You may find some explanation in the following article:MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS The Astrophysical Journal Volume 722 Number 2

http://dx.doi.org/10.1088/0004-637X/722/2/1342

Dear Elena, the isotopic anomalies you mention are mostly measured in the components of primordial materials, coming from undifferentiated asteroids or comets, but also in some planetary bodies to a lower extent. The minerals forming few-hundred km in diameter bodies (asteroids or comets) have preserved these primordial isotopic anomalies because they were never heated enough to chemically homogeneize their interiors. From them arrive to Earth chondrites or Interplanetary Dust Particles (IDPs) that are called: "highly unequilibrated materials". Their parent bodies have then experienced low degrees of thermal metamorphism, and sometimes aqueous alteration. Due to this, the materials have preserved the variable compositions of their forming environments, somes condensed in the protoplanetary disk, but others are even stellar grains formed in the surrounding interstellar environment from which the solar system formed. In the planetary bodies you mention is true that it can be found but to a lower extent due to the fact that are differentiated bodies. When going to Mars and Titan it is abvious that their level of thermal processing is high, but not complete. Some of these anomalies reflect different degrees of thermal processing. Going back to the extreme exemples that minor bodies offer us, you might find details in the literature concerning the collected particles by Stardust (NASA) mission of comet 81P/Wild 2, or in multiple references about undifferentiated meteorites, like e.g. chondrites. I particularly have a review paper about the role of thermal metamorphism and aqueous alteration in chondrites that might be good to start reading about: http://www.spmn.uji.es/ESP/articulo/PASAust09.pdf

There are several possibility. The anomalous isotopic presence may be because of nuclear reaction by cosmic rays/ solar cosmic rays etc. then even at the same time, different target may have varying isotopic abundances if the composition of target elements is different. Magnesium is a suitable target for neon production by protons. Aluminium is not so good. So the different ratios ingrains will have different neon isotopic abundance. This difference can happen even if the energy spectrum of the incident particles (e.g. protons) is different. This spectrum may be different for material at different depth. This happens for neon isotopes (20,21,220 produced in lunar regolith at different depths.

Another possibility is that the isotope in the grain is radioactive. With time its decay will change the isotopic abundance. This can be seen utilized in the Rb- Sr dating. If time of incorporation is different, then the material introduced in the condensate or aggregation can have different quantities of radiogenic (produced by radioactive isotope) isotope. For example I-129 has a half life of about 20 Ma. Depending upon how much iodine has decayed to xenon, the xenon 129 relative abundance in material will vary.

If the material studied has different formation ages but similar initial ratios (because input came from some ongoing process), even then the observed ratios will be different.

One way to obtain information on past atmospheric conditions is to look at current isotope ratios. Measurements from the Curiosity rover show that there are 4.2 atoms of argon-36 for every one of argon-38 on Mars. By way of comparison, the ratio is 5.5 to one in the atmospheres of the Sun and Jupiter, which can be considered the baseline for when the Solar System formed. The Earth is at about 5.3.

This indicates that Mars may have lost 85-95% of its atmosphere over several billion years. The original atmosphere would have been warmer and heavier providing conditions suitable for maintaining liquid water on its surface and an environment habitable to potential life.

The Curiosity data is very precise and resolves the large uncertainties in previous measurements acquired by the Viking landers in the 1970s and from the study of Martian meteorites.

A good friend of mine, Sushil Ateya has said: "We've been seeing the same kind of behavior in the carbon dioxide isotopes and the water isotopes - they're all telling us the same story; that gases have been escaping from Mars over time, and the argon isotope just really nails it."

There are several reasons for these isotopic "anomalies". As far as inanimate systems are concerned, and hence the isotopic distribution in our solar system and beyond, see the following selection:

(1) A fridgid environment (say 10 K), such as provided in a presolar cloud or on the surface of interstellar grains, favours the "survival" of the molecule containing the heavier isotope: The molecule containing the heavier isotope reacts at a slower rate (kinetic isotope effect) and is less volatile (thermodynamic isotope effect). An example is the enrichment of 13CO (as compared to 12CO) in interstellar clouds.

(2) The decay of "extinct" (i.e. short-lived) isotopes can favour enrichment of a specific isotope, e.g. 26Mg (formed from the decay of 26Al), 22Ne (from 22Na), ...

(3) Enrichment of 2H (deuterium, D) in organic molecules: In ion-molecule reactions, which are typical for interstellar clouds at low temperature, the formation of deuterated species is favoured because the chemical bonds to D are stronger than to 1H: An example is the following ion-molecule reaction: D+ + CH2 >> CHD+ + H+ .

