Geophysical Contribution to Knowledge of the Mediterranean Crust

Morelli, Carlo F.

doi:10.1007/978-1-4613-8572-1_4

Cited by 14 publications

(20 citation statements)

References 14 publications

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“…At the same time, the competing terrigenic 3 He is small because the terrigenic He has a 3 He/ 4 He ratio that is one order of magnitude lower than in most other ocean regions (Roether et al, 1998a). The explanation is that the Med's sub-floor lithosphere is characterised by high sediment load above crust that is largely of continental type (Morelli, 1985); in both these compartments, α-decay of the natural decay series is a source of pure 4 He. Using the isotopic ratio of terrigenic He, measured He isotope and neon (Ne) concentrations allow one to correct for the terrigenic 3 He contribution (Roether et al, 1998a).…”

Section: Introductionmentioning

confidence: 99%

The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup> He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

et al. 2013

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Abstract. We present a comprehensive account of tritium and 3 He in the Mediterranean Sea since the appearance of the tritium generated by the atmospheric nuclear-weapon testing in the 1950s and early 1960s, based on essentially all available observations. Tritium in surface waters rose to 20-30 TU in 1964 (TU = 10 18 ×[ 3 H]/[H]), a factor of about 100 above the natural level, and thereafter declined 30-fold up to 2011. The decline was largely due to radioactive tritium decay, which produced significant amounts of its stable daughter 3 He. We present the scheme by which we separate the tritiugenic part of 3 He and the part due to release from the sea floor (terrigenic part). We show that the tritiugenic component can be quantified throughout the Mediterranean waters, typically to a ± 0.15 TU equivalent, mostly because the terrigenic part is low in 3 He. This fact makes the Mediterranean unique in offering a potential for the use of tritiugenic 3 He as a tracer. The transient distributions of the two tracers are illustrated by a number of sections spanning the entire sea and relevant features of their distributions are noted. By 2011, the 3 He concentrations in the top few hundred metres had become low, in response to the decreasing tritium concentrations combined with a flushing out by the general westward drift of these waters. Tritium-3 He ages in Levantine Intermediate Water (LIW) were obtained repeated in time at different locations, defining transit times from the LIW source region east of Rhodes. The ages show an upward trend with the time elapsed since the surface-water tritium maximum, which arises because the repeated observations represent increasingly slower moving parts of the full transit time spectrum of LIW. The transit time dispersion revealed by this new application of tritium-3 He dating is considerable. We find mean transit times of 12 ± 2 yr up to the Strait of Sicily, 18 ± 3 yr up to the Tyrrhenian Sea, and 22 ± 4 yr up into the Western Mediterranean. Furthermore, we present full Eastern Mediterranean sections of terrigenic 3 He and tritium-3 He age in 1987, the latter one similarly showing an effect of the transit time dispersion. We conclude that the available tritium and 3 He data, particularly if combined with other tracer data, are useful for constraining the subsurface circulation and mixing of the Mediterranean Sea.

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Section: Introductionmentioning

confidence: 99%

The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup> He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

et al. 2013

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“…1 = Eurasian continenl and dependencies: 2 = African continent and dependencies: 3 = Kirsehir block: 4 = present oceanic basins: 5 = suture zones of ihe Mesozoic oceans: 6 = idem plus the major ophiolitic nappes (arrows) issued from them: 7= past and present subduction trenches. Byramjee (1975), Malovitskiy (1975), Biju-Duval and others (1979), Morelli (1985), Westaway (1990), and others…”

Section: Geographymentioning

confidence: 94%

“…North-south fault trends are predominant with a northtrending horst and graben complex in the northern part. The center is a relatively flat plain with large seamounts and ridges, some of volcanic origin and some composed of tilted blocks of continental crust (Morelli, 1985). The sedimentary cover is thin, underlain by oceanic crust (figs.…”

Section: Tyrrhenian Sea Basinmentioning

confidence: 99%

“…The pre-Neogene sedimentary cover in the Ionian Sea basin and adjacent area is as old as early to middle Mesozoic and ranges in thickness from as much as 8-10 km (25-30,000 ft) to less than 5 km (16,000 ft) (Morelli, 1985;Finetti, 1985), with minimal cover by young sediments in the more recently faulted areas, particularly the central abyssal plain (figs. 12-14).…”

Section: Negligible____20_______3mentioning

confidence: 99%

“…1,2). It has been described as the "external envelope" of the Hellenic Arc, separated from the main arc by the downwarped Hellenic trench (Morelli, 1985). The submarine swell or ridge consists of a series of structurally-deformed "bundles" of controversial origin.…”

Section: Mediterranean Ridge-hellenic Trench-herodotus Basinmentioning

confidence: 99%

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Geophysical Contribution to Knowledge of the Mediterranean Crust

Cited by 14 publications

References 14 publications

The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup> He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup> He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

Regional geology and hydrocarbon resource potential, the Mediterranean Sea region

Geological Evolution of the Mediterranean Basin

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Geophysical Contribution to Knowledge of the Mediterranean Crust

Cited by 14 publications

References 14 publications

The transient distributions of nuclear weapon-generated tritium and its decay product &lt;sup&gt;3&lt;/sup&gt; He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

The transient distributions of nuclear weapon-generated tritium and its decay product &lt;sup&gt;3&lt;/sup&gt; He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

Regional geology and hydrocarbon resource potential, the Mediterranean Sea region

Geological Evolution of the Mediterranean Basin

Contact Info

Product

Resources

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The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup> He in the Mediterranean Sea, 1952–2011, and their oceanographic potential

The transient distributions of nuclear weapon-generated tritium and its decay product <sup>3</sup> He in the Mediterranean Sea, 1952–2011, and their oceanographic potential