Determination of a Late Miocene rocky palaeoshore by bioerosion trace fossils from the Bozcaada Island, Çanakkale, Turkey

2012 ◽  
Vol 11 (5) ◽  
pp. 331-344 ◽  
Author(s):  
Huriye Demircan
Keyword(s):  
Late Miocene ◽  
Trace Fossils

scholarly journals The relative roles of CO<sub>2</sub> and palaeogeography in determining Late Miocene climate: results from a terrestrial model-data comparison

2012 ◽  
Vol 8 (2) ◽  
pp. 715-786 ◽  
Author(s):  
C. D. Bradshaw ◽  
D. J. Lunt ◽  
R. Flecker ◽  
U. Salzmann ◽  
M. J. Pound ◽  
...  
Keyword(s):  
Late Miocene ◽  
Ice Sheet ◽  
Co2 Concentration ◽  
Model Data ◽  
Data Comparison ◽  
Fully Coupled

Abstract. The Late Miocene (∼11.6–5.3 Ma) palaeorecord provides evidence for a warmer and wetter climate than that of today and there is uncertainty in the palaeo-CO2 record of at least 150 ppmv. We present results from fully coupled atmosphere-ocean-vegetation simulations for the Late Miocene that examine the relative roles of palaeogeography (topography and ice sheet geometry) and CO2 concentration in the determination of Late Miocene climate through comprehensive terrestrial model-data comparisons. Assuming that the data accurately reflects the Late Miocene climate, and that the Late Miocene palaeogeographic reconstruction used in the model is robust, then results indicate that the proxy-derived precipitation differences between the Late Miocene and modern can be largely accounted for by the palaeogeographic changes alone. However, the proxy-derived temperatures differences between the Late Miocene and modern can only begin to be accounted for if we assume a palaeo-CO2 concentration towards the higher end of the range of estimates.

scholarly journals Exploring Ichnofacies Distribution in Ancient Seaways: The Late Miocene Rifian Corridor as a Natural Laboratory

2020 ◽  
Author(s):  
Wouter de Weger ◽  
Francisco Rodríguez-Tovar ◽  
Olmo Miguez-Salas
Keyword(s):  
Ocean Circulation ◽  
Late Miocene ◽  
Trace Fossils ◽  
Shallow Marine ◽  
Climatic Variations ◽  
Fine Grain ◽  
Major Controlling Factor ◽  
Palaeoenvironmental Conditions ◽  
Natural Laboratory ◽  
Ophiomorpha Rudis

Abstract Oceanic gateways have modulated ocean circulation and have influenced climatic variations throughout the Earth´s history. During the Late Miocene (7.8 - 7.35 Ma), the Atlantic Ocean and the Mediterranean Sea were connected through the Rifian Corridor (Morocco). This gateway is one of the few examples of deep ancient seaways with a semi-continuous sedimentary record. Deposits comprise turbidites intercalated between deep-sea fine grain sediments (i.e., hemipelagites and drift deposits), channelized sandstone contourite facies, and shallow marine sandstones. Herein an ichnological analysis was conducted in these upper Miocene sediments to improve characterisation of palaeoenvironmental conditions. In addition, ichnofacies were analysed to elucidate how bottom currents control ichnofacies distribution and can modified their attributes. Turbidite deposits are typified by vertical trace fossils (i.e., Ophiomorpha), conforming the Ophiomorpha rudis ichnosubfacies. Contouritic sandstones exhibit high density and low diverse trace fossil assemblage, with predominant Macaronichnus and Scolicia, resembling a proximal expression of Cruziana ichnofacies. Shallow marine environments are dominated by vertical trace fossils (e.g., Conichnus, Ophiomorpha and Skolithos), allowing an assignation to Skolithos ichnofacies. This study reveals energy to be a major controlling factor determining ichnofacies attributes and distribution in ancient deep seaways. Within these seaways, highly energetic conditions typical of shallower settings are present in deeper environments (i.e., slope), contributing to ichnodiversity impoverishment in ichnofacies.

