Đặc điểm quặng hoá liti vùng đức phổ sa huỳnh tt tiếng anh

1

MINISTRY OF EDUCATION AND TRAINING
HA NOI UNIVERSITY OF MINING AND GEOLOGY

DUONG NGOC TINH

THE LITHIUM MINERALIZATION
CHARACTERITICS IN DUC PHO - SA HUYNH

MAJOR: GEOLOGICAL ENGINEERING
CODE: 9520501

PHD DISSERTATION SUMMARY

Ha Noi - 2019


2
The thesis is executed at Department of Prospecting
and Exploration, Faculty of Geology, Ha Noi University
of Mining and Geology

ADVISOR AND CO-ADVISORS:
1. Asc.Prof. PhD. Nguyen Quang Luat,
Ha Noi University of Mining and Geology
2. PhD. Do Van Nhuan
Ha Noi University of Mining and Geology

Referee 1: Asc.Prof. PhD. Dang Xuan Phong,
Vietnam Union of Geological Sciences

Referee 2: PhD. Tran Ngoc Thai
Vietnam Institute of Geosciences and Mineral Resources
Referee 3: PhD. Nguyen Van Nguyen
General Department of Geology and Minerals of Vietnam

This PhD thesis will be examined by University’s PhD
Committee at Hanoi University of Mining and Geology, Duc
Thang Ward, Bac Tu Liem District, Hanoi
Schedule time:

The full version is available at National Library
and Ha Noi University of Mining and Geology’s Library


1
INTRODUCTION
1. Overview
Lithium (Li) is one of the strategic metals, having particularly important
applications in the fields of science, technology, energy and environmental
protection. The demand for lithium has been increasing while the resources and
reserves in the world are limited. The prospecting discovery and evaluation of
lithium deposits become necessary.
The lithium mineralization zone in Duc Pho - Sa Huynh region was
discovered in 2002 during mineral geological survey mapping at the scale of 1:
50,000, Ba To sheet group and evaluated from 2004-2009. This is similar type of
mineralization to Na-Li granite pegmatite type, which are the industrial valuable
deposits, the major lithium supply as well as another rare and precious minerals:
Sn, Ta, Nb, Be, Rb.
It can be said that this is the first lithium deposit in Viet Nam, which was
evaluated in detail, is the basic for lithium exploration and exploitation in the next

time. However, many problems must to be kept studying for further clarification:
To clarify characteristics of material composition; to determine the geological
conditions of ore formation, the relationship between magmatic, metamorphic
formations and physic-chemical conditions of ore formation; to define the ore
controlling elements: magma, tectonic structure, lithology - stratigraphy,
metasomatism activities; to establish the deposit types, classify the ore forms.
The thesis "The lithium mineralization characteristics in Duc Pho - Sa
Huynh region” is completely necessary and derived from the urgent
requirements in science and life.
2. Objective
The thesis aims to clarify the characteristics of material compositions,
origin and conditions of lithium ore formation in the area of study, creating a
scientific basis for determining the deposit types for exploration prospecting.
3. Research accountability
- Studying on the characteristics of material composition: Mineral
components, the assemblages of paragenesis minerals, forming, ore structure;
lithium chemical components and the assemblages of useful minor ones.
- Studying on the formation conditions: The geological conditions,
physic-chemical conditions of lithium formation.
- To study the lithium ore controlling elements.
- To establish the deposit types, classify the ore forms.
- To define the prospecting-forcasting premises and signs.


2
4. Research subject and scope
The thesis focuses on lithium ore and the related geological subjects in
Duc Pho - Sa Huynh region.
5. Academic and practical denotation.
a. Academic denotation

The establishment of lithium deposit types in the study area is the scientific
and practical basic supplementing theories for deposit-ore geosciences.
b. Practical denotation
The research results will contribute to orienting the survey and discovery
of similar mineral deposits for the basic geological survey plan on mineral
resources.
6. Proposes
1. The lithium ore in La Vi area, Duc Pho - Sa Huynh region belongs to
Na-Li – type pegmatite granite, pegmatite lepidolite subtype, formed during
metasomatism of pegmatite bodies and gresenization with overlaping tin
mineralization.
2. The factors controlling lithium ore in La Vi area, Duc Pho - Sa Huynh
include of: The intrusive magma factors are granitoid formations, sa Huynh
Complex (P3-T1 sh); tectonic - structural factors are the northwestern southeastern fault system; lithological - stratigraphic factors are crystalline schists
combination of Kan Nack complex surrounding the ore.
7. Original contribution
1. The topic studying results has clarified the geological, formation
physic-chemical conditions, the isotope age of lithium ore and the age of the
intrusive magma formation, Sa Huynh Complex. The analysed results shows
that the litium ore and granitoid rocks of Sa Huynh Complex have formation
ages of Late Permi to Early Trias (P3-T1).
2. The research results of stable isotope (δO18 & δD), petrography,
mineralography, inclusion have have determined that the origin of ore forming
solution derives from intrusive magma and the metamorphic processes related to
Lithium in the area.
3. The lithium industrial deposit types in Sa Huynh – Duc Pho have
established as Na-Li - type pegmatite granite, pegmatite lepidolite subtype,
which formed during metasomatism of pegmatite bodies and gresenization with
overlaping tin mineralization.
4. The factors controlling lithium ore in La Vi area, Duc Pho - Sa Huynh

