Antalo Limestone

Antalo Limestone
Antalo Limestone
Ma PreꞒ Ꞓ O S D C P T J K Pg N
Approximate paleocoordinates	7°30′S 26°36′E / 7.5°S 26.6°E
Region	Tigray
Country	Ethiopia; Eritrea
Extent	Mekelle Outlier, Danakil Alps
Type section
Named for	Antalo town
Named by	William Thomas Blanford
Year defined	1868
	Antalo Limestone (Ethiopia)

The Antalo Limestone, also known as the Antalo Sequence, is a

fossiliferous limestones and marls that were deposited in a reef. Marine microfossils have shown an age between 165 and 150 million years.^[1]^[2]

Name and definition

The Antalo Supersequence includes two main stratigraphic units: the Antalo Sequence and the Agula Group.

British Expedition to Abyssinia in 1868.^[4] At that time, Hintalo was a major town on the route of the invading British army.^[5] So far the nomenclature has not been proposed for recognition to the International Commission on Stratigraphy

.

Geographical extent

The sedimentary succession is found in Ethiopia, in the

Harrar Plateau and around Dire Dawa.^[2]

Stratigraphic context

The Antalo Limestone overlies the Adigrat Sandstone, and is covered by the Agula Group or Agula Shale and the Mugher Mudstone.

Environment

The Antalo Limestone comprises sediment that was deposited in a shallow tropical sea in the

upper Jurassic. As the region had undergone a marine transgression, it was below the sea level. At that time, what would become Ethiopia was positioned just south of the equator.^[6]

Lithology

Dogu’a Tembien

The limestones and

lagoons; (3) micritic (very fine grained) limestone with intercalations of wackestone and coquina beds deposited in relatively deep water; and (4) a succession of marls and limestone, with cherty limestone at the base.^[2]^[3]

Addi Idaga

Miheno

Fossil content

Azef

The Antalo Limestone sediments were deposited at the time of dinosaurs and primitive birds. Well away from coasts, coral reefs formed the edge of the continental shelf. At shallow depth, the sea bottom was made of large

gastropods were common. There was also fish. As it was not a nutrient-rich ecosystem, larger predators were rare, maybe some marine reptiles like crocodiles. A striking scavenger in this fauna was a cephalopod mollusc, a giant nautilus with a characteristic spiral shell.^[6]

Invertebrates

Bivalves

Bivalves of the Antalo Limestone.^[7]
Genus	Species	Presence	Material	Notes	Images
Actinostreon	A. solitarium	10 specimens from AL1, 65 from AL2.	75 specimens.	A palaeolophid.
Arcomytilus	A. laitmairensis	AL1 and AL2.	3 left valves, 1 right valve and 4 articulated specimens.	A mytilid.
Eopecten	E. velatus	AL1.	1 left valve.	A pectinid .
Gryphaea	G.? (Bilobissa?) balli	AL1.	1 left valve.	A gryphaeid.
Integricardium	I. (Integricardium) cf. bannesianum	7 specimens from AL1, 1 from AL2.	4 left valves, 1 right valves and 3 double-valved specimens.	A cardiid .
Liostrea	L. sp.	AL1 and AL2.	2 specimens.	An ostreid.
"Lucina"	"L." cf. cecchii	AL2.	4 double-valved specimens.	A lucinid.
Modiolus	M. (Modiolus) imbricatus	2 specimens from AL1, 1 from AL2.	3 double-valved specimens.	A mytilid.
Musculus	M. (Musculus) somaliensis	AL1 and AL2.	2 articulated specimens.	A mytilid.
Nanogyra	N. nana	AL2.	2 articulated specimens.	A gryphaeid.
Pholadomya	P. (Bucardiomya) somaliensis	1 specimen from AL1, 6 from AL2.	7 double-valved specimens.	A pholadomyid.
Pholadomya	P. (Bucardiomya) lirata	AL2.	1 double-valved specimen.	A pholadomyid.
Plagiostoma	P. harronis	AL1 and AL2.	3 left valves, 5 right valves and 2 articulated specimens.	A limid.
Plagiostoma	P. sublaeviusculum	AL2.	1 left valve 1 right valve and 1 articulated specimen.	A limid.
Seebachia	S. ("Eoseebachia") sowerbyana	AL2.	2 left valves.	An astartid.
Spondylopecten	S. (Spondylopecten) palinurus	AL1.	2 left valves.	A pectinid .
Stegoconcha	S. gmuelleri	AL2.	2 articulated specimens.	A pinnid.

