scholarly journals Late Miocene volcanic rocks (Geiyo volcanic rock) and early-middle Miocene volcanic rocks (Setouchi volcanic rocks) from the Geiyo Islands in the western Setouchi region, southwest Japan.

2000 ◽  
Vol 29 (2) ◽  
pp. 20-27 ◽  
Author(s):  
Mamoru SENO ◽  
Hirohisa MATSUURA
Keyword(s):  
Volcanic Rock ◽  
Late Miocene ◽  
Middle Miocene ◽  
Volcanic Rocks ◽  
Southwest Japan

scholarly journals Melt equilibration depths as sensors of lithospheric thickness during Eurasia-Arabia collision and the uplift of the Anatolian Plateau

Geology ◽  
2019 ◽  
Vol 47 (10) ◽  
pp. 943-947 ◽  
Author(s):  
M.R. Reid ◽  
J.R. Delph ◽  
M.A. Cosca ◽  
W.K. Schleiffarth ◽  
G. Gençalioğlu Kuşcu
Keyword(s):  
Late Miocene ◽  
Large Scale ◽  
Middle Miocene ◽  
Volcanic Rocks ◽  
Suture Zone ◽  
Arabian Plate ◽  
Seismic Structure ◽  
Eurasian Plate ◽  
Lithospheric Thickness ◽  
Anatolian Plateau

Abstract A co-investigation of mantle melting conditions and seismic structure revealed an evolutionary record of mantle dynamics accompanying the transition from subduction to collision along the Africa-Eurasia margin and the >1 km uplift of the Anatolian Plateau. New 40Ar/39Ar dates of volcanic rocks from the Eastern Taurides (southeast Turkey) considerably expand the known spatial extent of Miocene-aged mafic volcanism following a magmatic lull over much of Anatolia that ended at ca. 20 Ma. Mantle equilibration depths for these chemically diverse basalts are interpreted to indicate that early to middle Miocene lithospheric thickness in the region varied from ∼50 km or less near the Bitlis suture zone to ∼80 km near the Inner Tauride suture zone. This southward-tapering lithospheric base could be a vestige of the former interface between the subducted (and now detached) portion of the Arabian plate and the overriding Eurasian plate, and/or a reflection of mantle weakening associated with greater mantle hydration trenchward prior to collision. Asthenospheric upwelling driven by slab tearing and foundering along this former interface, possibly accompanied by convective removal of the lithosphere, could have led to renewed volcanic activity after 20 Ma. Melt equilibration depths for late Miocene and Pliocene basalts together with seismic imaging of the present lithosphere indicate that relatively invariant lithospheric thicknesses of 60–70 km have persisted since the middle Miocene. Thus, no evidence is found for large-scale (tens of kilometers) Miocene delamination of the lower lithosphere from the overriding plate, which has been proposed elsewhere to account for late Miocene and younger uplift of Anatolia.

scholarly journals Flood basalts, rhyolites, and subsequent volcanism of the Columbia River magmatic province in eastern Oregon, USA

2021 ◽  
pp. 301-352
Author(s):  
Emily B. Cahoon† ◽  
Martin J. Streck† ◽  
Mark Ferns†
Keyword(s):  
Large Volume ◽  
Late Miocene ◽  
Middle Miocene ◽  
Volcanic Rocks ◽  
Columbia River ◽  
Flood Basalt ◽  
Lava Flows ◽  
Calc Alkaline ◽  
The North ◽  
High Lava Plains

