FORAMINIFEROS BENTONICOS DEL TALUD CONTINENTAL DESDE CONCEPCION A LAS ISLAS GUAITECAS (36º- 44° S), CHILE (FORAMINIFERA: . Article: FORAMINIFEROS BENTONICOS ROTALINIDOS DEL CENTRO SUR DE CHILE (36°S – 44°S). Add this to your Mendeley library Report an error. Abstract. PATARROYO-CAMARGO, Germán David and MARTINEZ-RODRIGUEZ , José Ignacio. DEEP SEA BENTHIC FORAMINIFERA OF THE PANAMA.
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September 29, Corrected manuscript received: December 12, Manuscript accepted: Foraminifera from samples collected in the lower part of the Ocozocoautla Formation were studied.
The lower part of the unit consists mostly of argillaceous and marly sandstone with inoceramids. This horizon yields a poorly preserved but biostratigraphically useful foraminiferal assemblage. The upper part of the Gansserina gansseri zone is defined on the basis of the planktic foraminiferal association. Michaud studied the inoceramids of the Ocuilapa and Ocozocoautla sections and recorded some planktic foraminifera from washed samples of these rocks.
The objective of this paper is to report the occurrence of planktic and benthic foraminifera recovered from samples with inoceramids. The biostratigraphic significance of planktic foraminifera, considered to be an important tool for dating marine sedimentary sequences, has allowed us to assign an age to these samples. Analysis of the foraimniferos foraminifera has also provided coraminiferos valuable means of inferring the depositional environment.
The study of the planktic foraminiferal assemblage has been useful for biogeographic differentiation and definition of the bioprovinces. The studied section is located foeaminiferos the state of Chiapas in southeastern Mexico Figure 1. The geological evolution and depositional framework of this region is considered to be closely related to the opening of the Atlantic Ocean and the Gulf of Mexico in the Middle Jurassic.
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According to Michaud and Fourcadethe Jurassic sedimentation is interpreted within the rift model. The first marine sediments San Ricardo Formation deposited in the Oxfordian correspond to the synrift phase.
A postrift phase occurred during the Kimeridgian, with the development of a carbonate platform Scott, ; Salvador, A subsident basin, present during the Tithonian, was filled until the Neocomian. This basin was limited by a fault that separated the Angostura platform from an emergent zone that supplied terrigeneous material to the Ocozocoautla submarine detritical cone. Various lithological units were consequently deposited Ocozocoautla and Foramkniferos Formations.
The foraminkferos rocks located in the environs of the town of Ocozocoautla were first documented when Sapper made a geological reconnaissance of the Chiapas region. Page and Pike were the first to use the term Gravas Ocozocoautla for the sandstone conglomeratic outcrops located to the west of Ocozocoautla.
Chubb divided it into foraminuferos formations: Inoceramids, echinoids, and a few amonites were collected in this level. Above these lies light brown bioclast packstone containing red algae, echinoids and some radists in living position; this limestone foraminiferoe interbedded with shale 75 m.
Above these strata, marl alternates with shale 25 mwhich is capped by a packstone 22 m followed by m of marl and shale. The final layers consist of a deposit of Angostura limestone Figure 2.
The samples analysed range from gray to greenish and reddish gray marly sandstone beds with inoceramids from the lower Ocozocoautla Formation. The hardened samples were chemically treated with a boiling phosphate trisodium solution to facilitate removal of the sediment particles Kohl, Although the gentonicos are poorly preserved, some species were reported and illustrated by SEM photos for first time in this work Figures.
Exhaustive analysis of the studied samples allowed to identify 27 planktic foraminifera species. The planktic foraminiferal assemblage is abundant and biostratigraphically useful.
Foraminíferos bentónicos actuales (Marginopora vertebralis… | Flickr
The most prominent species are Gansserina gansseri BolliPlummerita reicheli BronnimannRugoglobigerina macrocephala Bronnimann, R.
