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Article https://doi.org/10.1038/s41467-022-35676-6
Permafrost in the Cretaceous
supergreenhouse
Juan Pedro Rodríguez-López
1,2,3
, Chihua Wu
1,4
, Tatiana A. Vishnivetskaya
5
,
Julian B. Murton
3
, Wenqiang Tang
1,6
&ChaoMa
4
Earth’s climate during the last 4.6 billion years has changed repeatedly
between cold (icehouse) and warm (greenhouse) conditions. The hottest
conditions (supergreenhouse) are widely assumed to have lacked an active
cryosphere. Here we show that during the archetypal supergreenhouse Cre-
taceous Earth, an active cryosphere with permafrost existed in Chinese plateau
deserts (astrochonological age ca. 132.49–132.17 Ma), and that a modern ana-
logue for these plateau cryospheric conditions is the aeolian–permafrost
system we report from the Qiongkuai Lebashi Lake area, Xinjiang Uygur
Autonomous Region, China. Significantly, Cretaceous plateau permafrost was
coeval with largely marine cryospheric indicators in the Arctic and Australia,
indicating a strong coupling of the ocean–atmosphere system. The Cretaceous
permafrost contained a rich microbiome at subtropical palaeolatitude and
3–4 km palaeoaltitude, analogous to recentpermafrostinthewesternHima-
layas. A mindset of persistent ice-free greenhouse conditions during the Cre-
taceous has stifledconsiderationofpermafrostthawasacontributorofCand
nutrients to the palaeo-oceans and palaeo-atmosphere.
Permafrost is an amplifier of climate change1,2, emitting CO
2
and CH
4
from bacterial carbon degradation as permafrost thaws3,andprovid-
ing nutrients and carbon to aquatic ecosystems4,5. But evidence of
permafrost in the pre-Quaternary geological record (‘deep time’)is
limited, as is geological evidence of continental ice during super-
greenhouse periods. Intriguingly, however, a growing body of evi-
dence suggests that cryospheric conditions developed at different
times during the Cretaceous supergreenhouse.
Most evidence of a Cre taceous cryosphere comes in the form o f
marine ice-rafted debris (IRD) from the southern6,7and northern
hemispheres8–11,aswellasfromtherecognitionofmarineglendo-
nites (calcite pseudomorphs after ikaite) indicating cold tempera-
tures during formation12–15. Additional evidence includes
Cretaceous landforms in Yukon and Alaska16, patterned ground in
China17, and ice-rafted dropstones in desert oases indicating cold-
desert conditions in interdunes similar to those in the Badain Jaran
Desert11. Recently, the discovery of ultra-depleted hydrogen iso-
topes from Antarctica has suggested glaciation of the South Pole
during the Late Cretaceous18, and there is isotopic evidence for
continental ice sheets in China during the Early Cretaceous19.Col-
lectively, these studies hint at the likely occurrence of Cretaceous
periglacial and permafrost environments in polar and high-altitude
regions.
Here we report the former occurrence of Cretaceous permafrost
in a plateau desert in China analogous to modern permafrost in the
Western Himalayas (Fig. 1a). This raises new questions on the relative
role of allogenic controls on Mesozoic palaeoclimates, including a
cryosphere and the widespread release of nutrients to the palaeo-
Received: 25 July 2022
Accepted: 19 December 2022
Check for updates
1
PAGODA Research Group (Plateau & Global Desert Basins Research Group), Institute of Sedimentary Geology, Chengdu University of Technology, 610059
Chengdu, China.
2
Department of Geology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Ap. 644, E-48080 Bilbao, Spain.
3
Permafrost Laboratory, Department of Geography, University of Sussex, Brighton BN1 9QJ, UK.
4
State Key Laboratory of Oil and Gas Reservoir Geology and
Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059 Chengdu, China.
5
Center for Environmental Biotechnology,
University of Tennessee, Knoxville, TN 37996, USA.
6
Research Institute of Petroleum Exploration and Development, PetroChina Southwest Oil and Gas Field
Company, 610051 Chengdu, Sichuan, China. e-mail: wuchi-hua@foxmail.com
Nature Communications | (2022) 13:7946 1
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Arctic realm. The identification of past permafrost is crucial for
understanding climate dynamics and the ocean–continent coupling
during supergreenhouse conditions. Of particular importance is the
response of high-altitude permafrost thaw due to global warming.
Permafrost thaw in the eastern Tibetan Plateau between 1969 and
2017, has increased by a factor of 40, with 70% of the thawed area
forming since 2004, amplifying large-scale permafrost climate
feedbacks20.
Article https://doi.org/10.1038/s41467-022-35676-6
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Results
Cretaceous permafrost wedges and host desert dunes
Early Cretaceous westerly winds blew in eastern China21 forming
gigantic aeolian dunes (>352 m high)22 in the sandy deserts (ergs)
represented by the 110–430m-thick Luohe Formation (Fm) in the
Ordos Basin22 (Supplementary Notes 1 and 2, and Supplementary
Figs. 1a, b and 2a). This formation comprises aeolian cross-bedded
sandstones (Fig. 1b, and Supplementary Figs. 3–5) preserved in the
extensional Ordos Basin (North China Craton)23 that formed after the
late Mesozoic subduction of the Palaeo-Pacific Plate and the closure of
the Mongolia–Okhotsk Ocean24 (Supplementary Notes 1 and 2). The
studied outcrops of the Luohe Fm occur near Yayodi Village, Yucha
Grand Canyon, Shaanxi Province, China (Fig. 1a, and Supplementary
Fig. 1b–d). The preservation of the Cretaceous desert aeolian dune
fields (ergs) is exceptional. They exhibit a stratigraphic architecture
commonly observed in other recent and fossil draas (c omplex dunes)25
(Supplementary Note 2) characterized by a well-defined hierarchy of
aeolian bounding surfaces, including reactivation, superimposition,
interdune (interdraa) and supersurfaces (Fig. 1b–d, and Supplemen-
tary Figs. 3–5). The supersurfaces are erg sequence boundaries25 and
are commonly associated with horizons of sandstone wedges, indi-
cating a common genetic origin (Fig. 1b–d and Supplementary
Fig. 5a–c).
