MINERALOGY AND PETROLOGY OF THE SITTAMPUNDI COMPLEX SALEM DISTRICT, MADRAS STATE, INDIA

229 Pages·9.474 MB·English

by  SUBRAMANIAM, ANANTHARAMA PARAMESWARA

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MINERALOGY AND PETROLOGY OF THE SITTAMRJNDI COMPLEX
SALEM DISTRICT, MADRAS STATE, INDIA
f LV
kt
P . SUBRAMANIAM
- i -
CONTENTS
PREFACE..........................................................viii
ABSTRACT........................................................ xi
CHAPTER I - LOCATION AND HISTORICAL REVIEW ...................1
Introduction, location................................. 1
Historical review . . . . . . . . . . . . .................... 2
Present Study . ........................................... 8
CHAPTER II - REGIONAL GEOLOGY AND THE SETTING OF THE COMPLEX . . . . 10
Archaean Geology of Peninsular India. ............... 10
Geology of the Anorthosite-eclogite gabbro complex . . . . . . 18
Structure of the complex. ............. 22
CHAPTER III - MINERALOGY......................................... 24
Introduction, methods of separation, and determination
of optical properties . . . . . . . . . . . . . . . . . . . . . 24
Explanation of tabular statement of analyses of minerals. ... 51
Garnets............................... 55
Plagioclaee Feldspars . . . . . . . . . . . . . . . . . . . . . 42
Clinozoisite. . ................................ 57
' Cordierite . . . . . . . . . . . . .............. . . . . . . 65
Anthophyllite . ............................ 70
r
Clino-amphiboles. 75
• T, Chromite.................................................... 85
^ Pyroxenes . . . . . . . . . . . . . . . . . . . . . . 89
r Scapolite . . . . . . .......... . . . . . . . . . . . . . . . 91
I '
Corundum, sillimanite, rutile, sphene, etc. 92
a
"I Summary..................................................... 9^
c/
- ii -
CHAPTER IV - PETROGRAPHY.......................................... 95
Anorthooite series-* general description* 95
Description of principal types ............. 102
Chromitites . ............ ............................. 108
Cordierite-corundum-anthophyllite-amorthite-bytownite rock. . . 109
Eclogite gabbro series-general description. 110
Description of principal types......... ............... . H5
Retrograde characters of eclogitee..........................117
Pyroxenite - Websterite 119
Amphibolite.............................................. I20
CHAPTER V - CHEMICAL GEOLOGY AND .................... 125
Anorthosite series • • • • • • • • • • • • • • • • • • • • • * 125
Epidote-plagioclase equilibrium • * . • • • • • • • • • • • • • 127
Metamorphic facies.................... ................... I2®
Cordierite-corundum-anthophyllite-anorthite-bytownite rocks . . 129
Problem of the eclogites. 150
Eclogite rocks of the Sittampundi complex.................. 155
(FeO+MnO)tMgO,CaO, diagram................................. 15^
Origin of eclogites ............... . . • • • • • • • • • • • 157
Metamorphism of the complex as a whole . . * • . « • • • • • • 159
Origin of chromite 1^1
Origin of corundum................................... . 1^5
Origin of banding in the complex..........................1^5
Preferred orientation of minerals . . • * • • • • • • • • • • • 1^7
CHAPTER VI - FETROGENESIS..................................... 1*9
Comparison with stratiform sheets and evidence for
igneous origin of the complex . * • • * ........... . • • • • 149
Summary......... ....................................
BIBLIOGRAPHY..................................................
