Hutch 51 - Melajo Clay, Melago River area (Miocene of Trinidad and Tobago)

Where: Trinidad and Tobago (10.6° N, 61.1° W: paleocoordinates 10.5° N, 59.6° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Melajo Clay Member (Springvale Formation), Late/Upper Miocene (11.6 - 5.3 Ma)

• The Melajo Clay Member of the Springvale Formation is correlated with the Savaneta Glaconitic Sandstone Member of the Springvale Formation, although part of it may be younger. The Melajo fauna is late Miocene in age. The Melajo Clay rests transgressively on the phyllites of the Northern Range with a basal conglomerate of about 1 m thickness. The conglomerate graes into a 1.5 m thick limestone, which is overlain by a bed of sand of about 1 m thickness. Above the sand is the Melajo Clay. The total thickness of the Melajo Clay is about 200 ft. It is unconformably overlain by Pleistocene sand and gravel deposits.

• bed-level stratigraphic resolution

Environment/lithology: offshore; unlithified, yellow, blue, silty claystone and unlithified, coarse-grained sandstone

• The Melajo fauna can be divided into two assemblages: one occurring the limestone and coarse sand near the base of the Melajo Clay, the other on in the overlying clay and silty clay. The difference of the two assemblages is facies controlled. The basal assemblage represents a typical, tropical, near-shore fauna, whereas the overlying assemblage points to a deeper environment. This collection is derived from the clay assemblage, a siliciclastic and deeper water environment and is hence assigned to a siliciclastic - offshore environment.
• Blue, yellowish weatheirng clay and silty clay with occasional sandy layers. Sand is probably coarse.

Size class: macrofossils

Reposited in the PRI, USNM

Collection methods: quarrying,

• All material descibed in this report is reposited in the Naturhistorisches Mueum, Basel, or the USNM. Additional material collection from this unit is found at PRI.

Primary reference: P. Jung. 1969. Miocene and Pliocene mollusks from Trinidad. Bulletins of American Paleontology 55(247):293-697 [A. Miller/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 60402: authorized by Austin Hendy, entered by Austin Hendy on 14.05.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for Mollusca, although author suggests that further collection would reveal additional forms. Corals, bryozoa and spines of echinoderms also exists in the unit, though are not listed. Van de Bold (1963) also lists ostracords from several localities. Foraminiferal assemblages are also listed in unpublished reports by Saunders.
Bivalvia
 Arcida - Arcidae
"Anadara (Scapharca) placata" = Scapharca clam
 Arcida - Noetiidae
 Pectinida - Pectinoidae
"Aequipecten (Plagioctenium) cf. maturensis" = Argopecten
"Aequipecten (Plagioctenium) cf. maturensis" = Argopecten calico scallop
 Pectinida - Anomiidae
Anomia simplex d'Orbigny 1845 jingle
 Ostreida - Ostreidae
 Carditida - Crassatellidae
"Eucrassatella trinitaria" = Eucrassatella (Hybolophus) trinitaria
"Eucrassatella trinitaria" = Eucrassatella (Hybolophus) trinitaria Maury 1925 clam
 Pholadida - Corbulidae
 Cardiida - Veneridae
"Chione (Lirophora) caroniana" = Lirophora venus clam
Dosinia (Dosinia) sp. Scopoli 1777 venus clam
 Cardiida - Tellinidae
 Cardiida - Cardiidae
"Trachycardium (Dallocardia) sanctidavidis" = Dallocardia, Trigoniocardia (Trigoniocardia) maturensis
"Trachycardium (Dallocardia) sanctidavidis" = Dallocardia cockle
 Lucinida - Lucinidae
"Lucina (Lucinisca) roigi" = Lucinisca
"Lucina (Lucinisca) roigi" = Lucinisca clam
Gastropoda
 Cerithiacea - Turritellidae
Turritella (Broderiptella) bifastigata Nelson 1870 turret shell
Subspecies: T. (B.) bifastigata
Turritella (Broderiptella) aff. mimetes Brown and Pilsbry 1911 turret shell
 Neogastropoda - Borsoniidae
 Neogastropoda - Volutidae
"Bullata maiae" = Closia (Bullata)
"Bullata maiae" = Closia (Bullata) volute
 Neogastropoda - Muricidae
Eupleura lehneri Jung 1969 murex snail
 Neogastropoda - Buccinidae
Gordanops baranoanus Anderson 1929 true whelk
 Calyptraeoidea - Calyptraeidae
"Crepidula (Crepidula) cf. maculosa" = Crepidula maculosa
"Crepidula (Crepidula) cf. maculosa" = Crepidula maculosa Conrad 1846 slipper shell
 Naticoidea - Naticidae
"Natica (Naticarius) canrena" = Naticarius canrena, Polinices stanislasmeunieri
"Natica (Naticarius) canrena" = Naticarius canrena Linnaeus 1758 moon snail
Polinices stanislasmeunieri Maury 1917 moon snail
 Neritoidea - Neritidae
"Neritina (Vitta) cf. virginia" = Neritina virginea, "Nerita (Nerita) exuvioides" = Nerita (Theliostyla) exuvioides
"Neritina (Vitta) cf. virginia" = Neritina virginea Linnaeus 1758 snail
"Nerita (Nerita) exuvioides" = Nerita (Theliostyla) exuvioides Trechmann 1935 snail
 Trochoidea - Trochidae
"Calliostoma olssoni" = Calliostoma (Elmerlinia) olssoni
"Calliostoma olssoni" = Calliostoma (Elmerlinia) olssoni Maury 1925 top snail
Scaphopoda
 Dentaliida - Dentaliidae