Brachiopods

Brachiopods of the Antalo Limestone^[7]
Genus	Species	Presence	Material	Notes	Images
cf. Amydroptychus	cf. A. sp.	Base of AL2.	10 individuals.	A rhynchonellid.
Cererithyris	C. sp.	1 from AL1, 105 from AL2 .	106 individuals.	A terebratulid.
Cymatorhynchia	C. sp.	AL2.	16 individuals.	A rhynchonellid.
Daghanirhynchia	D. sp.	3 individuals from AL1, 51 from AL2.	54 individuals.	A rhynchonellid.
Monsardithyris	M. sp.	AL2.	20 individuals.	A terebratulid.
Somalirhynchia	S. africana	Mostly from AL2.	More than 100 individuals.	A rhynchonellid.

Cnidarian

Cnidarians of the Antalo Limestone^[7]
Genus	Species	Presence	Material	Notes	Images
Actinastrea	A. crassoramosa	47 specimens from AL1, 13 from AL2.	60 larger fragments of colonies.	A stony coral .
Coenastraea	C. arabica	AL2.	1 specimen.	A stony coral .
Collignonastraea	C. cf. grossouvrei	AL2.	1 specimen.	A stony coral .
Columnocoenia	C. gemmans	AL1.	2 specimens.	A stony coral .
Comoseris	C. meandrinoides	AL3.	1 complete colony.	A stony coral .
Cladophyllia	C. excelsa	AL3.	1 specimen.	A stony coral .
Cryptocoenia	C. slovenica	7 specimens from AL1, 4 specimens from AL2.	11 specimens.	A stony coral .
Ironella	I. arabica	AL1.	12 specimens.	A stony coral .
Isastrea	I. bernensis	20 specimens from AL1, 22 specimens from AL2.	42 specimens.	A stony coral .
Kobyastraea	K. lomontiana	AL1.	1 specimen.	A stony coral .
Latiastrea	L. greppini	2 from AL1, 3 from AL2.	5 specimens.	A stony coral .
Lochmaeosmilia	L. trapeziformis	AL1.	16 karger fragments of colonies.	A stony coral .
Ovalastrea	O. michelini	AL2.	3 specimens (including 1 complete colony).	A stony coral .

Echinoderms

Echinoderms of the Antalo Limestone
Genus	Species	Presence	Material	Notes	Images
Ausichicrinites	A. zelenskyyi		Nearly complete specimen.^[8]	A comatulid.
Pygurus	P. meslei	Upper part of the formation.^[9]		A sea urchin.

Molluscs

Molluscs of the Antalo Limestone^[10]
Genus	Species	Presence	Material	Notes	Images
Orthosphinctes	O. aff. tiziani	Top part of sub-unit II.	5 fragmentary specimens.	An ammonite .
Pachyceras	P. cf. lalandeanum	From the middle part of sub-unit II, GPS location 10°02′39.7″N, 38°13′53.7″E.	One poorly preserved specimen (no. AF020).	A ammonite .
Paracenoceras	P. cf. ennianus	Top part of sub-unit II.	1 specimen (no. AF012).	A nautiloid.
	P. aff. prohexagonum	Lower Limestone Member.^[11]		A nautiloid.
	P. cf. kumagunense	Top part of sub-unit II.	1 specimen (no. AF004).	A nautiloid.
	P. cf. giganteum	Middle part of sub-unit II.	1 specimen (no. AF005).	A nautiloid.
Purpuroidea	P. aff. gigas	One specimen (AF025) from the top part of sub-unit I; One specimen (AF026) from the top part of sub-unit II.	2 specimen (AF025 and AF026).	A gastropod.