A Complex Association of Invertebrates, Vertebrates and Trace Fossils in the Marine Camacho Formation (Late Miocene of Uruguay): Biostratigraphy and Paleoenvironments

Ameghiniana ◽  
2020 ◽  
Vol 57 (3) ◽  
pp. 266
Author(s):  
Daniel Perea ◽  
Mariano Verde ◽  
Pablo Toriño ◽  
Felipe Montenegro ◽  
Martín Ubilla ◽  
...  
Keyword(s):  
Late Miocene ◽  
Trace Fossils

scholarly journals Fossil trackways of the Baynunah Formation

2021 ◽  
Author(s):  
Faysal Bibi ◽  
Brian Kraatz ◽  
Mark Beech ◽  
Andrew Hill
Keyword(s):  
Late Miocene ◽  
Trace Fossils ◽  
Skeletal Remains ◽  
Sexual Segregation ◽  
Large Majority ◽  
Herding Behavior ◽  
Solitary Individual ◽  
Vertebrate Fauna ◽  
First Time

In addition to skeletal remains that record the presence of a diverse vertebrate fauna, the Baynunah Formation also preserves fossil trackways. These are found on deflated surfaces of carbonate-rich beds, mainly at sites located inland from the coast. Footprints, like other trace fossils, may be difficult to assign to particular species, but provide a window onto ancient behavior that is not attainable from skeletal remains alone. Nine sites bearing fossil footprints have been identified to date in the Baynunah Formation. These are presented and described here, most for the first time. The large majority of footprints (and the most easily identifiable) were made by proboscideans, but three trackways belong to a large ungulate, probably a giraffid, and one print may be that of a hippopotamid. The site of Mleisa 1 is particularly important for its remarkable preservation of the passage of a proboscidean herd intersected by the trackway of a large solitary individual, showing that herding behavior, and possibly also sexual segregation, both hallmarks of modern elephants, were already present in late Miocene proboscideans. Given the large areas across which the carbonates of the Baynunah Formation are exposed inland, many more trackways likely remain to be discovered.

scholarly journals The relative roles of CO<sub>2</sub> and palaeogeography in determining late Miocene climate: results from a terrestrial model–data comparison

2012 ◽  
Vol 8 (4) ◽  
pp. 1257-1285 ◽  
Author(s):  
C. D. Bradshaw ◽  
D. J. Lunt ◽  
R. Flecker ◽  
U. Salzmann ◽  
M. J. Pound ◽  
...  
Keyword(s):  
Late Miocene ◽  
Ice Sheet ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Model Data ◽  
Data Comparison ◽  
Fully Coupled

Abstract. The late Miocene palaeorecord provides evidence for a warmer and wetter climate than that of today, and there is uncertainty in the palaeo-CO2 record of at least 200 ppm. We present results from fully coupled atmosphere-ocean-vegetation simulations for the late Miocene that examine the relative roles of palaeogeography (topography and ice sheet geometry) and CO2 concentration in the determination of late Miocene climate through comprehensive terrestrial model-data comparisons. Assuming that these data accurately reflect the late Miocene climate, and that the late Miocene palaeogeographic reconstruction used in the model is robust, then results indicate that: 1. Both palaeogeography and atmospheric CO2 contribute to the proxy-derived precipitation differences between the late Miocene and modern reference climates. However these contributions exibit synergy and so do not add linearly. 2. The vast majority of the proxy-derived temperature differences between the late Miocene and modern reference climates can only be accounted for if we assume a palaeo-CO2 concentration towards the higher end of the range of estimates.

