Radiolarite

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Outcrop of Franciscan radiolarian chert in San Francisco, California Glen Canyon Park Chert Outcrop.jpg
Outcrop of Franciscan radiolarian chert in San Francisco, California
Radiolarian chert outcrop near Cambria, California. Individual beds range from about 2 to 5 cm thick Radiolarian chert, San Simeon state park.jpg
Radiolarian chert outcrop near Cambria, California. Individual beds range from about 2 to 5 cm thick
Radiolarite (Jurassic) from the Alps. Radiolarite 01.jpg
Radiolarite (Jurassic) from the Alps.

Radiolarite is a siliceous, comparatively hard, fine-grained, chert-like, and homogeneous sedimentary rock that is composed predominantly of the microscopic remains of radiolarians. This term is also used for indurated radiolarian oozes and sometimes as a synonym of radiolarian earth. However, radiolarian earth is typically regarded by Earth scientists to be the unconsolidated equivalent of a radiolarite. A radiolarian chert is well-bedded, microcrystalline radiolarite that has a well-developed siliceous cement or groundmass. [1]

Contents

Mineralogy and petrology

Radiolarites are biogenic, marine, finely layered sedimentary rocks. The layers reveal an interchange of clastic mica grains, radiolarian tests, carbonates and organic pigments. Clay minerals are usually not abundant. Radiolarites deposited in relatively shallow depths can interleave with carbonate layers. Yet most often radiolarites are pelagic, deep water sediments.

Radiolarites are very brittle rocks and hard to split. They break conchoidally with sharp edges. During weathering they decompose into small, rectangular pieces. The colors range from light (whitish) to dark (black) via red, green and brown hues.

Radiolarites are composed mainly of radiolarian tests and their fragments. The skeletal material consists of amorphous silica (opal A). Radiolarians are marine, planktonic protists with an inner skeleton. Their sizes range from 0.1 to 0.5 millimeters. Amongst their major orders albaillellaria, ectinaria, the spherical spumellaria and the hood-shaped nassellaria can be distinguished.

Sedimentation

According to Takahashi (1983) radiolarians stay for 2 to 6 weeks in the euphotic zone (productive surface layer to 200 meters water depth) before they start sinking. [2] Their descent through 5000 meters of ocean water can take from two weeks to as long as 14 months. [3]

As soon as the protist dies and starts decaying, silica dissolution affects the skeleton. The dissolution of silica in the oceans parallels the temperature/depth curve and is most effective in the uppermost 750 meters of the water column, farther below it rapidly diminishes. Upon reaching the sediment/water interface the dissolution drastically increases again. Several centimeters below this interface the dissolution continues also within the sediment, but at a much reduced rate.

It is in fact astonishing that any radiolarian tests survive at all[ citation needed ]. It is estimated that only as little as one percent of the original skeletal material is preserved in radiolarian oozes. According to Dunbar & Berger (1981) [4] even this minimal preservation of one percent is merely due to the fact that radiolarians form colonies and that they are occasionally embedded in fecal pellets and other organic aggregates. The organic wrappings act as a protection for the tests (Casey et al. 1979)[ full citation needed ] and spare them from dissolution, but of course speed up the sinking time by a factor of 10.

Diagenesis, compaction and sedimentation rates

Whetstone limestone from the Ammergau Alps, Upper Bavaria with round radiolarian remains (thin section). The abrasive effect of the whetstones results from the even distribution of the hard radiolarian skeletons in the soft limestone matrix. Wetzsteinkalk neu.jpg
Whetstone limestone from the Ammergau Alps, Upper Bavaria with round radiolarian remains (thin section). The abrasive effect of the whetstones results from the even distribution of the hard radiolarian skeletons in the soft limestone matrix.

After deposition diagenetic processes start affecting the freshly laid down sediment. The silica skeletons are etched and the original opal A slowly commences to transform into opal CT (opal with crystallites of cristobalite and tridymite). With increasing temperature and pressure the transformation proceeds to chalcedony and finally to stable, cryptocrystalline quartz. These phase changes are accompanied by a decrease in porosity of the ooze which becomes manifest as a compaction of the sediment.

