http://www.soton.ac.uk/~imw/messin.htm West, I.M. 2002. Messinian Salinity Crisis of the Mediterranean - select bibliography and lecture summary for students. Internet site: www.soton.ac.uk/~imw/messin.htm. Southampton University. Version: U.01.02.02

Messinian Salinity Crisis

Home and Index | |Dorset Geology Guides - List | Student Information, Southampton |




The Messinian Salinity Crisis
(Literature for a Student Lecture and Essay Topic)

Internet Links

Go back to top

Messinian Salinity Crisis - Select Literature Bibliography


.
Andersen, N. 2001. Large and rapid climate variability during the Messinian salinity crisis: Evidence from deuterium concentrations of individual biomarkers. Geology, 2001, August 24, pp. 799-802. Nils Andersen et al. Department of Earth Sciences, ETH-Z Zurich, CH-8092, Zurich, Switzerland. During the Messinian, ca. 6 Ma, massive sea-level fall and widespread deposition of evaporites occurred in the Mediterranean Sea when it became isolated from the world oceans. The stable hydrogen isotope composition of individual organic compounds (biomarkers) was analyzed for the first time in ancient sediments, providing a record of climatically driven hydrographic changes in response to extreme evaporation during the Messinian salinity crisis. The source waters of the biomarkers were in some cases extremely enriched in deuterium, producing isotopic values that are only known from desert climates today. This work shows that the stable hydrogen isotope composition of biomarkers is preserved in sediments as old as the Miocene, and that these compounds can be used for paleoenvironmental and climatic reconstructions.
.
Benson, R.H. and Rakic-El Bied, K. 1991. Biodynamics, saline giants and Late Miocene catastrophism. Carbonate and Evaporites, 6, 127-168.
.
Butler, R. 1999. How the Mediterranean dried up. Mercian Geologist, 15, 63-64.

Butler, R.W.H., Lickorish, W.H., Grasso, M., Pedley, H.M. and Ramberti, L. 1995. Tectonics and sequence stratigraphy in Messinian basins, Sicily: constraints on the initiation and termination of the Mediterranean "salinity crisis". Geological Society of America Bulletin, 107, 425-439.

