scholarly journals Middle Miocene climate of southwestern Anatolia from multiple botanical proxies

2018 ◽  
Author(s):  
Johannes M. Bouchal ◽  
Tuncay H. Güner ◽  
Thomas Denk
Keyword(s):  
Middle Miocene ◽  
Structural Complexity ◽  
Eastern Africa ◽  
Leaf Analysis ◽  
Pollen Zone ◽  
Forested Landscapes ◽  
Cooling Phase ◽  
Tropical Climates ◽  
Climate Transition ◽  
Warm Temperate

Abstract. The middle Miocene climate transition (MMCT) was a phase of global cooling possibly linked to decreasing levels of atmospheric CO2. The MMCT coincided with the European Mammal Faunal Zone MN6. From this time, important biogeographic links between Anatolia and eastern Africa include the hominid Kenyapithecus. Vertebrate fossils suggested mixed open and forested landscapes under (sub)tropical seasonal climates for Anatolia. Here, we infer the palaeoclimate during the MMCT and the succeeding cooling phase for a middle Miocene (14.8–13.2 Ma) of an intramontane basin in southwestern Anatolia using three palaeobotanical proxies: (i) Köppen signatures based on the nearest-living-relative principle. (ii) Leaf physiognomy analysed with the Climate Leaf Analysis Multivariate Program (CLAMP). (iii) Genus-level biogeographic affinities of fossil floras with modern regions. The three proxies reject tropical climates for the MMCT of southwestern Anatolia and instead infer warm temperate C climates. Köppen signatures reject summer-dry Cs climates but cannot discriminate between fully humid Cf and winter-dry Cw; CLAMP reconstructs Cf climate based on the low X3.wet/X3.dry ratio. Additionally, we assess whether the palaeobotanical record does resolve transitions from the warm Miocene Climatic Optimum (MCO, 16.8–14.7 Ma) into the MMCT (14.7–13.9 Ma), and a more pronounced cooling at 13.9–13.8 Ma, as reconstructed from benthic stable isotope data. For southwestern Anatolia, we find that arboreal taxa predominate in MCO floras (MN5), whereas in MMCT floras (MN6) abundances of arboreal and non-arboreal elements strongly fluctuate indicating higher structural complexity of the vegetation. Our data show a distinct pollen zone between MN6 and MN7+8 dominated by herbaceous taxa. The boundary MN6 and MN7+8, roughly corresponding to a first abrupt cooling at 13.9–13.8 Ma, possibly might be associated with this herb-rich pollen zone.

scholarly journals Middle Miocene climate of southwestern Anatolia from multiple botanical proxies

2018 ◽  
Vol 14 (10) ◽  
pp. 1427-1440 ◽  
Author(s):  
Johannes Martin Bouchal ◽  
Tuncay Hüseyin Güner ◽  
Thomas Denk
Keyword(s):  
Middle Miocene ◽  
Structural Complexity ◽  
Eastern Africa ◽  
Fossil Flora ◽  
Leaf Analysis ◽  
Pollen Zone ◽  
Forested Landscapes ◽  
Cooling Phase ◽  
Climate Transition ◽  
Warm Temperate

Abstract. The middle Miocene climate transition (MMCT) was a phase of global cooling possibly linked to decreasing levels of atmospheric CO2. The MMCT coincided with the European Mammal Faunal Zone MN6. From this time, important biogeographic links between Anatolia and eastern Africa include the hominid Kenyapithecus. Vertebrate fossils suggested mixed open and forested landscapes under (sub)tropical seasonal climates for Anatolia. Here, we infer the palaeoclimate during the MMCT and the succeeding cooling phase for a middle Miocene (14.8–13.2 Ma) intramontane basin in southwestern Anatolia using three palaeobotanical proxies: (i) Köppen signatures based on the nearest living-relative principle; (ii) leaf physiognomy analysed with the Climate Leaf Analysis Multivariate Program (CLAMP); (iii) genus-level biogeographic affinities of fossil flora with modern regions. The three proxies reject tropical and hot subtropical climates for the MMCT of southwestern Anatolia and instead infer mild warm temperate C climates. Köppen signatures reject summer-dry Cs climates but cannot discriminate between fully humid Cf and winter-dry Cw; CLAMP reconstructs Cf climate based on the low X3.wet∕X3.dry ratio. Additionally, we assess whether the palaeobotanical record resolves transitions from the warm Miocene Climatic Optimum (MCO, 16.8–14.7 Ma) to the MMCT (14.7–13.9 Ma), and a more pronounced cooling at 13.9–13.8 Ma, as reconstructed from benthic stable isotope data. For southwestern Anatolia, we find that arboreal taxa predominate in MCO flora (MN5), whereas in MMCT flora (MN6) abundances of arboreal and non-arboreal elements strongly fluctuate, indicating higher structural complexity of the vegetation. Our data show a distinct pollen zone between MN6 and MN7+8 dominated by herbaceous taxa. The boundary between MN6 and MN7+8, roughly corresponding to a first abrupt cooling at 13.9–13.8 Ma, might be associated with this herb-rich pollen zone.