ABSTRACT The Miocene Columbia River Basalt Group (CRBG) is the youngest and smallest continental flood basalt province on Earth. This flood basalt province is a succession of compositionally diverse volcanic rocks that record the passage of the Yellowstone plume beneath eastern Oregon. The compositionally and texturally varied suite of volcanic rocks are considered part of the La Grande–Owyhee eruptive axis (LOEA), an ~300-km-long, north-northwest–trending, Middle Miocene to Pliocene volcanic belt that extends along the eastern margin of the Columbia River flood basalt province. Volcanic rocks erupted from and preserved within the LOEA form an important regional stratigraphic link between the flood basalt–dominated Columbia Plateau to the north, the north and bimodal basalt-rhyolite volcanic fields of the Snake River Plain to the east, the Owyhee Plateau to the south, and the High Lava Plains to the south and east; the latter two have time transgressive rhyolite centers that young to the east and west, respectively. This field-trip guide details a four-day geologic excursion that will explore the stratigraphic and geochemical relationships among mafic rocks of the CRBG and coeval and compositionally diverse silicic rocks associated with the early trace of the Yellowstone plume and High Lava Plains in eastern Oregon. The trip on Day 1 begins in Portland then traverses across the western axis of the Blue Mountains, highlighting exposures of the widespread, Middle Miocene Dinner Creek Welded Tuff and aspects of the Picture Gorge Basalt lava flows and northwest-striking feeder dikes situated in the central part of the CRBG province. Travel on Day 2 progresses eastward toward the eastern margin of the LOEA, examining a transition linking the Columbia River Basalt province with a northwestward-younging magmatic trend of silicic volcanism of the High Lava Plains in eastern Oregon. Initial field stops on Day 2 focus on the volcanic stratigraphy northeast of the town of Burns, which includes regionally extensive Middle to Late Miocene ash-flow tuffs and lava flows assigned to the Strawberry Volcanics. Subsequent stops on Day 2 examine key outcrops demonstrating the intercalated nature of Middle Miocene tholeiitic CRBG flood basalts, temporally coeval prominent ash-flow tuffs, and “Snake River–type” large-volume rhyolite lava flows cropping out along the Malheur River. The Day 3 field route navigates to southern parts of the LOEA, where CRBG rocks are associated in space and time with lesser known and more complex silicic volcanic stratigraphy forming Middle Miocene, large-volume, bimodal basalt-rhyolite vent complexes. Key stops will provide a broad overview of the structure and stratigraphy of the Middle Miocene Mahogany Mountain caldera and of the significance of intercalated sedimentary beds and Middle to Late Miocene calc-alkaline lava flows of the Owyhee basalt. Initial stops on Day 4 will highlight exposures of Middle to Late Miocene silicic ash-flow tuffs, rhyolite domes, and calc-alkaline lava flows overlying the CRBG across the northern and central parts of the LOEA. The later stops on Day 4 examine more silicic lava flows and breccias that are overlain by early CRBG-related rhyolite eruptions. The return route to Portland on Day 4 traverses the Columbia River gorge westward from Baker City. The return route between Baker and Portland on Day 4 follows the Columbia River gorge and passes prominent basalt outcrops of large volume tholeiitic flood lavas of the Grande Ronde, Wanapum, and Saddle Mountains Formations of the CRBG. These sequences of basaltic and basaltic andesite lavas are typical of the well-studied flood basalt dominated Columbia Plateau, and interbedded silicic and calc-alkaline lavas are conspicuously absent. Correlation between the far-traveled CRBG lavas and calcalkaline and silicic lavas considered during the excursion relies on geochemical fingerprinting and dating of the mafic flows and dating of sparse intercalated ashes.

Middle Miocene (∼14 Ma) and Late Miocene (∼6 Ma) Paleogeographic Boundary Conditions

2021 ◽  
Author(s):  
Zhilin He ◽  
Zhongshi Zhang ◽  
Zhengtang Guo ◽  
Christopher R. Scotese ◽  
Chenglong Deng
Keyword(s):  
Boundary Conditions ◽  
Late Miocene ◽  
Middle Miocene

A new argyrolagoid (Mammalia: Marsupialia) from the middle Miocene of Bolivia

1988 ◽  
Vol 62 (3) ◽  
pp. 463-467 ◽  
Author(s):  
Villarroel A. Carlos ◽  
Larry G. Marshall
Keyword(s):  
South America ◽  
Late Miocene ◽  
Adaptive Radiation ◽  
Middle Miocene ◽  
Northwest Argentina ◽  
The Family ◽  
Size And Structure

A new argyrolagoid marsupial, Hondalagus altiplanensis n. gen., n. sp., from the middle Miocene (Santacrucian–Friasian) age locality of Quebrada Honda in southernmost Bolivia represents the smallest and most specialized member of the family Argyrolagidae known. The lower molars are hypselodont and lack vertical grooves labially and lingually, and M4 is greatly reduced relative to M3. In overall size and structure, H. altiplanensis compares best with Microtragulus catamarcensis (Kraglievich, 1931) from rocks of late Miocene (Huayquerian) age in northwest Argentina. Hondalagus altiplanensis demonstrates that the adaptive radiation of argyrolagoids was much greater than previously envisioned, and that generic differentiation of known taxa occurred no later than early–middle Miocene time in South America.

scholarly journals Peranan Kontrol Struktural dan Hidrologis dalam Perkembangan Lorong Gua Bagus-Jebrot di Malang-Indonesia

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Mohammad Ainul Labib ◽  
Agung Suprianto ◽  
Devi Prasetyo ◽  
Aan Seftian Hardianto ◽  
Alfi Sahrina ◽  
...  
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Cross Section ◽  
Frequency Analysis ◽  
Late Miocene ◽  
Structural Control ◽  
Middle Miocene ◽  
Field Measurements ◽  
Underground Water ◽  
And Control