Butler, R.W.H., McClelland, E. and Jones, R.E. 1999. Calibrating the duration and timing of the Messinian salinity crisis in the Mediterranean: linked tectonoclimatic signals in thrust-top basins in Sicily. Journal of the Geological Society, London, 156, 827-835. Abstract: The Messinian "salinity crisis" which affected the Mediterranean represents one of the most dramatic examples of base-level fluctuation known in the geological record: an amplitude of perhaps 2 km within a stage with a duration of less than 2 Ma. Deposits within the Caltanissetta Basin of central Sicily are used to calibrate the duration and timing of these fluctuations. Two successions of evaporites termed "First Cycle" and "Second Cycle" are separated by an inter-regional unconformity. The first cycle is regionally regressive while the second is transgressive. Chronostratigraphic calibration of these deposots has been provided by a linked magnetostratigraphic, structural and sedimentological study. The regression was protracted. The earliest evaporites in our study accumulated early in Chron C3Ar (pre 6.88 Ma) and the youngest accumulated late in chron C3An (post 6.0 Ma). During this interval the basinward shift in coastline was 70 km and in vertical section implies a relative fall in sea level at 0.3-0.4 m ka -1. Lowstand probably finally occurred at 5.8-5.5 Ma. Transgression, marked by accumulation of the "second cycle" deposits, which all record reversed magnetizations (C3r), apparently occurred far more rapidly (200 ka), prior to the return to "normal" marine conditioins in the central Mediterranean late in Chron C3r. Local rates of tectonic deformation are relatively slow within the thrust belt which underlies the Caltanissetta Basin. Therefore, it is likely that the timing and rates of the Messinian "salinity crisis" on Sicily are generally applicable to other basin in the region and help to underpin rates of climatic change within this part of the Neogene.
.
Cita, M.B. 1991. Development of a scientific controversy. In Muller, D.w., McKenzie, J.A. and Weissert, H. (eds.), Controversies in Modern Geology. Evolution of Geological Theories in Sedimentology, Earth History and Tectonics. Academic Press, London, 12-23.
.
Clauzon, G., Suc, J-P., Gautier, F., Berger, A. and Loutre, M.-F. 1996. Alternate interpretation of the Messinian salinity crisis: controversy resolved? Geology, 24, 363-366.
.
Danese, E. 1999 Upper Miocene Carbonate Ramp Depositsfrom the Southernmost Part of Maiella Mountain (Abruzzo, Central Italy). Facies, 41, 41-54, Pl. 9-11, 4 Figs. Abstract: The development of carbonate ramp depositional systems in the Neogene of the Mediterranean Region represents a widespread feature so far analysed in several papers. It is striking to note that the evolution of upper Miocene carbonate ramps, characterized by the presence of coralgal bioherms, highlights the events leading to the Messinian salinity crisis. The coralgal bioherms of pre-evaporite Messinian age exhibit fossil assemblages indicating marine waters with normal salinity, whereas stromatolitic and microbial encrustations underline the deterioration of the environment during the Messinian salinity crisis. Maiella Mountain is a broad carbonate massif located in Abruzzo (Central Italy). The late lower Oligocene-Messinian part of its stratigraphic succession consists of stacked non-tropical carbonate ramp deposits related to third and higher order sequences. The investigations performed in the southernmost portion of the massif allowed to recognize a complete fourth order carbonate depositional sequence on a homoclinal ramp of pre-evaporite Messinian age. The presence of small coralgal patch reefs and overlaying microbial encrustations is significant. A transect exhibits the stratigraphic framework of the area. The data show how local parameters play a notable role in the development of these deposits.
.
Drooger, C.W. 1973. Messinian Events in the Mediterranean. Geodynamics Scientific Report No. 7., North Holland Publishing Co.
.
Flecker, R. and Ellam, R.M. 1999. Distinguishing climatic and tectonic signals in the sedimentary succession of marginal basins using Sr isotopes: an example from the Messinian salinity crisis, Eastern Mediterrranean. Journal of the Geological Society of London, 156, 847-854. Abstract: The evolution of oceanic Sr-87/Sr-86 through the Tertiary has been sufficiently well documented to provide a useful stratigraphic tool for carbonate-rich marine sediments which were deposited in basins connected to the global oceans. In isolated basins, sea water Sr-87/Sr-86 Will diverge from coeval oceanic values; thus if independent age information exists, the geochemical signature can constrain the timing of isolation. In marginal basins formed in tectonically active settings, the timing of isolation is critical to the assessment of the relative importance of climate or tectonic controls on that event. Previously, isolation has been assumed to coincide with the last occurrence of open marine fauna. However, in an example from the Eastern Mediterranean, Sr-87/Sr-86 data challenge that assumption and can be interpreted as indicating a protracted period of isolation (c. 3 Ma), during which time marine conditions prevailed, prior to the Messinian salinity crisis at the end of the Miocene. This allows tectonic and climatic signals to be distinguished, since although convergence of Africa with Eurasia was responsible for isolation of this part of the Mediterranean, it is more likely that later climatic change triggered desiccation.
.
Friedman, G.M. 1989. Messinian (Miocene) evaporites of the Mediterranean Basin: a new approach to an old bandwagon. Program and abstracts, Geological Society of America Annual Meeting, St Louis, MO, November 6-9, 1989.

Friedman, G.M. 1991. Messinian (Miocene) evaporites of the Mediterranean Basin: a new approach to an old bandwaggon. Carbonates and Evaporites, 16, 169-176.

Griffin, .D.L. 1999. The late Miocene climate of northeastern Africa: unravelling the signals in the sedimentary succession. Journal of the Geological Society of London, 156, 817-826. The Messinian was a time of high rainfall and high sediment yield rates. The wet phase peaked in the late Messinian at the time of the low-stand of the Mediterranean during the Messinian Salinity Crisis.
.
Hsu, K.J. et al., 1973. Late Miocene desiccation of the Mediterranean. Nature, London, 242,N: 5395, 240-244. [Key Paper]

Hsu, K.J. l972. When the Mediterranean dried up. Scientific American. 227, 27-36. [Key Paper]

Hsu, K.J. 198? The Mediterranean was a Desert: A voyage of the Glomar Challenger. Princeton University Press, Princeton, New Jersey.

