Marne di Monte Serrone

The Marne di Monte Serrone ("Monte Serrone Marl") is a geological formation in Italy, dating to roughly between 181 and 178 million years ago,[1] and covering the early and middle Toarcian stage of the Jurassic Period of central Italy.[2] It is the regional equivalent to the Toarcian units of Spain such as the Turmiel Formation, units in Montenegro, such as the Budoš Limestone and units like the Tafraout Formation of Morocco.[2][3]

Marne di Monte Serrone
Stratigraphic range: Early Toarcian
~
Panoramic of Monte Serrone with the Jurassic in the background
TypeGeological formation
Sub-unitsValdorbia, Colle d'Orlando, Pale Vallone & Pozzale Sections
UnderliesRosso Ammonitico, Calcari e Marne a Posidonia & Calcari Diasprigni Formations
OverliesCorniola & Calcare Massicio Formations
Thickness64–80 m (210–262 ft)
Lithology
PrimaryCalcilutites & clay-rich greenish marls with calcareous lenses
OtherArgillaceous gray green marls with calcarenites alternated with marls
Location
Coordinates42°59′30.1″N 12°50′58.2″E
RegionUmbria
Country Italy
ExtentUmbria-Marche Basin
Type section
Named forMonte Serrone
Named byPialli
Year defined1969
Marne di Monte Serrone is located in Italy
Marne di Monte Serrone
Marne di Monte Serrone (Italy)

Description

The Marne di Monte Serrone was first defined by Pialli in 1969.[4] Represents mostly a marginal marine, from intertidal to hemipelagic unit, with several different depositional settings recovered on it. The lithology and sedimentology of the unit reflect the different positions within the Umbria-Marche Basin, where the layers located towards Pozzale are of typical hemipelagic nature, lacking proper amounts of carbonate sediments.[2] By contrast, towards Colle d’orlando and Fonte Cerro areas the influence of a nearby emerged landmass is evident, based on the amount of reworked calcareous sediments.[4] This terrigenous material was likely derived from the nearby Lazio-Abruzzo Platform, where likely a significant amount of terrigenous residue developed as Terra Rossa deposited, likely on island settings.[5]

The formation is characterised for be one of the most complete sections to measure the chaggues of the marine microbiota of the Toarcian around Europe.[6] It is also one of the best places on southern Europe where the strata shows the effects of the Lower Toarcian anoxic event (T-OAE). The formation also provides data about the changes after the Toarcian AE, with changes on the deposited micritic limestones and marls, what shows a local sedimentary response to the Toarcian climatic perturbation induced by the Vulcanism of the Southern Karoo-Ferrar that boiled the carbon cycle and change the mechanism of Earth climate. The dawn after the Toarcian AE is presented locally by changes on the environments, to more seashore to lagoonal ones.[7]

Depositional environment

The environment of the formation has been compared to the present on the Toarcian Betic Cordillera strata, with a corridor of pelagic environments with influence from emerged reliefs.[8] Other sections are related to nearby emerged lands, seashore deposits and even inland deposition, due to the changes in lithology (especially with the clay minerals kaolinite and smectite). Due to that, the main depositional layers of the formation are believed to come from an environment intermediate between pelagic and nearshore settings.[8]

Due to the influence of different depositional settings, the lithology of the formation was widely distributed, with changes on the mineralological composition. The clay Mineral assemblages, with the neritic sedimentation, expose a change on the deposition, as it can be seen on the Valdorbia Section, where on the Middle Toarcian the reduction of this minerals indicate a sea-level fall, with a change from a bathyal to a middle shelf environment. Additionally there is a record of changes on the fauna, specially bivalves that suggests a variable flow regime at the major wave base as a result of a storm event.[9]

Fossil content

The biota of the formation comprise mostly marine microinvertebrates and algae, with the presence of ammonites and abundant pollen in the Middle Toarcian sections. Nanoplankton is one of the most representative finds of the layers, appearing deposited with interruptions, probably due to changes on the oxygen content of the sea floor.[10] Phytoplankton includes abundant dinoflagellate cysts and acritarchs, specially the genus Micrhystridium. There registered a transgression on the sea level on the Lower Toarcian, with a rise, giving the Umbria-Marche Basin pelagic conditions, and a regression during the Middle Toarcian. Those changes implicate the disappearance of genera of dinoflagellates from the strata to be replaced with new ones.[11][12] Some dinoflagellate genera such as Mendicodinium are more abundant, being the dominant palynological residue recovered in some samples.[13]

Foraminiferal analysis had been done, revealing changes in the salinity, with Spirillina as the most abundant genus found, followed by Prodentalina, Eoguttulina, Lenticulina, Nodosaria, Lingulonodosaria and Pseudonodosaria.[14] Invertebrate remains are mainly brachiopods (Pseudokingena, Nannirhynchia and Lokutella, among others) and ammonites; Eodactylites, Pleuroceras, Canavaria, Trinacrioceras, Lioceratoides, and Praepolyplectus as predominant genera.[15]