Sandstone wedges have been identified in three different out-
crops of the Luohe Fm. Outcrop one (Fig. 1b, and Supplementary
Figs. 4 and 6e) shows two distinct levels of wedges separated by
trough-cross bedded aeolian sandstones with tangential downlapping
of aeolian toeset sediments on the wedge tops. Outcrop two (Sup-
plementary Figs. 3 and 6a–d) shows two wedges penetrating aeolian
dune cross-bedded sets. Outcrop three (Figs. 1c, d, 2a–e and Supple-
mentary Fig. 5) shows 10 wedges concentrated in two discrete hor-
izons bounding three draa successions (Fig. 1c, d).
The sandstone wedges from the Cretaceous Luohe Fm show evi-
dence of both primary and secondary infilling during the formation of
thermal contraction crack wedges in permafrost and periglacial
environments (Tables 2 and 3 of refs. 26,27 (Supplementary Note 3)).
Primary infilling of open thermal contraction cracks by aeolian sand is
indicated by vertical to subvertical lamination within many of the
sandstone wedges. Individual sandstone veins that branch away from
the toes of the wedges represent individual crack infills. The same
sedimentary structures typify cryogenic veins and wedges of primary
infilling in present-day Arctic and Antarctic regions28, mid-latitude
Pleistocene permafrost regions29,30, and in Proterozoic sandstones in
Australia31,32.
Secondary infilling with sand of voids created by the melt of ori-
ginal ice veins or small ice wedges within the overall wedge forms is
indicated by several lines of evidence. First, small normal faults, some
step-like, in strata adjacent to some wedges, indicate extensional
faulting during the melt of ice33. Second, collapse structures34,and
involutions in the upper part of some wedge infills indicate subsidence
of adjacent sediment from the sides or roof during the melt of ice
veins35,36. Third, fallen and rotated intraclasts were derived from the
host sediments once adjacent to the upper margins of the original
wedge33. Fourth, some parts of the infills appear massive, either
because secondary infilling has disrupted the original primary
lamination or because the lamination did not develop due to very
uniform particle size (Fig. 2, and Supplementary Fig. 6).
Some sandstone wedges show a polygenic infill characterized by
multiple wedges crossing horizontal lamination preserved in the
wedges (Fig. 2). These complex patterns and superimposed wedges
are similar to those in Upper Pleistocene wedges in western Europe
(ref. 33, and references therein) and northwest Russia37.Super-
imposition results from the reactivation of thermal contraction
cracking when the appropriate thermal conditions resume after a
period of inactivity38.
Collectively, the sedimentaryproperties of the sandstone wedges
in the Luohe Fm indicate that many of the wedges represent
composite-wedge pseudomorphs, because they have composite
infillings that comprise evidence for both primary and secondary
infilling26,39 (Figs. 1b, 2, and Supplementary Fig. 6). Wedges lacking
evidence for secondary infilling are interpreted as relict sand wedges.
Although small sand veins and wedges up to 0.5 m wide and up to 1.2 m
deep may develop in regions of permafrost and deep seasonal frost40,
the presence of composite-wedge pseudomorphs strongly supports
the interpretation that they developed in a permafrost environment.
This interpretation is also consistent with the dimensions of the
sandstone wedges (up to at least 2m high, and up to ~1 m wide),
dimensions that are common in modern permafrost environments28
but have not been demonstrated to form purely under conditions of
seasonal freezing. Overall, therefore, it is highly likely that the sand-
stone wedges of the Luohe Fm developed under conditions of past
permafrost (Supplementary Note 3).
A late Pleistocene analogue for the Cretaceous aeolian–permafrost
system of the Luohe Fm is provided by the composite wedges and sand
wedges within aeolian dune deposits of the Kittigazuit Fm., Hadwen
Island, NT, Canada41. Analysis (Supplementary Note 4) of the sedi-
mentological and architectural analogies demonstrates multiple fea-
tures shared by both the aeolian–permafrost systems from the
Canadian Pleistocene and the Chinese Cretaceous (Supplementary
Figs. 7–9).
Recent permafrost analogue from the Western Himalayas
The evidence of past permafrost in a desert basin during the Cre-
taceous supergreenhouse period poses an apparent conundrum, but
one that can be explained by reference to a modern analogue of a
high-altitude aeolian–permafrost system at Qiongkuai Lebashi Lake,
Xinjiang Uygur Autonomous Region, in the western Himalayas, China
(Figs. 1a, 3–6, Supplementary Note 5 and Supplementary Fig. 10).
Here, evidence from satellite imagery of permafrost persisting in the
plateau lake–aeolian system for a period of 8 years (Fig. 3c–f, and
Supplementary Fig. 10) corroborates the permafrost modelling for
the study area42,43 (Fig. 5), and the measured altitudes for the aeolian
dunefield and associated frozen oases of 3308 m above sea level (asl)
(Figs. 4,and6a–d) agrees with the probability of permafrost occur-
rence at this altitude44 (Fig. 6a–d). Satellite imagery and topographic
elevation sections of the study area (Fig. 6a) show that the terrain
near Qiongkuai Lebashi Lake varies in altitude from 3.3 to 5.1 km
(asl) (Fig. 6a).
