Occurrence of recent dedolomite crust on pedogenic calcrete in Al-Jabal Al-Akhdar, Northern Oman
Keywords:
Al-Jabal Al-Akhdar, calcrete, crust, dedolomite, Oman.Abstract
Rusty dedolomitized crust occurs in fractured pedogeniccalcrete horizon within terra rossa soil contained in shallow phytokarstic cavities in the calcareous rocks exposed at Al-Jabal Al-Akhdar Mountain, Oman. Two lithotypes were recognized: (a) dedolomitizeddetrital dolomite and (b) dedolomitizedauthigenic dolomite. The first is light brownish, has an undulating
sharp contact with the nodular calcretes and consists of euhedral to subhedral moderately to poorly sorted dolomite grains floating in a micritic groundmass. The second is relatively thicker, dark brown, and consists of idiotopic mosaic of moderately sorted well euhedral dolomite crystals that reach up to 200 um in size. Microscopic examination of stained thin sections indicated that most of both detrital and authigenic dolomite crusts have been partially or completely dedolomitized. XRD analysis indicated that both types of crusts mostly consist of calcite and dolomite with traces of quartz, where abundance of
calcite reflects their dedolomitization. The chemical composition of these crusts reflects their mineralogy. The paragenetic events of the crust formation are discussed. The availability of dolomitic source rocks and the present prevailed semiarid climate characterized by intermittent wet and dry periods have played a significant role in its development. This work presents a unique mode of occurrence of dedolomitized dolomite associated with recent pedogeniccalcretes.
References
Al-Busaidi, M. (2012). The struggle between nature and
development: Linking local knowledge with sustainable
natural resources management in Al-Jabal Al-Akhdar
Region, Oman. PhD thesis, University of Glasgow, School
of Geographical and Earth Sciences. P 433.
Al-Hashimi, W.S. &Hemingway, J. E.(1973). Recent
dedolomitization and the origin of the rusty crusts of
Northumberland.Journal of Sedimentary Petrology, 43:82 -91.
Arakel, A.V. (1986). Evolution of calcrete in palaeodrainages
of the lake Napper Area, central Australia. Palaeogeography
Palaeoclimatology Paleoecology, 54:283 -303.
Back, W., Hanshaw, B.B., Plummer, L.N., Rahn,
P.H., Rightmire, C.T.et al.(1983). Process and rate of
dedolomitization: Mass transfer and 14C dating in a regional
carbonate aquifer.Geol. Soc. Amer. Bull., 94:1415- 1429.
Baud, A.& Richoz, S. (2013). Permian–Triassic Transition
and the Saiq/Mahil Boundary in the Oman Mountains:
Proposed correction for lithostratigraphic nomenclature.
GeoArabia, 18:87- 98.
Budai, J.M., Lohmann, K.C.& Owen, R.M. (1984).
Burial dedolomite in the Mississippian Madison Limestone,
Wyoming and Utah thrust belt. Journal of Sedimentary
Petrology, 54: 276- 288.
Burns, S.J., Fleitmann, D., Mudelsee, M., Neff,
U., Matter, A.et al. (2001). Speleothem evidence from
Oman for continental Pluvial events during Interglacia
l Periods. Geology, 29(7):623 -626.
Cantrell, D.L., Al-Khammash, A.& Jenden, P.D. (2007).
Characterization and significance of dedolomite in Wadi
Nisah, central Saudi Arabia. GeoArabia, 12 (3):15–30.
Carlisle, D. (1983). Concentration of uranium and vanadium
in calcretes and gypcretes. In: Residual Deposits (Ed. by
R. C. L. Wilson). Geological Society of London, Special
Publication, 11:185- 195.
Carpenter, A.B., Trout, M.L.& Pickett, E.E. (1974).
Preliminary report on the origin and chemical evolution of
lead- and zinc-rich oil field brines in central Mississippi.
Economic Geology, 69:1191- 1206.
Chafetz, H.S. (1972). Surface diagenesis of limestone.
