Journal of Environmental Protection, 2010, 1, 143-154
doi:10.4236/jep.2010.12019 Published Online June 2010 (http://www.SciRP.org/journal/jep)
1
Metallic Iron and Nickel in Cretaceous and Cenozoic
Sediments: The Results of Thermomagnetic Analysis
Diamar M. Pechersky
Institute of Physics of the Earth, Russian Academy of Scienses, Moscow, Russia.
Received December 6th, 2009; revised February 1st, 2010; accepted February 3rd, 2010.
ABSTRACT
With the aid of thermomagnetic analysis (TMA) up to 800ºС the composition and distribution of particles of native iron
and Fe-Ni alloy was studied in 15 sections, Gams (Austria), Verhorechie and Selbuhra (Crimea), Kvirinaki and Tetrit-
skaro (Georgia), Aimaki, Bass, Dzhengutaj, Madzhalis and Gergebil (North Caucasus, Russia), Klyuchi and Teplovka
(Volga Region, Russia), Koshak (Kazakhstan), Kara-Kala and Khalats (Turkmenistan). The age of sediments varies
from Miocene to Early Cretaceous. Iron particles are present at 521samples out of 921studied. Their percentage varies
from 10 -5% to 0.05%. The distribution consists of two groups: 1) “zero” group (iron is not found by TMA); 2) group of
logarithmic normal distribution with a differing modes. The global enrichment by iron particles in synchronous depos-
its of Miocene, Maastrichtian-Danian, Santonian and Cenomanian was discovered. With respect to nickel content, the
iron particles fall into two groups: 1) nearly pure iron without nickel; and 2) iron with nickel content up to 20%, with
modal value of 5% . The source of iron particles is the cosmic dust. Particles of pure nickel and the alloy containing
more of 20% of nickel are very rare. Possibly, such particles are related mainly with impact events. A peak of elevated
iron content with nearly constant nickel of 5-6% was found in almost all studied sections. It is a global effect which is
not dependent of place and time of deposition of iron particles.
Keywords: Cosmic Dust, Metallic Iron, Nickel, Fe-Ni Alloy, Meteorites, Sediments, Thermomagnetic Analysis, Curie
Point
1. Introduction
Modern data on distribution of native iron and nickel in
the cosmic dust is rather limited, since only “direct” me-
thods of detecting such particles were used. Thermo-
magnetic analysis (TMA) up to 800ºC was employed
during petromagnetic (rock-magnetic) studies of sedi-
ments [1-7]. The increase of ТMA temperature interval
by 100о has given the chance to observe a detailed pic-
ture of a distribution of metallic iron in space and time.
Thermomagnetic investigations of composition and
distribution of particles of native iron and Fe-Ni alloy
was performed in 15 sediment sections: Gams (Austria,
Upper Maastrichtian-Danian, 48oN, 15.2oE), Verhorechie
and Selbuhra (Crimea, Barrem-Apt, Senomanian, 44.7oN,
34oE), Kvirinaki and Tetritskaro (Georgia, Miocene,
Upper Maastrichtian-Danian, 42оN, 43oE), Aimaki, Bass,
Dzhengutaj, Madzhalis and Gergebil (North Caucasus,
Russia, Cretaceous, 42.1-42.9oN, 46-47.9oE), Klyuchi
and Teplovka (Volga Region, Russia, Upper Maas-
trichtian-Danian, 51.9oN, 46.5oE and 52.2oN, 46.2oE),
Koshak (Kazakhstan, Mangyshlak, Upper Maastrichtian-
Danian, 39.5oN, 54oE), Kara-Kala and Khalats (Turk-
menistan, Upper Cretaceous, 38.47oN, 56.2oE and Mio-
cene, 38oN, 58.3oE).
The spatial spread of the objects, from Gams in the
west to Khalats in the east, is approximately 3000km. It
allows to evaluate the global character of accumulation
of cosmic particles in coeval deposits. Detailed selection
of samples from Cretaceous sequences helps to find out
features of accumulation of particles in time.