The development of Cretaceous permafrost composite wedges
and sand wedges associated with major bounding surfaces
Fig. 1 | Cretaceous permafrost wedges. a Elevation map of the Himalayas and the
Tibetan Plateau showing the location of the study sites in the Ordos Basin (Cre-
taceouspermafrost)and the QiongkuaiLebashi Lake (recent permafrost analogue).
The Digital Elevation Model (DEM) data were downloaded from the Shuttle Radar
Topography Mission (SRTM) on the USGS EarthExplorer (https://earthexplorer.
usgs.gov/). Image was generated by using the Global Mapper 18.0 (Blue Marble
Geographics) programme based on the Digital Elevation Model data. bPermafrost
sandstone wedges horizon covered and preserved by downlapping aeolian dune
toeset sandstones. cField photograph of two wedge horizons hosted in aeolian
dune sandstones of the Luohe Fm. dTen wedges are identified (labelled wedge 1
“w1”to wedge 10 “w10”in c). Detailed sedimentological observations of the per-
mafrostwedges can be seen in Fig.2and Supplementary Fig. 6.Aeolian architecture
in dis based on the recognition of aeolian bounding surfaces hierarchy25;“SS”
aeolian supersurface; “IS”interdune surface; “S”superimposition surface; “R”
reactivation surface. Wedges are marked in blue colour. See the enlarged image in
Supplementary Fig. 5.
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Fig. 2 | Sedimentology of sandstone wedges in the aeolian dunes of the Luohe
Fm. See location of wedgesin Fig. 1c and Supplementary Fig. 5b. aWedgew3, white
arrows mark the termination of the wedge toes in the cross-bedded aeolian dune
sandstones. bClose-up view from ashowing two wedges and their downward
terminations. cWedges w5 and w4, and dclose-up view from c, showing rotated
blocks of host sandstones into the margin of the wedge and overlying grain-flow
facies downlapping and burying the wedge. eWedge w6 showing internal parallel
vertical lamination and downward propagation of wedge toe into host aeolian
sandstones. The wedge is sharply overlain by laminated aeolian sandstones.
Article https://doi.org/10.1038/s41467-022-35676-6
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(supersurfaces) in the Ordos Basin (Fig. 1c, d) is compatible with var-
iations on the desert-basin phreatic level as those recorded in satellite
imagery of Qiongkuai Lebashi Lake (Supplementary Note 5). There,
both permafrost persisting for at least 8 years (Fig. 3c–f, and Supple-
mentary Fig. 10), and coeval lake transgression led to the recognition
of permafrost affecting the interdunes and margins of the aeolian
dunefields (Fig. 4)atanaltitudeof3–4 km asl.
Permafrost processes are active on plateau lacustrine–aeolian
dunefields near Qiongkuai Lebashi Lake (Figs. 4–6). Sublake perma-
frost polygons are visible in the shallow bottom of the lake (Fig. 3aand
b), and despite the transgression observed in the lake in 2007 (Sup-
plementary Fig. 10), the sublake permafrost polygons persisted for a
period of 8 years (2004–2012) (Fig. 3c–f, and Supplementary Fig. 10).
Satellite imagery reveals patterned ground, showing some regular
Fig. 3 | Persistent permafrost in the Qiongkuai Lebashi Lake, Xinjiang Uygur
Autonomous Region, China. a Evidence of widespread sublake permafrost poly-
gon network visible through clear lake ice. bNote how fractures within lake ice do
not affect the underlying permafrost polygon pattern. c–fEvidence of sublake
permafrost patterned ground persisting for 8 years in the lake.c, Satellite imagery
from March2004, and dsatelliteimagery from April 2012 showing the same area of
the lake. eand fshow the mapping of the individually identified permafrost poly-
gons persistingover a time periodof 8 years. Roundedisomorphicwhite dots in the
satellite image are interpreted as permafrost features known as earth hummocks.
See text for discussion (a–ffrom Image@2021 Maxar Techologies and Goo-
gle Earth).
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Fig. 4 | Close-up views of the plateau cold aeolian–lake system in the western
Himalayas. a Southern margin of the Qiongkuai Lebashi Lake. bImage dated
December 2010, and cImage dated December 2013, showingevident transgression
of the lake shore and onto the aeolian dunefield. dClose-up view from c, rotated
indicating the geographic north to the left of the image. See location in (c).
eClose-up view from dshowing frozen interdunes and possible patterned ground.
fand gClose-up view of the frozen interdunes showing patterned ground. See 1,
and 2 labelled frozen oases in (e)(a–g: Image @2021 Maxar Technologies and
Google Earth).
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orthogonal (rectangular) thermal contraction crack polygons adjacent
to the western and southern shorelines (Fig. 3). The lake ice looks to be
melting, with ice-free (very dark) areas at the lake margin (Fig. 3aand
b). The high transparency of the lake ice with no snow cover allowed
good visibility of lake bottom permafrost polygons (Fig. 3).
In addition to the large-scale polygonal patterns, small-scale pat-
terns are visible in the form of persistent rounded structures (Fig. 3e
and f). These structureshave dimensions and shapes similar to those of
earth hummocks, which are commonly observed in arctic permafrost
terrain45,46. The same hummocks are visible in 2004 and 2012 asso-
ciated with the permafrost polygons (Fig. 3c–f), providing further
evidence of permafrost persisting beneath the bottom of the shallow
plateau lake. Such persistence of hummocks and polygons indicates
beyond reasonable doubt that these parts of the lake were sufficiently
shallow to freeze to the bottom in winter, enabling permafrost to
persist beneath a lake-bottom active layer (Fig. 3). As a result, the
patterned ground was preserved.
