Modelo Formation

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Modelo Formation
Stratigraphic range: Late Miocene, 13–5.5  Ma
Type Formation
Unit of Los Angeles Basin
Underlies Pico Formation
Overlies Rincon Shale
Thickness600 metres (2,000 ft)
Lithology
Primary Shale
Location
Region Los Angeles County and Ventura County, California
Country United States
Extent Simi Hills, Santa Susana Mountains

The Modelo Formation is a Miocene geologic formation in the Simi Hills and western Santa Susana Mountains of southern California, including under parts of Los Angeles.

Contents

It preserves fossils dating back to the Late Miocene of the Neogene period, among them a high number of fossil representatives of modern pelagic and deep-sea fish taxa (as well as some with benthic affinities), in addition to some seabirds and cetaceans. As suggested from this fauna, the sediments of the formation were likely deposited in a deepwater marine habitat at middle to upper bathyal depths within an abyssal fan, with geological changes along the San Andreas fault causing a rapid uplift during the latest Miocene, bringing these former deepwater sediments to the surface. [1] It is likely partially contemporaneous with the Monterey Formation in some areas, such as the Ventura Basin. [2]

Volcanic ash beds are known from the formation; these, along with fossil microorganisms, indicate that the formation was deposited between 13 and 5.5 million years ago. [3]

Paleobiota

Based on the Paleobiology Database and Fierstine et al (2012). Much of the fauna is shared with the Monterey Formation, though some distinct taxa are also known: [4] [5]

Bony fish

Based on Fierstine et al (2012). Many of these taxa were described by David Starr Jordan from specimens excavated during the construction of the Sepulveda Boulevard Tunnel through the Santa Monica Mountains. [5]

GenusSpeciesLocationMemberMaterialNotesImages
Absalomichthys A. veliferArticulated skeletonsA manefish. Absalomichthys velifer.jpg
Araeosteus A. rothiArticulated skeletonsA relative of the prowfish.
Argyropelecus A. bullockii Articulated skeletonsA marine hatchetfish. Argyropelecus olfersii1.jpg
Bathylagus B. angelensis Articulated skeletonsA deep-sea smelt. Bathylagus euryops 46786071731.jpg
Bolinichthys B. sp.Articulated skeletonsA lanternfish. [6] Bolinichthys photothorax.jpg
Chalcidichthys C. malacopterygiusArticulated skeletonsA manefish. Chalcidichthys malacapterygius.jpg
Chauliodus C. eximius Articulated skeletonsA viperfish. Chauliodus eximus LACM.jpg
? Clupea ? C. tiejei Articulated skeletonA herring, classification in Clupea uncertain. Clupea pallasii pallasii.jpg
Cyclothone C. solitudinis LowerArticulated skeletonA bristlemouth. Cyclothone microdon1.jpg
Decapterus D. hopkinsi Articulated skeletonA mackerel scad. Decapterus punctatus.jpg
D. sp.
Diaphus D. bolini Articulated skeletonsA lanternfish. Diaphus metopoclampus.jpg
Eclipes E. santamonicaeArticulated skeletonsA cod.
E. veternus
Etringus E. scintillansArticulated skeletons, isolated scalesA herring, possibly a round herring.
Ganolytes G. aratusArticulated skeletons, isolated scalesA herring.
G. cameo
Hipposyngnathus H. imporcitorUpperArticulated skeletonsA pipefish. Hipposyngnathus neriticus Oligozan Jamna Dolna Polen Ch1817.jpg
Plectrites P. classeniArticulated skeletonsA seabream.
Quaesita Q. quisquiliaArticulated skeletonsA deep-sea smelt.
Lampanyctus L. petrolifer Articulated skeletonsA lanternfish, L. petrolifer potentially in an undescribed genus. Lampanyctus macdonaldi.jpg
L. sp.
Laytonia L. californicaArticulated skeletonA halosaur. Bolbocara Laytonia.JPG
Lompoquia L. culveriArticulated skeletonA drumfish. Lompoquia retropes.JPG
L. retropes
L. sp.
Molidae indet.An ocean sunfish.
Myctophum M. sp.Articulated skeletonsA lanternfish. [6] Myctophum affine.jpg
Pseudoseriola P. gilliandiArticulated skeletonsA relative of the bluefish.
P. sp.
Rhomurus R. fulcratusPartial skeletonA halfbeak, either in the Hemiramphidae or the extinct Forficidae.
Sarda S. stockii Partial skeletonsA bonito. Sarda sarda.jpg
Scomber S. sanctaemonicae Partial skeletonA true mackerel. Scomber japonicus drawing.jpg
S. cf. japonicus (=Pneumatophorus cf. grex)Scale
S. sp. Mulholland Drive Partial skeletons
Scomberesox S. edwardsi LowerSkull, partial segment with scalesA saury. Scomberesox saurus saurus.jpg
Scorpaena S. ensiger Articulated skeletonsA scorpionfish. Scorpaena colorata.jpg
Sebastes S. davidi Articulated skeletonsA rockfish. Sebastes melanops drawing.jpg
S. sp.
Syngnathus S. avus Articulated skeletonsA pipefish. Syngnathus rostellatus.jpg
Thyrsocles T. kriegeriArticulated skeletonsA euzaphlegid. Euzaphlegidae.JPG
Xyne X. grexArticulated skeletons, isolated scalesA herring.
Zanteclites Z. sp.Isolated scalesA Neotropical silverside.
Zaphlegulus Z. venturaensisA euzaphlegid. Zaphlegulus venturaensis.JPG

