Cool equatorial terrestrial temperatures and the South Asian monsoon in the Early Eocene: Evidence from the Gurha Mine, Rajasthan, India

Shukla, Anumeha; Mehrotra, R. C.; Spicer, Robert A.; Spicer, Teresa E.V.; Kumar, Madhav

doi:10.1016/j.palaeo.2014.08.004

Cited by 107 publications

(80 citation statements)

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“…Eberle and Greenwood, 2012;Zachos et al, 2001Zachos et al, , 2003 and immediately post-dates the short-lived thermal spike known as the Paleocene-Eocene Thermal Maximum (Zachos et al, 2001), but despite its equatorial palaeoposition a recent physiognomic study of leaves preserved in the Gurha Mine, Rajasthan, showed that northwestern India experienced a climate characterised by strongly seasonal rainfall, implying a significant disruption to the 'ever wet' precipitation regime that normally exists at equatorial latitudes today. Moreover the overall temperature regime, while being megathermal, was cooler than perhaps one might have expected for a equatorial position under global 'hothouse' conditions (Shukla et al, 2014).…”

Section: Introductionmentioning

confidence: 77%

“…The Gurha lignite mine, near Bikaner, in the Nagaur-Ganganagar Basin, Rajasthan (27.87398° N,72.86709° E) provides access to a rich megaflora of early Eocene age. While the fauna has yet to be explored, insect fossils are common (Shukla et al, 2014). Here we investigate the microflora and palynofacies of the Gurha mine.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…In Gurha, a 38.5 m thick lignite seam (Fig. 2) was found at the depth of 105 m below the surface (Shukla et al, 2014).…”

Section: Stratigraphic Settingmentioning

confidence: 99%

“…Its abundance in parts of the Gurha section indicates massive blooms during the period of deposition. The abundant and diverse terrestrial palynoflora assignable to fresh water algae, pteridophytes and angiosperms, along with megafloral leaf remains typical of tropical vegetation of the early Eocene realm though the presence of elements like Gunnera, which is not exclusively tropical, indicates conditions were possibly cooler than in today's equatorial regions (Shukla et al, 2014) The A C C E P T E D M A N U S C R I P T A C C E P T E D M A N U S C R I P T…”

Section: Palaeoenvironmentmentioning

confidence: 99%

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Palynostratigraphy and palynofacies of the early Eocene Gurha lignite mine, Rajasthan, India

Kumar¹,

Spicer

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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A 105 m early Eocene section exposed in the Gurha Mine in the Nagaur-Ganganagar Basin, Rajasthan, India, archiving remains of equatorial vegetation at a time of extreme global warmth and close to the onset of the India-Eurasia collision, is investigated using palynostratigraphic and palynofacies analyses. Four palynozones e.g., Palmidites plicatus Singh, Botryococcus braunii Kützing, Triangulorites bellus Kar and Ovoidites ligneoulus are identified stratigraphically on the basis of abundance of these pollen taxa over others. The occurrence of taxonomically highly diverse angiosperm pollen in all the four palynozones attest to an extremely rich near-coastal tropical flora subject to frequent wildfires under a strongly seasonal precipitation regime. Palynotaxa characteristic of these palynozones are widely distributed in other early Paleogene sediments of India. Sedimentary organic matter (structured terrestrial, biodegraded, amorphous, grey amorphous, resins, charcoal/black- A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 brown debris and algal remains) recovered from mire and lacustrine sediments are of terrestrial origin, recording fluctuations in burial anoxia and salinity. Episodes of elevated salinity are due either to seepage of marine waters and/or a periodic excess of evaporation over precipitation at times when the depositional system was closed.

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Section: Introductionmentioning

confidence: 77%

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…In Gurha, a 38.5 m thick lignite seam (Fig. 2) was found at the depth of 105 m below the surface (Shukla et al, 2014).…”

Section: Stratigraphic Settingmentioning

confidence: 99%

Section: Palaeoenvironmentmentioning

confidence: 99%

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Palynostratigraphy and palynofacies of the early Eocene Gurha lignite mine, Rajasthan, India

Kumar¹,

Spicer

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Licht et al, 2014), and terrestrial fossil records, usually translated via a variety of transfer functions into rainfall seasonality, have to be used (e.g. Shukla et al, 2014;Srivastava et al, 2012;West et al, 2015;Xing et al, 2012). Consequently the individual monsoon systems are hard to differentiate from each other and their origin and development are difficult to document.…”

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confidence: 99%

Asian Eocene monsoons as revealed by leaf architectural signatures

Spicer

Yang

Herman

et al. 2016

Earth and Planetary Science Letters

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Cenozoic epeirogeny of the Indian peninsula

Richards

Hoggard

White

2016

Geochem Geophys Geosyst

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Peninsular India is a cratonic region with asymmetric relief manifest by eastward tilting from the 1.5 km high Western Ghats escarpment toward the floodplains of eastward‐draining rivers. Oceanic residual depth measurements on either side of India show that this west‐east asymmetry is broader scale, occurring over distances of > 2000 km. Admittance analysis of free‐air gravity and topography shows that the elastic thickness is 10 ± 3 km, suggesting that regional uplift is not solely caused by flexural loading. To investigate how Indian physiography is generated, we have jointly inverted 530 river profiles to determine rock uplift rate as a function of space and time. Key erosional parameters are calibrated using independent geologic constraints (e.g., emergent marine deposits, elevated paleosurfaces, uplifted lignite deposits). Our results suggest that regional tilt grew at rates of up to 0.1 mm a−1 between 25 Ma and the present day. Neogene uplift initiated in the south and propagated northward along the western margin. This calculated history is corroborated by low‐temperature thermochronologic observations, by sedimentary flux of clastic deposits into the Krishna‐Godavari delta, and by sequence stratigraphic architecture along adjacent rifted margins. Onset of regional uplift predates intensification of the Indian monsoon at 8 Ma, suggesting that rock uplift rather than climatic change is responsible for modern‐day relief. A positive correlation between residual depth measurements and shear wave velocities beneath the lithosphere suggests that regional uplift is generated and maintained by temperature anomalies of ±100 °C within a 200 ± 25 km thick asthenospheric channel.

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Cool equatorial terrestrial temperatures and the South Asian monsoon in the Early Eocene: Evidence from the Gurha Mine, Rajasthan, India

Cited by 107 publications

References 58 publications

Palynostratigraphy and palynofacies of the early Eocene Gurha lignite mine, Rajasthan, India

Palynostratigraphy and palynofacies of the early Eocene Gurha lignite mine, Rajasthan, India

Asian Eocene monsoons as revealed by leaf architectural signatures

Cenozoic epeirogeny of the Indian peninsula

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