Other marine fauna includes Holothuriidan Sclerites, unidentified crinoids, fragmentary asteroideans and fish teeth, similar to the genera Saurostomus and Dapedium.[16]

There are terrestrial fossils and sediments, specially clay. The main source area for the clay could have been the palaeosoils developed on the Carbonate Latium-Abruzzo Platform, although more recent studies prove a continental origin.[17] The Main fossils from terrestrial deposits are plant Pollen, mostly Pteridophyta spores and Circumpolles, and Palynomacerals.[18] The genera includes Leptolepidites (Lycopsida) spp., Trilites (Filicopsida) spp., Ischyosporites (Pteridopsida) spp. or Foveosporites (Selaginellaceae) spp. and others less abundant, such as the genus Callialasporites (Coniferales). There is a curious reduction of the Cheirolepidiaceae genus Classopollis, abundant on coeval associations from northern Europe, Portugal, northeast Italy and Israel, as a possible effect of paleoclimatic changes.[19]

Megaflora

Several plant leaves and fragments of wood were not identified.[5][16]

Genus Species Stratigraphic position Material Notes Images

Brachyphyllum[5][20]
  • Brachyphyllum spp.

Mount Palombo, Marsica

Branched Shoots

Affinities with the Cheirolepidiaceae and Araucariaceae. Usually linked with coastal settings as shrub-alike conifers

Cycadopteris[5][20]
  • Cycadopteris spp.

Leaflets

Affinities with Corystospermales inside Pteridospermopsida.

Dactylethrophyllum[5][20]
  • Dactylethrophyllum cf.peristictum

Branched Shoots

Affinities with Cheirolepidiaceae inside Coniferales.

Otozamites[5][20]
  • Otozamites molinianus

Leaflets

Affinities with Williamsoniaceae inside Bennettitales. Overall, the genus Otozamites is among the most abundant flora genus recovered

Pagiophyllum[5][20]
  • Pagiophyllum cf. revoltinum
  • Pagiophyllum cf. veronense

Branched Shoots

Affinities with the Cheirolepidiaceae and Araucariaceae. Arbustive to arboreal plants with several leaf morphotypes, probably from nearshore environments.

Sphenozamites[5][20]
  • Sphenozamites rossii

Leaflets

Affinities with Williamsoniaceae inside Bennettitales. Related with Cycad-like trees.

Taeniopteris[5][20]
  • Taeniopteris spp.

Leaflets

Affinities with either Williamsoniaceae inside Bennettitales or Pentoxylales. Leafs related with plans of suggested habit similar to that of brambles