scholarly journals Boundary conditions for the Middle Miocene Climate Transition (MMCT v1.0)

2017 ◽  
Author(s):  
Amanda Frigola ◽  
Matthias Prange ◽  
Michael Schulz
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Middle Miocene ◽  
Climate Models ◽  
Global Climate ◽  
Co2 Concentration ◽  
General Circulation Models ◽  
Global Climate Models ◽  
Ice Volume ◽  
Climate Transition

Abstract. The Middle Miocene Climate Transition was characterized by major Antarctic ice-sheet expansion and global cooling during the interval ~ 15–13 Ma. Here we present two sets of boundary conditions for global general circulation models characterizing the periods before (Middle Miocene Climatic Optimum; MMCO) and after (Middle Miocene Glaciation; MMG) the transition. These boundary conditions include Middle Miocene global topography, bathymetry and vegetation. Additionally, Antarctic ice volume and geometry, sea-level and atmospheric CO2 concentration estimates for the MMCO and the MMG are reviewed. The boundary-condition files are available for use as input in a wide variety of global climate models and constitute a valuable tool for modeling studies with a focus on the Middle Miocene.

Distinguishing tectonic versus climatic forcing on landscape evolution: An example from SE Tibetan Plateau

2020 ◽  
Vol 133 (1-2) ◽  
pp. 233-242 ◽  
Author(s):  
Fangbin Liu ◽  
Martin Danišík ◽  
Dewen Zheng ◽  
Kerry Gallagher ◽  
Junsheng Nie
Keyword(s):  
Tibetan Plateau ◽  
Middle Miocene ◽  
Asian Summer Monsoon ◽  
Late Eocene ◽  
Crustal Shortening ◽  
Lateral Extrusion ◽  
Granite Belt ◽  
Cooling Phase ◽  
Forcing Mechanisms ◽  
Exhumation History

Abstract Distinguishing climate from tectonic forcing in shaping the Earth’s surface has been a long-standing issue in the Earth sciences. Great debate exists regarding when and how the SE Tibetan Plateau achieved its current low-relief topography, and both lateral extrusion and lower crust flow have been proposed as the dominant mechanism. Reconstruction of the exhumation history of the SE Tibetan Plateau is key to understanding these formation processes and resolving the significance of different forcing mechanisms. Here we report zircon and apatite (U-Th)/He ages from steep transects across the Lincang granite belt of the SE Tibetan Plateau. Our results reveal a two-stage exhumation history during the Cenozoic with rapid cooling phases in the late Eocene and the middle Miocene. In the late Eocene, the climate was generally dry and there is plenty of evidence for increased extrusion and upper crustal shortening. We suggest tectonic processes are responsible for the first inferred cooling. In contrast, the Asian summer monsoon precipitation increased during the middle Miocene, and we posit the middle Miocene cooling phase records a phase of rapid river incision triggered by the intensified precipitation and associated fault movements. The results are consistent with recent paleo-altimetry work in this region suggesting that the present-day topography of the SE Tibetan Plateau had been largely constructed by the late Eocene. Together, these data suggest that extrusion and/or upper crustal shortening setup the first order topography of the SE Tibetan Plateau, which was then modified by climate-triggered fluvial incision and feedbacks initiated in the middle Miocene.

Stromatolites in the Paratethys Sea during the Middle Miocene climate transition as witness of the Badenian salinity crisis

Facies ◽  
2013 ◽  
Vol 60 (2) ◽  
pp. 429-444 ◽  
Author(s):  
Mathias Harzhauser ◽  
Jörn Peckmann ◽  
Daniel Birgel ◽  
Erich Draganits ◽  
Oleg Mandic ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Climate Transition

scholarly journals Discovery of the Badenian evaporites inside the Carpathian Arc: implications for global climate change and Paratethys salinity

2017 ◽  
Vol 68 (3) ◽  
pp. 193-206 ◽  
Author(s):  
Katalin Báldi ◽  
Felicitász Velledits ◽  
Stjepan Ćorić ◽  
Viktor Lemberkovics ◽  
Katalin Lőrincz ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Normal Saline ◽  
Middle Miocene ◽  
Global Climate ◽  
Great Plain ◽  
Geological Record ◽  
Central Paratethys ◽  
Growing Body ◽  
Climate Transition

Abstract Massive evaporites were discovered in the Soltvadkert Trough (Great Plain, Hungary) correlating to the Badenian Salinity Crisis (13.8 Ma, Middle Miocene) on the basis of nannoplankton and foraminifera biostratigraphy. This new occurrence from Hungary previously thought to be devoid of evaporites is part of a growing body of evidence of evaporitic basins inside the Carpathian Arc. We suggest the presence of evaporites perhaps in the entire Central Paratethys during the salinity crisis. Different scenarios are suggested for what subsequently happened to these evaporites to explain their presence or absence in the geological record. Where they are present, scenario A suggests that they were preserved in subsiding, deep basins overlain by younger sediments that protected the evaporites from reworking, like in the studied area. Where they are absent, scenario B suggests recycling. Scenario B explains how the supposedly brackish Sarmatian could have been hyper/normal saline locally by providing a source of the excess salt from the reworking and dissolving of BSC halite into seawater. These scenarios suggest a much larger amount of evaporites locked up in the Central Paratethys during the salinity crisis then previously thought, probably contributing to the step-like nature of cooling of the Mid Miocene Climate Transition, the coeval Mi3b.