Lastly, frozen oases (interdunes) also show polygonal patterns
(Fig. 4a–g). Considering that both the shallow lake water and the
interdune waters are frozen, and permafrost patterned ground is
preserved beneath parts of the lake, then the water table in the aeolian
dunefield mustbe also frozen, defining permafrost in thesubsurface of
the aeolian dunefield.
The occurrence of discrete horizons showing permafrost sand-
stone wedges (Figs. 1b–d, 2, and Supplementary Fig. 5) in a Cretac-
eous plateau aeolian dunefield is consistent with a long-lasting
permafrost plateau aeolian system similar to that observed recently
in the Qiongkuai Lebashi Lake area, Xinjiang Uygur Autonomous
Region, China, where during transgressive periods the plateau lake
favoured permafrost persisting in aeolian interdunes (Fig. 4d–g).
Well-defined permafrost horizons recorded in the lower Cretaceous
Luohe Fm (Fig. 1c and d, and Supplementary Fig. 5) attest to a similar
process, where persistent plateau freezing conditions allowed the
development of composite wedges and sand wedges in an aeolian
dunefield. The occurrence of these permafrost wedge horizons
associated with aeolian supersurfaces is further evidence of the
temporal relationship among permafrost development and a variable
phreatic level controlled by allogenic forcing47, as demonstrated in
the satellite images of the recent analogue from the western Hima-
layas (Fig. 4b–g).
The satellite imagery evidence of modern permafrost at Qiong-
kuai Lebashi Lake is consistent with a map that combines a digital
elevation model (DEM) with modelled permafrost probability (PER-
PROB) data from refs. 42,43. The map indicates that this area is
probably underlain by permafrost; PERPROB values of 0.5–0.9 are
classified as discontinuous permafrost, and values of >0.9 as con-
tinuous permafrost43 (Figs. 5a–d, and 6c).
Regionally, the statistical distribution of modern high-altitude
permafrost, glaciers, and the zero-degree quantiles for high-mountain
Asia (Fig. 6b)44 indicates that permafrost presently underlies 2–3.7% of
the terrain at altitudes matching those of the cold aeolian dunefields
and surrounding relief (3.3–3.6 km asl) and 7.3–11.8% of the surrounding
glaciated mountain ranges (4.5–5.2 km asl) (Fig. 6a, b). The occurrence
of Cretaceous permafrost in the plateau aeolian system supports the
palaeotemperature modelling for this area for this time (ca. 0 °C)48
(Supplementary Fig. 2b), and two scenarios are proposed for the Cre-
taceous palaeolatitude of the plateau desert system in the Ordos Basin:
53°N for the Barresian–Valanginian48, and 32.6–41.0°N for the Early
Cretaceous49,50 (Fig. 6e). A palaeolatitude of 53°N for the Cretaceous
permafrost is similar to the latitudinal distribution of modern perma-
frost and glaciers in the North Asia area defined by the IPCC, and a
palaeolatitude of 41°N for it is similar to the latitudinal distribution of
permafrost and glaciers in the High Mountain Asia area defined by the
IPCC (Fig. 6e). The 53°N scenario suggests an elevation mode of past
permafrost at 899 m asl (range 186–3841 m asl), with permafrost
underlying 17% of the surface (Fig. 6e). The 41°N scenario yields an
elevation range for permafrost of 2196–6204 m asl, with a mode of
4672 m asl, and permafrost underlying 12% of the surface (Fig. 6e).
Permafrost astrochronology and the orbital control on the
Hauterivian cold snap
The revised magnetostratigraphic studies were based on the geomag-
neticpolaritytimescale(MHTC12)
51 and cyclostratigraphic analysis
(Supplementary Note 6). The observed magnetic polarities are corre-
lated with chrons CM5n–CM12r.1n of the geomagnetic polarity time
scaleMHTC12,yieldingtheagerangeof134.0–126.1 Ma for the mea-
sured section (Supplementary Note 6 and Supplementary Fig. 11). The
top boundary of the Luohe Fm is ca. 129.4 Ma. The Luohe Fm of Well
Wuqi created a ca. 4.19 myr long floating astronomical time scale
(sedimentation rate: 8.243 cm/kyr, dominated cycle: long eccentricity
with the frequency of 33.09 m/cycle; Supplementary Note 6 and Sup-
plementary Fig. 12), and the astronomical age of the Well Wuqi is ca.
133.59–129.4 Ma during the Luohe Fm interval (Supplementary Note 6).
Some notable low-power eccentricity (E7 and E8) occurs in the
405-kyr Gaussian bandpass filter (Fig. 7). The eccentricity signal during
this period also became weaker in the evolutionary fast Fourier
transform (FFT) spectral analysis of Well Wuqi (Fig. 7). In addition, an
extended period of low-amplitude variability in obliquity is identified
in the lower part of the Luohe Fm (ca. 132.49–132.17 Ma) (Fig. 7).
A similar phenomenon has been documented for the Mi-1 glacia-
tion event52. The lower the obliquity, the less solar radiation the polar
regions receive, which favours the creation of ice s heets52,53.Compared
to Mi-1, the extent and duration of cooling reflected in our records are
weaker and shorter. Thus, we presume that from ca. 132.49 Ma
onwards, the polar summer continued to be cooler, and the ice sheets
temporarily expanded with the appearance of minimum eccentricity
and a sustained low amplitude in obliquity52,53. The evolutionary FFT
spectrum and the power of eccentricity and obliquity can be corre-
lated with the horizon of the permafrost wedges, which supports the
accuracy of the revised palaeo-magnetic age framework (Fig. 7).
