Study of impact materials of akhnoor meteor crater in Jammu and Kashmir (India)

doi:10.4236/ns.2011.36058

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Vol.3, No.6, 426-429 (2011) Natural Science

http://dx.doi.org/10.4236/ns.2011.36058

Study of impact materials of Akhnoor Meteor Crater in

Jammu and Kashmir (India)

Naseer Iqbal1*, Ajaz Ahmad1, Tabasum Masood1, Mayank Nalinkant Vahia2

1Department of Physics, University of Kashmir, Srinagar, India; *corresponding author: [email protected]

2Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai, India

Received 12 February 2011; revised 28 March 2011; accepted 10 April 2011.

ABSTRACT

A sample of Akhnoor meteor crater, which fell

on 2nd January 2009 in Jammu District, Jammu

& Kashmir, India, has been analyzed for ele-

mental composition by Spectroscopic tech-

niques. Concentrations of 17 major, minor and

trace elements were determined. The authentic-

ity of the meteorite sample was established by

comparing its composition with those of stan-

dard meteorites/chondrite. The classification of

the sample has been made by comparing the

abundances and concentration ratios of ele-

ments with other known meteorites.

Keywords: Meteor Impact; Creator; Stony

Meteorite

1. INTRODUCTION

Meteorites are generally dense, magnetic and contain

oxides of metals. They show high enrichment of ele-

ments like Fe, Ni and Cr compared to crustal elemental

abundances. They are classified on the basis of their

mineralogy, structure and chemical compositions [1-4].

The main classes of meteorites are: 1) stony meteorites

constituting 92.8% of all meteorites, 2) stony iron me-

teorites constituting nearly 1.5% and 3) iron meteorites

with abundance of 5.7%. One of the important features

of meteorite analysis is to distinguish the sample from

that of a terrestrial one and to classify the meteorite

regarding its origin. The standard method for identify-

ing meteorites is to compare the chemical composition

of the sample with that of the meteoritic rock previously

studied. Intermetallic elemental concentration ratios like

Fe+ Mg: Al, Fe: Ni, Fe: Mn, As: K and Th: Sm are fre-

quently used for classification [4-6]. The elemental

abundances of platinum group elements (PGEs) such as

Ir, Os and Pt along with gold play an important role in

the study of meteorites [6,7]. In impact craters, these

elements occur in concentrations that are 20 - 100 thou-

sand times greater than those on the earth’s crust. Such

abnormal concentrations are also used as evidence for

meteor impact.

On January 2009, a meteorite fall was witnessed in the

Jammu division of Jammu and Kashmir (India). The

meteorite arrived from north-east with high inclination

path. The fireball produced by the meteoritic fall was

exceptionally bright and was witnessed by the residents

of the Akhnoor region of Jammu division. The fall took

place on a cemented ladder as a result the formation of

the crater was very small (Figures 1 and 2). From the

morphological analysis we report the radius of the me-

teor to be roughly about 4 cm. Samples from the crater

was collected for investigation. The present study on

chemical composition analysis corresponds to a meteor-

ite sample collected from one of the craters which we

have named as Akhnoor Meteor crater.

2. METEORITIC COMPONENTS

Meteoritic composition is the common way adopted

for the confirmation of

Meteorite. The analysis of planetary material by Wat-

son and others has marked the presence of following

elemental concentrations in stony and iron meteorites in

comparison with the abundance of the elements in the

earth’s crust [8] Table 1. A comparison of some of the

elemental concentrations obtained for the meteorite

sample with those of the earth’s crust and an ordinary

chondrite [4] is given in Table 2. There is good agree-

ment among these values except for lanthanum, con-

firming that the sample under investigation is of meteor-

itic origin. The Fe/Mn ratio is another indicative pa-

rameter for samples of meteoritic origin. The ratio for

the present meteorite sample is 106. This value is com-

parable with that of the Czech meteorite (Fe/Mn = 94),

but is lower than that of the Kobe meteorite (Fe/Mn =

175). We have compared the Ni to Cr ratio obtained in

this work with some of the typical values of chondrites.

The value obtained in the present case is 4.26 compared

N. Iqbal et al. / Natural Science 3 (2011) 426-429

427

to the values for the chondrites which range from 4.1 to

4.8. Further inter-comparison of the analytical data with

some known meteorites [1,2] was carried out with the

aim to classify the Akhnoor meteorite according to its

elemental content. The classification of Kobe meteorites

for one of CK class are mainly based on the Si-norma-

lized Al, Mg, Ca and Ti values [1]. Comparison of the

Al/Ca, Al/Mg and Ca/Mg ratios in our case with those of

the Kobe and Czech Meteorites show good agreement;

hence we believe that the Akhnoor meteorite may be of

the same class as that of the Kobe meteorite, namely CK,

which is a carbonaceous.