Limestone and karst geomorphology

Santarfa

The layering is sub-horizontal, the same as that of the underlying sedimentary formations.

Dogu’a Tembien district of Tigray.^[12]

Traditional uses of Antalo Limestone

Dogu’a Tembien

Given its nearly rectangular shape and its strength, the hard layers of Antalo Limestone are used for

House building. Traditionally, fermented mud will be used as mortar

Fencing of homesteads, generally in dry masonry
Milling stone: for this purpose plucked-bedrock pits, small rock-cut basins that naturally occur in rivers with kolks, are excavated from the river bed and further shaped. Milling is done at home using an elongated small boulder (mano)^[13]^[14]
Door and window
lintels
Footpath
paving
Stone bunds or gedeba: terrace walls in dry masonry, typically laid out along the contour for sake of soil and water conservation

gully erosion

control

Cobble stones

, sold to the towns for paving secondary streets

References

ISBN 978-3-030-04954-6
.

^ ^a ^b ^c ^d Bosellini, A.; Russo, A.; Fantozzi, P.L.; Assefa, G.; Tadesse, S. (1997). "The Mesozoic succession of the Mekelle Outlier (Tigrai Province, Ethiopia)". Mem. Sci. Geol. 49: 95–116.

^
S2CID 199102740
.

^ Blanford, W.T. (1870). Observations on the geology and zoology of Abyssinia, made during the progress of the British expedition to that country in 1867-68. London: Macmillan and Co.

^ Markham, C.; Prideaux, W. (1869). A history of the Abyssinian expedition. Macmillan.

^
ISBN 978-3-030-04954-6
.

^
ISSN 1464-343X
.

PMID 35875469
.

S2CID 219739555
.

S2CID 239211851
.

S2CID 134655647
.

^ Catlin, D; Largen, M; Monod, T; Morton, W (1973). "The caves of Ethiopia". Transactions of the Cave Research Group of Great Britain. 15: 107–168.

^ Nixon-Darcus, L.A. (2014). The cultural context of food grinding equipment in Northern Ethiopia: an ethnoarchaeological approach. PhD thesis. Canada: Simon Frazer University.

^ Gebre Teklu (2012). Ethnoarchaeological study of grind stones at Lakia'a in Adwa, Tigray Regional State, Ethiopia. PhD diss (PDF). Addis Ababa University.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Antalo_Limestone&oldid=1184050125"

[1] ISBN 978-3-030-04954-6
.

[bosellini-2] Bosellini, A.; Russo, A.; Fantozzi, P.L.; Assefa, G.; Tadesse, S. (1997). "The Mesozoic succession of the Mekelle Outlier (Tigrai Province, Ethiopia)". Mem. Sci. Geol. 49: 95–116.

[dramis2019-3] 
S2CID 199102740
.

[4] Blanford, W.T. (1870). Observations on the geology and zoology of Abyssinia, made during the progress of the British expedition to that country in 1867-68. London: Macmillan and Co.

[5] Markham, C.; Prideaux, W. (1869). A history of the Abyssinian expedition. Macmillan.

[lerouge&aerts-6] 
ISBN 978-3-030-04954-6
.

[:1-7] 
ISSN 1464-343X
.

[8] PMID 35875469
.

[9] S2CID 219739555
.

[:0-10] S2CID 239211851
.

[11] S2CID 134655647
.

[catlin-12] Catlin, D; Largen, M; Monod, T; Morton, W (1973). "The caves of Ethiopia". Transactions of the Cave Research Group of Great Britain. 15: 107–168.

[13] Nixon-Darcus, L.A. (2014). The cultural context of food grinding equipment in Northern Ethiopia: an ethnoarchaeological approach. PhD thesis. Canada: Simon Frazer University.

[14] Gebre Teklu (2012). Ethnoarchaeological study of grind stones at Lakia'a in Adwa, Tigray Regional State, Ethiopia. PhD diss (PDF). Addis Ababa University.

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