Birds

Based on the Paleobiology Database: [4]

GenusSpeciesLocationMemberMaterialNotesImages
Osteodontornis O. orri Sherman Oaks A pseudotooth bird. Osteodontornis BW cropped.png
Phalacrocorax P. femoralis A cormorant. Cormorant (Phalacrocorax carbo) (14).JPG
Puffinus P. diatomicus Sherman OaksIncomplete skeleton.A shearwater. Manx Shearwater.JPG
Sula S. willetti Sherman OaksLeg bones.A booby. Sula nebouxii -Santa Cruz, Galapagos Islands, Ecuador-8 (1).jpg

Mammals

Based on the Paleobiology Database: [4]

GenusSpeciesLocationMemberMaterialNotesImages
Atocetus A. nasalisUpperA kentriodontid toothed whale. Atocetus iquensis skull 4554.jpg
Mixocetus M. elysius Lincoln Heights Elysian Park SandstoneSkullA tranatocetid baleen whale, for which the formation is the type locality. Mixocetus elysius LACM.jpg

See also

References

  1. Rumelhart, Peter E.; Ingersoll, Raymond V. (1997). "Provenance of the upper Miocene Modelo Formation and subsidence analysis of the Los Angeles basin, southern California: Implications for paleotectonic and paleogeographic reconstructions" . Geological Society of America Bulletin. 109 (7): 885–899. Bibcode:1997GSAB..109..885R. doi:10.1130/0016-7606(1997)109<0885:POTUMM>2.3.CO;2.
  2. Gilbert, J. Clark; Jobe, Zane R. (2023-08-29). "Submarine-Channel Element Architecture Demonstrates Facies Heterogeneity in Both Strike and Dip Views: Miocene Modelo Formation, Lake Piru, California, USA". The Sedimentary Record. 21 (1). doi: 10.2110/001c.84246 .
  3. Knott, Jeffrey R.; Sarna-Wojcicki, Andrei M.; Barron, John A.; Wan, Elmira; Heizler, Lynn; Martinez, Priscilla (2022-09-26), Aiello, Ivano W.; Barron, John A.; Ravelo, A. Christina (eds.), "Tephrochronology of the Miocene Monterey and Modelo Formations, California", Understanding the Monterey Formation and Similar Biosiliceous Units across Space and Time, Geological Society of America, pp. 187–214, doi:10.1130/2022.2556(08), ISBN   978-0-8137-2556-7 , retrieved 2024-09-23
  4. 1 2 3 Czaplewski, John J. "PBDB Navigator". Paleobiology Database . Retrieved 2024-09-23.
  5. 1 2 California Academy of Sciences (1890). Occasional papers of the California Academy of Sciences. California Academy of Sciences. San Francisco : California Academy of Sciences.{{cite book}}: CS1 maint: publisher location (link)
  6. 1 2 Denton, John S. S. (2013). "Lanternfish (Teleostei, Myctophiformes, Myctophidae) body fossils from the Modelo Formation (upper Miocene) of Los Angeles County, California" . Journal of Vertebrate Paleontology. 33 (4): 786–793. Bibcode:2013JVPal..33..786D. doi:10.1080/02724634.2013.751919. ISSN   0272-4634.