The Menuha Formation is the name given to an
Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', th ...
(
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. ...
-
Early Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian ...
)
chalk
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...
, marly chalk and conglomeratic chalk unit exposed throughout the
Makhtesh Ramon region of southern
Israel
Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
and parts of northern Israel (Avni, 1991).
Stratigraphy and paleoenvironment
The Menuha Formation records the earliest occurrence of tectonic activity within the Ramon anticline, forming the present erosive valley known as "
Makhtesh Ramon" as an outcome of a sequence of erosive events evolving since the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
(Avni, 1993). It consists of white and yellow/brown chalk that is often glauconitic and sometimes conglomeratic or marly. The Menuha Formation likely represents a temperate to subtropical, open shelf environment deposited during the formation of the Ramon anticline. Reworked conglomeratic chalks in the western section represent marginal facies derived from this structural uplift.
The paleoenvironment is based on the occurrences of several shark and fish teeth,
oysters, trace fossils, phosphatic peloids, and
foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...
ns. The isolated teeth represent at least ten different species:
*''Cretalamna appendiculata''
*''
Cretoxyrhina mantelli''
*''
Squalicorax falcatus?''
*''
Squalicorax kaupi''
*''
Scapanorhynchus rapax''
*''
Scapanorhynchus raphiodon?''
*''
Carcharias samhammeri''
*''
Carcharias cf. C holmdelensis''
*''
Hadrodus priscus''
*''
Micropycnodon kansasensis?''
References
*
*
*
*{{cite journal , last1 = Wilson , first1 = M.A. , last2 = Zaton , first2 = M. , last3 = Avni , first3 = Y. , year = 2012 , title = Origin, paleoecology and stratigraphic significance of bored and encrusted concretions from the Upper Cretaceous (Santonian) of southern Israel , journal = Palaeobiodiversity and Palaeoenvironments , volume = 92 , issue = 3 , pages = 343–352 , doi=10.1007/s12549-012-0082-8
Image:MenuhaThalassinoides.jpg, ''Thalassinoides'' burrowing system throughout the Menuha Formation chalk.
Image:MenuhaCretalamnaAppendiculata.jpg, ''Cretalamna appendiculata'' tooth, Menuha Formation.
Image:MenuhaSqualicoraxKaupi.jpg, ''Squalicorax kaupi'' tooth, Menuha Formation.
Image:MenuhaSqualicoraxPristodontus.jpg, ''Squalicorax falcatus?'' tooth, Menuha Formation.
Image:MenuhaCarchariasSamhammeri.jpg, ''Carcharias samhammeri'' tooth, Menuha Formation.
Image:MenuhaCarchariasHolmdelensis.jpg, ''Carcharias cf. C holmdelensis'' tooth, Menuha Formation.
Image:MenuhaCretoxyrhinaMantelli.jpg, ''Cretoxyrhina mantelli'' tooth, Menuha Formation.
Image:MenuhaScapanorhynchusRapax.jpg, ''Scapanorhynchus rapax'' tooth, Menuha Formation.
Image:MenuhaScapanorhynchusRaphiodon.jpg, ''Scapanorhynchus raphiodon?'' tooth, Menuha Formation.
Image:MenuhaHadrodusPriscus.jpg, ''Hadrodus priscus'' tooth, Menuha Formation.
Image:MenuhaMicropycnodonKansasensis.jpg, ''Micropycnodon kansasensis?'' tooth, Menuha Formation.
Image:MenuhaForaminiferaPlate.jpg, Several foraminiferans replaced by silica from the Menuha Formation.
Image:MenuhaPycnodonteVesicularisPlate.jpg, Several oysters, possibly ''Pycnodonte vesicularis'', from the Menuha Formation.
Image:MenuhaEchinoidSpine.jpg, Irregular echinoid spine from the chalk sediments of the Menuha Formation.
Image:MenuhaFormationMakhtesh.jpg, Menuha Formation and capping Mishash Formation south of Makhtesh Ramon.
Geologic formations of Israel
Cretaceous Asia
Campanian Stage
Santonian Stage
Chalk
Conglomerate formations
Limestone formations
Marl formations
Open marine deposits