(4) The enrichment of 15N is due to the fact that dinitrogen 14N14N is split less easily than 14N15N, i.e. the ion 15N+ is more readily available for reactions in interstellar clouds than the ion 14N+. For an example, see the following reaction sequence: 15N+ + H2 >> 15NH3 >> HC15N

Argon is a noble gas and it does not react with any other element. It does not even react at high temperatures or under any other special conditions that I know of. That is why it is of particular importance in the studies of atmospheric evolution in the solar system.

All of the answers given above discuss important mechanisms for changing isotope ratios. One additional mechanism is chemistry combined with radioactive decay. Suppose, for example, that when a mineral is formed, the chemistry favors including Al but not Mg. The mineral will have standard ratios for Al isotopes and for Mg isotopes. But if the mineral was formed early in the history of the solar system, when 26Al was abundant, and it later decayed to 26Mg, then if we look at the mineral today, we would see an anomalously high 26Mg/24Mg ratio. Minerals that were formed after the 26Al decayed, or where the chemistry favored inclusion of Mg but not Al would have more standard 26Mg/24Mg ratios.

As Planets become larger, they act more and more like fractional

distillation columns where the lighter fractions move upward

toward the surface, and the denser materials are left behind

deeper inside the planets.

The gasses end up on top, then the liquids, then the solids.

Whether or not a planet keeps its gases depends on its size

and mass, and surface gravity, and if it has a protective magnetic shield.

Putting the Planets in size order from smallest to largest will help

clarify this process of fractional distillation by internal layered shearing

motions as layers slid over one another internally.

Isotopic relations in refractory minerals of primordial matter depend on reservoirs of their condensations, which may differ in their radiation conditions (see it in Attachment).

For Venus H/D

Beside of change of the production rates of isotopes in spallation reactions with shock wave accelerated particles there is also fractionation of isotopes in the matter reprocessed by shock waves due to more rapid acceleration of heavier ions (see, e.g. Attachment).

However, in the case of noble gases a paradox exists: Xe, Ar, and Ne in atmospheres of planets are much heavier than the solar Xe, Ar, and Ne, respectively, but Kr in atmospheres of planets is identical with the solar Kr (see, please, Fig.7 (from: Ustinova (2007) DOI:10.1134/S0038094607030069) in Attachment). It is a subject of one of my questions in RG:

https://www.researchgate.net/post/Why_is_Xe_in_the_atmospheres_of_Earth_and_Mars_much_heavier_than_the_solar_Xe_but_Kr_in_the_atmospheres_of_the_planets_is_similar_to_the_solar_Kr

Dear All!

Thank you very much for your activity. I see that this question is significant not only for me and V. Ostrovskii. One of our papers dedicated to this problem is even titled as “Oxygen isotopic anomalies in the rocks of celestial objects: Are they the key to the planet formation mechanism?”, E.A. Kadyshevich, V.E. Ostrovskii, EPSC Abstr., v.5, EPSC2010-3, 2010.

This and all following our papers are available at ResearchGate.

Of course, the Venusian high D/H ratios are easily explainable; as for the other isotopic anomalies, their understanding is much more complicated. Understanding of the isotopic anomalies of a stoichiometric character, such as those described by R.N. Clayton (Annu. Rev. Earth Planet. Sci., 21 (1993) 115), is especially mysterious, and their denouement is, in our opinion, rather informative. We tried to unravel them in the framework of the PFO-CFO hypothesis of Solar System formation in our above-mentioned paper and also in

Elena A. Kadyshevich and Victor E. Ostrovskii, Proc. Intern. Astron. Union (Adv. in Plasma Astrophys.) 01/2011; 6(IAUS274):95–101, and in

V.E. Ostrovskii, E.A. Kadyshevich, “PFO-CFO Hypothesis of Solar System formation: the notion of the Sun-like stars and their transformations”, Proc. Europ. Planet. Sci. Congr. (EPSC2013), London, UK.

(In Russian, see also:

Victor Ostrovskii, Elena Kadyshevich, “Physicochemical model of formation of the Solar System planets: the causes of differences in the chemical composition of planets”, in: "Phys. Chem.-2010" Selected papers, Ch. 2, Publ."Rosintal", Obninsk, Russia, (2011) 46-61 and

V.E. Ostrovskii, “Hypothesis of the natural gas abiotic origin in the context of living matter origination”, in: “Gas chemistry at the present stage of development”, Ch. 4, Gubkin RSU NG: Moscow, Russia, (2010) 35-69).