region have been defined: Magma factors (Sa Huynh Complex granitoid); tectonic
- structural factors (the northwestern - southeastern fault system and sub-resulting


3
structures); lithological - stratigraphic factors (crystalline schists combination of
Kan Nack complex).
8. Data
The thesis is completed basing on own PhD candidate data when he had
carried out the Science and Technology project of TNMT.03.52 “Studying on the
distribution rules of rare lithium metallization in Kontum zone, orienting to the
investigation, discovery of rare metal ores”, the analyzed results (ore ages, magma
ages) and had referenced the projects such as: Assessment of tin ore and rare metal
potential (Ta, Li, Be) in La Vi, Quang Ngai province (Pham Van Thong, 2009);
Geological mapping and mineral investigation of Ba To sheets, scale 1: 50,000
(Duong Van Cau, 2004).
During carrying out the thesis as well as taking part in the other projects,
PhD candidate had the field excursions, studied some detailed sections of Duc
Pho - Sa Huynh area. Collected and analyzed different kind of samples: 139
thinsection lithological samples, 85 polished samples, 30 microsond, 15
roentgen, 20 chemical silicate, 38 panning samples, 206 36-element ICP
samples, 380 atomic absorption samples, 269 Sn chemical samples, 20 ICP-MS
samples, 20 rare earth 15-element ICP samples, 33 inclusion samples; 5 sets of
samples to determine the age of lithium ore isotopes by Rb/Sr method; 2 sets the isotope age of granitoid rocks, Sa Huynh Complex by U-Pb isotope method
in zircon and 06 δO18 & δD isotope samples in pegmatite quartz containing
lepidolite.
9. The structure
In addition to the introduction, conclusion and references, the thesis consists
of 5 chapters with 132 pages, 18 tables and 57 figures, images.
10. Place of thesis implementation

The thesis has been carried out and completed at Department of Prospecting
and Exploration, Faculty of Geology, Ha Noi University of Mining and Geology
under scientific advisory of Asc.Prof. PhD. Nguyen Quang Luat and PhD. Do Van
Nhuan.
During the thesis, PhD candidate has received the attention and assistance
from the Board of Directors of the University of Mining - Geology and the units:
Department of Minerals, Department of Prospecting and Exploration, Faculty of
Geology, Postgraduate Department; the attention and assistance of Mid-Central
Geological Division, General Department of Geology and Minerals of Vietnam,
Ministry of Natural Resources and Environment. PhD candidate also expresses his
thanks to scientists, lecturers and colleagues for the valuable and constructive
comments to increase the quality of this thesis.


4
RESEARCH CONTENT
Chapter 1
GEOLOGICAL STRUCTURAL CHARACTERISTICS
IN DUC PHO - SA HUYNH
1.1.
Location of the study area.
The study area belongs to Duc Pho - Sa Huynh geological map, the scale of
1:50,000, with the area of 590km2, limited by geographical coordinates:
Longitude: 108º44’55” - 109º4’55”; Latitude: 4º40’2,6” - 15º50’2,6”. Detailed
study area covers an area of 40km2.
On the regional structural diagram, the study area is located in the eastern
margin of Kon Tum terrane, the structure of ancient basement.
1.2. Studying history of geology and Li minerals.
1.2.1. Studying history of regional geology
Pre-1975 period: occured mainly French geologists' study works at small