The compaction of radiolarites is dependent on their chemical composition and correlates positively with the original SiO2-content. The compaction factor varies generally between 3.2 and 5, which means that 1 meter of consolidated sediment is equivalent to 3.2 to 5 meters of ooze. The alpine radiolarites of the Upper Jurassic for instance show sedimentation rates of 7 to 15.5 meters/million years (or 0.007 to 0.0155 millimeters/year), which after compaction is equivalent to 2.2 to 3.1 meters/million years. As a comparison the radiolarites of the Pindos Mountains in Greece yield a comparable value of 1.8 to 2.0 meters/million years, whereas the radiolarites of the Eastern Alps have a rather small sedimentation rate of 0.71 meters/million years. [5] According to Iljima et al. 1978 the Triassic radiolarites of central Japan reveal an exceptionally high sedimentation rate of 27 to 34 meters/million years. [6]

Recent non-consolidated radiolarian oozes have sedimentation rates of 1 to 5 meters/million years. [7] In radiolarian oozes deposited in the equatorial Eastern Atlantic 11.5 meters/million years have been measured. In upwelling areas like off the Peruvian coast extremely high values of 100 meters/million years were reported[ citation needed ].

Depth of deposition

The view that radiolarites are mainly deposited under pelagic, deep water conditions cannot be asserted any longer. Layers enriched in radiolarians do even occur in shallow water limestones like the Solnhofen limestone and the Werkkalk Formation of Bavaria. What seems to be important for the preservation of radiolarian oozes is that they are deposited well below the storm wave base and below the jets of erosive surface currents. Radiolarites without any carbonates have most likely been sedimented below the calcite compensation depth (CCD). One has to bear in mind that the CCD has not been stationary in the geological past and that it is also a function of latitude. At present, the CCD reaches a maximum depth of about 5000 meters near the equator. [8]

Banding and ribbons

The characteristic banding and ribbon-like layering often observed in radiolarites is primarily due to changing sediment influx, which is secondarily enhanced by diagenetic effects. In the simple two component system clay/silica with constant clay supply the rhythmically changing radiolarian blooms are responsible for creating a clay-chert interlayering. These purely sedimentary differences become enhanced during diagenesis as the silica leaves the clayey layers and migrates towards the opal-rich horizons. Two situations occur: with high silica input and constant clay background sedimentation thick chert layers form. On the other hand, when the silica input is constant and the clay signal varies rhythmically fairly thick clay bands interrupted by thin chert bands accumulate. By adding carbonates as a third component complicated successions can be created, because silica is not only incompatible with clays but also with carbonates. During diagenesis the silica within the carbonate-rich layers starts pinching and coagulates into ribbons, nodules and other irregular concretions. Resulting are complex layering relationships that depend on the initial clay/silica/carbonate ratio and the temporal variations of the single components during sedimentation.

Occurrence in time and space

Paleozoic

Silurian lydite of Saxony, near Nossen (Nossen-Wilsdruff Slate Mountains) Lydite kbt 2.jpg
Silurian lydite of Saxony, near Nossen (Nossen-Wilsdruff Slate Mountains)

The oldest known radiolarites come from the Upper Cambrian of Kazakhstan. [9] Radiolarian ooze was sedimented here over a time span of 15 million years into the Lower Ordovician. The deep water sediments were deposited near the paleoequator and are associated with remnants of oceanic crust. The dating has been done with conodonts. In more lime-rich sections four radiolarian faunal associations were identified. The oldest, rather impoverished fauna dates back well into the second stage of the Ordovician (Arenigian). The youngest fauna consists already of 15 different taxa and belongs to the fifth stage (Lower Caradocian). [10]

During the Middle Ordovician (Upper Darriwilian) radiolarites were formed near Ballantrae in Scotland. Here radiolarian cherts overlie spilites and volcanic rocks. Radiolarites are also found in the nearby Southern Uplands where they are associated with pillow lava.