There are a number reactions which can change ( at least partly )isotopic composition of elements.1. Nuclear reactions : decay,fission,spallation, 2.physical and chemical fractionation. But all of them can't change primordial isotopic composition of elements on the whole. Only possibility such changing is mixture of matter of two ( at least) reservoirs with different thermonuclear origin. 1. Addition to solar nebula of "fresh" nuclear substance from explosion of the neighbour supernova. As i remember one of the ftrst authors this idea was g.wasserburg. To me it is rather exotic hypothesis. 2. Collision of two ( main and margin-auxiliary) gas-dust nebulos with different isotopic composition of elements ( see above), at the same time this collision was trigger ( notorios "the first shock") for untwist and origin of solar system. From matter with " normal" isotopic compositio was formed the sun, from margin reservoir and main one were formed planets and meteorites parent bodies with anomlies isotopic composition of elements

Isotopic anomalies in solar system objects can be due to 1) nucleosynthetic effects, i.e., material that has been synthesized in other stars and preserved in presolar stardust grains, 2) molecular cloud fractionation effects at very low temperatures that have been preserved in very primitive organic matter as H-C-N anomalies, 3) anomalies in short-lived radionuclides like 26Al that are due to their different decay at different times after solar system formation, 4) cosmogenic effects due to exposure to the galactic high energy environment (e.g., spallation reactions), 5) Anomalies in oxygen isotopes that are due to CO self shielding under UV irradiation of the young Sun (mass-independent fractionation), and 6) mass dependent fractionation. The question is to what composition you want to refer your anomalies. For instance, the Earth and most meteoritic materials are isotopically anomalous in N and O with respect to the Sun (see results by the GENESIS mission)!

Dear Dr. Lev Levskii and other participant of this discussion,

I would like to accenuate that Elena Kadyshevich in her last issue writes about specific isotopic anomalies, which are discovered by R.N. Clayton and which have clearly expressed stoichiometric character. In our common opinion, just such anomalies are of the most interest. Their explanation is embarrassing in the framework of the widely distributed views on the Solar System origination. These data are translated by us in our papers cited by Elena and available at ResearchGate. We think that just these Clayton's data are important for understanding the mechanism of the Solar System formation, and the PFO-CFO hypothesis explains them as it can be seen from our papers cited by Elena.

Best regards.

Dear All, 

On the basis of our PFO-CFO Theory, we predict that Venus contains no nitrogen or a rather small quantity of N14 only and contains oxygen almost solely in the form of O16; as for Mars, it contains nitrogen in the form of N14, generally, like Earth, but the admixture of N15 is rather significant.  As for colonization of Mars, this idea is  crazy by a number of causes. As for Jupiter, it contains O18  in a great proportion and nitrogen in the forms of N14 and N15. We also predict that neither Jupiter nor remoted planets contain iron. As for Mars, the Fe content in its composition is, apparently, zeroth.  We call you to check our predictions. Please, write us the results of your checkings. I write about the body content and about the gaseous atmosphere.                                                        

Victor,

>As for Mars, the Fe content in its composition is, apparently, zeroth

The surface of Mars is known, with certainty, to have many iron-bearing minerals on it: principally hematite and goethite.

Dear Garry, 

Thank you for your notice. Yes, you are right. 

I write about planets in whole, and I write about theoretical conclusions which could be compared with the real data. Our PFO-CFO theory gives a very wide spectrum of knowledge about Universe and, in particular, about the Solar System. This theory explains the so-called isotopic anomalies anywhere over the Solar System. They could be understandable on the basis of our works of 2015-2013 performed in development of the theory and presented in my and Elena Kadyshevich ResearchGate site pages.

Again in particular, nothing says up to now that P, which is necessary for life, is available either in the Mars composition in whole or at  the Martian surface. We don't refuse fully the occurrence of P on Mars, but we concluded that its quantity is there, apparently, less than on Earth, and it is well-known that its concentration on Earth is rather small. Meanwhile, there is no doubt that this is one of the questions which should be solved before the talks about the possibility of colonization of Mars.  

Dear Christian, 

The fact of the matter is that your opinions represent no more than the idle talks which could somehow or other explain anything. As for our explanations and our predictions, they are unique consequences of the PFO-CFO Theory, follow from its logically, and are based in their ground on the SR and not on the GR which is mistaken because it assume the Space gravitation homogeneity and light speed constancy over Universe Space what contradicts common sense and experimental data on the influence of gravity on light. If the grounds of our explanations and predictions are of interest for you, I address you to our publications of 2013-2015 that are available at the ResearchGate by the address https://www.researchgate.net/profile/Victor_Ostrovskii and to the ResearchGate discussion, for example, by the address https://www.researchgate.net/post/Einsteins_relativity_what_is_eternal_questionable_and_erroneous_in_the_starting_points_of_the_theory_and_in_the_subsequent_conclusions_from_it . The fact of the matter is that all your talks go from big bang and big bang goes from nothing but GR. However, the GR is mistaken or, as writes its active advocate and author of handbook Matts Roos, is approximate with an unknown degree of approximation. But big bang could follow only from the exact GR, which doesn’t exist.