Hsu, K.J. et al. 1977. History of the Mediterranean salinity crisis. Nature, London, 267. 399-403. [Key Paper]

Hsu, K.J. , Montadert, L., Bernoulli, D., Cita, M.B., Erickson, A., Garrison, R.E., Kidd, R.B., Mielieres, F., Muller, C. and Wright, R. 1978. History of the Messinian Salinity Crisis. In: Hsu, K.J., Montadert, L. et al., Initial Reports of the Deep Sea Drilling Project. U.S. Government Printing Office, 42 (1), 1053-1078.
.
Kastens, K. A., and J. Mascle, Note added in proof: Did a glacio-eustatic sea-level drop trigger the Messinian salinity crisis in the Mediterranean?, in D. Kennett, A. Masterson, and N. Stewart et al, Proc. ODP, Initial Results, v. 113, p. 993.
.
Kennet, J.P. 1982. The Terminal Miocene Event, Global Cooling and the Mediterranean Salinity Crisis. Pp. 738-742 in Kennet, J.P. 1982. Marine Geology. Prentice Hall, Englewood Cliffs, New Jersey, 813 pp.
.
Keogh, S.M. and Butler, R.W.H. 1999. The Mediterranean water body in the Late Messinian: interpreting the record from the marginal basins on Sicily. Journal of the Geological Society, London. 156, 837-846. Abstract: The stratigraphic record of climatic and palaeoceanographic changes in the Mediterranean during the late Messinian is controversial. On Sicily, sedimentary facies show a steady transgression, suggesting that sub-basins were hydrodynamically linked to a larger water body. Here we test this hypothesis using strontium isotope studies from Messinian materials collected from a range of sites in the Caltanissetta Basin of central Sicily. The strata include a regionally regressive 'First Cycle' of early-mid-Messinian age and a younger, transgressive 'Second Cycle'. These cycles are separated by an inter-regional unconformity which may be correlated with base-level low stand in the Mediterranean. Sr-87/Sr-86 ratios for all First Cycle gypsum fail within the expected global marine composition (0.70891-0.70897). All Second Cycle analyses fall within a grouping of significantly lower values (0.70868-0.70878), a surprisingly tight but discrepant grouping for data collected from shells of a brackish water fauna and from gypsum. Analyses from these different Second Cycle materials are statistically indistinguishable. These results indicate that the strontium isotopic composition of waters from different sub-basins on Sicily are indistinguishable regardless of salinity during the late Messinian. Therefore these basins must have mixed with a larger, homogenized reservoir which we infer was the ancestral Mediterranean. Thus circum-Mediterranean basins may indeed chart regional palaeoceanographic and climatic events. By the end of Messinian times the base-level of the Mediterranean was within the range of the world's oceans but the water-body probably had a distinctly different but internally homogeneous strontium isotopic composition.
.
Krijgsman, W., Hilgen, F.J., Raffi, I., Sierro, F.J. and Wilson, D.S. 1999. Chronology, causes and progression of the Messinian salinity crisis. Nature, London, 400 (6745), 652-655. Abstract: The Messinian salinity crisis is widely regarded as one of the most dramatic episodes of oceanic change of the past 20 or so million years. Earliest explanations were that extremely thick evaporites were deposited in a deep and desiccated Mediterranean basin that had been repeatedly isolated from the Atlantic Ocean, but elucidation of the causes of the isolation - whether driven largely by glacio-eustatic or tectonic processes - have been hampered by the absence of an accurate time frame. Here we present an astronomically calibrated chronology for the Mediterranean Messinian age based on an integrated high-resolution stratigraphy and 'tuning' of sedimentary cycle patterns to variations in the Earths orbital parameters. We show that the onset of the Messinian salinity crisis is synchronous over the entire Mediterranean basin, dated at 5.96 +/- 0.02 million years ago. Isolation from the Atlantic Ocean was established between 5.59 and 5.33 million years ago, causing a large fall in Mediterranean water level followed by erosion (5.59-5.50 million years ago) and deposition (5.50-5.33 million years ago) of non-marine sediments in a large 'Lago Mare' (Lake Sea) basin. Cyclic evaporite deposition is almost entirely related to circum-Mediterranean climate changes driven by changes in the Earths precession, and not to obliquity-induced glacio-eustatic sea-level changes. We argue in favour of a dominantly tectonic origin for the Messinian salinity crisis, although its exact timing may well have been controlled by the 400-kyr component of the Earths eccentricity cycle.
.
Lofi, J., Gorini, C., Berné, S., Clauzon, G., De Clarens, P., Dos Reis, T. and Fouchet, C., 2001. Plio-Quaternary reconstruction of the western part of the Gulf of Lion contiental shelf (NW Mediterranean): prograding clinoform wedges fill the accommodation space created during the Messinian Salinity Crisis. Submitted to Marine Geology.
