A large "foram" from the Eocene of Java, Indonesia

Camerina specimen in a Beijing museum

close-up [435 kb]

Fig. 1: Camerina specimen at the Yifu Museum at the China University of Geosciences - Beijing. This is a large example of a foraminiferan ("foram"), a type of single-celled organism belonging to the Protozoa. Camerina, specimen d29, of Eocene (E2) age, from Java, Indonesia. This is a genus of relatively large foraminifera, organisms generally flagged in the MINLIB bibliographic database as microfossils, to make them easy to compare with smaller relatives. However, this Camerina is one of the large foraminifera (nummulites), an exception: this one is about 20-25 mm in diameter, with a distinctive concentric shell structure.

A central area of the 11th floor of the Yifu Museum, with interesting network decor obviously inspired by colonial forms of corals, displays a range of fossil families, mostly corals and sponges. There are some "macro" microfossils, large fusulinids and other foraminifera, such as Verbeekina, Neoschwagerina, Sumatrina, Triticites, Fusulina, Nankinella, and our featured genus, Camerina.

"Rock of the Month # 226, posted for April 2020" ---

Forams are protozoans (Barnes, 1968). They belong to a group of protozoans known as the Sarcodina, which include amoebae, forams, heliozoans and radiolaria (the latter also of geologic note, being largely planktonic and having skeletons composed of silica, or even of strontium sulphate). The shells of forams can be multi-chambered, with apertures linking chambers, which often grow in a spiral manner, the whole being infilled by protoplasm. While many of these relatives of the amoeba are microscopic, they may reach as much as 5 cm in the case of some Nummulites ("coin stones"). The majority are benthic (bottom-dwelling) but some are planktonic, like Globigerina and Orbulina, and float in the sea. They are represented in palaeontology textbooks and collectors' guides (e.g., Woods, 1946; Morley Davies, 1961; Turek et al., 1988; Stinchcombe, 2012), as well as in dedicated monographs (e.g., Loeblich and Tappan, 1964).

Although easily overlooked, forams appeared in the Cambrian, and have been an important part of marine sedimentary sequences from the Carboniferous period to the present, and especially in Cretaceous and Eocene times. They are of worldwide extent. Forams persist to this day, found around, e.g., the coasts of Ireland (Praeger, 1937, pp.342-344). The various kinds range within the limits prescribed for their species by controlling factors such as temperature, depth and salinity. Forams may be so abundant as to assume rock-forming proportions in some sediments. Their contribution is reviewed in petrographic reference works such as Scholle and Ulmer-Scholle (2003, pp.33-50, with examples from Malta to Mexico, and Greenland to New Zealand).

Forams are sufficently varied and widespread that they are useful to geologists for the information they can yield on a) the age of the host rocks (Ogg et al., 2008), b) correlation between outcrops, and c) the paleoecological setting in which they lived. The study of forams plays a part in subdividing large thicknesses of similar rocks, such as the limestones of the Carboniferous of Ireland (Sevastopulo and Wyse Jackson, 2001) As a special example, approaching the Cretaceous-Tertiary boundary (circa 66 Ma), Princeton palaeontologist Gerta Keller, a leading critic of the Alvarez asteroid impact hypothesis, sees a gradual lead-up to the mass extinction, in microfossils such as foraminifera, and also a chemical signature that could be related to the massive volcanic eruption in the Deccan Traps of India. The implication is that, while the end-Cretaceous asteroid impact off the coast of Mexico's Yucatan peninsula may finally have killed off the dinosaurs and other life forms, they may have been in decline, and facing other challenges, for some time before the impact (Bosker, 2018). An example of this work (Keller et al., 2011) details the decline and extinction of planktonic forams, correlating faunal changes to the progression of the gigantic, episodic yet geologically rapid extrusion of over 1 million km3 of lava to form the Deccan volcanic province formed (today, the province covers an area of 512,000 km2).

Gerth (1935) suggested that the larger foraminifera may help solve problems in correlation of Tertiary strata (which are not resolved by the confusing diversity of other fossils such as the bivalves). Gerth reviewed the Tertiary of Java, with brief comparisons with the literature for Borneo and the West Indies. Camerina occurs not only in Java, but also, for example, in Curacao and Cuba. In Java, fossil localities record species of Camerina from the Paleocene to the upper Oligocene.

fossil and CUGB label [240 kb]

Fig. 2: The Camerina sample and label at the Yifu museum.

The Cretaceous-Eocene fauna is diverse and locally abundant. In Egypt, forams are prominent in the strata along the Nile valley (Alcosser et al., 1991, p.164). Cretaceous and lower Tertiary rocks underlie a 90,000 km2 area of Egypt. Correlation is aided by forams such as species of Globigerina (Hermina, 1990).

