MIOCENE NERITIC BENTHIC FORAMINIFERAL COMMUNITY DYNAMICS, CALVERT CLIFFS, MARYLAND, USA: SPECIES POOL, PATTERNS AND PROCESSES

Palaios ◽  
2021 ◽  
Vol 36 (7) ◽  
pp. 247-259
Author(s):  
STEPHEN J. CULVER ◽  
SETH R. SUTTON ◽  
DAVID J. MALLINSON ◽  
MARTIN A. BUZAS ◽  
MARCI M. ROBINSON ◽  
...  
Keyword(s):  
Sea Level ◽  
Benthic Foraminifera ◽  
Middle Miocene ◽  
Community Dynamics ◽  
Abundant Species ◽  
Common Species ◽  
Species Pool ◽  
Regional Species Pool ◽  
Patterns And Processes ◽  
Climate Transition

ABSTRACT The presence/absence and abundance of benthic foraminifera in successive discrete beds (Shattuck “zones”) of the Miocene Calvert and Choptank formations, exposed at the Calvert Cliffs, Maryland, USA, allows for investigation of community dynamics over space and time. The stratigraphic distribution of benthic foraminifera is documented and interpreted in the context of sea-level change, sequence stratigraphy, and the previously published distribution of mollusks. Neritic benthic foraminiferal communities of four sea-level cycles over ∼4 million years of the middle Miocene, encompassing the Miocene Climatic Optimum and the succeeding middle Miocene Climate Transition, are dominated by the same abundant species. They differ in the varying abundance of common species that occur throughout most of the studied section and in the different rare species that appear and disappear. Transgressive systems tracts (TSTs) have higher species diversity than highstand systems tracts (HSTs) but much lower density of specimens. In contrast to some previous research, all beds in the studied section are interpreted as being from the inner part of a broad, low gradient shelf and were deposited at water depths of less than ∼50 m. It is suggested that species are recruited from a regional species pool of propagules throughout the duration of TSTs. Recruitment is curtailed during highstands leading to lower diversity in the HSTs.

scholarly journals Timing of the Middle Miocene Badenian Stage of the Central Paratethys

2014 ◽  
Vol 65 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Johann Hohenegger ◽  
Stjepan Ćorić ◽  
Michael Wagreich
Keyword(s):  
Sea Level ◽  
Middle Miocene ◽  
Planktonic Foraminifera ◽  
Sea Level Changes ◽  
Vienna Basin ◽  
Central Paratethys ◽  
Polarity Reversals ◽  
Global Events ◽  
Geomagnetic Polarity ◽  
Climate Transition

Abstract A new and precisely defined chronometric subdivision of the Badenian (Middle Miocene, regional stage of Central Paratethys) is proposed. This uses global events, mainly geomagnetic polarity reversals as correlated chronometric boundaries, supported by climatic and sea-level changes in addition to isotope events and biostratigraphic data. The Karpatian/ Badenian boundary lies at 16.303 Ma, at the top of Chron C5Cn.2n, which is near the base of the Praeorbulina sicana Lowest-occurrence Zone (LOZ). The Badenian/Sarmatian boundary is placed at the top of polarity Chron C5Ar.2n, thus at 12.829 Ma. In relation to three sea level cycles TB 2.3, TB 2.4 and TB 2.5 and astronomically confirmed data, the Badenian can be divided into three parts of nearly equivalent duration. The Early Badenian as newly defined here ranges from 16.303 to 15.032 Ma (top of polarity Chron C5Bn.2n). The younger boundary correlates roughly to the base of the planktonic foraminifera Orbulina suturalis LOZ at 15.10 Ma, the HO (Highest Occurrence) of the nannofossil Helicosphaera ampliaperta at 14.91 Ma (NN4/NN5 boundary) and the Lan2/Ser1 sequence boundary at 14.80 Ma. The subsequent Mid Badenian ranges from 15.032 Ma to 13.82 Ma; the latter datum correlates with the base of the Serravallian, characterized by a strong global cooling event reflected in the oxygen isotope event Mi3b. The main part of cycle TB 2.4 falls into the Mid Badenian, which can be subdivided by a short cooling event at 14.24 Ma during the Middle Miocene Climate Transition (14.70 to 13.82 Ma). The HCO (Highest common occurrence) of the nannofossil Helicosphaera waltrans at 14.357 Ma supports this division, also seen in the tropical plankton Zones M6 Orbulina suturalis LOZ and M7 Fohsella peripheroacuta LOZ that correspond roughly to the lower and upper Lagenidae zones in the Vienna Basin, respectively. The Late Badenian is delimited in time at the base to 13.82 Ma by the Langhian/Serravallian boundary and at the top by the top of polarity Chron C5Ar.2n at 12.829 Ma. The Mediterranean Langhian/Serravallian boundary can be equated with the Mid/Late Badenian boundary at 13.82 Ma. However, the Karpatian/Badenian boundary at 16.303 Ma, a significant event easily recognizable in biostratigraphy, paleoclimate evolution and sequence stratigraphy, cannot be equated with the proposed global Burdigalian/Langhian, and thus Early/Middle Miocene boundary, at 15.974 Ma