- ill -
TABLES
Par,
I. Chemical composition and physical and optical properties of
some minerals from the Sittampundi complex 52A
II. Composition and physical properties of Garnet C.12 54
III. Physical properties of Garnet end members 56
Refractive indices of some garnets with estimated composition
and the compositions of associated plagioclase and orthopyroxene
IV. Composition and physical properties of Garnet C.41 57
V. Composition and physical properties of Garnet C.60 58
VI. Chemical composition and physical properties of eclogite garnets 59
VII. Chemical composition of anorthite from Sittampundi 44
Partial spectroscopic analyses of rome anorthitic feldspars
VIII. Chemical composition and physical properties of some anorthites 4^
IX. Anorthite content of plagioclaees in Sittampundi rocks by
various methods 50
X. Twinning laws of Plagioclase Feldspars in the Sittampundi Rocks 55
XI. Analyses of clinozoisite from Anorthite—corundum rocks of Salem 58
XII. Composition of clinozoisite C.59 59
XIII. Molecular formula and physical properties of clinozoisite C.59 60
XIV. Chemical composition and physical properties of some clinozoisites 6l
XV. Composition of Cordlerite C.71 64
XVI. Composition and physical properties of someo agnesian cordierites 65
XVII. Composition and optical properties of Cordierite C.71 66
XVIII. Composition of Anthophyilite C.58 71
XIX. Composition of amphibole 0.54 74
XX. Composition of amphibole C.70 75
XXI. Composition of amphibole from rock C.55 (calculation) 76
XXII. Composition of amphibole C.55 77
XXIII. Structural account of the analyzed amphiboles, after Sundius,
indicating affinities to the Edenlte and Fargaaite type 78
%
- iv -
XXIV. Optical and physical properties of analyzed amphiboles 79
XXV. Optical properties of some amphiboles 80
XXVI. Composition of Chromite from Chromitite C.101 85
XXVII. Calculation of atoms per unit cell of chromite C.101 86
XXVIII. Chemical composition of some chromites from stratiform sheets 87
XXIX. Approximate modes of rocks from the Sittampundi complex(weight^) 96
XXX. Chemical composition with normative and modal mineralogical
composition of some rocks from the Sittampundi complex 120
XXXI. Analyses of anorthosites from South Africa, Sweden, and
Sittampundi Complex 125
XXXII. Chemical composition of Eclogite gabbro C.4l, together with
comparable analyses 124
XXXIII. Molecular ratios (FeO+MnO), C&O, and MgO of Qabbroic and
eclogitic rocks, together with those of the garnets in them
in so far as available, recalculated to 100$6 155
XXXIV. Comparative vertical sequence in some gravity stratified sheet
complexes 150
*
ILUJSTRATICNS
Plate Between Pages
I. 5-4
i)View of ancient corundum workings on anorthosite band,
south of Sittampundi. Note barren nature of country.
ii)Low hill of anorthosite north of Kattipalaiyam,towards
the N.E. end of complex.
II. 18-19
i)Steeply dipping anorthosite near Pamandapalaiyam.
ii;Anorthosite outcrop east of Kattupaliyam,note lower dip.
III. 18-19
i)Foliated amphibolite on northern margin of complex,south
of Konaaamudram.
ii)Typical exposure of weathered anorthosite south of Sittam­
pundi.
IV. 20-21
i)Typical exposure of anorthosite with mafic bands on high
ground south of Sittampundi.
ii)0utcrop of eclogite-gabbro near Gangarapalaiyam, note
visible foliation.
V. 20-21
i)Anorthosite with mafic layers, near Molasi, western end
of complex.
ii)Large band of hornblende rock in anorthosite, outcrop near
Sanarpalaiyam.
VI. 20-21
i)Banded anorthosite near Syakkadupudur
ii; Mafic bands in anorthosite, outcrop near Mannadipalaiyam.
VII. 21-22
i)P«eudo-Boudinage structure of mafic bands in anorthosite,
outcrop north of Kattipalaiyam
ii) Seam of chromitite in old corundum quarry at Karungalpatti
VIII. 21-22
i)Jointing in chromitite at Karungalpatti quarry.
Xi)Jointing in chromitite at Karungalpatti quarry.
IX. 21-22
i)Jointing in anorthosite, old corundum quarry south of
Sittampundi.
ii)Jointing in anorthosite outcrop at Kottakkaradu east of Karungalpatti.
X. 22-25
Diagramstic interpretation of the form and structure of Complex*.
Vi -
XI. 54-55
i )Bhotomicrograph, showing garnet replacing anorthite. X 10
Ii)Photomicrograph, showing garnets with dactylitic rims,
in eclogite-gabbro. X 55
XII. 54-55
Micrograph showing garnet selectively replacing anorthite.
XIII. 41-42
Micrograph of garnet in eclogite gabbro, with plagioclase
hornblende symplectite.
XIV. 41-42
Micrograph of garnet crystal in eclogite gabbro
XV. 48-49
Curve correlating the indices of refration and 'An1 content
for calcic plagioclase indicating position of Sittampundi
pl&giocl&ses.