2. Methods of Petromagnetic Studies
Petromagnetic studies included measurements of sample
magnetization and its dependence upon temperature, i.e.
thermomagnetic analysis (TMA). TMA was carried out
with the aid of Curie express balance [8]. The curves of
М (T) after the first and second heating to 800°C were
obtained for all samples. It is possible to analyze distri-
bution of Curie points. It is known that in particles of
cosmic iron the basic impurity is nickel. Converting Cu-
rie points into Ni content facilitates subsequent compari-
son of TMA data with those of microprobe and other
analyses.

144 Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis
For this purpose, we assumed a linear dependence of
Curie points on Fe-Ni alloy compositions. Then the nick-
el content will be defined by the simple formula:
Ni (wt. %) = 0.243 (770 – TC),
where 770 is the Curie point of iron, TC is a Curie point
of the sample. This assumption has to be checked up. It is
known that the Ni-Fe alloys with nickel content of less
than 30% preserve the ordered α - phase with body-cen-
tred lattice close to the room temperature. α - phase
transforms into γ' - phase with ordered face-centred lattice
and γ - phase with disordered face-centred lattice at
higher concentrations of nickel and/or at higher tem-
perature [9-11]. In such γ and γ'- alloys, Curie points de-
viate from the above linear dependence, “underestimates”
being more often than “overestimates” (Table 1). For
example, invar (36% Ni) has TC = 230-270oC, i.e. below
Curie point of pure nickel (358оС), but increases to
400оС under mechanical stress [12]. There are apparent
“Curie points” as a result of transformation α → γ at
sample heating and γ → α transformation at its cooling.
Such situations mainly occur in Fe-Ni alloys of interme-
diate composition, with nickel of > 20% and < 80%. For
them, appreciable deviations in the estimation of nickel
content with the aid of linear dependence ТС - Ni are
common (Table 1).
In our case, it was more important not to understand
the nature of such deviations, but to address two topics: 1)
application the linear dependence ТС - Ni to the natural
meteorites containing Fe-Ni alloys of intermediate com-
position, and 2) distribution of particles of a Fe-Ni alloy
of intermediate composition in a cosmic dust.
To answer the first question, the data from papers [10,
13,14] has been used, where both microprobe analysis
data and ТMA results for samples of metal meteorites
and metal inclusion in stone meteorites are available
(Table 2). Samples contain kamacite (α - phase), tetra-
taenite (γ' - phase) and taenite (γ - phase) in different
proportion. Appreciable divergences were noted only for
two samples of alloys of intermediate composition: Ya-
mato79069 and San-Cristobal. Hence, the use of linear
dependence of TC - Ni for definition of the nickel con-
centration on ТMA is admissible as the first approxima-
tion.
To answer the second question, we collected the data
on composition of metal particles in the cosmic dust from
the icecaps of Antarctica and Greenland, deep-sea ocean
sediments, Pleistocene sediments of Canada, Eocene
limestone of Tuamotu, the deposits from the area of
Tunguska catastrophe, and sediments at the К/Т bound-
ary in Gams [1,15-17]. Figure 1 shows that the particles
with nickel content of > 20% and < 80% are very rare.
For the other compositions, the estimation of the per-
centage of nickel content with the linear dependence ТС -
Ni is quite applicable.
Figure 1. The histogram of nickel content in Ni-Fe particles
from cosmic dust. N is number of cases. Data [1,15-17]
Table 1. Comparison of nickel content in artificial NiFe alloys (wt.%) with estimations on ТМА
Mark of an alloy Composition of alloy Curie point, оC Ni, wt.% on ТМА
Vacaperm Ni100 400 90
cryoperm Ni90Fe10 430 83
M7904 Ni80, Мо5, Fe15 443 80
Ni80 Ni80Fe20 560 51
Supermuniperm Ni80Mn5Fe15 410 87
Perm77 Ni77, Mo4, Cu4,4 Fe14 410 87
M75 Ni75, Cr2, Cu5, Fe18 438 81
Ni60 Ni60Fe40 600 41
Carpenter Ni55Fe45 530 58
AlloyNi50 Ni52Fe48 530 58
AlloyNi50 Ni50Fe50 500 66
Ni50 Ni50Fe50 530 58
M50 Ni48, Fe52 471 73
Nifemax Ni48Fe52 470 73
Ni40 Ni40Fe60 356 100
Normaperm Ni36Fe64 240 ?
