Gaiman Formation
| Gaiman Formation | |
|---|---|
| Stratigraphic range: Burdigalian (Colhuehuapian) ~ | |
| File:Cerro Castillo stratigraphy.png Gaiman Formation stratigraphy at Cerro Castillo | |
| Type | Geological formation |
| Underlies | Puerto Madryn Formation |
| Overlies | Sarmiento Formation |
| Thickness | 70 m (230 ft) |
| Lithology | |
| Primary | Mudstone, sandstone |
| Other | Tuff, phosphate |
| Location | |
| Coordinates | Lua error in Module:Coordinates at line 489: attempt to index field 'wikibase' (a nil value). |
| Approximate paleocoordinates | Lua error: callParserFunction: function "#coordinates" was not found. |
| Region | Chubut Province |
| Country | Argentina |
| Extent | Peninsula Valdés Basin |
| Type section | |
| Named for | Gaiman |
| Named by | Mendía & Bayarsky |
| Year defined | 1981 |
Gaiman Formation (Argentina) | |
The Gaiman Formation (Spanish: Formación Gaiman), in older literature also referred to as Patagonian Marine Formation (Spanish: Formación Patagonia Marino, Patagoniense), is a fossiliferous geologic formation of the Peninsula Valdés Basin in the eastern Chubut Province of northwestern Patagonia, eastern Argentina.
The 70 metres (230 ft) thick formation overlies the Sarmiento Formation and is overlain by the Puerto Madryn Formation and comprises grey and white tuffaceous mudstones and sandstones, deposited in a shallow marine environment.
The Gaiman Formation has provided fossils of many extinct penguins, among which five species in the genus Palaeospheniscus, as well as whales and dolphins, most notably Aondelphis talen, Prosqualodon australis, Idiorophus patagonicus and Argyrocetus patagonicus, indeterminate seal and turtle fossils, shark and other fossils. The richness of the formation, and the other formations in the area, such as the underlying Sarmiento Formation, led to the establishment of the Bryn Gwyn Paleontological Park, with a Welsh name, reflecting the number of Welsh settlers in the region.
Description
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The Gaiman Formation was first defined by Mendía & Bayarsky in 1981,[1] and further described by Mendía in 1983, taking its name from Gaiman in Chubut Province, eastern Patagonia.[2] Gaiman in the local language of the native Tehuelche people means "rocky point".[3] The formation crops out in the lower course of the Chubut River,[4] and overlies the continental Trelew Member of the Sarmiento Formation and is overlain by the Late Miocene Puerto Madryn Formation. The formation is 70 metres (230 ft) thick,[5] and comprises marine tuffs, tuffaceous mudstones, sandstones and coquinas.[1]
The Gaiman Formation is correlated with the Chenque Formation of the Golfo San Jorge Basin and the Monte León Formation of the Austral Basin to the south, the Saladar Member of the lower Gran Bajo del Gualicho Formation of the Colorado Basin to the north and the Vaca Mahuida Formation of the Neuquén Basin to the northwest.[6]
Depositional environment
[edit | edit source]The basal stratum of the Gaiman Formation is a thin transgressive lag with some gravels, bones and teeth from marine vertebrates.[5] The unit displays a concentration of phosphatic concretions, ooids, bones and teeth.[7] The marine sediments overlying this basal stratum are composed of white, tuffaceous, thoroughly bioturbated mudstones and fine sandstones with occasional mollusk molds and thin oyster horizons, deposited in a shallow shelf environment.[5]
The marine transgression leading to the deposition of the Gaiman Formation is the first of two major South Atlantic transgressions of the Miocene, the second causing the deposition of the overlying Puerto Madryn Formation.[8]
Facies analysis shows that the formation represents a transgressive-regressive stratigraphic cycle, with palaeoenvironments including coastal, storm-dominated shoreface, inner shelf embayment and open inner shelf.[9]
The age of the Gaiman Formation is established on stratigraphic correlations to other absolutely-dated sections in Patagonia and biostratigraphic data and dates to the Early Miocene (Burdigalian, or Colhuehuapian in the SALMA classification).[5]