.
Lyell, C. 1833. Principles of Geology. Murray, London.
.
MacKenzie, J.A. 1999. From desert to deluge in the Mediterranean. Nature, London, 400 (6745), 613-614.
.
Martin, J.M. and Braga, J.C. 1994. Messinian events in the Sorbas Basin in southeastern Spain and their implications in the recent history of the Mediterranean. Sedimentary Geology, 90, 257-268.
.
McInnis, D. 1999. Vanished. Who pulled the plug on the Mediterranean and could it happen again? New Scientist, 163 (2198), 15 (Supplement).
.
McClelland, E., Finigan, B. and Butler, R.W.H. 1996. A magnetostratigraphic study of the onset of the Mediterranean Salinity Crisis; Caltanissetta Basin, Sicily. In: Morris, A. and Tarling, D.H. (eds), Palaeomagnetism and Tectonics of the Mediterranean Region. Geological Society of London, Special Publications, 105, 205-217.
.
McKenzie, J.A. 1999. Deluge in the Mediterranean. Nature, UK, 400, 613-614. ["A time when the Mediterranean became cut off from, then reconnected to, the Atlantic has been securely dated. An approach known as astrochronology lies behind this achievement." See also Krijgsman et al. (1999).]
.
Mevlenkamp, J.E. 1984. Fundamentals of stratigraphic units; the Neogene Mediterranean - case history. Abstract; 27th International Geological Congress, (Bogdanov, N? A. ed). International Geological Congress, 27 (1), p. 123, 1984. Meeting Aug. 4-14, 1984. Moscow, USSR.
.
Michalzik, D., Elbracht, J., Mauthe, F., Reinhold, C. & Schneider, B. 1993. Messinian facies relations in the San Miguel de Salinas Basin, SE-Spain. Z. dt. geol. Ges., 144: 352-369. Abstract: According to several authors, the Neogene basins in SE-Spain represent the connection between the Atlantic Ocean and the deep desiccated Mediterranean Sea during the "Messinian salinity crisis". The vast amounts of water required to precipitate the thick Messinian evaporites are thought to have cascaded through the cataract-like basins of the Betic Strait and a final waterfall into the Mediterranean Basin. Within the San Miguel de Salinas Basin, which represents the easternmost basin of the Betic Strait, a successive shallowing of the marine depositional environment can be shown for the Late Tortonian and Messinian. Thick marine Tortonian marls are increasingly superimposed by calcareous arenites during the Early Messinian. These are succeeded in the central part of the basin by the formation of the characteristic Messinian selenitic gypsum. The different sulfate facies are considered to be of primary and secondary origin. In the marginal parts of the basin primarily platform carbonates developed, including some pre-evaporitic Porites reefs. The Messinian succession is concluded by calcareous arenites, oolites, stromatolites and marls that can be correlated with the "Terminal Carbonate Complex". For the central part of the basin these carbonates confirm continuous marine conditions up into the Pliocene. There is no evidence for strong one-way water flow, as should be expected for a cataract basin.
.
Pedley, H.M. and Maniscalco, R. 1999. Lithofacies and faunal succession (faunal phase analysis) as a tool in unravelling climatic and tectonic signals in marginal basins; Messinian (Miocene) Sicily. Journal of the Geological Society of London, 156, 855-863.
.
Penzo, E. et al. 1998. Messinian Salinity Crisis and the Origin of Freshwater Lifestyle in Western Mediterranean Gobies. Mol. Biol. Evol., 15 (11), 1472-1480.
.
Riding, R., Braga, J.C. and Martin, J.M. 1999. Late Miocene Mediterranean desiccation: topography and significance of the 'Salinity Crisis' erosion surface on-land in southeast Spain. Sedimentary Geology, 123, 1-7. Abstract: The result of sea level fall at the margins of the Mediterranean during the Late Miocene 'Salinity Crisis' was the creation of an extensive erosion surface. However, the shape of this 'Salinity Crisis' unconformity reflects local factors and in turn significantly determined local conditions during subsequent reflooding. At Sorbas, in southeast Spain, erosional overdeepening of a pre-existing basin during drawdown created a depression over 200 m deep with an incised floor patterned by 30-m-deep gullies. During reflooding this semi-enclosed palaeovalley temporarily became a barred basin in which gypsum was deposited. These Sorbas evaporites thus resulted from local basin sculpture. Diverse local effects elsewhere during drawdown and reflooding account for marked stratigraphic variations that continue to complicate recognition and correlation of the 'Salinity Crisis' in marginal successions. The drawdown erosion surface is itself the key indicator of this important event in marginal Mediterranean basins.