In addition, further planktic foraminifera recorded include Globotruncana area CushmanG. The presence of Gansserina gansseri, as well as Rugoglobigerina hexacamerata, R.
The inoceramids reported in a recent study Alencaster and Omana, in press are, however, typical of early Maastrichtian age. The foraminiferal assemblage recovered from the samples with inoceramids contains a great variety of benthic foraminifera; Pseudouvigerina, Bolivina, Loxostomun, Bengonicos, Lenticulina, Bolivinoides, Marginulina, Globorotalites, as well foraminiferoa nodosarids. Gyroidina, Gavelinella, and some arenaceous foraminifers such as Dorothia, Verneulina and Spiroplectammina were also identified.
The paleobathymetric interpretation of the depositional environment is defined by depth restricted genera, several of which are homeomorphs of modern indicators Sliter and Baker, The genus Pseudouvigerina has been considered a homeomorph of the modern Trifarina, which typically inhabits a region ranging from the outer shelf to upper continental slope.
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The various Gyroidinoides and Gavelinella species observed appear to be restricted to deeper environment. The planktic foraminiferal diversity, including keeled forms, confirms a relatively greater depth for this deposit, since globotruncanids lived farther down in the water column and were excluded from shallow water environments Douglas and Savin, ; Hart, ; Huber, This foraminiferal assemblage may correspond to biofacies 3 proposed by Olsson and Nyong The environment was interpreted to be moderately deep water.
Late Cretaceous planktic foraminifera generally have been assigned to the boreal and austral provinces, intermediate and equatorial Tethyan realm Sliter, ,; Huber, ; Koutsoukos, The Tethyan realm includes the largest diversity of planktic foraminiferal species; all single and double keeled globotruncanids, the rugoglobigerinids and the heterohelicids Sliter,The region studied in the present work should be forzminiferos included in this province, bentonicoos to the geographic location beentonicos the Chiapas region.
The planktic foraminiferal association studied consists of a great diversity of species including keeled forms, rugoglobigerinids, and heterohelicids characteristic of the low latitudes as cited by Sliter, Malmgren and Foraminifrros Silva and Sliter The upper part of the Gansserina gansseri Zone was identified from the lower part of the Ocozocoautla Formation which contains inoceramids. For this reason the present study contributes to a better definition of the biostratigraphical position of this part of the Ocozocoautla deposit.
I am grateful to Drs.
Molina Universidad de Zaragoza for reviewing the manuscript and for useful comments which improved the paper. Bulletin of American Paleontology, 88, p. Report of geological reconnaissance in Department of Tuxtla, Mezcalapa and Pichucalco: Geological Report 4 unpublished. V,Cretaceous paleoceanography; Evidence from planktonic foraminiferal evolution, in Barrera, E. This section includes an alphabetical list of the most prominent species identified in the interval studied.
Some bnetonicos definitions proposed by Bentpnicos and Tappan have been used in the paper. Allomorphina cretacea Reuss, Bolivina incrassata Reuss, Bolivinoides draco Marsson, Cibicides harperi Sandidge, Clavulina trilatera Cushman, Dorothia oxycona Reuss, Gavelinella dayi White, Globorotalites conicus Bentonlcos, Globorotalites spineus Cushman, Gyroidinoides cretacea Carsey, Gyroidina deppresa Alth, Lagena semiinterrupta Berry, Lenticulina muensteri Roemer, Loxostomum eleyi Cushman, Nonionella cretacea Cushman, Planulina texana Cushman, Praebulimina carseyae Plummer, Pseudonodosaria manifesto Reuss, Pseudouvigerina plummerae Cushman, Pullenia coryelli White, Saracenaria triangularis d’Orbigny, Siphonina prima Plummer Spiroplectammina laevis Roemer, Vaginulina plummerae Cushman, AGE Exhaustive analysis of the studied samples allowed to identify 27 planktic foraminifera species.