Paleontological significance
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The Gaiman Formation has provided several fossil penguins, of which nine are assigned to specific species and include five species of the genus Palaeospheniscus. Also, shark teeth, fossils of indeterminate seals and turtles, and several dolphins, baleen and toothed whales have been found in the formation. Argentine paleontologist Florentino Ameghino described an isolated tooth from the formation first as an ichthyodectiform fish, Portheus patagonicus in 1901, however this fossil was assigned to a delphinoid cetacean of the family Kentriodontidae by Cione and Cozzuol in 1990.[10] Fish recorded from the formation are hexanchiform hexanchids, lamniform isurids, odontaspidids, cetorhinids, carcharhiniform carcharhinids, heterodontiform heterodontids, squatiniform squatinids myliobatiform myliobatids, perciform oplegnathids and labrids, and tetraodontiform molids.[11] Rays are abundant in the formation.[12] The lack of somatic remains of most molluscs, bryozoans, polychaetes and cirripeds in the formation is attributed to the high-energy and corrosive environment at time of deposition, as well as diagenesis after the formation was deposited.[13]
The bird species Eretiscus tonnii solely occurs in the Gaiman Formation.[14] Bite marks on several of the penguin bones are attributed to terrestrial mammals such as didelphid or hathliacyniid sparassodont marsupials, common in Patagonia during the Miocene.[15] Other ichnofossils found on the bones are presumably caused by dental erosion by regular echinoids,[16] and bite marks by sharks, as Galeocerdo aduncus.[17]
The paleontological richness of the formation, as well as the more fossiliferous underlying Sarmiento Formation, led to the establishment of the Bryn Gwyn Paleontological Park.[18]
Fossil content
[edit | edit source]The formation has provided the following fossils:[19][20][21][22][23]
Mammals
[edit | edit source]Cetaceans
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Aglaocetus | A. moreni | Cerro del Castillo and Bahia Solano | A skull | An early baleen Whale | [24] | |
| Aondelphis | A. talen | Bryn Gwyn Locality | A partial skull | An early river dolphin | [25] | |
| Argyrocetus | A. patagonicus | Bryn Gwyn Locality | A skull | An early toothed whale | [12] | |
| Crisocetus | C. lydekkeri | Estancia El Crisol | A partial skull | An early toothed whale | [26] | |
| Dolgopolis | D. kinchikafiforo | Estancia El Crisol | A partial skull | An early toothed whale | [27] | |
| Eurhinodelphinidae | indet. | [20] | ||||
| Idiorophus | I. patagonicus | Bryn Gwyn Locality | A complete skull | An early toothed whale | [24] | |
| Kentriodon | K. sp. | Bryn Gwyn Locality | A specimen | An early toothed whale | [12] | |
| Morenocetus | M. parvus | Cerro del Castillo, Trelew | A partial cranium | An early baleen whale | [24] | |
| Phoberodon | P. arctirostris | Playa Magagna and Cerro del Castillo, Trelew | A partial skeleton with skull | An early river dolphin | [12] | |
| Plesiocetus | P. dyticus | Cerro del Castillo | A specimen | An early rorquals | [24] | |
| Prosqualodon | P. australis | Playa Magagna and Cerro del Castillo | A preserved skeleton | An early toothed whale | [12][28] | |
| Squalodontidae | indet. | [20] |
Pinnipeds
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Phocidae | indet. | [22] |
Birds
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Anseriformes | indet. | [20] | ||||
| Apterodytes | A. ictus | Cerro del Castillo | An early penguin | [21] | ||
| Arthrodytes | A. sp. | [20] | ||||
| Cayaoa | C. bruneti | Cerro Castillo | A specimen | An early anatid water bird | [4][29] | |
| Eretiscus | E. tonnii | An early prenguin | [30] | |||
| Palaeospheniscus | P. bergi | Cerro del Castillo, Trelew | A set of limb elements (humerus, radius, tarsometatarsus) | An early penguin | [30][19] | |
| P. bilocular | Cerro del Castillo | Two characteristic humeri (AMNH 3341 and 3346) | A early penguin, formally named Chubutodyptes biloculata | [30] | ||
| P. gracilis | Gran Bajo de San Julian and Cerro del Castillo | A specimen | An early penguin | [20] | ||
