Middle Pliocene paleoenvironmental reconstruction; PRISM2

1999 ◽  
Author(s):  
H.J. Dowsett ◽  
J.A. Barron ◽  
R.Z. Poore ◽  
R.S. Thompson ◽  
T. M. Cronin ◽  
...  
Keyword(s):  
Paleoenvironmental Reconstruction ◽  
Middle Pliocene

Segregation and speciation in the Neogene planktonic foraminiferal clade Globoconella

Paleobiology ◽  
1999 ◽  
Vol 25 (3) ◽  
pp. 383-395 ◽  
Author(s):  
Cynthia E. Schneider ◽  
James P. Kennett
Keyword(s):  
Morphological Evolution ◽  
Evolutionary Divergence ◽  
Clinal Variation ◽  
Near Surface ◽  
Surface Warming ◽  
Isotopic Analyses ◽  
Oxygen Isotopic ◽  
Morphological Differences ◽  
Middle Pliocene ◽  
Water Depths

The origin of the Neogene planktonic foraminifer Globorotalia (Globoconella) pliozea in the subtropical southwest Pacific has been attributed to its isolation resulting from intensification of the Subtropical Divergence (Tasman Front). Oxygen isotopic analyses suggest that, although the Subtropical Divergence may have played a role, the evolution of Gr. (G.) pliozea was facilitated by depth segregation of Gr. (G.) conomiozea morphotypes (low and high conical) during an interval of near-surface warming and increasing thermal gradient. Oxygen isotopic analyses suggest that low conical morphotypes of Gr. (G.) conomiozea inhabited greater depths than high conical morphotypes. Low conical forms of Gr. (G.) conomiozea are considered ancestral to the low conical species, Gr. (G.) pliozea. Oxygen isotopes indicate that Gr. (G.) pliozea inhabited greater depths than its ancestor, Gr. (G.) conomiozea.These data are consistent with depth-parapatric and depth-allopatric models, but not with a sympatric model of speciation. In the allopatric model, reproduction at different water depths acts as a barrier between morphotypes. In the parapatric model, clinal variation along a depth gradient acts as a barrier between morphotypes living at the limits of the gradient. Depth segregation in both models results in genetic isolation and evolutionary divergence. Our data support a correlation between morphological evolution and habitat changes in the Globoconella clade, implying separation of populations as a driving force for morphological evolution.Ecological segregation of morphotypes and species may be related to morphology (height of the conical angle), based on the data from Gr. (G.) conomiozea and Gr. (G.) pliozea. However, morphological differences alone do not necessarily produce depth differences. Large morphological differences between Gr. (G.) pliozea and closely related Gr. (G.) puncticulata did not result in isotopic and therefore depth differences between these species. These species coexisted at the same water depths for nearly 1 m.y. Thus, it is unlikely that the extinction of Gr. (G.) pliozea in the middle Pliocene resulted from competition with Gr. (G.) puncticulata, as previously suggested.

Geochemistry and provenance of the lower-middle pliocene cheleken formation, Iran

2021 ◽  
Author(s):  
Houshang Mehrabi ◽  
Seyed Mohammad Zamanzadeh ◽  
Abdolhossein Amini ◽  
Vahid Tavakoli ◽  
Freshteh Sajjadi ◽  
...  
Keyword(s):  
Middle Pliocene

Paleoenvironmental reconstruction of the headwaters of the preto river, Minas Gerais state, Brazil, through siliceous bioindicators

2021 ◽  
Vol 108 ◽  
pp. 103349
Author(s):  
David Oldack Barcelos Ferreira Machado ◽  
Karina Ferreira Chueng ◽  
Heloisa Helena Gomes Coe ◽  
Alexandre Christófaro Silva ◽  
Camila Rodrigues Costa
Keyword(s):  
Minas Gerais ◽  
Paleoenvironmental Reconstruction ◽  
Minas Gerais State
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