Bagus-Jebrot Cave is located in Donomulyo District, Malang Regency which is in the Wonosari Formation which was formed in the Middle Miocene and Late Miocene. The purpose of this study is related to the developmental control that affects the cave passageways. The approach used is a geomorphological approach by conducting field measurements and documentation. The analysis used is frequency analysis and cross-section of the passage. Bagus-Jebrot Cave is a type of Epigenic Cave which is formed from surface water flowing into doline/sinkhole. It can be seen from the planview map that has a curvilinear passage pattern. The existence of groundwater flow also forms a physiographic cave passage with ellipse passage formation, asymmetrical ellipse, potholes, callops, solution notches, cups, solution pockets. Besides underground water flow, the development of the Bagus-Jebrot Cave aisle is related to the process of structural lifting and control. The lifting process is marked by the formation of 4 levels of the cave passage. While the formation of the canyon, joint passage, rectangular passage and keyhole is the result of structural control

scholarly journals The distribution of <i>Triebelina raripila</i> and <i>Carinocythereis carinata</i> (Ostracoda) from the Middle Miocene of the Central Paratethys and their palaeogeographic implications

1998 ◽  
Vol 17 (2) ◽  
pp. 125-130 ◽  
Author(s):  
J. Szczechura
Keyword(s):  
Shallow Water ◽  
Late Miocene ◽  
Middle Miocene ◽  
Early Miocene ◽  
Central Paratethys ◽  
Eastern Paratethys ◽  
Main Species ◽  
Late Middle Miocene ◽  
The Mediterranean

Abstract. Late Middle Miocene (Upper Badenian) strata of the Fore-Carpathian Depression of Poland yield a shallow-water ostracod fauna which contains the species Triebelina raripila (G. W. Müller, 1894) and Carinocythereis carinata (Roemer, 1838). The palaeobiogeographic distribution of the two main species suggests, that in the late Middle Miocene, Central Paratethys was still connected to the Mediterranean, although still separated from the Eastern Paratethys and from southeastern Eurasia. The continuous occurrence of Triebelina raripila and Carinocythereis carinata in the Mediterranean basins, from the Early Miocene to Recent, indicates that marine conditions existed throughout, thereby allowing them to survive the Late Miocene salinity crisis.

A new genus and species of Sieblosiidae from the Middle Miocene of Germany (Odonata: Epiproctophora)

Zootaxa ◽  
2012 ◽  
Vol 3582 (1) ◽  
pp. 64
Author(s):  
ANDRÉ NEL ◽  
GUNTHER FLECK
Keyword(s):  
Late Miocene ◽  
Middle Miocene ◽  
New Genus ◽  
New Genus And Species ◽  
The Third

Germanostenolestes lutzi, new genus and species of Sieblosiidae is described from the Middle Miocene of Öhningen (Germany). It probably belongs to the clade (Paraoligolestes + (Parastenolestes (Germanolestes + Stenolestes))) sensu Nel et al. (2005). It is the third representative of the Sieblosiidae described from this outcrop, showing that this family was still quite diverse in the Middle-Late Miocene.

Using ecological niche modeling for quantitative biogeographic analysis: a case study of Miocene and Pliocene Equinae in the Great Plains

Paleobiology ◽  
2009 ◽  
Vol 35 (4) ◽  
pp. 587-611 ◽  
Author(s):  
Kaitlin Clare Maguire ◽  
Alycia L. Stigall
Keyword(s):  
Great Plains ◽  
Late Miocene ◽  
Ecological Niche ◽  
Middle Miocene ◽  
Ecological Niche Modeling ◽  
Environmental Parameters ◽  
Geographic Range ◽  
Individual Species ◽  
Geographic Ranges ◽  
Speciation Rates

The subfamily Equinae in the Great Plains region of North America underwent a dramatic radiation and subsequent decline as climate changed from warm and humid in the middle Miocene to cooler and more arid conditions during the late Miocene. Here we use ecological niche modeling (ENM), specifically the GARP (Genetic Algorithm using Rule-set Prediction) modeling system, to reconstruct the geographic distribution of individual species during two time slices from the middle Miocene through early Pliocene. This method combines known species occurrence points with environmental parameters inferred from sedimentological variables to model each species' fundamental niche. The geographic range of each species is then predicted to occupy the geographic area within the study region wherever the set of environmental parameters that constrain the fundamental niche occurs. We analyze changes in the predicted distributions of individual species between time slices in relation to Miocene/Pliocene climate change. Specifically, we examine and compare distribution patterns for two time slices that span the period from the mid-Miocene (Barstovian) Climatic Optimum into the early Pliocene (Blancan) to determine whether habitat fragmentation led to speciation within the clade and whether species survival was related to geographic range size. Patchy geographic distributions were more common in the middle Miocene when speciation rates were high. During the late Miocene, when speciation rates were lower, continuous geographic ranges were more common. Equid species tracked their preferred habitat within the Great Plains region as well as regionally throughout North America. Species with larger predicted ranges preferentially survived the initial cooling event better than species with small geographic ranges. As climate continued to deteriorate in the late Miocene, however, range size became irrelevant to survival, and extinction rates increased for species of all range sizes. This is the first use of ENM and GARP in the continental fossil record. This powerful quantitative biogeographic method offers great promise for studies of other taxa and geologic intervals.

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