XVI. 51-52
Fnotomicrograph of anorthite clinozoisite rock showing a
crystal of anorthite displaying complex albite-Ala twinning. X 22
XVII. 61-62
Micrograph showing replacement of anorthite cy clinozoisite
XVIII. 61-62
Micrograph showing well developed crystal of clinozoisite in
anorthite gneiss.
XIX. 66-67
i)Fhotomicrograph of zoned crystal of clinozoisite. X 50•
ii)Photomicrograph of cordierite showing twinning. X 100.
XX. 66-67
Sketch of exposure of footwall of old dorundum quarry south
of Sittampundi, showing paragenetic relationship of corundum,
clinozoisite, garnet, and anorthite.
XXI. 71-72
i)Fhotomicrograph showing bladed anthophyllite in anorthosite.X9
ii)Photomicrograph showing bladed anthophyllite in chromitite.X10
XXII. 71-72
Micrograph showing anthophyllite in anorthosite.
XXXII. 82-65
Curves expressing the optical properties of hornblendes from
Sittampundi rocks, in relation to their chemical composition.
XXIV. 87-68
i)Faotomicrograph of polished section of chromite with
rutile. X 180.
ii)Photomicrograph of polished section of chromite with pAft.tea of
unknown mineral, note their geometric orientation. X 400
- vii -
XXV. 38-89
Triangular diagram after Stevens, showing position of
Sittampundi chromite.
XXVI. 90-91
i)Photomicrograph-8keletal crystals of diopside in anorthosite.
X.22.
ii)Photomicrograph-Ilmenite, rutile and aphene in snorthoBite, X.7.
xxvii. 90-91
2-a.crograph of skeletal crystals of diopside in anorthosite
showing p&ramorphic alteration to edenite.
XXVIII. 91-92
Micrograph of corundum replacing anorthite.
xxix. 96-9 7
i )Porphyroblast of corundum in anorthosite.
ii)Porphyroblast of corundum in anorthosite.
XXX. 105-104
i)Coarse anorthosite with anthophyllite
ii )Chromitite layer in hand specimen of anorthosite.
XXXI. 105-106
i)Photomicrograph of anorthosite displaying mosaic texture. X 10
ii)Fhotomicrograph of anorthosite showing preferred orientation. X7
XXXII. 105-106
i ^Photomicrograph of eclogite gabbro. X 9 •
ii )Photomicrograph of bytownite gneiss. X 7»
XXXIII. 114-115
Micrograph of eclogite
XXXIV. 114-115
Micrographs of garnet coronas in eclogite
XXXV. 114-115
i)Photomicrograph of eclogite gabbro. X 10
ii)Photomicrograph of bronzitic pyropite. X 10
XXXVI. 128-129
A C F Diagram for Amphibolite facies.
XXXVII. 129-150
A C F Diagram for Sanidinite facies
XXXVIII. 155-154
A C F Diagram for Eclogite facies.
XXXIX. 155-154
(FeO+MnO), MgO, OaO diagram.
XL. In pocket.
Petrological map of Sittampundi complex.
- viii -
PREFACE
During my official duties with the Geological Survey of India, I
had opportunities to make a fairly detailed field study of a group of
basic rocks from the Archaean complex of Peninsular India. The results
presented in this dissertation are the outcome of laboratory studies of
these rocks, carried out in the Department c-f Geology, Princeton University,
for the last tvro years.
I am deeply grateful to the Graduate School, Princeton University,
for the award of Scholarship and Fellowship for the academic years 19^9~50f
and 1950-51* covering the cost of tuition, and the Department of Geology
for generous grants, covering the cost of 18 chemical analyses of rocks and
minerals, 60 thin sections, and the illustrations in this paper.
I am under a deep debt of gratitude to ProfeesorsA. F. Buddington and
H. H. Hess, under whose general supervision this investigation was carried
out. Their stimulating discusssions of the problem and helpful criticisms
of the manuscript have greatly contributed to this study. The mineralogical
and petrographic studies were carried out principally under the generous
guidance of Professor Hess, and I am indebted to him for initiating me
in several optical methods with which I was unfamiliar. To Professor
E. Sampson, my thanks are due for useful discussions on the chromite
problem and for introducing me to the study of polished sections. I am
specially obliged to him for the photomicrographs in Plate XXIV, and for
polishing some of my chromites for microscopic study. Ify thanks are also
due to Dr. J. C. Maxwell for discussing some aspects of my problem and for
various suggestions, much appreciated by me. To the other members of
the faculty I am most grateful for the encouragement I have received