Cretaceous permafrost microbiome
A diverse complex of recognizable, and often exceptionally well-
preserved ancient filamentous, bacillar, and coccoid fossilized micro-
organisms was found in the Cretaceous permafrost wedges (Fig. 8and
Supplementary Figs. 13–16). Microbial fossils in the sample OR37b4
appeared to be more diverse in comparison to sample OR15b1 (Fig. 8).
The fossils include remnants of prokaryotes (rod-shaped and coccoid
bacteria, hyphae of actinomycetes, filamentous cyanobacteria), and
aquatic eukaryotic unicellular microalgae (e.g., prasinophytes). The
permafrost biome shows mineralized eukaryotic microorganisms
gathered in monolayers where microbial cells were enveloped in
sheaths and formed a film containing numerous ovalcells about 1.4 μm
long and 1–1.2 μm wide. Rounded cells with a diameter of about 1.4 μm
and oval-flattened cells are also visible (Fig. 8a–c). Rod-shaped bac-
terial forms are 2.5–3.5 μmlongand0.4–0.5 μm wide, slightly curved
with rounded ends and resemble Bacilli (Fig. 8d–f). All these sizesare in
agreement with the most common dimensions of fossil bacteria,
within the range of 0.2–2μm, although maximum sizes of fossil bac-
teria can be >100 μm54.
Several lines of evidence indicate the mineralized stage of fossil
bacteria and its fossilization. First, a lack of morphological variation
and neither dehydration nor shrinkage of cells indicates a mineralized
stage of fossil bacteria, as demonstrated by SEM images taken before
and after the EDX analysis (Supplementary Figs. 13and 15). Second, the
geochemical composition of analysed fossil bacteria reveals a C and O
composition (carbon ca. 16–44%, oxygen ca. 25–43%) different from
that of living organisms but very similar to lignite coal, peat and humic
substances (Supplementary Figs. 14 and 16). Third, geochemical EDX
analysis demonstrates that thishigh C content occurs in fossils already
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mineralized with high-weight elemental concentrations of O, Si and Ca
(Supplementary Figs. 14 and 16), demonstrating the mineralized stage
(calcitization and silicification) of fossil bacteria55. Calcitization and
silicification are two early diagenetic/taphonomic processes leading to
the exceptional preservation of fossil bacteria56. Silicification leads to
the excellent preservation of cells56, as shown by the preservation of
the Cretaceous permafrost biome cells with high-weight elemental
concentrations of O and Si, similar to the exceptionally preserved
bacteria in Proterozoic rocks from the Mesoproterozoic WumishanFm
in Jixian, north China55.
Evidence of synsedimentary growth of bacterial colonies in the
aeolian facies that host the sandstone wedges during deposition
includes the widespread occurrence of mineral grains and cements
covering microbial fossilized cells54 (Fig. 8). Based on previous
research57,58 we summarize that gram-positive bacteria, cyanobacteria,
and unicellular eukaryotic algae are more often found as fossilized
remains. Bacterial colonies, as those from the Cretaceous permafrost
in China, indicate that the permafrost microbiome was organized in
communities for efficient exploitation of energy and nutrients54 in this
extremely cold environment, where permafrost thaw might hamper
Fig. 5 | Permafrost probability fraction(PERPROB) mapsof modern permafrost
distribution in the Himalayan–TibetPlateau region. a,b,anddMaps producing
by combining a DEM with Permafrost Probability Fraction (PERPROB) data from
refs. 42,43 https://doi.pangaea.de/10.1594/PANGAEA.888600?format=html#
download, using GlobalMapper software. The colour ramp showing PERPROB
values is on the left of the figure. cSatellite imagery indicating the location of the
study area in the western Himalayas. Image Landsat/Copernicus and Google Earth.
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trophic or cooperative interactions in the long-term among different
microorganisms colonizing the permafrost59.
The fossils found in the Cretaceous permafrost wedges include
prokaryotes (rod-shaped and coccoid bacteria, hyphae of actino-
mycetes, filamentous cyanobacteria), and aquatic eukaryotic uni-
cellular microalgae (e.g., prasinophytes), resembling microbiomes
from late Pliocene through Holocene permafrost60,61. Analyses of
shotgun metagenomes from modern permafrost and the overlying
active layer in Alaska62, in the High Arctic (Svalbard)63, and Canada64
showed the presence of actinomycetes, filamentous cyanobacteria
and eukaryotic algae. Siberian permafrost contains cyanobacteria
and unicellular eukaryotic algae that can survive harsh permafrost
conditions for millennia61. The preserved Cretaceous permafrost
microbiome assemblage contains decomposers of organic matter
Fig. 6 | Altitudinal and geographical distribution of high-altitude Himalayan
permafrost. a Satellite imagery and topographic elevation profile of the cold
aeolian dunefield, high mountain lake and surrounding mountain systems. Image
@2022 Maxar Technologies, Image @ CNES/Airbus, and Google Earth. bRegional
summary statistics for the area of glaciers and permafrost in mountains of the High
Mountain Asia region and the median elevation of the annual mean 0°C free-
atmosphere isotherm with 25–75% quantiles in grey. Adapted from Fig. 2.1from ref.