scholarly journals It’s All about the Zone: Spider Assemblages in Different Ecological Zones of Levantine Caves

Diversity ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 576
Author(s):  
Jordan P. Cuff ◽  
Shlomi Aharon ◽  
Igor Armiach Steinpress ◽  
Merav Seifan ◽  
Yael Lubin ◽  
...  
Keyword(s):  
Common Species ◽  
Species Pool ◽  
Assemblage Composition ◽  
Ecological Zones ◽  
Dark Zone ◽  
Rapid Speciation ◽  
Cave Entrance ◽  
Composition And Structure ◽  
Regional Species Pool

Caves possess a continuum of ecological zones that differ in their microhabitat conditions, resulting in a gradient of nutrients, climate, and illumination. These conditions engender relatively rapid speciation and diverse assemblages of highly specialised spider fauna. It is unclear, however, how zonation of these caves affects spider assemblage composition and structure. Surveys of 35 Levantine caves were conducted to compare the assemblages of spiders between their different ecological zones. The diverse spider assemblages of these caves differed between the entrance, twilight, and dark zones, with troglophiles and accidental species occupying the cave entrance, endemic troglobites occupying the dark zones, and hybrid assemblages existing in the twilight zones. The progression of assemblage composition and divergence throughout cave zones is suggestive of processes of ecological specialisation, speciation, and adaptation of cave-endemic troglobites in the deepest zones of caves, while cave entrance assemblages are composed of relatively common species that can also be found in epigean habitats. Moreover, the cave entrance zone assemblages in our study were similar in the different caves, while the cave dark zone assemblages were relatively distinct between caves. Cave entrance assemblages are a subset of the regional species pool filtered by the cave conditions, while dark zone assemblages are likely a result of adaptations leading to local speciation events.

scholarly journals Cenozoic carbonate burial along continental margins

Geology ◽  
2019 ◽  
Vol 47 (11) ◽  
pp. 1025-1028 ◽  
Author(s):  
Robin van der Ploeg ◽  
Bernard P. Boudreau ◽  
Jack J. Middelburg ◽  
Appy Sluijs
Keyword(s):  
Sea Level ◽  
Middle Miocene ◽  
Carbon Sink ◽  
Global Climate ◽  
Continental Margins ◽  
Marine Carbonate ◽  
Major Increase ◽  
Continental Weathering ◽  
Climate Transition

Abstract Marine carbonate burial represents the largest long-term carbon sink at Earth’s surface, occurring in both deep-sea (pelagic) environments and shallower waters along continental margins. The distribution of carbonate accumulation has varied over geological history and impacts the carbon cycle and ocean chemistry, but it remains difficult to quantitatively constrain. Here, we reconstruct Cenozoic carbonate burial along continental margins using a mass balance for global carbonate alkalinity, which integrates independent estimates for continental weathering and pelagic carbonate burial. Our results indicate that major changes in marginal carbonate burial were associated with important climate and sea-level change events, including the Eocene-Oligocene transition (ca. 34 Ma), the Oligocene-Miocene boundary Mi-1 glaciation (ca. 23 Ma), and the middle Miocene climate transition (ca. 14 Ma). In addition, we find that a major increase in continental weathering from ca. 10 Ma to the present may have driven a concomitant increase in pelagic carbonate burial. Together, our results show that changes in global climate, sea level, and continental weathering have all impacted carbonate burial over the Cenozoic, but the relative importance of these processes may have varied through time.