Invar Ni36Fe64 230 ?
Invar Ni36Fe64 375 96
Invar film standard (1) Ni36Fe64 250 ?
Invar film after stress (2) Ni36Fe64 400 90
Superinvar Ni32Co5Fe63 279 ?
AlloyNi30 Ni30Fe70 610 39

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis145
Table 2. Comparison of percentage nickel and iron in meteorites according to a microprobe and ТМА data
meteorite NiFe Tc1(percentage) Tc2(percentage) Tc3 (perc.) NiFe sum
St.Catharina 50/50 565 50/50
Twin City 50/50 560 51/49
Toluca(γ-lamella) 50/50 580 46/54
Itutinga (γ-lamella) 50/50 565 50/50
St. Severin 50/50 565 50/50
Apply Bridge 50/50 565 50/50
Yamato74354 16/84 543(15)
55Ni × 0.15
750(85)
5 × 0.85
13/87
Yamato74362 14/86 545(17)
55Ni × 0.17
740(83)
7 × 0.83
15/85
Yamato74442 28/72 365(7)
98Ni × 0.07
555(21)
52Ni × 0.21
756(72)
3.4Ni × 0.72
21/79
Yamato790964 66/34 560(50)
51Ni × 0.5
610(50)
39Ni × 0.5
45/55
Yamato790448 40/60 575(80)
47Ni
770(20) 47/53
ALH76009 13/87 570(20)
49 × 0.2
765(80)
1.2Ni × 0.8
11/89
San-Cristobal 26/74 565 50/50
Lime Creek 30/70 41/59
The footnote: NiFe – the content (wt. %) of nickel and iron in a metal part of a meteorite according to a microprobe etc. analyses; TC
– Curie points in oC (in brackets the portion of a magnetic phase in percents is specified); NiFe sum (wt. %) – the total content of
nickel and iron on linear dependence of TC – Ni (see text).
(1) (2)
(3) (4)
Figure 2. Examples of dM/dT curves at which there are the Ni-Fe alloy signs. From top to down dM/dT curves for samples:
1– sample 2029-100 (Bass, ТC = 500оC), 2 – sample 2029-110 (Bass, ТC = 365оC), 3 – sample 2035-7 (Aimaki, ТC = 445оC), 4 –
sample 2562-4 (Selbuhra, ТC = 440оC). Bold-faced line is the dM/dT curve of first heating; thin line is the curve of second
heating
Another problem is that detecting Fe-Ni alloys be-
tween 360оC and 680оC is very difficult, as their Curie
points and those for the hemoilmenite and titanomagnet-
ite series overlap. For an identification of such Ni-Fe
alloys, the samples have been chosen, in which Curie
points are reproducible upon the second heating, and the

146 Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis
contribution of these magnetic phases in magnetization
did not change noticeably (Figure 2). This provision
allows to assume that such samples contain particles of
Ni-Fe alloy with nickel from 100% (ТC = 360оС) to 27%
(ТC = 660оС). Really, magnetic minerals like pyrrhotite,
titanomagnetite, and hemoilmenite are unstable and are
oxidized during heating to 800оС, are destroyed and/or
homogenized and their Curie points are decreased; hence
their contribution to sample magnetization varies greatly.
To estimate the content of native iron, Ni-Fe alloy,
magnetite + titanomagnetite, the contribution of each
mineral into magnetization M was determined using the
M (T) curves and, then, it was divided by the specific
saturation magnetization of each mineral. The values of
Ms = 90 Аm2/kg for magnetite + titanomagnetite with TC
= 540-580oC, and Ms = 200Аm2/kg for iron with TC =
700-770oC was used. The linear dependence Ms between
nickel (Мs = 56.7Аm2/kg) and iron (Мs = 212Аm2/kg)
was accepted for Ni-Fe alloy [9]:
Мs (Ni-Fe alloy) = 56.7 + 0.37 (ТC – 360).
The contribution of a mineral into bulk magnetization
cannot be estimated with the accuracy of better than 10%.