44. Adapted from Fig. 2.1 from Hock, R., G. Rasul, C. Adler, B. Cáceres, S. Gruber, Y.
Hirabayashi, M. Jackson, A. Kääb,S. Kang, S. Kutuzov, Al. Milner, U. Molau,S. Morin,
B. Orlove, and H. Steltzer, 2019: High Mountain Areas. In: IPCC Special Report on
the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V.
Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A.Alegri
a, M.
Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press. The altitudes of
selected geomorphological elements (1–4) from aare indicated, as well as their
correspondent % of the area covered by permafrost. cMaps produced by com-
bining a DEM with permafrostprobability fraction (PERPROB) data fromrefs. 42,43
https://doi.pangaea.de/10.1594/PANGAEA.888600?format=html#download,using
GlobalMapper software. dSatellite imagery showing the location measured point, 2
in the plateau cold aeolian dunefield. See location in (a). Image @2022 Maxar
Technologies, Image @ CNES / Airbus, and Google Earth. eComparison of the
palaeolatitudinal reconstructions of the studied Cretaceous permafrost system
from China (53°N and 41°N scenarios), with the statistics on the present-day alti-
tudinaldistributionof permafrost,glaciers, and zero-degreequantiles in North Asia
and High Mountain Asia from Fig. 2.1 of ref.44. Adapted from Fig. 2.1 fromHock, R.
et al., 2019: High Mountain Areas. In: IPCC Special Report on the Ocean and
Cryosphere in a Changing Climate (eds Pörtner, H.-O. et al.) (in press).
Article https://doi.org/10.1038/s41467-022-35676-6
Nature Communications | (2022) 13:7946 9
Content courtesy of Springer Nature, terms of use apply. Rights reserved
such as actinomycetes, mycelial fungi, and bacteria, along with
photosynthetic cyanobacteria and unicellular algae that controlled
the net carbon dioxide emissions during Cretaceous perma-
frost thaw.
Discussion
Permafrost underlay a plateau desert in interior Asia during the Cre-
taceous supergreenhouse and was analogous to modern permafrost in
a desert in the western Himalayas surrounding Qiongkuai Lebashi
Lake. Identification of this past permafrost corroborates the palaeo-
temperature models for the Valanginian–Hauterivian stages48 that
predicted an annual mean surface air temperature (at 1.5 m) of ≤0°C
for the Ordos Basin plateau desert basin and –8 °C for the bounding
desert mountain ranges (Supplementary Fig. 2b). The age of the per-
mafrost sandstone wedges from the Luohe Fm is ca. 132.49–132.17 Ma
(Hauterivian), based on the astronomical age constraint, and corre-
lates with the occurrence of glendonites in Svalbard65, ca. 132.36 Ma
[boundary between B. Balearis and P. Ligatus biozones66], ice-rafted
debris (IRD) in Australia6, and glendonites and IRD in Alaska67,and
slightly later than the Weissert event68 (Fig. 7).The occurrence of well-
known Valanginian-age glendonites13,andIRD
9, together with the
identification of geochemical anomalies in western Tethys69 points to
extensive glacial ice in the Valanginian–Hauterivian, opening the door
to the recognition of Valanginian permafrost in other polar and high-
altitude paleolatitudes.
Major perturbations of the global carbon cycle during the Cre-
taceous have previously been attributed to increased levels of atmo-
spheric CO
2
related to intensified global tectonic activity and/or
widespread volcanic activity70. However, the effect of large igneous
provinces (LIPs) seems to have a different correlation with the global
variation of the palaeo-atmospheric pCO
2
71 and sea-surface tempera-
ture (SST) (°C)72. Moreover, the relative role of these controls has been
re-evaluated and an alternate trigger for increased fertilization of the
oceans should have existed73.
We hypothesize that global permafrost thaw during the Cretac-
eous released significant volumes of greenhouse gases to the atmo-
sphere as well as dissolved organic carbon (DOC) and other nutrients
into watersheds, and marine waters. Thaw of organic-rich permafrost
increases carbon release and may affect aquatic systems through
carbon and nutrient additions5. The contribution of permafrost thaw
to the Cretaceous global C balance, including during oceanic anoxic
events(OAE) will haveto be determined in future research dealing with
ocean–continental cryosphere coupling associated with events of
cryosphere degradation in the aftermaths of supergreenhouse
cold snaps.
Thaw of permafrost in plateau desert basins as that reported from
the Cretaceous of China may constitute a neglected example of abrupt
permafrost thaw74, postdating a global cold snap in the Hauterivian
(Fig. 7) with plateau permafrost in China coeval with marine cryo-
spheric indicators in Svalbard65,Alaska
67,75, and Australia6.Globalthaw
of permafrost after the cold snap likely released carbon as greenhouse
gases (CO
2
and CH
4
) due to microbial decomposition of carbon pre-
viously frozen in permafrost, an example of positive feedback and
likely to amplify climate warming76.
The development of plateau permafrost during the Hauterivian
correlates with a global drop of SST (°C)72. Furthermore, its dis-
appearance correlates with a global increase in atmospheric pCO
2
inferred from pedogenic carbonates71, with a global shift towards
heavier values of δ13Cc (‰)65, coinciding also with a rapid rise of global
SST (°C)72. The global synchroneity (interval 132.5–128 Ma) of the
positive carbon isotope event, the SST variation, and the rise of
atmospheric pCO
2
postdating the terrestrial record of plateau perma-
frost collectively points to a strong coupling of the ocean–atmosphere
system. It also suggests that the disappearance of cryospheric systems
Fig. 7 | Chronostratigraphic interval containing permafrost sandstone wedges
based onthe astrochronology of WellWuqi in the OrdosBasin, and correlation
with global multi-proxy ocean temperature trends and with other evidence of
and active Cretaceous cryosphere. The δ13Ccarb curve, TEX
86
,oxygenisotopes,
and Mg/Caratio palaeo-thermometry from ref. 68 and references therein. Modified
after ref. 68. Temporal distribution of Svalbard glendonites from ref. 65 and bios-
tratigraphy based on ref. 66 after chronostratigraphy of ref. 65.AlaskanIRDand
glendonites from ref. 67,75 and Australian IRD from ref. 6. Glendonites from the
Deer Bay Fm in the Sverdrup Basin, Arctic Canada from refs.12,13. Dropstonesfrom
the Deer Bay Fm in Ellesmere Island, Arctic Canada from ref. 9.