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.

scholarly journals Quaternary benthic Foraminifera in the Tu Chinh - Vung May marine areas (continental shelf of Vietnam) and island, coral reef regions of the Truong Sa archipelago, Vietnam and their significance

2019 ◽  
Vol 19 (3B) ◽  
pp. 137-147
Author(s):  
Nguyen Ngoc ◽  
Bui Thi Luan ◽  
Nguyen Thi Hong Nhung
Keyword(s):  
Coral Reef ◽  
Continental Shelf ◽  
Benthic Foraminifera ◽  
Common Species ◽  
Subtropical Climate ◽  
Stratigraphic Division ◽  
Reef Islands ◽  
Sea Level Fluctuation ◽  
Marine Areas ◽  
Sediment Age

The results of identifying and studying micropaleontological samples from the Quaternary sediments in the Tu Chinh - Vung May marine areas (1) and some coral reef islands of Truong Sa archipelago (2) have found more than 300 species of Benthic foraminifera, in which 291 species have been studied and described in detail, belonging to 112 genera, 43 families, 5 orders and 3 classes of the phylum Foraminifera. Among them, there are 19 new species, 3 new subspecies and 3 new genera. In the first region there are 195 species and the second one - 121 species (including 25 common species for both regions). They have important significations in the stratigraphic-biostratigraphic, ecological, paleogeographic studies, in sedimentary lithology... Regarding stratigraphy, the characteristic of Pleistocene is the first emergence of four genera: Baculogypsina, Cymbaloporetta, Parasorites, and Schlumbergerella; for Holocene - the appearance of the following genera: Ammomassilina, Baulogypsinoides, Cymbaloporella, Falsotextularia, Fijiella, Flintina, Gyroidina, Lugdunum, Neoconorbina, Planoperculina, Ptychomiliolata, Pseudoflintina, Pseudomassilina, Sahulia, Schlumbergerina, Septotextularia, Siphoniferoides, Tawitawia and Truongsaia. These fossils are the basis for dating sediment age, Quaternary stratigraphic division and correlation. In terms of paleoecology, benthic Foraminifera in the region (1) characterize the shallow offshore environment of the continental shelf, where there are the high and stable salinity, and the relatively strong environmental dynamics; in some places there are coral reef Foraminifera populations. In the region (2), they characterize the coral reef ecosystem of shallow and warm sea areas in the belt of tropical-subtropical climate of the Earth, where the salinity is high and stable, the transparency of water is high, and the environmental dynamics is relatively strong to strong... In addition, the paper also mentioned some other issues such as paleogeography (sea-level fluctuation), value of creating sediments of Foraminifera, environmental monitoring (for modern Foraminifera).

scholarly journals Species ethnobotanical values rather than regional species pool determine plant diversity in agroforestry systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel K. N’Woueni ◽  
Orou G. Gaoue
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Plant Diversity ◽  
Agroforestry Systems ◽  
Natural Vegetation ◽  
Species Pool ◽  
Higher Plant ◽  
Natural Habitats ◽  
Natural Systems ◽  
Regional Species Pool

AbstractThe conversion of natural systems into farms and agroecosystems is the main cause of biodiversity loss. In human-dominated landscapes, understanding the interactions between agroforestry systems and adjacent natural vegetation is fundamental to developing sustainable agricultural systems. Species can move between these two systems with natural systems providing the regional pool of species that shape the agricultural values and conservation value of the agroforestry systems. We investigated the influence of neighboring natural habitats on traditional agroforestry systems in the buffer zone of Pendjari Biosphere Reserve in Benin to understand the contribution of regional processes on the quality of agroforestry systems. We expected that agroforestry parklands adjacent to natural vegetation with high species diversity will also have higher plant species diversity. We found no similarity in plant species composition between agroforestry systems and adjacent natural habitats. A small proportion of species in adjacent natural habitats were found in agroforestry systems. The proportion of shared species was not significantly influenced by plant diversity in adjacent natural habitats or the distance from the agroforestry systems to the natural adjacent habitat. However, plant diversity in agroforestry systems was strongly associated with site ethnobotanical values indicating that farmers act as a supplemental but severe environmental filter of the regional species pool. Our study suggests that promoting the plantation of plants with high ethnobotanical use-value is a potentially viable strategy for sustainable agriculture and ecological restoration in Biosphere reserves.

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