See also

References
  1. Sabatino, N.; R. Neri; A. Bellanca; H.C. Jenkyns; F. Baudin; G. Parisi, and D. Masetti. 2009. Carbon‐isotope records of the Early Jurassic (Toarcian) oceanic anoxic event from the Valdorbia (Umbria–Marche Apennines) and Monte Mangart (Julian Alps) sections: Palaeoceanographic and stratigraphic implications. Sedimentology 56. 1307–1328. Accessed 2020-03-17.
  2. Baldanza., A. (1989). "The type section of Marne di Monte Serrone Formation: stratigraphic analysis based on ammonites, calcareous nannofossils and foraminifera assemblages". Mere. Descr. Carta Geol. Ital. 39 (1): 185–202.
  3. Monaco, P. (1994). "Hummocky cross-stratifications and trace fossils in the Middle Toarcian of some sequences of Umbria-Marche Apennines". Geobios. 27 (3): 679–688. Bibcode:1994Geobi..27..679M. doi:10.1016/S0016-6995(94)80231-9. Retrieved 7 July 2023.
  4. Pialli, G. (1969). "Un episodio marnoso del Lias superiore nel bacino umbro-marchigiano: le marne di M. Serrone". Boll. Sot. Nat. Napoli. 78 (3): 1–23.
  5. Praturlon, A. (1968). "Cycadophyta and Coniferophyta from the Lias of M. Palombo (Marsica, Central Apennines)". Geol. Romana. 7: 1–26. Retrieved 7 July 2023.
  6. Bucefalo Palliani, R .; Mattioli, E. (1994). "Enrichment in organic matter within the Early Toarcian Marne di Monte Serrone Formation: a synchronous event in the Umbria-Marche Basin (central Italy)". Paleopelagos. 4 (4): 129–140.
  7. Satolli, Sara; Luca Lanci; Giovanni Muttoni, and Andrea Di Cencio. 2018. The Lower Toarcian Serrone Marls (Northern Apennines, Italy): A 3.5 Myr record of marl deposition in the aftermath of the T-OAE. Palaeogeography, Palaeoclimatology, Palaeoecology 508. 35–47. Accessed 2020-03-17.
  8. Nini, C.; Nocchi, M.; Venturi, F. (1996). "The Toarcian marly-calcareous succession in the M. Martani area (Northern Apennines): lithostratigraphy, biostratigraphy, paleoecology and effects of Tethysian event on the depositional environment". Bollettino-Societa Paleontologica Italiana. 35: 281–320. Retrieved 7 July 2023.
  9. Ortega Huertas, M.; Monaco, P.; Palomo, I. (1993). "First Data on Clay Mineral Assemblages and Geochemical Characteristics of Toarcian Sedimentation in the umbriamarche basin (central Italy)". Clay Minerals. 28 (2): 297–310. Bibcode:1993ClMin..28..297O. doi:10.1180/claymin.1993.028.2.10. S2CID 140680602. Retrieved 7 July 2023.
  10. Noël, D.; Busson, G.; Cornée, A.; Manginin, A. M. (1993). "Le nannoplancton calcaire et la formation des alternances calcaires-marnes dans le Lias des bassins de Marches-Ombrie (Italie)". Rivista italiana di paleontologia e stratigrafia. 99 (4): 515–550. Retrieved 7 July 2023.
  11. Palliani, R. B.; Cirilli, S.; Mattioli, E. (1998). "Phytoplankton response and geochemical evidence of the lower Toarcian relative sea level rise in the Umbria-Marche basin (Central Italy)". Palaeogeography, Palaeoclimatology, Palaeoecology. 142 (1): 33–50. Bibcode:1998PPP...142...33P. doi:10.1016/S0031-0182(97)00152-1. Retrieved 7 July 2023.
  12. Palliani, R. B.; Riding, J. B. (1999). "Relationships between the early Toarcian anoxic event and organic-walled phytoplankton in central Italy". Marine Micropaleontology. 37 (2): 101–116. Bibcode:1999MarMP..37..101P. doi:10.1016/S0377-8398(99)00017-1. Retrieved 7 July 2023.
  13. Palliani, R. B.; Riding, J. B.; Torricelli, S. (1997). "The dinoflagellate cyst Mendicodinium Morgenroth, 1970, emend. from the lower Toarcian (Jurassic) of central Italy". Review of Palaeobotany and Palynology. 96 (2): 99–111. Bibcode:1997RPaPa..96...99P. doi:10.1016/S0034-6667(96)00019-X. Retrieved 7 July 2023.
  14. Rodríguez Tovar, F.J.; E. Pardo Iguzquiza; M. Reolid, and A. Bartolini. 2016. Spectral analysis of Toarcian sediments from the Valdorbia section (Umbria-Marche Apennines): the astronomical input in the foraminiferal record. Rivista Italiana di Paleontologia e Stratigrafia 122. 45–60. Accessed 2020-03-17.
  15. Bilotta, M.; F. Venturi, and S. Sassaroli. 2010. Ammonite faunas, OAE and the Pliensbachian–Toarcian boundary (Early Jurassic) in the Apennines. Lethaia 43. 357–380. Accessed 2020-03-17.
  16. Monaco, P.; Nocchi, M.; Ortega Huertas, M.; Palomo, I.; Martínez, F. (1994). "Depositional trends in the Valdorbia Section (Central Italy) during the Early Jurassic, as revealed by micropaleontology, sedimentology and geochemistry". Eclogae Geologicae Helvetiae. 87 (1): 157–223. Retrieved 7 July 2023.
  17. Perilli, N.; V. Reale, and L.C.V. De Oliveira. 2008. Ages of the onset of marly sedimentation and of the black shales in the Tuscan Basin (Northern Apennines, Italy). Rivista Italiana di Paleontologia e Stratigrafia 114. 45–60. Accessed 2020-03-17.
  18. Palliani, R.B.; Riding, J.B. (1997). "Lower Toarcian palynostratigraphy of Pozzale, central Italy". Palynology. 21 (1): 91–103. Bibcode:1997Paly...21...91P. doi:10.1080/01916122.1997.9989489. JSTOR 3687591. Retrieved 7 July 2023.
  19. Palliani, R.B. (1997). "Toarcian sporomorph assemblages from the Umbria‐Marche basin, central Italy". Palynology. 21 (1): 105–121. doi:10.1080/01916122.1997.9989490. Retrieved 7 July 2023.
  20. Dalla Vecchia, F. M. (2000). "Macrovegetali terrestri nel Mesozoico italiano: un'ulteriore evidenza di frequenti emersioni". Natura Nascosta. 20: 18–35. Retrieved 7 July 2023.
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