Accordingly accuracy for iron and alloy particles content
cannot be better. The accuracy of Curie point determina-
tion is ~5о-10o, which corresponds to a nickel admixture
of 1-2%. The lack of the linear dependence of TC - Ni
and the limited accuracy of ТMA are compensated by the
simplicity of sample preparation and their TMA, allow-
ing quick acquisition of large datasets.
The content of magnetite and titanomagnetite were
determined to take into account re-deposition during ac-
cumulation of iron particles. Their formation and accu-
mulation, unlike native iron, has a terrestrial origin. The
coefficients of linear correlation of iron and magnetite +
titanomagnetite were calculated (Table 3).
Sequences of deposition of all sections are translated
into a time for convenience of their comparison as fol-
lows: it was assumed that the sediments accumulated
with a constant velocity during each stratigraphic stage.
Table 3. Coefficients of linear correlation between particles
of magnetite + titanomagnetite and iron
Gams 0,048
Selbuhra –0,034
Verhorechie –0,319
Kvirinaki –0,041
Tetritskaro 0,068
Klyuchi + Teplovka –0,198
Aimaki 0,147
Dzhengutaj 0,093
Madzhalis –0,094
Bass –0,077
Gergebil –0,083
Kara-Kala 0,187
Khalats –0,212
Koshak –0,206
This velocity was defined by dividing the duration of a
stage by its thickness. Then, the age of each sampling
point was defined by multiplying the distance (thickness)
to the stage boundary by the sedimentation velocity. The
stage ages were taken from the geological time scale-
2008 [18].
3. Results of Thermomagnetic Studies and
Discussion
Content of metallic particles in sediments. The particles
of native iron were found in 521 samples out of 901 stu-
died, their concentration ranging from 10-5% to 0.05%.
The bimodal distribution of concentration of iron parti-
cles is usually clearly visible for separate sections, areas,
and the sum of the data (Figure 3): the first set with the
"zero" mode comprises the deposits, in which iron is
absent (it is not found out by ТMA); distribution of such
sediments in the studied sections is irregular. The second
set has more often lognormal distribution with the slight-
ly age-dependent modes: the Late Cretaceous modes are
~0.05-0.1 × 10-3% (Gams, Crimea, Caucasus, Mangy-
shlak, and Kopetdag), the Early Cretaceous mode for the
North Caucasus is 0.15 × 10-3% (Gergebil), and the larg-
est modal values of 0.5 × 10-3% (Khalats) and 3 × 10-3%
(Kvirinaki) are for Miocene sediments.
Four types of accumulation of metallic particles in the
sediments are recognized:
Dotty type: the increased iron content is found in one
sample, in a "dot", and is absent in the adjacent samples.
This type has a random character and can result from the
primary fall of iron into the sediment and from its
re-deposition.
Local type: the increased content of iron is found in a
series of adjacent samples from a section and cannot
trace from section to section. Such local accumulation of
iron can occupy a long enough interval of time. Most
likely, it is combination of primary accumulation and
secondary re-deposition. Example of long non-uniform
local primary accumulation of iron is the Bass section in
the interval from 81 Ma to 72 Ma. An example of long
mainly secondary accumulation of iron as a result of
re-deposition is the Kara-Kala section in interval from 95
Ma to 99 Ma [7].
Regional type: the enrichment by iron is found in
synchronous intervals at several sections in a region. It is
unlikely that it is a result of re-deposition, which was
synchronous over a wide area. The regional effect of
enrichment by iron of sediments becomes more clearly
visible if to combine all studied sections (Figure 4).
Global type: the enrichment by iron is found in syn-
chronous intervals at several sections from different re-
mote regions.
It is possible to recognize the following intervals of
regional and global enrichment by iron (Figure 4):
1) 12-13 Ma, the Middle-Late Miocene. The iron con-

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis 147
tent that reaches 4 × 10-3% is found at two sections (Kha-
lats and Kvirinaki) that are more than 1500 km apart.
2) 64-67 Ma, Early Danian-Late Maastrichtian. The
iron content that reaches 4 × 10-3% is found in the Gams,
North Caucasus, Teplovka sections, but isn’t detected in
the Crimea, Tetritskaro, and Koshak sections.
