Where: Ecuador (1.0° N, 79.8° W: paleocoordinates 0.2° N, 76.9° W)
• coordinate based on nearby landmark
• outcrop-level geographic resolution
When: Borbon Formation, Middle Miocene (16.0 - 11.6 Ma)
• 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.
• bed-level stratigraphic resolution
Environment/lithology: deep-water; unlithified, tuffaceous, argillaceous mudstone
Size classes: mesofossils, microfossils
Collection methods: bulk, chemical, hydrochloric, sieve,
• 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.
Primary reference: P. F. Hasson and A. G. Fischer. 1986. Observations on the Neogene of Northwestern Ecuador. Micropaleontology 32(1):32-42 [A. Hendy/A. Hendy]more details
Purpose of describing collection: biostratigraphic analysis
PaleoDB collection 90852: authorized by Austin Hendy, entered by Austin Hendy on 19.08.2009
Creative Commons license: CC BY (attribution)
Taxonomic list
Foraminifera | |
Nodosariata | |
Foraminifera | |
unclassified | |
Foraminifera | |
Bolivina pisciformis Calloway and Morrey 1929 | |
Uvigerina auberiana d'Orbigny 1839 | |
Sphaeroidina bulloides d'Orbigny 1826 | |
Orbulina universa, "Globigerina venezuelana" = Dentoglobigerina venezuelana
Orbulina universa d'Orbigny 1839
"Globigerina venezuelana" = Dentoglobigerina venezuelana Hedberg 1937 | |
Globothalamea | |
Reticulofenestra | |
Coccolithophyceae | |
Sphenolithus abies Deflandre 1954 | |
Discoaster variabilis, Discoaster intercalaris, Discoaster brouweri, Coccolithus pelagicus, Cyclococcolithina leptoporus, Cyclococcolithina macintyri
Discoaster variabilis Martini and Bramlette 1963
Discoaster intercalaris Bukry 1971
Discoaster brouweri Tan Sin Hok 1927
Coccolithus pelagicus Wallich 1877 | |
Protozoa | |
Theocorythium vetulum radiolarian | |
Stichocorys delmontensis radiolarian | |
"Spongocore puella" = Spongurus
"Spongocore puella" = Spongurus radiolarian |