scholarly journals Paleoecological and sedimentological characterisation of Middle Miocene sediments from the Hrvatska Kostajnica area (Croatia)

2020 ◽  
Vol 73 (3) ◽  
pp. 153-175
Author(s):  
Anita Grizelj ◽  
◽  
Monika Milošević ◽  
Koraljka Bakrač ◽  
Ines Galović ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Middle Miocene ◽  
Pannonian Basin ◽  
Temperate Climate ◽  
Terrigenous Material ◽  
Calcareous Nannofossil ◽  
Marginal Part ◽  
Local Input ◽  
Warm Temperate ◽  
Basin System

The Miocene deposits of the Hrvatska Kostajnica (KOS-I) area belong to the south-western marginal part of the Pannonian Basin System (PBS). Investigation of the lithostratigraphical column included: mineralogical, geochemical, sedimentological and integrated palaeontological (calcareous nannofossil, foraminifers, ostracodes, palynomorphs) analyses. Badenian and Sarmatian sediments of this column were deposited in a marine offshore environment with local input of terrigenous material represented by marls and silty marls. Based on palaeontological data, the recorded palaeoclimate was subtropical in the late Badenian changing to a warm temperate climate of the early Sarmatian. Marly sediments predominantly consist of carbonate (calcite and aragonite) and clay minerals, while quartz and plagioclase are less abundant. Most samples contain a small amount of zeolite minerals from the clinoptilolite/heulandite series. Among the clay minerals, smectite and illite/muscovite are the most abundant. Based on provenance analyses we concluded that the Badenian-Sarmatian marls were predominantly formed by the weathering of acidic (Si-rich) source rock derived material from the neighbouring Inner Dinarides.

scholarly journals Mid-Tertiary paleoenvironments in Thailand: pollen evidence

2010 ◽  
Vol 6 (4) ◽  
pp. 461-473 ◽  
Author(s):  
P. Sepulchre ◽  
D. Jolly ◽  
S. Ducrocq ◽  
Y. Chaimanee ◽  
J.-J. Jaeger ◽  
...  
Keyword(s):  
Middle Miocene ◽  
High Variability ◽  
Late Oligocene ◽  
Climate Variations ◽  
Tropical Environments ◽  
Palynological Assemblages ◽  
Tropical Woodlands ◽  
Mae Moh ◽  
Warm Temperate ◽  
Northeastern Thailand

Abstract. Only few well-dated records document the evolution of Southeast Asian paleoenvironments during the Cenozoic. Here we analyse continental pollen assemblages from Late Oligocene and Miocene fossil sites of Thailand. In agreement with previous studies, palynoflora from the Oligocene suggests warm temperate forested habitats at 24–26 Ma, whereas Middle Miocene assemblages are made of thermophilous taxa. This change can be linked to the major climate reorganization that brought warmer and wetter conditions over Southeast Asia around 22 Ma. This study also provides the first submillional records from the Middle Miocene of Thailand. Thirteen samples of lignite layers from the sivaladapid-bearing Mae Moh site, dated between 13.3 and 13.1 Ma, and six samples from the hominoid-bearing Chiang Muan deposit, dated between 12.4 and 12.2 Ma, document oscillations between tropical woodlands and grasslands in northern Thailand. These pollen records likely reflect climate variations linked to insolation variations. Late Miocene palynological assemblages from Khorat, northeastern Thailand, document fluviolacustrine paleoenvironments alternatively covered by thermophilous trees and grasslands. These records show that both sivaladapids and early hominoids from Thailand have evolved in tropical environments with high variability in the vegetation cover.

A checklist of vascular plants of the Amatole Mountains, eastern Cape Province/Ciskei

Bothalia ◽  
1987 ◽  
Vol 17 (2) ◽  
pp. 237-256 ◽  
Author(s):  
P. B. Phillipson
Keyword(s):  
Physical Environment ◽  
Vascular Plants ◽  
Cape Floristic Region ◽  
Eastern Africa ◽  
Vegetation Types ◽  
Eastern Cape ◽  
Botanical Exploration ◽  
Form Part ◽  
History Of ◽  
Warm Temperate

A checklist of vascular plants of the Amatole Mountains is presented. The physical environment, climate and vegetation of the study area and the history of its botanical exploration are described. The mountains form part of the Winterberg Range in the eastern Cape/Ciskei region of south-eastern Africa, and cover an area of approximately 900 km2. The altitude ranges from about 700 m to 2 000 m above sea level, and the topography is very varied. The climate is warm temperate and supports various vegetation types including forest, sclerophyllous shrubland, grassland and marshland. The checklist records the occurrence of 1 215 taxa. The largest families and genera in the area contain predominantly grassland herbs. Many of the characteristic families of the Cape Floristic Region and of the arid areas of southern Africa are poorly represented in the Amatole Mountains.

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