3) 84-86 Ma, Santonian. The increased iron concentra-
tion is found at five sections that are more 1000 km apart,
with the maximum content ranging from 0.2 × 10-3%
(Madzhalis) to 2.9 × 10-3% (Kara-Kala). This interval
nearly coincides with the upper boundary of the Dzhalal
paleomagnetic hyperchron (the interval of the geomag-
netic field without reversals, 125-85 Ma [19]). The lower
boundary of the Dzhalal hyperchron is not defined accu-
rately, probably because of sparse sampling at the Ger-
gebil (Caucasus) and Verhorechie (Crimea) sections (Fig-
ure 4).
4) 94-96 Ma, Late Cenomanian. The increased iron
concentration is found at the Aimaki (94.9-95.6 Ma) and
Kara-Kala (93.8-97.4 Ma) sections that are more than
1000 km apart. With a less certainty, this interval can be
related to the global enrichment by iron because of some
role of iron re-deposition in the lower parts of both sec-
tions [7].
The wide spatial distribution of iron particles and
global character of the above noted intervals of the in-
creased iron concentration testifies to the cosmic dust as
their main cause. The iron particles fell on the Earth sur-
face irregularly and probably came from different
sources, as is indicated by the bimodal distribution of
their concentrations (Figure 3).
In contrast to iron particles, the particles of Ni-Fe alloy
with > 20% Ni are rare, their concentration does not cor-
relate with the concentration of iron particles (r = –0.045).
Appreciable correlation with the magnetite + titanomag-
netite concentration (r = 0.7) in the sediments may mean
that the noticeable part of these particles is not a Ni-Fe
alloy, while the terrestrial minerals, like titanomagnetite
and hemoilmenite, are fully preserved after heating to
800оС, which is unlikely. Otherwise, these are the parti-
cles of a Ni-Fe alloy that were re-deposited together with
terrestrial minerals. Such a sharp difference in the quan-
tity and accumulation conditions between iron and Ni-Fe
alloy particles and the absence of correlation between
their contents most likely testifies to their different origin.
If the first are produced by cosmic dust fall on the Earth
surface, the second are possibly connected with impact
events. Irrespective of the reliability of detecting Ni-Fe
alloy particles, it is possible to assert that their concentra-
tion is likely to be below 10-5% (i.e., below of sensitivity
threshold of ТMA) in the cosmic dust.
Figure 3. Histograms of iron particles concentrations in the
studied sections. Intervals of iron concentrations (logarith-
mic scale): 1 – 0-0.01(10-3%); 2 – 0.01-0.03; 3 – 0.03-0.07; 4
– 0.07-0.15; 5 – 0.15-0.31; 6 – 0.31-0.63; 7 – 0.63-1.27; 8 –
1.27-2.55; 9 – 2.55-5.11; 10 – 5.11-10.23; 11 – 10.23-20.49;
12 – 20.49-54 (10-3%). Histograms are arranged on age
from Miocene to Early Cretaceous
Composition of metallic particles. Judging by the Cu-
rie points, composition of iron particles varies approxi-
mately in the same range from 680оC to 780оC in all sec-
tions that corresponds to Ni-content from 22% to zero

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis 148
(a) (b)
Figure 4. Iron distribution in (a) Miocene and (b) Cretaceous sediments. The sum of the data
(Figure 5). From TC = 690oC to 360оC, the number of
particles sharply decreases, they are absent altogether.
Really, just 46 samples with Curie points of 360oC to
660оC, and hence probably containing particles of a
Ni-Fe alloy, are found (Table 4, Figure 5). The errors in
detection of Ni-Fe alloy are quite probable, and so the
proven cases of Ni-Fe alloy cannot exceed the above
number. The rarity of Ni-Fe alloys of intermediate com-
position among metal particles of cosmic dust is con-
firmed with direct measurements of composition of dust
particles (Figure 1). Dust particles of pure nickel (Ni80-
100%) were met indeed (Figure 1), but practically all of
them are from one point of the К/Т boundary layer in the
Gams section [1].