Article https://doi.org/10.1038/s41467-022-35676-6
Nature Communications | (2022) 13:7946 10
Content courtesy of Springer Nature, terms of use apply. Rights reserved
associated with a global cold event may have affected the total
exchangeable carbon reservoir.
Estimations made from mid-Pliocene (3.3–3.0 Ma) lacustrine sys-
tems from Tibet highlight that ca. 60% of alpine permafrost is vul-
nerable to thawing compared to ca. 20% of circumarctic permafrost77.
These authors estimated that ca. 25% of permafrost carbon and the
permafrost–climate feedback could arise from alpine areas77.
At present, permafrost stores ~1600 BT of carbon78 over 20% of
Earth’s terrestrial surface62. This store is nearly twice as large as the
carbon stored today in the atmosphere78.Weconcludethatthawof
permafrost76 aftertheHautiveriancoldsnappromotedglobalwarming
of Cretaceous climates and fertilized the oceans. Antarctic evidence
for glaciation of the South Pole during the Late Cretaceous18 raises the
likelihood that permafrost occurred at that time in Antarctica. Further
investigation on recent permafrost analogues and of Cretaceous
oceanic deposits may shed light on the exact contribution of perma-
frost thaw79 to the radiative forcing of global Cretaceous events.
Methods
Fieldwork and sample collection
During our field investigations from October 8th to 15th, 2020, we
conducted sedimentological analysis of aeolian sandstones in the
Luohe Fmat the Yucha Grand Canyon, GanquanCounty, Central Ordos
Basin. We focused on the sandstone wedge structures within the
aeolian sandstones of a well-exposed outcrop, OR15 (Supplementary
Fig. 1c and d). The Yucha Grand Canyon is located on the north side of
mineral crystals covering microbes
mineral
crystals
covering
microbes
e
f
5 μm
5 μm
2.5 μm
2.5 μm
5 μm
5 μm
mineral grain
covering microbes
mineral grain
covering microbes
b
c
4μm
4μm
4μm
4μm
OR37b4-15
OR37b4-14
ad
e
f
b
c
8μm
8μm
Fig. 8 | Cretaceous permafrost microbiome. a Sample OR37b4-14 shows miner-
alized fossil microorganisms gathered in a monolayer. The microbial cells are
enveloped in sheaths and form a film, which contains numerous oval cells about
1.4 μmlongand1–1.2 μm wide. Rounded cells with diameters of about 1.4 μmand
oval-flattened cells are also visible. The cells are attributed to eukaryotic micro-
organisms. See Supplementary Figs. 13, 14. band cshow mineralized micro-
organisms gathered in a monolayer. The microbial cells are enveloped in sheaths
and form a biofilm, which contains numerous oval cells about 1.4 μmlongand
1–1.2 μm wide. Rounded cells with a diameter of about 1.4 μm and oval-flattened
cells are also visible. Probably these cells belong to eukaryotic microorganisms.
Areas band cdemonstrate evidenceof mineral grains covering microbial fossilized
cells. dSample OR37b4-15 shows the accumulation of rod-shaped bacterial forms
2.5–3.5 μm long and 0.4–0.5 μm wide. Rod-shaped cells are slightly curved with
rounded ends and resemble Bacilli. See Supplementary Figs. 15, 16. dshows the
accumulation of rod-shaped bacterial forms 2.5–3.5 μmlongand0.4–0.5 μm wide.
Rod-shaped cells are slightly curved with rounded ends and resemble Bacilli. eand
fmineral grains and cements cover fossil bacteria (white arrows).
Article https://doi.org/10.1038/s41467-022-35676-6
Nature Communications | (2022) 13:7946 11
Content courtesy of Springer Nature, terms of use apply. Rights reserved
the Second Level Road of Ganquan County to Zhidan County, 40 km
west of Ganquan County, and 72 km east of Zhidan County (Supple-
mentary Fig. 1c and d). The entrance to the visitor center is in Zhang-
jiagou Village. From the visitor center, drive 3.7 km north to Yayaodi
Village, and walk 366 m west to OR15 (Supplementary Fig. 1c and d).
As the outcrop OR15 with the wedges in the aeolian sandstone
represents a steep cliff, we used a drone to investigate and photograph
the upper portion of the outcrop. The drone model is the Mavic Air 2
(SZ DJI Technology Co., Ltd., Shenzhen, China).
For microscopy, samples from the wedges were collected with
sterile tools and placed into sterile tightly sealed bags. In the labora-
tory, samples were ground up and prepared for microscopy inside a
sterile box.
Natural gamma ray (GR) logging data
The intensity of GR levels in the rock relates to its content of uranium
(U), thorium (Th), and potassium (K), reflecting the amount of clay and
organic matter80. Potassium is concentrated in common minerals such
as clays, feldspar, mica, and chloride salts. U and Th are commonly
found in minerals such as clays, heavy minerals, feldspars, and phos-
phate, whereas U is usually concentrated in organic matter80.The
distribution of these radioactive elements, determined from GR data
with the advantage of continuous and high resolution, has been used
as a palaeoclimatic proxy for many cyclostratigraphic studies81,82.GR
logs of Well Wuqi were selected for cyclostratigraphic analysis of the
early Cretaceous in Ordos Basin (Supplementary Data 1 and 2).