Riding, R., Braga, J.C., Martin, J.M. and Sanchez-Almazo, I.M. 1998. Mediterranean Messinian Salinity Crisis: Constraints from a coeval marginal basin, Sorbas, southeastern Spain. Marine Geology, 146, 1-20. Abstract: The extent, timing and effects of Late Miocene desiccation and evaporite deposition in the Mediterranean Sea remain controversial. Marginal basins containing Messinian (5.3-7.1 Ma) sequences now exposed onland supplement information from the deep Mediterranean, but have evaporites of a variety of ages. Some of these Messinian evaporites pre-date, and others post-dale, deep desiccation. None appears to be exactly coeval with those of the deep Mediterranean. In the Betic Cordillera of southern Spain, basins (e.g. Granada Basin) far from the present-day Mediterranean lost connection with the Mediterranean due to uplift similar to 1 Ma before the Salinity Crisis, and have marine evaporites of early, not late, Messinian age. In contrast, basins such as the Sorbas Basin in southeastern Spain, adjacent to the present-day Mediterranean, record events directly reflecting the course of the Salinity Crisis. The Sorbas Basin retained marine connection with the western Mediterranean up until evaporative drawdown in the mid-Messinian and was rapidly reflooded immediately afterwards. The Sorbas Messinian sequence is up to 320 m thick. It is complete and normal marine, except for an incised basin wide erosion surface overlain by a 130 m thick gypsum deposit. We propose that this surface marks the interval of deep desiccation of the adjacent Mediterranean basin. Erosion occurred shortly after 5.9 Ma and the irregular unconformity has relief of at least 240 m, confirming Mediterranean drawdown significantly below the Atlantic level. Sorbas gypsum deposits overlie the unconformity and are intercalated with marls estimated at similar to 5.5 Ma containing normal marine Messinian biotas. These gypsum deposits therefore post-date deep desiccation and formed in a silled basin immediately following marine reflooding. They mark the end of the Salinity Crisis and are overlain by 70 m of normal marine sediments containing unreworked foraminifers of latest Messinian age. This succession demonstrates that the Salinity Crisis occurred faster and was completed sooner than previously believed. It took place within similar to 0.4 Ma (time-scale of Berggren et al., 1995b, is similar to 0.2 Ma on the time-scale of Baksi, 1993) and was completed before the end of the Messinian. This corrects previous views that the Salinity Crisis continued until the Early Pliocene. There is no evidence in the Sorbas Basin for brackish 'Lago Mare' conditions, and the normal marine biotas that directly precede and follow drawdown rebut earlier suggestions of prolonged salinity effects.
.
Rouchy, J.M. 1980. La genese des evaporites Messiniennes de Mediterranee: un bilan. Bull. Centre Rech. Pau, SNPA, 4, 5ll-545

Rouchy, J.M. 1982. La crise evaporitique messinienne de Mediterranee: nouvelles propositions pour une interpretation genetique. Bull. Mus. Natn. Hist. Nat., Paris, 4th ser.4, sect C, no.3-4, pp. l07-l36.

