and change in dynamic topography (c) are 0.000 across the full dataset. Even at each individual million-year time step (d, e), r values have remained close to zero. An animation of Central Asian crustal cooling rates in relation to predicted dynamic topography and change in dynamic topography for the full 230 Ma modelling period can be found in the Supplementary Video S5.
By integrating these models with plate-tectonic reconstructions of the Tethys Ocean, precipitation data, and mantle-convection simulations, the researchers were able to create a detailed timeline of mountain-building events across Central Asia.
“We analyzed a compilation of thermal history models in function of plate-tectonic models for the Tethys Ocean evolution, as well as deep-time precipitation and mantle-convection models,” Glorie explained.
The methodology unveiled episodes of mountain formation that had been invisible to earlier studies, showing that oceans can exert influence far beyond their immediate shores.