Time series analysis and modelling
Time series analysis of the GR data was performed with Acycle
2.0 software83. The long-term linear trend in GR data was removed by
the detrending function. The 2πmultitaper (MTM) method of spectral
analysis with a red-noise null model was performed to detect significant
frequency peaks. Sliding-window analysis with the evolutionary fast
Fourier transform (FFT) method was used to examine changes in
dominant frequency patterns. The Gaussian bandpass filter was used to
filter 405-kyr signals. In addition, the correlation coefficient (COCO)
analysis was applied to evaluate the optimal sedimentation rate for the
studied sequence83. The La2004 orbital solution has been identified as a
preciseastronomicaltargetfortheperiod134–129.4 Ma84.
Scanning electron microscope (SEM) analysis
The SEM instrument model was SIGMA300 (Carl Zeiss AG, Germany)
and the whole experiment was carried out at the Institute of Multi-
purpose Utilization of Mineral Resources, Chinese Academy of Geo-
logical Sciences, Chengdu, China. A total of 9 samples for SEM analysis
was collected. The sandstone wedge structures cropping out in the
field weregently tapped into small blocks to obtain the naturalsection
and then processed to a size of 1.5 cm*1.5 cm. The samples were fixed
to the sample stage (1.3 cm*1.3 cm) by means of conductive adhesive
and coated using the gold plating instrument with three sprays of
10 min each. Three samples were placed in the SEM sample compart-
ment at a time. Sterile gloves and masks were worn throughout the
processand the samples were cleaned repeatedly with compressed air
to ensure they were not contaminated. The SEM was operated at 10 kV,
HDBSD mode. The sample number was specified on the operating
screen and the microbial phenomena were photographed at different
magnifications after the optimum photographic definition was
obtained by adjusting the axis distance, contrast, brightness, and
focus. The energy dispersive X-ray spectroscopy energy spectrum was
scanned as a point and surface scan, with the Au elements, removed
and normalized to give the results. Photomicrographs were taken
before and after the energy spectrum scan to observe any changes in
microbial morphology and make sure the microbes observed were
fossils and that no morphological changes occurred after the electron
beam was fired.
Data availability
The Gamma Ray log data of Wells Wuqi and Lingtai of the Cretaceous
Luohe Fm. used in this study are available in the University of Sussex
data Repository under accession code https://doi.org/10.25377/
sussex.21610635.
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Acknowledgements
We thank Yuxiang Shi and Qiushuang Fan for their assistance in the field
and helpful discussion. This work was jointly funded by the National
Natural Science Foundation of China (Nos. 41872099,
42230310, 41888101, 91855213, 41602127) to Ch.W., Wq.T., C.M. This
work is also funded by the “Convocatoria de Ayudas para la recualifica-
ción del sistema universitario Español 2021–2023, Financiado por la
Unión Europea-Next Generation EU”,Vicerrectorado de Investigación,
Universidad del País Vasco UPV/EHU to J.P.R.L. This work is a contribution
to the Research Group of the Basque Government IT-1602-22 (Grupo
Consolidado del Gobierno Vasco IT-1602-22). This work is partially sup-
ported by the US Department of Energy, Office of Science, Office of
Biological and Environmental Research, Genomic Science Programme
under award number DE-SC0020369 to T.A.V. We are grateful to the
PETROCHINA CHANGQING OILFIELD COMPANY for granting permission
to use the subsurface data of the wells. We thank IPCC for granting
permission for the use of Fig. 2.1 from ref. 44 (Hocketal.,2019).Wethank
Dr. Bernd Etzelmüller for the discussion of high-altitude permafrost, and
Dr. Chris Burn for the discussion of permafrost patterned ground per-
sisting beneath shallow lakes.
Author contributions
J.P.R.L. and Ch.W. developed the scientific original idea. J.P.R.L.
prepared the narrative of the main manuscript, sedimentological and
architectural analyses, discussion, and figures, the Cretaceous palaeo-
climates and global implications, the Supplementary Material
(sedimentology description and discussion, permafrost wedge analy-
sis description and discussions), prepared fossil figures and discus-
sion, the West Himalayan analogue description and discussion, and its
figures. Ch.W. gathered the fieldwork photographs, carried out the
sampling, and the SEM analysis, contributed to the main manuscript,
magnetostratigraphic correlation, geological setting, global implica-
tions, discussion, figure preparations and preparation of the Supple-
mentary material and Methods sections. T.A.V. carried out the
microbiological analysis of fossil bacteria and has contributed to the
main manuscript, Supplementary material and figures. J.M. provided
the discussion and analysis of recent analogue analysis and con-
tributed to the main manuscript and Supplementary materials. Wq.T.
carried out the astrochronological analysis of wells, developed the
“Methods”section, and contributed to the Supplementary materials,
as well as to the main manuscript and figures. C.M. carried out the
comparative analysis of astronomical signals and palaeo-climatic
events, Supplementary materials, and contributed to the main
manuscript and figures.
Competing interests
The authors declare no competing interests.
Article https://doi.org/10.1038/s41467-022-35676-6
Nature Communications | (2022) 13:7946 14
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Chihua Wu.
Peer review information Nature Communications thanks Bernhard
Diekmann, Jennifer Galloway and the other, anonymous, reviewer(s) for
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