Rouchy, J.M. 1986. Les evaporites Miocenes de la Mediterranee et de la mer Rouge et leur enseignements pour l'interpretation des grandes accumulations evaporitiques d'origine marine. Bull. Soc. Geol France, l986(8) t.ll pp.5ll-520.

Rouchy, J-M. and Saint Martin, J.-P. 1992. Late Miocene events in the Mediterranean as recorded by carbonate-evaporite relations. Geology, 20, 629-632.
.
Schmalz, R.F. 1991. The Mediterranean Salinity Crisis: alternative hypothesis. In: Mediterranean Messinian and other evaporites (Friedman, G.M. ed), Carbonates and Evaporites, 6, 121-126. [Argues that most modern evaporite environments are small, thin and dirty. The Mediterranean is an excellent model for deep evaporite deposition. Isolation from the Atlantic with continued inflow from the Black Sea would evaporate the Mediterranean to dryness in 2000yrs. Deposit would be 42m thick with sedimentation rate of 21mm per annum. Alternatively Atlantic seawater flowed in at a rate just sufficient to replace the volume of water lost by evaporation. Under these conditions the entire basin will be saturated with gypsum after 6000 yrs. After 18000 yrs the basin will be filled to sill depth with halite-saturated brine. Then - no limits to halite accumulation. See also Hsu's papers and the Selli, R. 1985 tectonic model in: Stanley, D.J and Wezel, F.C. Geological Evolution of the Mediterranean Basin.]
.
Schreiber, B.C. 1986. Arid shorelines and evaporites. In: Reading, H.G., Sedimentary Environments and Facies, 2nd Edition. Blackwell Scientific Publications Limited, Oxford.
.
Selli, R. 1985. Tectonic evolution of the Tyrrenhian Sea: Chapter 7 in: Stanley, D.J. and Wezel, F.C. (eds), 1985, Geological Evolution of the Mediterranean Basin. New York, Springer Verlag, 571 p. + appendix, index. (Tectonic model for the Messinian evaporites. Portions of the basin floor were subjected to repeated vertical tectonic movements. Key Paper)
.
Sonnenfeld, P. l985. Models of Upper Miocene evaporite genesis in the Mediterranean region. In: Geological Evolution of the Mediterranean Basin (ed. by Stanley, D.J. and Wezel,F.C.), Springer-Verlag, New York, 589 p, 323-346.

Sonnenfeld, P. & Finetti, I. l985. Messinian evaporites in the Mediterranean: a model of continuous inflow and outflow. PP.347-353 in: Geological Evolution of the Mediterranean Basin (ed. by Stanley, D.J. & Wezel,F.C.), Springer-Verlag, New York, 589 p.
.
Stanley, D.J. and Wezel, F.C. (eds), 1985, Geological Evolution of the Mediterranean Basin. New York, Springer Verlag, 571 p. + appendix, index.
.
Warren, J.K. 1989. Evaporite Sedimentology. Prentice-Hall (UK) Limited, London.

Warren, J.K. 1999. Evaporites, their Evolution and Economics. Blackwell Science Limited, Oxford.
.
Westaway, R. 1990. Neogene evolution of the Aegean region. AGU Fall Meeting, 1990. 71 (43) p. 1643. Oct 23. 1990.

Go back to top

Summary of Lecture - GY 308 (Southampton University)

Objectives

To examine critically the theories of origin of the late Miocene evaporites of the Mediterranean Sea, in particular considering the model of a deep desiccated basin.