Figure 5 demonstrates that the distribution of iron par-
ticles composition falls into two groups (not counting the
“tail” in the interval 350oC-660оС): 1) pure iron without
nickel addition and 2) nearly lognormal distribution with
the mode of nickel of 5%. Bimodal distribution of parti-
cles of iron, probably, reflects different sources of pure
iron and iron with the nickel impurity.
The second set with the mode Ni of 5% is sufficiently
proven by the data on composition of dust particles
(Figure 1). The first set of pure iron agrees with the data
on lunar samples. For example, metal particles from the
lunar material such as volcanic glass, basalts and breccias
that was delivered by Apollo 11 and 12 consist mainly of
nearly pure iron [20-29]. Curie points close to 770оC
prevail, with average TC = 765oC. It is quite probable that
it is specificity of lunar magmatic rocks. Fragments of
meteorites, which have been picked up on the Moon
during the Apollo missions, contain Fe-Ni alloys of in-
termediate composition that are usual for metal meteor-
ites. Numerous microspherules (products of impacts)
contain of nickel from < 1 to > 20 wt. % [29-31]. Irre-
versible character of heating-cooling M (T) curves, pecu-
liar for α - γ transformation in Fe-Ni alloys, was marked.
Visible regularities in Curie point distribution and,
accordingly, the nickel content in iron particles, were not
found between sections. The compositions of iron parti-
cles form a diffuse cloud (Figure 6(а)), which is typical
for the cosmic dust. Nearly constant smoothed values of
Ni content are observed in the 110-60 Ma interval (Figure
6(b)). They vary within 6-8%, i.e. within the error limits
of Curie point estimation. The average content of nickel
is 5% in Lower Cretaceous and Miocene sediments. The

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis 149
Figure 5. The histogram of distribution of Curie points (the content of nickel impurity in iron particles ±1%). The sum of the
data. 1 – 350оC (100%Ni); 2 – 360оC (100%Ni); 3 – 370 (97.6%Ni); 5 - 390 (92.7%Ni); 7 – 410 (87.8%Ni); 10 – 440оC
(80.5%Ni); 11 – 450 (78.1%Ni); 12 – 460оC (75.6%Ni); 14 – 480оC (70.8%Ni); 15 – 490оC (68.3%Ni); 16 – 500оC (65.9%Ni);
17 – 510оC (63.4%Ni); 18 – 520оC (61%Ni); 19 – 530оC (58.6%Ni); 29 – 630оC (34.2%Ni); 31 – 650оC (29.3%Ni); 32 – 660оC
(26.8%Ni); 35 – 690оC (19.5%Ni); 36 – 700оC (17.1%Ni); 37 – 710оC (14.6%Ni); 38 – 720оC (12.2%Ni); 39 – 730оC (9.8%Ni);
40 – 740оC (7.3%Ni); 41 – 750оC (4.9%Ni); 42 – 760оC (2.4%Ni); 43 – 770оC (0%Ni)
(a) (b)
Figure 6. The distribution of contents of nickel impurity in iron particles depending on age of sediments. (a) The sum of the
data; (b) Result of their smoothing. Interval of smoothing is 9 million years; a step is 1 million years

150 Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis
Table 4. Ni-Fe-alloys in sediments
section Sample TC %Ni Ni Fe МТ Ма N N(Fe) N(Ni)
Aimaki 2035-7 450 78,5 0,11 0,09 1 99,06 112 60 1
Bass 2029-110 370 97 0,1 0 0,4 62,78 104 57 2
2029-100 500 66,6 0,08 0,01 0,3 64,96
Gergebil 2038-206 460 76,2 0,12 0 0,9 110,13 44 36 4
83 380 93 0,4 0 2 123,8
31 455 77,4 0,3 0 24,5 127,36
6 360 100 0,35 0 23,2 129,43
Madzhalis 2061-48 440 81 0,02 0 0,7 86,1 57 39 2
37 365 98 0,05 0 0,3 87,2
Dzhengutaj 2057-78 445 79,7 0,04 0,8 1,28 84,4 13 8 2
19 455 77,4 0,03 0,03 1,3 89,5
Karakala 2048-128 455 77,4 0,13 0,04 6,3 69,72 181 98 3
138 450 78,5 0,05 0,03 2 70,64
175 440 81 0,01 0,01 8,6 74,5
Selbuhra 2562-4 440 81 0,1 0,14 0,8 99,02 46 36 2
2562-7 440 81 0,07 0,12 0,75 98,44
Kvirinaki 384 525 60 0,46 1,1 20 15,04 77 31 2?
