A Reassessment of the Chronostratigraphy of Late Miocene C<sub>3</sub>–C<sub>4</sub> Transitions

Tauxe, Lisa; Feakins, Sarah J.

doi:10.1029/2020pa003857

Cited by 26 publications

(26 citation statements)

References 85 publications

(119 reference statements)

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“…This study demonstrated that pCO 2 and climate both contributed to the spread of C 4 grasslands and made very specific predictions of where that innovation was favored, but the simulations were colder and had weaker temperature gradients than found in proxy data. The model finds were in general agreement with the diachronous progression of timings found in Tauxe and Feakins (2020). Improving the ability of GCMs to reproduce Miocene climates requires improved paleorecords from regions that are sensitive to CO 2 forcing, but insensitive to differences between Miocene and modern geographic configuration (Bradshaw et al., 2015).…”

Section: Climate Modeling Of the Miocenesupporting

confidence: 84%

The Miocene: The Future of the Past

Steinthorsdottir

Coxall

Boer

et al. 2021

Paleoceanog and Paleoclimatol

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268

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The Miocene epoch (23.03-5.33 Ma) was a time interval of global warmth, relative to today.Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhouse interval-the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, pCO 2 , and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher pCO 2 (∼400-600 ppm), the MCO has been suggested as a particularly appropriate analog for future climate scenarios, and for assessing the predictive accuracy of numerical climate models-the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re-interpretation of proxies, which might mitigate the model-data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here, we review the state-of-the-art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modeling studies. Plain Language Summary During the Miocene time period (∼23-5 million years ago),Planet Earth looked similar to today, with some important differences: the climate was generally warmer and highly variable, while atmospheric CO 2 was not much higher. Continental-sized ice sheets were only present on Antarctica, but not in the northern hemisphere. The continents drifted to near their modernday positions, and plants and animals evolved into the many (near) modern species. Scientists study the Miocene because present-day and projected future CO 2 levels are in the same range as those reconstructed for the Miocene. Therefore, if we can understand climate changes and their biotic responses from the Miocene past, we are able to better predict current and future global changes. By comparing Miocene climate reconstructions from fossil and chemical data to climate simulations produced by computer models, scientists are able to test their understanding of the Earth system under higher CO 2 and warmer conditions than those of today. This helps in constraining future warming scenarios for the coming STEINTHORSDOTTIR ET AL.

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Section: Climate Modeling Of the Miocenesupporting

confidence: 84%

The Miocene: The Future of the Past

Steinthorsdottir

Coxall

Boer

et al. 2021

Paleoceanog and Paleoclimatol

Self Cite

268

179

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“…It has a conformable contact with the overlying Nagri Formation, which consists of greenish-grey medium to coarse-grained sandstone layers with some subordinate claystone intervals. The age of this formation is late Miocene to early Pliocene (Yeats and Hussain 1987;Baker et al 1988;Gee 1989;Tauxe and Feakins 2020). The Nagri Formation is conformably overlain by the Dhok Pathan Formation, the uppermost unit of the Lower Siwaliks.…”

Section: Neogene Stratigraphy Of Potwar Plateaumentioning

confidence: 94%

Neogene Kinematics of the Potwar Plateau and the Salt Range, NW Himalayan Front: A Paleostress Inversion and AMS study

Qayyum

Poessé

Kaymakçı

et al. 2021

International Geology Review

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We provide new kinematic data from the Potwar Plateau (Pakistan) to evaluate the tectonic evolution of the region during the Neogene. The plateau is bound by two major strike-slip faults in the west and the east, accommodating its southwards translation.We have recognized two Neogene deformation phases in the plateau, based on paleostress inversion and Anisotropy of Magnetic Susceptibility (AMS) tensors. The first phase lasted until the early Pliocene and was characterized by vertical minor stress and N-S compression, implying thrust tectonics. The second deformation phase is characterized by a near-vertical intermediate principal stress and near-horizontal major and minor stresses, interpreted to be associated with strike-slip tectonics since the late Pliocene.K int vectors from 21 sites are relatively compatible with the major principal stress orientations (σ 1 ) and indicate two distinct domains. This is possibly because K min orientations are related to compaction, whereas K int orientations were always parallel to tectonic shortening and hence compression direction during both strike-slip (post-late Pliocene) and thrusting (pre-late Pliocene) phases. These phases are characterized by swapping of (σ 2 ) and (σ 3 ) orientations while (σ 1 ) maintained its orientation. The most prominent change occurs at the western part of the Potwar Plateau, where major principal stress directions (σ 1 ) and K int axes fan out south-westwards. The eastern domain is dominated by NE-SW trending folds and thrust faults, which are absent in the western domain. These structural features are interpreted to be the result of the distribution of deposits of the Neoproterozoic Salt Range Formation as a substratum below the Potwar Plateau. The Salt Range Formation is very thick and widespread in the west area and almost absent in the east. This factor led to unconstrained southwards gliding of the Potwar Plateau over the salt deposits in the west as opposed to frictional sliding and substantial internal deformation in the east.

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“…1.5 and 1.6). Recently Tauxe and Feakins (2020) provided updated ages for Siwalik Group sedimentary sections, including the data set of Sanyal et al (2004) from the Northwest Indian region. We also updated sample ages for the data set from the Surai Khola, Nepal section (Section S1.7), and use updated ages for the Pakistani Siwaliks data set (Behrensmeyer et al, 2007;Quade & Cerling, 1995) provided by John Barry and Kay Behrensmeyer on the GTS 2012 timescale.…”

Section: 1029/2020pa004108 6 Of 22mentioning

confidence: 99%

Hydrologic Changes Drove the Late Miocene Expansion of C₄ Grasslands on the Northern Indian Subcontinent

Polissar

Uno

Phelps

et al. 2021

Paleoceanog and Paleoclimatol

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During the Cenozoic (66 Ma to present), grasslands and open habitats replaced forests across large swaths of the tropics and subtropics (Jacobs et al., 1999;Strömberg, 2011), reshaping the vegetation structure and faunal communities in terrestrial ecosystems around the world (Anderson, 2006). In many regions, the late Miocene (∼11-5 Ma) conclusion of this ecological trajectory was the establishment of grasslands dominated by grass species using the C 4 photosynthetic pathway (Edwards et al., 2010). A substantial number of studies have mapped out when C 4 ecosystems became established around the globe. The earliest onset of C 4 ecosystem expansion occurred around 10

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A Reassessment of the Chronostratigraphy of Late Miocene C₃–C₄ Transitions

Cited by 26 publications

References 85 publications

The Miocene: The Future of the Past

The Miocene: The Future of the Past

Neogene Kinematics of the Potwar Plateau and the Salt Range, NW Himalayan Front: A Paleostress Inversion and AMS study

Hydrologic Changes Drove the Late Miocene Expansion of C₄ Grasslands on the Northern Indian Subcontinent

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A Reassessment of the Chronostratigraphy of Late Miocene C3–C4 Transitions

Cited by 26 publications

References 85 publications

The Miocene: The Future of the Past

The Miocene: The Future of the Past

Neogene Kinematics of the Potwar Plateau and the Salt Range, NW Himalayan Front: A Paleostress Inversion and AMS study

Hydrologic Changes Drove the Late Miocene Expansion of C4 Grasslands on the Northern Indian Subcontinent

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A Reassessment of the Chronostratigraphy of Late Miocene C₃–C₄ Transitions

Hydrologic Changes Drove the Late Miocene Expansion of C₄ Grasslands on the Northern Indian Subcontinent