Journal of Sedimentary Petrology, 42: 325 -329.
Chilingar, G.V. (1956). Dedolomitization: A review.
American Association of Petroleum Geologists Bulletin,40:
- 778.
Clemens, S.C., Murray, D.W.& Prell, W.L. (1996).
Nonstationary phase of the Plio-Pleistocene Asian monsoon.
Science, 274:943 -948.
Coniglio, M. (2003). Dedolomitization. In: Encyclopedia of
Earth Science. Part 4: Sedimentology, pp 300 -303.
De Groot, K. (1967). Experimental dedolomitization.Journal
of Sedimentary Petrology, 37: 1216- 1220.
Dickson, J.A.D. (1966). Carbonate identification and genesis
as revealed by staining. Journal of Sedimentary Petrology,
:491- 505.
Dixon, J.C. (2010). Origin of calcrete and dolocrete in
the carbonate mantle of St Vincent Basin, southern South
Australia. Cadernos Lab. Xeoloxico de Laxe Coruna,
:109 -122.
Escorcia, L.C., Gomez-Rivas, E., Daniele, L.& Corbella,
M. (2013). Dedolomitization and reservoir quality: insights
from reactive transport modelling, Geofluids, 13: 221–231.
Evamy B.D.(1967). Dedolomitization and the development
of rhombohedral pores in limestones.Journal of Sedimentary
Petrology, 37:1204 -1215
Goldberg, M. (1967). Supratidal dolomitization and
dedolomitization in Jurassic rocks of Hamakhtesh Haqatan,
Israel. Journal of Sedimentary Petrology, 37: 760 -773.
Holail H., Lohmann K.C.& Sanderson, I. (1988).
Dolomitization and dedolomitization of Upper Cretaceous
carbonates; Babariya Oasis, Egypt, In: V. Shukla and
P.A, Baker (Editors), Sedimentology and Geochemistry
of Dolostones. Soc. Eeon. Paleontol. Mineral. Special
Publication, 43:191- 207.
Hutton, J.T.& Dixon, J.C. (1981). The chemistry and
mineralogy of some South Australian calcretes and associated
soft carbonates and their dolomitization. Geological Society
of Australia, 28:71 -79.
Jacobson, G., Arakel, A.V.& Yijian, Ch. (1988). The
central Australian groundwater discharge zone: Evolution of
associated calcrete and gypcrete deposits. Australian Journal
of Earth Science, 35:549- 565.
James, N.P., Bone, Y.& Kyser, T.K.(1993). Shallow burial
dolomitization and dedolomitization of mid-Cenozoic, coolwater,
calcitic, deep-shelf limestones, southern Australia.
Journal of Sedimentary Petrology, 63:528 -538.
Jones, B., Pleydell, S.M., Ng, K.C.& Longstaffe, F.J.(1989).
Formation of poikilotopic calcite-dolomite fabrics in the Oligocene-
Miocene Bluff formation of Grand Cayman, British West Indies.
Bulletin of Canadian Petroleum Geology, 37:255 -265.
Katz, A. (1968). Calcian dolomites and dedolomitization.
Nature, 217:439 -440
Kenny, R. (1992). Origin of disconformity dedolomite in
the Martin Formation (Late Devonian, northern Arizona).
Sedimentary Geology, 78:137- 146.
Khalaf, F.I.& Abdal, M.S. (1993). Dedolomitization of
dolocrete deposits in Kuwait, Arabian Gulf. Geologische
Rundschay, 82:741 -749
Khalaf, F.I.& Al-Zamel, A. (2016). Petrography,
micromorphology and genesis of Holocene pedogenic
calcrete in Al-Jabal Al-Akhdar, Sultanate of Oman. Catena,
: 496–510.
Khalaf, F.I., Al-Ajmi, D.& Al-Dousari, A.(1994).Detrital
palygorskite in recent terrestrial and marine sediments of
Kuwait. Egyptian Journal of Geology, 38 (2): 537- 554.