and outlined scales.
Post-1975 period:
The study area has been mapped at scales of 1:500.000, 1:200.000,
1:50.000; metallogenic mapped and mineral forecasted in Kon Tum terrane at
scale of 1:200.000. The work of geological and minerals mapping, Ba To sheet
group (Duong Van Cau, 2004) [3] had found the mineralization zone containing
tin, lithium rare metal in La Vi and had detailed investigation, forcasted the
mineral prospect.
1.1.2. Overview on lithium studies in Viet Nam
The study projects on litium minerals in Viet Nam: Prospecting the uranium
and other minerals such as beryl, fluorite, lithium in Cao Son, Cao Lan, Cao Bang
(Nguyen Dac Dong, 1990); The study on pegmatite and related minerals in Hong
river basin (Hoang Sao, 1995); the study on pegmatite containing gemstone in
Luc Yen (Nguyen Thi Minh Thuyet, Nguy Tuyet Nhung, 2016); Geological and
mineral mapping at scale of 50.000, Ba To sheet (Duong Van Cau, 2004);
Evaluating tin minerals and rare metals (Ta, Li, Be) in La Vi, Quang Ngai (Pham
Van Thong, 2009); The study on sorting and processing technology of lithium ore
in La Vi, Quang Ngai (Dao Duy Anh, 2014); Studying on the distribution rules of
rare lithium metallization in Kontum zone, orienting to the investigation,
discovery of rare metal ores (Duong Ngoc Tinh, 2017).
In general, the study of lithium ore is still new and sketchy in Viet Nam. In
the area of study have basically been detemined material composition
charactertistics, in which Li and Sn have particularly industrial value, and the
other rare valuable minerals such as Ta-Nb, Be, Rb,... have not been studied yet.
The researching results have showed that the structure of ore bodies is very


5
complex, the mineralization characteristics, the rule of ore distribution is not
clear, the level of study is still not high and must to be kept studying the material

composition characteristics, geological conditions, phisical chemical formation,
the factors of ore controlling as well as establishing types of origin deposits.
1.3. Duc Pho-Sa Huynh geological structure
1.3.1. Stratigraphic overview
In the study area, the stratigraphy consists of: the eruption formation of Late
Miocen bazan, Dai Nga Formation, N2-Q11 bazan eruption - sediments, they are
distributed into the higher buttes on terrain surface; the unconsolidated sediments of
Quaternary are distributed in the lower part of the terrain.
1.3.2. Intrusive magma overview
In the area, the intrusive magma occupies as granitoid of Sa Huynh Complex
(γP3-T1 sh), moreover, there are some another ones: Ben Giang (δ-γδ PZ3 bg), Phu
Loc (υT1-2 pl), Hoang Lan (σT2hl), Son Dung (γδ-γξ T2 sd), and some dykes which
have not been defined their age.
- Ben Giang Complex: consists of the dykes distributed in the eastern
margin of the study area, an area of 2km2. The components comprise Phase 1
(fine-grained quartz diorite), Phase 2 (medium-grained biotite-hornblende
granodiorite). This complex’s granitoid belongs to I-S type, lime-alkaline,
aluminum saturation, formed in the environment of active continental margin.
There is a high concentration of Co, Ni, Sn, Cu, Ag elements (2-3 times higher
than clark), especially Mo is 250 times higher than clark.
- Phu Loc complex: consists of small intrusions in the isometric forms of
0.2-0.3 km2 area. The petrographic composition comprises gabbro, pyroxene
gabro, websterite and a little pyroxenite. The rock has fine-grained, mediumgrained, little coarse-grained; massive structure. The rocks of this complex are
tholeite, high iron and magnesium serries.
- Sa Huynh Complex
In the area, Sa Huynh complex consists of Dong Ram lagre block, with an
outcrop area of over 150km2. The compositions consist of: Phase 1 (medium to
coarse-grained biotite granite, two-mica granite), Phase 2 (fine-grained biotite
granite, two-mica granite), Phase of ore stone comprises pegmatite, aplite.
The granitoid formations of Sa Huynh complex have similar geochemical

characteristics to tin-containing granite and rare metals. S-granite type,
aluminum saturation, formed in the environment of
synkinematic collision.
The elements have higher content than clark value as Sn, Li, Ta, Th, Rb, Hf, B,
W, Mo, Zn, Pb.
The contents of Sn, Li, Be, and Ta elements have strongly increased from
Phase 1 to ore stone Phase and the clack, albitization, greisenization altered