Forams are especially widespread and well-studied across the Indian subcontinent, and, indeed, along the ancient seaway of the Tethys, across south and west Asia, from Thailand to Turkey (Okay et al., 2001), as a quick search of the MINLIB database affirms. The significance of forams was recognized early in the development of geological sciences in the region, including what are today northern India, Pakistan and Afghanistan (Medlicott and Blanford, 1893). Detailed research continues to this day (e.g., Mathur, 2010; Saraswati et al., 2012). Nummulites as large as 19 mm are reported from Kachchh in Gujarat (Sengupta, 2000).

In addition to serving as time markers, foram species are flags of climatic and environmental conditions. The Middle Eocene Climatic Optimum (MECO) is a long-lasting warming event dated at circa 40 Ma. The MECO event occurs at the Lutetian- Bartonian boundary, and at its maximum, sea surface and deep water seawater temperatures rose circa 5-6°C over a peak lasting >100 ky. Ongoing research at CUGB (Kamran et al., 2020) examines Eocene shallow-marine strata of the Kohat Formation along the Indus Highway section in Pakistan. This study aims to place MECO within a shallow marine carbonate sequence, to document the response and diversity pattern of the LBF (large benthic forams), and to reconstruct the depositional setting based on LBF. The Kohat section is especially rich in LBF such as Nummulites, Alveolina, Assilina, orthophragminids, Lockhartia and Orbitolites, plus a few planktonic and small benthic forams. Foram extinctions at the end of the middle Miocene are referred to as the LFT (large foraminifera turnover) event.

In North America and the Caribbean, detailed studies are available on foram habitat, as in the Bahamas (Cloud, 1962) and Cuba (Thiadens, 1937). In Saskatchewan, the lower Cretaceous strata include the Haplophragmoides gigas marine microfauna, which is dominated by foraminifera (Fraser et al., 1935). These microfossil assemblages extend the known boundaries of ancient seas, in this case (with later research: Koke and Stelck, 1985) across Alberta and beyond the Peace River Arch, to the Hudson Hope area of British Columbia.

References (n=24)

Alcosser,M, Eldredge,N and Gould,SJ (1991) Fossils: the Evolution and Extinction of Species. Princeton University Press, xx+220pp.

Barnes,RD (1968) Invertebrate Zoology. W.B. Saunders Company, Philadelphia, 2nd edition, 743pp.

Bosker,B (2018) What really killed the dinosaurs? Atlantic 322 no.2, 44-55, September.

Cloud,PE (1962) Environment of calcium carbonate deposition west of Andros Island, Bahamas. USGS Prof.Pap. 350, 138pp. plus 10 plates.

Fraser,FJ, McLearn,FH, Russell,LS, Warren,PS and Wickenden,RTD (1935) Geology of Southern Saskatchewan. GSC Memoir 176, 137pp. plus map folder with map 267A plus sections.

Gerth,H (1935) The distribution and evolution of the larger foraminifera in the Tertiary sediments. Paper, 8pp. available at "www.dwc.knaw.nl" [dwc, the digital web centre for the history of science in the Low Countries]. Originally communicated by H.A. Brouwer and read at a meeting on 30 March 1935.

Hermina,M (1990) The surroundings of Kharga, Dakhla and Farafra oases. In `The Geology of Egypt' (Said,R editor), A.A.Balkema, Rotterdam, 734pp., 259-292.

Kamran,M, Wan,X, Frontalini,F, Xi,X, Mirza,K, Jafarian,A, Kashif,M, Ali,F, Fawad,N and Shafi,M (2020) Larger benthic foraminiferal assemblages and their response to Middle Eocene Climate Optimum in the Kohat basin (Pakistan, eastern Tethys). Paleoworld, in press.

Keller,G, Bhowmick,PK, Upadhyay,H, Dave,A, Reddy,AN, Jaiprakash,BC and Adatte,T (2011) Deccan volcanism linked to the Cretaceous-Tertiary boundary mass extinction: new evidence from ONGC wells in the Krishna-Godavari basin. J.Geol.Soc.India 78, 399-428.

Koke,KR and Stelck,CR (1985) Foraminifera of a Joli Fou Shale equivalent in the Lower Cretaceous (Albian) Hasler Formation, northeastern British Columbia. Can.J.Earth Sci. 22, 1299-1313.

Loeblich,AR and Tappan,H (1964) Protista 2: Sarcodina, Chiefly "Thecamoebians" and Foraminiferida. Treatise on Invertebrate Paleontology, volume TRE-C2V, 936pp., 2 volumes.