Khalaf, F.I. (1990). Occurrence of phreatic dolocrete
within Tertiary clastic deposits of Kuwait. Arabian Gulf.
Sedimentary Geology, 68: 223- 239.
Kharaka, Y.K., Callender, E.& Wallace, R.H. (1977).
Geochemistry of geopressured geothermal waters from
the Frio Clay in the Gulf Coast region of Texas.Geology,
: 241- 244.
Koehrer, B., Zeller, M., Aigner, T., Poeppelreiter, M.,
Milroy, P., Forke, H.& Al-Kindi, S. (2010). Facies and
stratigraphic framework of a Khuff outcrop equivalent:
Saiq and Mahil formations, Al Jabal al-Akhdar, Sultanate of
Oman. GeoArabia, 15: 91- 156.
Land, L.S.& Prezbindowski, D.R. (1981). The origin
and evolution of saline formation water, Lower Cretaceous
carbonates, south-central Texas, U.S.A.Journal of Hydrology,
: 51 -74.
Mann, A.W.& Horwitz, R.C. (1979). Groundwater calcrete
deposits in Australia: some observations from Western
Australia. Journal of the Geological Society of Australia,
:293- 303.
Nader, F.H., Swennen, R.& Keppens, E. (2008).
Calcitization/dedolomitization of Jurassic dolostones
(Lebanon): results from petrographic and sequential
geochemical analyses. Sedimentology, 55:1467–1485.
Neff, U., Bums, S.G., Mangini, A., Mudelsee, M.,
Fleitmann, D.&Matter, A. (2001). Strong coherence
between solar variability and the monsoon in Oman between
and 6 kyr ago. Nature,4111: 290- 293.
Netterberg, F. (1980). Geology of Southern African calcretes:
Terminology, description, macrofeatures, and classification.
South African Journal of Geology, 83:255- 283.
Phillips, S.E.& Milnes, A.R. (1988). The Pleistocene
terrestrial carbonate mantle on the southeastern margin of
the St. Vincent Basin, South Australia. Australian Journal of
Earth Science, 35:463- 481.
Rameil, N. (2008). Early diagenetic dolomitization and
dedolomitization of Late Jurassic and earliest Cretaceous platform
carbonates: A case study from the Jura Mountains (NW Switzerland,
E France). Sedimentary Geology, 212(1 -4): 70- 85.
Saddiqi, O., Michard, A., Goffe, B., Poupeau, G.&
Oberhansli, R. (2006). Fission- track thermochronology
of the Oman Mountains continental windows, and current
problems of tectonic interpretation: Societe Geologique de
France Bulletin, 177: 127- 134.
Stoessell,R.K., Klimentidis, R.E.& Prezbindowski,
D.R.(1987). Dedolomitization in Na-Ca-Cl brines from 100°
to 200°C at 300 bars.Geochimica et Cosmochimica Acta, 51:
-855.
Theriault, F.& Hutcheon, L. (1987). Dolomitization and
calcitization of the Devonian Grosmont Formation, Northern
Alberta.Journal of Sedimentary Petrology, 6: 955- 966.
Vandeginste, V.& John, C.M. (2012). Influence of climate
and dolomite composition on dedolomitization: insights
from a multi-proxy study in the Central Oman Mountains.
Journal of Sedimentary Research, 82: 177- 195.
Von Morlot, A. (1847). Veber Dolomit und seine Kunstliche
Darstelling aus Kalkstein: Naturwissenschaftliche
Abhandlungen, gesammelt und durch Subscription lursg:
Von Wilhelm Haidinger, 1:305 -315.
Warrak, M.(1974). The petrology and origin of dedolomitized
veined or brecciated carbonated rocks, the cornieules, in the
Frejus region, French Alps. Journal of Geological Society,
: 229 -247.
Watts, N.L. (1980). Quaternary pedogenic calcretes from
the Kalahari (Southern Africa): Mineralogy, genesis and
diagenesis.Sedimentology, 27:661- 686.