The Scottish radiolarites are followed by deposits in Newfoundland from the Middle and Upper Ordovician. The red Strong Island Chert for instance rests on ophiolites.

At the Silurian/Devonian boundary black cherts (locally called lydites or flinty slates) developed from radiolarians mainly in the Franconian Forest region and in the Vogtland in Germany.

Of great importance are the novaculites from Arkansas, Oklahoma and Texas which were deposited at the close of the Devonian. The novaculites are milky-white, thinly-bedded cherts of great hardness; they underwent a low-grade metamorphism during the Ouachita orogeny. Their mineralogy consists of microquartz with a grain-size of 5 to 35 μm. The microquartz is derived from the sclerae of sponges and the tests of radiolarians.

During the Mississippian black lydites were sedimented in the Rhenish Massif in Germany. [11] The Lower Permian of Sicily hosts radiolarites in limestone olistoliths, [12] at the same period radiolarites have been reported from northwestern Turkey (Karakaya complex of the Pontides). Radiolarites from the Phyllite Zone of Crete date back to the Middle Permian. [13] The radiolarites from the Hawasina nappes in Oman closed the end of the Permian. [14] Towards the end of the Paleozoic radiolarites formed also along the southern margin of Laurasia near Mashad in Iran. [15]

Mesozoic

During the Triassic (Upper Norian and Rhaetian) cherty, platy limestones are deposited in the Tethyan region, an example being the Hornsteinplattenkalk of the Frauenkogel Formation in the southern Karawanks of Austria. [16] They are composed of interlayered cherts and micrites separated by irregular, non-planar bedding surfaces. The cherty horizons have originated from radiolarian-rich limestone layers which subsequently underwent silicification. Similar sediments in Greece incorporate layers with calcareous turbidites. On local horsts and farther upslope these sediments undergo a facies change to red, radiolarian-rich, ammonite-bearing limestones. [17] In central Japan clay-rich radiolarites were laid down as bedded cherts in the Upper Triassic. Their depositional environment was a shallow marginal sea with rather high accumulation rates of 30 meters/million years. Besides radiolarians sponge spicules are very prominent in these sediments. [6]

From the Upper Bajocian (Middle Jurassic) onwards radiolarites accumulated in the Alps. The onset of the sedimentation was diachronous but the end in the Lower Tithonian rather abrupt. These alpine radiolarites belong to the Ruhpolding Radiolarite Group (RRG) and are found in the Northern Calcareous Alps and in the Penninic of France and Switzerland (Graubünden). Associated are the radiolarites of Corsica. The radiolarites of the Ligurian Apennines appear somewhat later towards the end of the Jurassic.

From the Middle Jurassic onwards radiolarites also formed in the Pacific domain along the West Coast of North America, an example being the Franciscan complex. The radiolarites of the Great Valley Sequence are younger and have an Upper Jurassic age.

The radiolarites of California are paralleled by radiolarite sedimentation in the equatorial Western Pacific east of the Mariana trench. The accumulation of radiolarian ooze on Jurassic oceanic crust was continuous here from the Callovian onward and lasted till the end of the Valanginian. [18]

Mookaite from the Kennedy Ranges, near Gascoyne Junction, Western Australia in the permanent collection of The Children's Museum of Indianapolis. Mookaite5.jpg
Mookaite from the Kennedy Ranges, near Gascoyne Junction, Western Australia in the permanent collection of The Children's Museum of Indianapolis.

The Windalia radiolarite is a Lower Cretaceous (Aptian) formation in Western Australia. The formation contains abundant foraminifera, radiolaria and calcareous nanoplankton fossils [19] Locally the varicolored opaline to chalcedonic radiolarite is mined and used as an ornamental stone termed mookaite. [20] At the same time radiolarites were deposited at the Marin Headlands near San Francisco.