385 515? 63,1 0,45 0,2 20 14,96
Klyuchi 2 370 97 0,08 0,12 0,5 65,7 9 3 2
3 390? 92,8 0,07 0,02 1,6 65,6
Teplovka 10 5 0
Koshak 104 455 77,4 0,02 0,02 0,15 67,3 20 13 1
Tetritskaro 1--1 475 72,6 0,09 0 0,17 65,5 81 37 13
1--4 485 70,2 0,04 0 0,02 65,5
5 360? 100 0,11 0 0,12 65,47
6 530? 59,5
0,0040 0,1 65,45
14 410? 88,1 0,02 0 0,4 64,94
15 635? 34,5 0,03 0 1 64,81
19--1 355 100 0,12 0,07 1 65,51
21 350? 100 0,03 0,02 0,4 65,52
23 350? 100 0,02 0 7,6 65,54
24 355 100 0,21 0,05 2,6 65,58
25 355? 100 0,09 0 1,3 65,65
39 350? 100 0,06 0 0,9 67,1
глина б. 515 63,1 0,1 0 0,7 65,5
Khalats 16-68 350? 100 0,06 0,1 3 16,4 49 30 7
41-68 510? 64,3 0,13 1,5 11,5 12,35
44-68 515 63,1 0,08 0,1 8 12
49-68 510? 64,3 0,13 1 12 10,95
54-68 510? 64,3 0,14 0,3 14,5 10,4
59-68 510 64,3 0,09 0,2 10 9,5
68-68 505? 65,5 0,18 0 18 2,85
Gams J6 355 100 200 0,05 50 65,5 98 68 2
J4 355 100 5 0,05 2 65,5
J3-1 650 22 0,2 0,2 5 65,5
J4-1 650 22 0,19 0,16 6 65,5
T14 660 27 0,09 0,1 8 65,47
sum 901 521 43
Footnote: TC – Curie point of Ni-Fe alloy particles, oC; %Ni – content of nickel in alloy, determined by linear dependence TC – Ni; Ni – percentage
of Ni-Fe alloy (10-3%) in sample; Fe – percentage of iron (10-3%) in the same sample; МТ– percentage of magnetite + titanomagnetite (10-3%) in the
same sample; Ma – the age of sediment in the point of selection of the sample; N – total number measured ТМА samples in the given section; N (Fe)
– number of samples in which iron particles are revealed; N (Ni) - number of samples in which Ni-Fe alloy with TC < 670°C is found out.

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis 151
permanent average composition of iron particles is likely
to imply the constancy of the cosmic dust cloud, through
which our planet moved. It is important to emphasize
that, unlike the concentration of iron in sediments, which
depend on re-deposition, the re-deposition does not affect
the composition of iron grains.
The time-distribution of iron particles with nickel con-
tent close to the modes of the two sets (zero and 5% ± 1%)
also has no prominent features (Figure 7). It is important
to note that their distributions are not correlated with each
other (Figure 8). This indicates the different sources of
particles of pure iron and iron with nickel addition.
(a) (b)
Figure 7. The distribution of contents of nickel impurity in iron particles, close to modes, depending on age of sediments: (a)
Pure iron; (b) Iron with a nickel impurity 5 ± 1%. The percentage of cases is display in one million years carried to total
number of cases in the same one million years interval since the number of the data on one million years considerably varies
from units to 70
Figure 8. The correlation between number of cases with modal nickel impurity of 0% and 5 ± 1%. For comparability of the
data on axes the percentage of cases is display in each one million years in relation to total number of the data on the same
one million years (see Figure 7)

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis 152
During four intervals of global enrichment of sedi-
ments by iron, the particles of the second set (Fe with Ni
addition) obviously prevail (Figure 9). The number of
cases of pure iron is insignificant and varies from interval
to interval: 1) Just one sample with pure iron out 16
ТMA data is found for the 10-13 Ma interval. The nickel
content varies from 3% to 10%, 5.2% on average. 2) For
the 64-66 Ma interval, pure iron is found in eight cases
out of 150 ТMA data. The nickel admixture varies from
2 to 34%, 7.6% on average. 3) For the interval 84-86 Ma,
pure iron is found in twelve cases out of 68 ТMA data.
