Loc. 9-15 [Borbon Fm]: Middle Miocene, Ecuador

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
unclassified
Phomistochoartus corbula
Globigerinidae
Orbulina universa d'Orbigny 1839
Globigerina venezuelana Hedberg 1937
recombined as Dentoglobigerina venezuelana
Nodosariata - Polymorphinida - Plectofrondiculariidae
Plectofrondicularia jarvisi
Nodosariata - Nodosariida - Stilostomellidae
Stilostomella lepidula
Buliminidae
Bulimina mexicana
Bulimina pagoda
Cassidulinidae
Ehrenbergina cf. pacifica
Cassidulina tricamerata
Globocassidulina subglobosa
Rotaliidae
Rotalia ecuadorana
Uvigerinidae
Uvigerina auberiana d'Orbigny 1839
Bolivinidae
Bolivina pisciformis Calloway and Morrey 1929
Discorbinellidae
Laticarinina pauperata
Chilostomellidae
Sphaeroidina bulloides d'Orbigny 1826
unclassified
Cibicorbis herricki
Globothalamea - Rotaliida - Discorbidae
Hanzawaia wuellerstorfi
Epistominella culter
Globothalamea - Rotaliida - Nonionidae
Melonis affinis
Globothalamea - Rotaliida - Cibicididae
Cibicides floridanus
Cibicidoides haidingeri
Coccolithophyceae - Ceratolithaceae
Angulolithina arca
Coccolithophyceae
Discoaster variabilis Martini and Bramlette 1963
Discoaster brouweri Tan Sin Hok 1927
Discoaster intercalaris Bukry 1971
Coccolithus pelagicus (Wallich 1877)
Cyclococcolithina leptoporus
synonym of Coccolithus
Cyclococcolithina macintyri
synonym of Coccolithus
Sphenolithus abies Deflandre 1954
unclassified
Reticulofenestra pseudoumbilica
Protozoa - Spumellaria - Sponguridae
Spongocore puella
synonym of Spongurus
Protozoa - Nassellaria - Pterocorythidae
Theocorythium vetulum
Protozoa - Nassellaria - Eucyrtidiidae
Stichocorys delmontensis
see common names

Geography
Country:Ecuador
Coordinates: 1.0° North, 79.8° West (view map)
Paleocoordinates:0.2° North, 76.9° West
Basis of coordinate:based on nearby landmark
Geographic resolution:outcrop
Time
Period:Neogene Epoch:Miocene
10 m.y. bin:Cenozoic 5
Key time interval:Middle Miocene
Age range of interval:15.98000 - 11.63000 m.y. ago
Stratigraphy
Formation:Borbon
Stratigraphic resolution:bed
Stratigraphy comments: STRATIGRAPHIC RELATIONS: From the Borbon Fm, which is regionally overlain by the Esmeraldas Fm (Pliocene). AGE: Middle Miocene, on the basis of microfossil biostratigraphy; nannofossil zones N11-13; planktonic zones N13-N14. STRATIGRAPHIC POSITION: From unknown position within formation.
Lithology and environment
Primary lithology:tuffaceous unlithified argillaceous mudstone
Includes fossils?Y
Lithology description: SPECIFIC LITHOLOGY: Tuffaceous clays and mudstones. LITHIFICATION: Unlithified, as stated in text.
Environment:deep-water indet.
Geology comments: ENVIRONMENT: Siliceous organisms (diatoms, radiolar- ians) are well preserved in the Miocene rocks, but the cal- careous fauna has been modified. The nannoflora and the globigerinacean assemblage are impoverished. This may re- flect dissolution of the more delicate forms before burial and suggests that these sediments were deposited at bathyal depths.
Taphonomy
Modes of preservation:body
Size of fossils:mesofossils,microfossils
Collection methods and comments
Collection methods:bulk,chemical,hydrochloric,sieve,field collection
Reason for describing collection:biostratigraphic analysis
Collection method comments: COLLECTOR: Presumably the authors. REPOSITORY: Not stated, but presumably Princeton University, New Jersey. PREPARATION: Eighty-five gram samples were crushed and boiled with Calgon, then washed through 420-,m, 177-Am, 74-,m and 63- ,m screens. A cut of the fines was saved for nannofossils. The two largest fractions and half of the 74-gm fraction were dried, floated on CC14 and picked for foraminifera. The re- maining half of the 74-um fraction and the 63-,um fraction were decalcified with HC1 and washed again, then dried and floated on CClI, before mounting on slides for study of ra- diolarians. The flotation in this case was found to enrich radiolaria by a factor of about 30, and to raise the proportion of unbroken specimens. Nannofossils were concentrated from the fines that passed the 63-um mesh, in two steps: settling for 1.5 minutes in a 1-liter beaker separated a coarser fraction, to be discarded. The poured-off liquid was then settled in a similar beaker for 30 minutes, which settled out such nannofossils as could be handled by optical microscopy, while the ultra-fine ma- terial was discarded. Radiolaria and nannofossils were pre- pared for study as strewn slides mounted in balsam. Nan- nofossils were identified by optical phase contrast and polarized microscopy, at 1200 x.
Taxonomic list comments:COVERAGE: Exhaustive for foraminifera, nannofossils, and radiolarians. NOMENCLATURE: Not an authoritative publication, but with modern nomenclature and species-resolution identifications.
Metadata
Database number:90852
Authorizer:A. Hendy Enterer:A. Hendy
Modifier:A. Hendy Research group:marine invertebrate,micropaleontology
Created:2009-08-19 13:34:46 Last modified:2013-11-25 13:37:23
Access level:the public Released:2009-08-19 13:34:46
Creative Commons license:CC BY
Reference information

Primary reference:
30557. P. F. Hasson and A. G. Fischer. 1986. Observations on the Neogene of Northwestern Ecuador. Micropaleontology 32(1):32-42 [A. Hendy/A. Hendy]