Radiolarites from the Upper Cretaceous can be found in the Zagros Mountains and in the Troodos Mountains on Cyprus (Campanian). The radiolarites of Northwestern Syria are very similar to the occurrences on Cyprus and probably have the same age. Red radiolarian clays associated with manganese nodules are reported from Borneo, Roti, Seram and Western Timor. [21]

Cenozoic

A good example for Cenozoic radiolarites are radiolarian clays from Barbados found within the Oceanic Group. The group was deposited in the time range Early Eocene till Middle Miocene on oceanic crust which is subducting now under the island arc of the Lesser Antilles. [22] Younger radiolarites are not known – probably because younger radiolarian oozes did not have sufficient time to consolidate.

Use

Radiolarite is a very hard rock and therefore was extensively used in prehistoric technology and has been called the "iron of the Paleolithic". Axes, blades, drills and scrapers were manufactured from it. The cutting edges of these tools, however, are somewhat less sharp than flint.

Related Research Articles

<span class="mw-page-title-main">Sedimentary rock</span> Rock formed by the deposition and cementation of particles

Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus. The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies. Sedimentation may also occur as dissolved minerals precipitate from water solution.

<span class="mw-page-title-main">Chert</span> Hard, fine-grained sedimentary rock composed of cryptocrystalline silica

Chert is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.

<span class="mw-page-title-main">Microfossil</span> Fossil that requires the use of a microscope to see it

A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil.

<span class="mw-page-title-main">Calcareous</span> Adjective meaning mostly or partly composed of calcium carbonate

Calcareous is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.

The carbonate compensation depth (CCD) is the depth, in the oceans, at which the rate of supply of calcium carbonates matches the rate of solvation. That is, solvation 'compensates' supply. Below the CCD solvation is faster, so that carbonate particles dissolve and the carbonate shells (tests) of animals are not preserved. Carbonate particles cannot accumulate in the sediments where the sea floor is below this depth.

<span class="mw-page-title-main">Pelagic sediment</span> Fine-grained sediment that accumulates on the floor of the open ocean

Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays.

<span class="mw-page-title-main">Biogenic silica</span> Type of biogenic mineral

Biogenic silica (bSi), also referred to as opal, biogenic opal, or amorphous opaline silica, forms one of the most widespread biogenic minerals. For example, microscopic particles of silica called phytoliths can be found in grasses and other plants.

<span class="mw-page-title-main">Marine sediment</span>

Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor. These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from chemical precipitation in seawater, as well as from underwater volcanoes and meteorite debris.

<span class="mw-page-title-main">Siliceous ooze</span> Biogenic pelagic sediment located on the deep ocean floor

Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica SiO2·nH2O, as opposed to calcareous oozes, which are made from skeletons of calcium carbonate (CaCO3·nH2O) organisms (i.e. coccolithophores). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes.

Hemipelagic sediment, or hemipelagite, is a type of marine sediment that consists of clay and silt-sized grains that are terrigenous and some biogenic material derived from the landmass nearest the deposits or from organisms living in the water. Hemipelagic sediments are deposited on continental shelves and continental rises, and differ from pelagic sediment compositionally. Pelagic sediment is composed of primarily biogenic material from organisms living in the water column or on the seafloor and contains little to no terrigenous material. Terrigenous material includes minerals from the lithosphere like feldspar or quartz. Volcanism on land, wind blown sediments as well as particulates discharged from rivers can contribute to Hemipelagic deposits. These deposits can be used to qualify climatic changes and identify changes in sediment provenances.

The Ruhpolding Formation is a sedimentary formation of the Northern Calcareous Alps deposited during the Upper Jurassic. The open marine radiolarite is very rich in silica.

The Pignola-Abriola section is a ~63 m long stratigraphic sequence of cherty limestones deposited in the Lagonegro Basin during the latest Norian and the early Rhaetian Stages. The main outcrop is on the western side of Mount Crocetta along the SP5 road connecting the villages of Pignola and Abriola. A smaller outcrop, overlapping the central part of the main section, is located near a former railway tunnel, few meters below the road level. The Pignola-Abriola section has been recently proposed as GSSP of the Rhaetian Stage.