Short Note: Late Miocene marine trace fossils from James Ross Island

2008 ◽  
Vol 20 (6) ◽  
pp. 591-592 ◽  
Author(s):  
Anna E. Nelson ◽  
John L. Smellie ◽  
Mark Williams ◽  
Jan Zalasiewicz
Keyword(s):  
Antarctic Peninsula ◽  
Late Miocene ◽  
Short Note ◽  
Trace Fossils ◽  
Sediment Surface ◽  
North West ◽  
The North ◽  
Fossil Material ◽  
James Ross Island ◽  
Continuous Beds

Williams et al. (2006) reported asterozoans preserved in Late Miocene volcanic tuffs of the James Ross Island Volcanic Group. The material, from the north-west of James Ross Island at 64°01.9′S 58°20.07′W, was sourced from the newly named Asterozoan Buttress locality, and represented reconnaissance collecting. The volcaniclastic sediments in which the fossils are found are fine- to medium-grained volcanic sandstones with planar, laterally continuous beds 0.5–8 cm thick containing decimetre-scale ripple cross-lamination. In the absence of part and counterpart rock slabs, Williams et al. (2006) hypothesised that the fossils represented the external moulds of starfish or brittlestars pinioned by rapid sedimentation of volcanic tuffs. They noted that these tuffs represented a potential untapped source of fossil material for interpreting Neogene marine shelf environments on the northern Antarctic Peninsula. New fossil material collected at Asterozoan Buttress in February 2007 (by Anna Nelson) includes part and counterpart rock slabs, and demonstrates that the asterozoans are resting traces of animals, referable to the ichnogenus Asteriacites, and not external moulds of entombed animals (Fig. 1a & d). We reinterpret the ‘detached’ arm and ‘current-entrainment’ specimens of Williams et al. (2006, fig. 5c & d) as representing a possible scull mark and movement of the asterozoan across the sediment surface respectively (see Bell 2004, text-fig. 11 for comparison).

scholarly journals The Late Miocene Rifian corridor as a natural laboratory to explore a case of ichnofacies distribution in ancient gateways

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Olmo Miguez-Salas ◽  
Francisco J. Rodríguez-Tovar ◽  
Wouter de Weger
Keyword(s):  
Ocean Circulation ◽  
Late Miocene ◽  
Trace Fossils ◽  
Shallow Marine ◽  
Low Diversity ◽  
Shallow Marine Sediments ◽  
First Time ◽  
Palaeoenvironmental Conditions ◽  
Natural Laboratory ◽  
Ophiomorpha Rudis

AbstractOceanic gateways have modulated ocean circulation and have influenced climatic variations throughout the Earth´s history. During the late Miocene (7.8–7.35 Ma), the Atlantic Ocean and the Mediterranean Sea were connected through the Rifian Corridor (Morocco). This gateway is one of the few examples of deep ancient seaways with a semi-continuous sedimentary record. Deposits comprise turbidites intercalated between deep-sea mudstone (i.e., hemipelagites and drift deposits), channelized sandstone contourite facies, and shallow marine sandstone. Herein an ichnological analysis was conducted in these upper Miocene sediments to improve characterisation of palaeoenvironmental conditions. In addition, ichnofacies were analysed to elucidate how bottom currents control ichnofacies distribution and can modify their attributes. Turbidite deposits are typified by vertical trace fossils (i.e., Ophiomorpha), conforming the Ophiomorpha rudis ichnosubfacies. Contouritic sandstone exhibits high density and low diversity trace-fossil assemblage, with predominant Macaronichnus and Scolicia, resembling a proximal expression of the Cruziana ichnofacies. Shallow marine environments are dominated by vertical trace fossils (e.g., Conichnus, Ophiomorpha, Skolithos), allowing an assignation to the Skolithos ichnofacies. This study reveals for the first time a variability in ichnofacies attributes and distribution at the Rifian Corridor, associated with turbidites, contourite and shallow marine sediments. Hydrodynamic energy reveals as the major factor controlling trace maker communities in the studied seaway. Highly energetic conditions typical of shallower settings are present in deeper-water environments (i.e., slope), contributing to ichnodiversity impoverishment in ichnofacies.

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