Figure 1. Samples of the meteor, collected from inside

the crater.

Figure 2. An outline of the Akhnoor meteor crater

showing circular ring structure.

Table1. Concentration of elements of Akhnoor meteorite along

with with corresponding values from Kobe and Crech meteor-

ite.

Element Akhnoor

meteorite

Kobe

meteorite

Czech me-

teorite

Fe 20.2 23.1 24.02

Si 15.7 15.1 18.1

Mn 0.19 0.132 0.255

Cr 0.34 0.365 0.280

Co 0.05 0.0714 0.061

K 0.09 0.0260 NA

Na 0.65 0.22 0.58

Cu 0.027 NA 0.0179

Mg 14.5 14.2 15.98

Ca 1.35 1.63 1.39

Al 1.18 1.29 1.18

Ni 1.42 1.46 1.32

Sc NA NA 7.91

As NA NA 2.24

Au NA NA 0.23

La NA NA 0.44

Eu NA NA 0.077

Sm NA NA 0.261

Ir (mg/kg) 0.29 NA 0.603

Br NA NA 9.6

V NA NA 85.25

Table 2. Average Concentration of different elements in Iron

meteorites, stony meteorites and earth’s crust.

Elements

Percentage

present in Iron

Meteorites

Percentage

present in Stony

Meteorites

Percentage

present in Earth’s

Crust

Iron 90.8% 25.6% 4.7%

Cobalt 0.59 0.14 -

Nickel 8.5 1.4 0.02

Sulphur 0.04 - -

Carbon 0.03 - -

Copper 0.02 - -

Chromium 0.01 0.27 0.03

Oxygen - 36.3 49.4

Silicon - 18.0 25.8

Magnesium- 14.2 1.9

Aluminum - 1.5 7.5

Calcium - 1.3 3.4

Sodium - 0.6 2.6

Manganese - 0.18 0.08

Potassium - 0.13 2.4

Titanium - 0.10 0.58

Samarium - - -

Europium - - -

Phosphorus0.17 0.14 0.12

N. Iqbal et al. / Natural Science 3 (2011) 426-429

428

Figure 3. Graph plotted between Energy and Pressure [9].

Figure 4. Graph plotted between speed and Energy [9].

Iridium is present in small amounts in the earth’s crust

and upper mantle, but is more abundant in both the

earth’s core and meteorites. We observed Ir in the pre-

sent case and its concentration (0.29 mg/ kg) is ~ 290

times higher than that in the earth’s crust. The concen-

tration values obtained for all the elements were com-

pared with their respective crustal elemental abundance

values. It is observed that the values corresponding to Fe,

Mg, Cr and Ni are higher than the crustal values, whe-

reas the values for elements like Al, Ca and Na are lower.

Data obtained based on chemical composition claims

that the said sample collected is of meteoritic origin.

3. ANALYSIS

While analyzing the graph plotted between the radius

of the Meteor and the corresponding energy of the Me-

teor we report here that the energy associated with

Figure 5. Graph plotted between Radius of Meteor and En-

ergy. The value has been calculated at rough radius of the

meteor 2.0 cm.

the Akhnor Meteor crater is approximately 1,000 GJ [9]

(Figures 3-5). By comparing the Energy of the Meteor-

ite with the speed and the pressure exerted by the mete-

orite and by using the graphs reported by Mark and oth-

ers [9], plotted between the Energy of the meteorite with

pressure exerted by it and the Energy with speed, we

reveal here an another remark that the Meteor has hit the

surface of the Earth with a speed of 30,000 m/s and has

exerted a pressure of 2128 kbars.

4. RESULTS

The following conclusions have been drawn about the

Akhnoor Meteor crater.

The Akhnoor meteor crater is a stony Meteorite.

The approximate energy of the meteorite had been

1000 GJ.

The meteor had hit the earth’s surface with a velocity

of 30,000 m/s and exerted a pressure of 2128 kbars.

5. ACKNOWLEDGEMENTS

The Authors are grateful to the Jamestiji Tata trust Mumbai for their

support in Carrying out this work. Thanks are also due to Sheri Kash-

mir University of Agricultural Sciences and Technology, University

Scientific instrumentation Centre (University of Kashmir Srinagar

India) and Department of Geology and Geophysics University of

Kashmir for their help in carrying the necessary scientific investiga-

tions. Thanks are also due to IUCAA Pune India for their hospitality in

preparing this manuscript.

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