6
rocks. The clark contents of Sn in Phase 1 is 0,21, in Phase 2 is 1,38, in ore
stone Phase (aplite, pegmatite) is 9,95, in greisenization altered rocks is 48,19.
The clark contents of lithium in the corresponding phases as 1,04, 7,34, 10, 14,
9,02, of Be as 0,08, 0,96, 2,29, 4,37; of Ta: 0,95, 1,23.
- Hoang Lan Complex: comprises the dark lamproit phlogopite and
lamprophyr dykes. The rocks of this complex have a high increase from 3.1 to
47.6 times in the light rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd) and a
high increase (over 10 times) of elements: Ba, Ta, Hf, Th.
- Son Dung Complex: In the region occured 2 small monzogabromonzodiorite blocks of Phase 1 distributed in the west and severals kersantite
dykes. The rocks of this complex belongs to the series of alkaline-lime, aluminum
saturatio, the samples of Phase 1 are mainly I-granite field. On the maps according
to Sattran, 1977, Son Dung Complex has Au-Mo mineralization potential.
1.3.3. Metallogenic metamorphic complexes
- Kan Nack Complex
Kan Nack Complex is divided into 6 rock assemblages as follows: Granulite
mafic (gr/A-PPkn); Gabroamphibolite (Gba/A-PPkn); Gneis pyroxen (gpx/Appkn); Gneis biotite mixed marble; crystallined schist mixed marble, quarzite (fh/A-PPkn); aluminum saturatio crystalline schist (nf/A-PPkn).
In Dong Ram, La Vi discovered the pegmatoid dykes interpenetrating the
assemblages of crystallined schist (f-h/A-PPkn). The attitude and country rocks of
most these pegmatite veins were consistent, some rock-cut veins. Besides, there
were microvein, vein rays which injected into rocks.

- Song Re Complex: Consists of 02 small areas distributing in the north-west.
The major petrographic compositions comprise biotite gneis, biotite plagiogneis,
biotite schist interbeding a few thin layers of amphibol gneis.
1.3.4. Structural and tectonic characteristics
1.3.4.1. Petrotectonic assemblages (PTAS)
- Tectonic setting unknown PTAS of Arkei- Paleoproterozoi age: Consist of
the metamorphic rocks of Kan Nack complex. The rocks were metamorphosed
to granulite facies and superimposed amphibolite facies.
- Tectonic setting unknown PTAS of Paleoproterozoi age: Comprise biotite
gneis of Song Re complex. The obvious characteristic is that they are rather
homogeneously metamorphosed in amphibolite facies.
- The pluton volcanic arc PTAS belonging to active continental margin of Late
Paleozoi age: Consist of the assemblages of intrusive horblend granodiorite, biotitehornblend granodiorite (Ben Giang complex).
- The plate collision PTAS of Late Permi - Early Trias age: consist of two
main rock assemblages: the mafic intrusive rocks of Phu Loc complex and felsic


7
intrusive ones of Sa Huynh complex which is typical for the plate collision
regime re-melting crust.
- The thermal renovation due to extension after plate collision PTAS of
Middle Trias age: comprise differentiated intrusive rock assemblages from
monzogabro to granite of Son Dung Complex, I-granite type.
- The boulder uplift PTAS with basalt eruption appended (N13-Q1): consist
of two main rock assemblages: basalt eruptions and unconsolidated sediments.
1.3.4.2. Folding
The study area is the northern wing of An Lao fold. The folds shown on the
current structural plan are the structures of 2, 3 and higher level. They play a role
complicating the structure plan of the study area.
1.3.4.3. Joints

The study area is located in the southeast of the Ba To - Gia Vuc faults, the
strong fractured rocks create many cracks. The mineralization vein systems
containing Li-Sn are the northwest - southeast, a few centimeters-meters wide
separated structures, mainly strikes to the southwest with the common dip of
50o. They are extension fractures created of Ba Trang - Nui Chua fault system.
1.3.4.4. Faults
In the study area, the faults are developed according to 4 principal axis
systems: northeast - southwest, northwest - southeast, meridian - submeridian,
parallel - subparallel. In which, the northeast - southwest, northwest - southeast and
meridian fault system is the most strongly developed, the parallel fault system is
weaker developed. The northwest-southeast fault system plays a role in localizing
the pegmatoid bodies containing Li, Sn.
Chapter 2
RATIONALE AND METHODOLOGIES
2.1. Geochemical and mineralogical characteristics of lithium (Li)
Lithium of group I is an alkali metal, of the litophil group, and in terms of
minerals, Li is classified into rare metals. Silvery white to gray. Atomic weight:
6.94. Density (g/cm3): 0.534. Melting temperature: 453.69oK (180.54oC). Boiling
temperature: 1615oK (1342oC).
The average content in the earth's crust is 0.006%, increasing according to
the rule: in gabro 0.0003%, in bazan 0.003%, in granite 0.03%. The highest
depositional level of lithium is in the formations after granite magma and mainly in
the late phases of the pegmatit process, herein it is most closely associated with Na.
The lithium largest industrial deposits are known to be in granite pegmatite (Na-Li
type). At lower level, lithium accumulates in gas formations to become
hydrothermal, the typical type is the assemblages between Li and F to form a