Mathur,NS (2010) Classification of species of larger foraminiferal genus Nummulites Lamarch 1801 of the Tethyan Realm based on significant characters. Himalayan Geology 31 no.1, 51-69.

Medlicott,HB and Blanford,WT (1893) Encyclopedia of Indian Geology. 2nd edition, revised and rewritten by Oldham,RD and republished by Cosmo Publications, New Delhi, in 1994. 2 volumes, 543pp.

Morley Davies,A (1961) An Introduction to Palaeontology. Thomas Murby & Company, London, 3rd edition, 322pp.

Ogg,JG, Ogg,G and Gradstein,FM (2008) The Concise Geologic Time Scale. Cambridge University Press, 177pp.

Okay,AI, Tansel,I and Tuysuz,O (2001) Obduction, subduction and collision as reflected in the upper Cretaceous-lower Eocene sedimentary record of western Turkey. Geol.Mag. 138, 117-142.

Praeger,RL (1937) The Way that I Went. Collins Press Ireland, 2nd edition, xii+394pp., republished 2014.

Saraswati,PK, Sarkar,U and Banerjee,S (2012) Nummulites solitarius- Nummulites burdigalensis lineage in Kutch with remarks on the age of Naredi Formation. J.Geol.Soc.India 79, 476-482 (see also discussion in J.Geol.Soc.India 80 no.6, 869-872, December 2012).

Sengupta,S (2000) Problems of classifying early Oligocene reticulate Nummulites (foraminiferida) from southwestern Kutch, Gujarat. J.Geol.Soc.India 56, 673-677.

Sevastopulo,GD and Wyse Jackson,PN (2001) Carboniferous (Dinantian). In `The Geology of Ireland' (Holland,CH, editor), Dunedin Academic Press, Edinburgh, 531pp., 241-288.

Stinchcombe,BL (2012) More Paleozoic Fossils. Schiffer Publishing, 160pp.

Thiadens,AA (1937) Geology of the southern part of the province Santa Clara, Cuba. J. Van Boekhoven, Utrecht, Holland, 69pp. plus 1 plate and 4 maps.

Turek,V, Marek,J and Benes,J (1988) Fossils of the World: a Comprehensive Practical Guide to Collecting and Studying Fossils. Arch Cape Press, New York, 1990 edition, 495pp.

Woods,H (1946) Invertebrate Palaeontology. Cambridge University Press, 8th edition, 477pp.

Graham Wilson, 06,08,09, 11 March 2020.

Visit the "Rock of the Month" Archives!

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"Rock of the Month Index"
(specimens related to China, and Beijing, appear below).
Provenance of specimens:
CAGS = China Academy of Geological Sciences, Beijing
CUGB = China University of Geosciences, Beijing (Grounds and Yifu Museum)
NGMC = National Geological Museum of China, Beijing
TGSL = Turnstone / Wilson collection
Various = Other private collections
YMY = Yuanmingyuan, Old Summer Palace, Beijing

Class/Group/Family Topics in China --- 中国 (Zhong guo) --- such as samples in Beijing museums Site
The "Rock of the Month"
Tektite (glass) ---- #55 --- Tektites from Guangdong, China TGSL
Feldsparphyric ornamental "peony" stone --- #178 --- Porphyritic metabasite from Henan, China CUGB
Rapakivi granite (building stone) --- #179 --- Textures in a rapakivi granite, Beijing, China CUGB
Arsenic ore minerals --- #180 --- Arsenic sulphides, realgar and orpiment, from (?) Hunan, China CUGB
Superb crinoid fossils --- #181 --- Traumatocrinus, exceptional crinoid fossil from Guizhou, China NGMC
Beryl, beryllium cyclosilicate, gemstone --- #186 --- Prismatic beryl from (?) Yunnan, China CUGB
Vertebrate fossil, historically significant --- #201 --- Mesosaurus, fossil reptile & mascot for Gondwanaland (Brazil, via Guangxi, China) CUGB
Ornamental carving stone, China --- #203 --- Qingtian stone, superb lapidary material from Zhejiang, China CUGB
Ophiolitic chromitite --- #205 --- Chromitite, Luobusa ophiolite, southern Tibet (Xizang, China) CAGS
Nephrite jade --- #207 --- Massive jade as decorative piece, from China Various
Peridotite xenoliths in basalt --- #217 --- Mantle nodules and megacrysts, Hebei, China TGSL / CAGS
Tempestite dolostone of Jixian age --- #219 --- Tempestite with algal mats, Tianjin, China CUGB / YMY
Foraminifera from Java, Indonesia --- #226 --- Nummulite fossil Camerina CUGB