<span class="mw-page-title-main">Silica cycle</span> Biogeochemical cycle

The silica cycle is the biogeochemical cycle in which biogenic silica is transported between the Earth's systems. Silicon is considered a bioessential element and is one of the most abundant elements on Earth. The silica cycle has significant overlap with the carbon cycle and plays an important role in the sequestration of carbon through continental weathering, biogenic export and burial as oozes on geologic timescales.

Allison Guyot is a tablemount (guyot) in the underwater Mid-Pacific Mountains of the Pacific Ocean. It is a trapezoidal flat mountain rising 1,500 metres (4,900 ft) above the seafloor to a depth of less than 1,500 metres (4,900 ft), with a summit platform 35 by 70 kilometres wide. The Mid-Pacific Mountains lie west of Hawaii and northeast of the Marshall Islands, but at the time of their formation were located in the Southern Hemisphere.

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<span class="mw-page-title-main">Geology of Slovakia</span> Overview of the geology of Slovakia

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<span class="mw-page-title-main">Úrkút Manganese Ore Formation</span>

The Úrkút Manganese Ore Formation is a Jurassic geologic formation in Hungary. It covers the Early Toarcian stage of the Early Jurassic, and it is one of the main regional units linked to the Toarcian Anoxic Events. Different fossils heve been recovered on the locations, including marine life such as Ammonites Fish and terrestrial fossils, such as Palynomorphs and fossil wood. Úrkút and Eplény are the main deposits of the Formation. Are related to the Bakony Range, an ancient massif that was uplifted gradually and exposed to a long period of erosion, where the deposits of Úrkút appear to be a basin inclined gently to the north, while the highest point to the south is the basalt mass of Kab Mountain. Eplény region consists of a broad N-S trending open valley between fiat-topped, small hills.

<span class="mw-page-title-main">Silicification</span> Geological petrification process

In geology, silicification is a petrification process in which silica-rich fluids seep into the voids of Earth materials, e.g., rocks, wood, bones, shells, and replace the original materials with silica (SiO2). Silica is a naturally existing and abundant compound found in organic and inorganic materials, including Earth's crust and mantle. There are a variety of silicification mechanisms. In silicification of wood, silica permeates into and occupies cracks and voids in wood such as vessels and cell walls. The original organic matter is retained throughout the process and will gradually decay through time. In the silicification of carbonates, silica replaces carbonates by the same volume. Replacement is accomplished through the dissolution of original rock minerals and the precipitation of silica. This leads to a removal of original materials out of the system. Depending on the structures and composition of the original rock, silica might replace only specific mineral components of the rock. Silicic acid (H4SiO4) in the silica-enriched fluids forms lenticular, nodular, fibrous, or aggregated quartz, opal, or chalcedony that grows within the rock. Silicification happens when rocks or organic materials are in contact with silica-rich surface water, buried under sediments and susceptible to groundwater flow, or buried under volcanic ashes. Silicification is often associated with hydrothermal processes. Temperature for silicification ranges in various conditions: in burial or surface water conditions, temperature for silicification can be around 25°−50°; whereas temperatures for siliceous fluid inclusions can be up to 150°−190°. Silicification could occur during a syn-depositional or a post-depositional stage, commonly along layers marking changes in sedimentation such as unconformities or bedding planes.

Biogenous ooze is marine sediment that accumulates on the seafloor and is a byproduct of the death and sink of the skeletal remains of marine organisms.