Content

6 Ma ago - biological revolution. marine fauna of mixed Atlantic/Indian Ocean departed to west of Gibralter. only a few hardy species survived in deteriorating Med. In Pliocene refugees returned with new Atlantic species. Lyell 1833 chose end of faunal revolution as end Miocene. Cause? Nr end of 19th C Rhone gorge about 160km long discovered. Cut into granite, filled with oceanic seds, covered with Rhone sand and gravels. 1961 American ocean. res. vessel Chain used seismic. CSP - continuous seismic-profiling. penetrated hundreds of feet. Med floor underlain by array of pillar-like structures.salt domes. exploration contin. in 60s. Ryan found M reflector. geometry simulates bottom topography. Glomar Challenger of DSDP.southeast of Barcelona bottom 2000m and bored 200m . core barrel with pea gravel. gravel - oceanic basalt, hardened oceanic ooze and gypsum . not a turbidite anydrite .. M reflector is a Miocene evaporite. anomaly evaporite at thousands of metres below sea-level. gravel not from land but from dried-up ocean . suggested Med had been like Dead Sea. Med abyssal plains 3000m deep. basin holds almost million cubic miles of water. climate Med area arid annual evap loss 1000 cubic miles. if Gib closed now Med dried up in about 1000yrs. a tenth compensated by rainfall and influx of fresh water from rivers. shrinkage of Med, increased salinity, death of normal marine animals. eventually salt lake like Dead Sea. gypsum precipitation. anhydrite formed in brine saturated for NaCl above 35°C . brine pools rarely reach this temperature thus anhydrite usually sabkha. nodular anhyrite and stromatolitic limestone. stomatolites require light. isotopes - oxygen 18, oxygen 16 normal. evaps from sea-water have narrow range of values. those from playa lakes have wide range. Med samples showed high variability - playa origin. Desert flat very deep - now 3000m below sea-level . evidence that the Med floor was so deep? microfossils from above and below the anhydrite are normal deep ocean ones. M reflector an evaporite everywhere. Most boreholes - sulphate. last borehole 130 km (80 miles) west of Sardinia - halite at 3000m (10000ft) below sea-level. interbedded wind-blown silts. land-formed quartz and broken forams. salt filled mud-cracks. halite showed repeated solution and recrystallisation .like Lower California or Death Valley. floodplain silts and wadi gravels from nearby - flash floods. salt about 2000m thick . Sicily has pushed up example. Over the Mess. dark grey marl 5 inch thick then white ooze with patches of red ooze. gigantic waterfall . 1000 cubic miles per year (10 times Victoria Falls) insufficient for water loss influx had to exceed evap by 10times. 10,000 cubic miles per year (100 times bigger than Victoria and 1000 bigger than Niagara). needed 100 years. white ooze oceanic sed of microfossils and nannofossils. Benthic forams show bottom was colder and deeper than today when Straits of Gib deeper unusual laminated sed. in evaporite formation. diatoms in this, some fresh or brackish. 6 or 7 ma. Lake Mer. Eastern Europe covered with fresh or brackish waters during Late Miocene and the Pliocene . Lake Mer (French term) Vienna to Urals and Aral Sea. Descendents - Caspian and Black Sea. Lake Mer collected precip from the wet and cold northeastern Europe. during early part of late Miocene. uplift of Carpathian caused outlet to north. Boreholes from eastern Med - middle Miocene. Med once broad seaway linking Indian and Atlantic Oceans. collisions closed Indian Ocean connection Atlantic connection by Betic and Riphean straits. Buried gorges result of deep dry Med. Gorge at Aswan 213m (700 feet) below sea-level cut into granite. 1200 km (750 miles) from Med coast. in Nile Delta bhs more than 300m (1000 feet) do not reach bottom of Nile canyon. old Grand Canyon, 1500m (5000ft)? Oil Geologists had already found deep channels in Libya. other Algeria, Israel, Syria. submarine channels. Yugoslavian karst. other examples - Zechstein may have been similar . potash of Alberta and Saskatchewan. Gulf of Mexico . Nova Scotia. Updating by later literature. Overview. Summary.

Go back to top

Home Page and Index| Dorset Field Guides - List | Last week's visitors

Copyright © 2002 of Ian West.

Dr Ian West,
School of Ocean and Earth Sciences,
Southampton University,
Southampton Oceanography Centre,
Empress Dock, Southampton, SO14 3ZH.