| P. patagonicus | Cerro del Castillo | An early penguin | [19][31] | |||
| P. wimani | Cerro del Castillo | An early penguin | [22] | |||
| Paraptenodytes | P. antarcticus | A partial skeleton | [30] | |||
| P. robustus | [19][31] | |||||
| Sphenisciformes | indet. | [20] |
Reptiles
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Dermochelyidae | indet. | [20] | ||||
| Helianthochelys | H. redondita. | Coastal creek located 5 km east of La Redonda Chica House in La Redonda Chica Farm | A near-complete carapace (secondary ossicles and nuchal bone) with a putative skull fragment (jugal) and postcranial elements. | A sea turtle belonging to the family Dermochelyidae. | [32] |
Fish
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Carcharoides | C. totuserratus | A mackeral shark | [17] | |||
| Echinorhinus | E. pozzii | [12] | ||||
| Galeocerdo | G. aduncus | [17] | ||||
| Megascyliorhinus | M. trelewensis | [12] | ||||
| Heterodontus | H. sp. | [12] | ||||
| Odontaspis | O. sp. | [12] | ||||
| Pristiophorus | P. sp. | [12] | ||||
| Squalus | S. sp. | [12] | ||||
| Oplegnathidae | O. sp. | [12] | ||||
| Tetraodontiformes | T. sp. | [33] |
Mollusk
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Crassostrea | C. ? hatcheri | A bivalve | [23] | |||
| Balanus | B. sp. | A bivalve | [34] | |||
| Turritella | T. sp. | A gastropod | [34] |
Ichnofossils
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Chondrites | A Bioturbation | [11] [16] | ||||
| Ophiomorpha | ||||||
| Planolites | ||||||
| Skolithos | ||||||
| Gnathichnus | G. pentax | Bite marks | ||||
| Entobia | Bite marks |
Flora
[edit | edit source]| Taxa | Species | Locality | Material | Description | Images | Notes |
|---|---|---|---|---|---|---|
| Chenopodipollis | C. chenopodiaceoides | Isla Escondida | A chenopodiaceae | |||
| Cyatheacidites | C. annulatus | A dicksoniaceae | ||||
| Equisetosporites | E. claricristatus | |||||
| Margocolporites | M. vanwijhei | A fabaceae | ||||
| Nothofagidites | N. saraensis | |||||
| Peromonolites | P. vellosus | A blechnaceae | ||||
| Thalassotaenia | T. notophyllum | A hydrocharitaceae |
See also
[edit | edit source]- South American land mammal ages
- Uitpa Formation, contemporaneous fossiliferous formation of the Cocinetas Basin, Colombia
- Castillo Formation, contemporaneous fossiliferous formation of the Falcón Basin, Venezuela
- Biblián Formation, contemporaneous fossiliferous formation of Ecuador
- Bahía Inglesa Formation, contemporaneous fossiliferous formation of Chile
References
[edit | edit source]- ^ a b Cione et al., 2010, p.434
- ^ Rodríguez, 2015, p.198
- ^ (in Spanish) Significado de los nombres de los Municipios de Chubut
- ^ a b Noriega & Tambussi, 2008, p.272
- ^ a b c d Viglino et al., 2018, p.263
- ^ Reichler, 2018, p.185
- ^ Cione et al., 2011, p.424
- ^ Cuitiño, 2017, p.47
- ^ Cuitiño et al., 2019
- ^ Cione & Cozzuol, 1990, p.451
- ^ a b Cione et al., 2010, p.443
- ^ a b c d e f g h i j k l Cione et al., 2010, p.429
- ^ Cione et al., 2010, p.450
- ^ Chávez Hoffmeister, 2008, p.82
- ^ Cione et al., 2010, p.437
- ^ a b Cione et al., 2010, p.439
- ^ a b c Cione et al., 2010, p.441
- ^ (in Spanish) Parque paleontológico Bryn Gwyn
- ^ a b c d Cerro del Castillo, Trelew at Fossilworks.org
- ^ a b c d e f g h Bryn Gwyn at Fossilworks.org
- ^ a b Patagonian at Fossilworks.org
- ^ a b c Gaiman (marine vertebrates) at Fossilworks.org
- ^ a b Playa Santa Isabel, south at Fossilworks.org
- ^ a b c d Cione et al., 2011, p.428
- ^ Viglino et al., 2018, p.264
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Viglino et al., 2020
- ^ Gaetán, 2019
- ^ Tonni, 1979, p.12
- ^ a b c d Cione et al., 2010, p.433
- ^ a b Acosta et al., 2008, p.568
- ^ Sterli, J.; Vlachos, E.; Cuitiño, J. I.; Cerda, I. A.; Buono, M. R. (2025). "Southernmost dermochelyid turtle from the Miocene". Ameghiniana.
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Acosta et al., 2008, p.566
Bibliography
[edit | edit source]- Geology
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- Paleontology
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Further reading
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