The nickel admixture varies from 2 to 20%, 8.4% on
average. 4) For the 94-96 Ma interval, pure iron is de-
tected in two cases out of 48 ТMA data. The nickel ad-
mixture varies from 2 to 20%, 8.1% on average. So, the
average nickel contents nearly coincide in the Late Cre-
taceous intervals and significantly differ in the Miocene.
No correlation between the concentration of iron parti-
cles and the nickel content in them is observed (r =
–0,024). On this background, a peak of enrichment by
iron with almost constant nickel content of 5% is visible,
irrespective of the place and age of sediments (Figure
10). This enrichment is found even in Crimea, where the
iron content very low (Figure 10). Thus this is a certain
global effect.
4. Conclusions
The detailed pattern of distribution of native iron parti-
cles in place and time during the Cretaceous, Danian and
Miocene is discovered with the aid of thermomagnetic
analysis up to 800ºС.
The main results of our studies are as follows:
1) The concentration of native iron particles in sedi-
ments ranges from 10-5% to 0.05%; they are found in 521
samples out of 921 studied from 15 Cretaceous, Danian
and Miocene sections of Austria, Russia (the Volga re-
gion, Caucasus), Georgia, Kazakhstan and Turkmenistan.
Irrespective of sediment age and locality, their bimodal
distribution is typical. The first set with the zero mode
includes the sediments, in which iron is not revealed by
ТMA; the distribution of such deposits in the studied
sections is irregular and likely reflects the non-uniformity
of iron particle fall. The second set has lognormal distri-
bution with the mode of 0.04-0.15 (10-3%).
2) The global enrichment by iron particles is discov-
ered in Miocene (12-13 Ma), Maastrichtian-Danian
(64-66 Ma), Santonian (84-86 Ma) and Cenomanian
(94-96 Ma) deposits in the sections more than 1000km
apart.
The omnipresence of iron particles and global spread
Figure 9. The content of nickel impurity in intervals of global enrichment of iron particles in sediments

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis 153
Figure 10. Dependence of nickel impurity in iron particles
from their content in the sediment. The maximum concen-
trations of iron particles are denoted by red color
of the above-noted intervals of iron enrichment indicates
the cosmic dust as their main source. Iron particles fall to
the Earth surface irregularly and probably from different
sources, as may be inferred from bimodal distribution of
their concentration.
3) Distribution of iron particles composition falls into
two sets: the first one corresponds to pure iron without
nickel, and the second set has the nearly lognormal dis-
tribution with the modal nickel of 5%. This bimodal dis-
tribution implies different origin for of pure iron particles
and those with a nickel addition. The lunar rocks are may
be the source for the first type. It is worth noting that
there are quite few particles with Curie points between
680оС and 360оС; hence the particles of Fe-Ni alloys of
such composition are very rare.
The difference in quantities of iron and Ni-Fe alloy
particles and the absence of correlation between their
contents indicates their different origin. If the first ones
are mainly produced by the fall of cosmic dust on the
Earth surface, the second ones are possibly connected
with meteorites and impact events.
In all cases, it is possible to assert that the possible
concentration of Ni-Fe alloy particles is below 10-5%
(which is the ТMA sensitivity) in the cosmic dust. This
conclusion is valid irrespective of the reliability, with
which Ni-Fe alloy particles are detected.
4) There is no correlation between the concentration of
iron particles in sediments and nickel content in them. At
the same time, the peak of high iron concentration with
the same nickel content of 5% is found in almost all stu-
died sections irrespective of the location and age of these
sediments. Thus it is a certain global effect.
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