References

  1. ↑ Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, J.A., eds. (2005) Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. ISBN   0-922152-76-4
  2. ↑ Takahashi, K. and Honjo, S.(1983). Radiolarian skeletons: size, weight, sinking speed, and residence time in tropical pelagic oceans. Deep-Sea Research, 30, p. 543–568
  3. ↑ Takahashi, K.(1981). Vertical flux, ecology and dissolution of Radiolaria in tropical oceans: implications for the silica cycle. Unpublished Ph.D. Thesis, Woods Hole Oceanographic Institution and Massachusetts Institute of Technology
  4. ↑ Dunbar, R. B. and W. H. Berger (1981) Fecal pellet flux to modern bottom sediment of Santa Barbara Basin (California) based on sediment trapping,Bulletin of the Geological Society of America, v. 92, pp. 212–218
  5. ↑ Garrison, R. E., and Fischer, A. G., 1969. Deep-Water limestones and radiolarites of the Alpine Jurassic. In Friedman, G. M. (Ed.) Depositional environments in carbonate rocks. Soc. Econ. Palentol. Mineral. Spec. Pübl. 14. 20
  6. 1 2 Iljima, A. et al. (1978). Shallow-sea, organic origin of the Triassic bedded chert in central Japan. J. of the Faculty of Sci., Univ. of Tokyo, Sec. 2, Vol. XIX, 5, p. 369-400
  7. ↑ De Wever, P., and I. Origlia-Devos; 1982, Datations novelles par les Radiolarites de la serie des Radiolarites s. l. du Pinde-Olonos, (Greece), C. R. Acad. Sc. Paris., 294, p. 399–404
  8. ↑ Berger, W. H. & Winterer, E. L. (1974). Plate stratigraphy and the fluctuating carbonate line. Editors: Hsü, K. J. & Jenkyns, H. C., Spec. Publ. Int. Ass. Sediment. Pelagic sediments: on Land and under the Sea, p. 11–48
  9. ↑ Tatiana J. Tolmacheva, Taniel Danelian & Leonid E. Popov. Evidence for 15 m.y. of continuous deep-sea biogenic siliceous sedimentation in early Paleozoic oceans
  10. ↑ Taniel Danelian, Leonid Popov (2003). La biodiversité des radiolaires ordoviciens: regard à partir des données nouvelles et révisées provenant du Kazakhstan. Bulletin de la Société Géologique de France, 174, Nº. 4, p. 325–335, ISSN 0037-9409
  11. ↑ Schwarz, A. (1928). Die Natur des culmischen Kieselschiefers. Abh. senckenberg. naturf. Ges., 41, p. 191–241
  12. ↑ Catalano, R. et al. (1991). Permian circumpacific deep-water faunas from the western Tethys (Sicily, Italy) – New evidences for the position of the Permian Tethys. Palaeogeogr. Palaeocli. Palaeoeco., 87, p. 75–108
  13. ↑ Kozur, H. & Krahl, J. (1987). Erster Nachweis von Radiolarien im tethyalen Perm Europas. N. Jb. Geol. Paläontol. Abh., 174, p. 357–372
  14. ↑ De Wever, P. et al. (1988). Permian age of the radiolarites from the Hawasina nappes. Oman Mountains. Geology, 16, p. 912–914
  15. ↑ Ruttner, A.E. (1991). The southern borderland of Laurasia in NE Iran. Editors: European Union of Geosciences, Strasbourg. Terra Abstracts, 3, p. 256-257
  16. ↑ Lein, R. et al. (1995). Neue Daten zur Geologie des Karawanken-Strassentunnels. Geol. Paläontol. Mitt. Innsbruck, 20, p. 371–387
  17. ↑ Bosselini, A. & Winterer, E.L. (1975). Pelagic limestone and radiolarite of the Tethyan Mesozoic: A generic model. Geology, 3, p. 279–282
  18. ↑ Ogg, J. G. et al. (1992). 32. Jurassic through early Cretaceous sedimentation history of the central equatorial Pacific and of sites 800 and 801. Proceedings of the Ocean Drilling Program, Scientific Results, 129
  19. ↑ D. W. Haig, et. al. Mid-Cretaceous calcareous and siliceous microfossils from the basal Gearle Siltstone, Giralia Anticline, Southern Carnarvon Basin, Alcheringa: An Australasian Journal of Palaeontology , Volume 20, Issue 1, 1996, pages 41–68
  20. ↑ Mookaite at mindat.org
  21. ↑ Margolis, S. V. et al. (1978). Fossil manganese nodules from Timor: geochemical and radiochemical evidence for deep-sea origin. Chem. Geol., 21, p. 185-198
  22. ↑ Speed, R. C. & Larue, D. K. (1982). Barbados architecture and implications for accretion. J. geophys. Res., 87, p. 3633–3643
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