8
sequence of Li containing F. In endogenous deposits, lithium minerals often

combine with Be and B minerals.
Lithium is a reactive metal, which gives priority to link more with silicate
than with sulfide or metal. During the magmatism Li + replaced Mg2+ and Fe2+ in
pyroxene, tourmaline and amphibol. It can also replace Mg and Al in mica, such
as lepidolite and chlorite, but its small charge and ion radius limit its
competitiveness for network cell locations, so it still exists in late differentiation
phase. Under exogenous conditions, lithium is easily adsorbed by clay minerals.
Lithium is a cation of I valence, in terms of its properties, it is closest to Na
but due to the size of Li+ ions is small in comparision with the size of Na+ ions,
lithium can be limited substitute for sodium in crystals. The replacement of ions
can occur between Li+ and Al3+, Fe2+ and especially Mg2+ because of the radius
similarity of these ions regardless of their chemical nature. This replacement takes
place in the late magmatic crystallization stage and affects to the composition of
some minerals such as clinopyroxen and mica.
Lithium is found in more than 150 minerals, but the true minerals of Li
are only about 30, of which, the most common are spodumene, lepidolite,
petalite, amblygonite and zinwaldite.
2.2. Uses of lithium
Lithium has been currently widely used in many different areas: electrical
industry, energy battery electronics, aerospace engineering, environmental
technology, nuclear materials, metallurgy, chemicals, ceramics - glass, polymer
technology, refrigerants, fireworks and medical. Currently, the demand for using Li
as is very large and increases rapidly including cost.
2.3. Types of lithium deposits
- Granite-pegmatite deposits of Na-Li type
The granite-pegmatite Na-Li deposit type is classified into the following
sub-types: spodumene pegmatite, spodumene-lepidolite pegmatite, petalitepegmatite, lepidolite pegmatite. The basic lithium minerals have industrial value
(spodumene, lepidolite and pentalite and little ambligonite, in a complex with
other useful minerals such as beryl, columbite, tantalite, puluxite, microlite,
cassiterite, feldspar, ...).

"The formation of lithium minerals is related to the metamorphic
processes in pegmatite. Moreover, it is characterized by the replacement of K
metamorphic metasomatism by Na metamorphic metasomatism, and then Li by
metamorphic metasomatism. This deposit type supplies about 95% of the world's
lithium mining production" (Tatarinov and Kariakin, 1975).


9
Recently, the geologists from the US Geological Survey (USGS) have
classified the pegmatite deposits containing lithium into a model which called
"Lithium-Cezi-Tantan Pegmatit (LCT Pegmatite).
- Thermal pneumatogenic deposits: This deposit type is characterized by
zilwaldite as well as amblygonit ore. This type often occurs in medium-sized
deposits.
- Continental saline deposits: This deposits have high lithium
concentrations, distributed in places with the high altitude in Chile, Argentina,
Bolivia, Tibet and China.
- Hectorite clay: is a magnesium smectite lithium clay mineral, which was
discovered in some places in the west of the United States along the
Nevada/Oregon border, where occured a series of prolonged geological lenses.
World lithium reserves are not much, about 14.5 million tons (USGS,
2016). Annual output is about 35,000 tons.
2.4. Academic terms and concepts in thesis
- Mineral paragenesis assemblages (MPAS): is an assemblage of agedefined minerals, formed in a mineralization phase, due to crystallization from a
solution with the same certain physico-chemical conditions.
- Mineralization phase: The mineralization phase is a short - time mineral
accumulation within the scope of a mineralization period, forming a mineral
assemblage with certain components in the stable geological and
physicochemical conditions.
- Pegmatite deposit: Pegmatite deposits are formed in late magmatic

crystallization stages from residual liquids or during metamorphism when there
are positive effects of volatile compounds. Pegmatite is characterized by the large
crystal structures, the combination of monomineralic block in the pocket and
banded forms, occurs complete and lagre crystals. The important minerals of
pegmatite are: mica; ceramic porcelain materials: quartz and feldspar; rare and
radioactive metals: Li, Nb-Ta, U, Th; tin, topa, precious and semi-precious stones.
- Pegmatoid: is a magmatic rock with a large-grained structure of
pegmatite, but is not crystallographic texture and/or granite typical composition
structure.
- Deposit type: The deposits are classified into the same type is defined as
ones which have the similar characteristics of mineral composition, origin and
formation conditions.
- Ore type: A type of deposit may have one or more mineralization stages
corresponding to different mineral paragenesis assemblages, they form specific
ore types for each stage.
- Other concepts: Mineralization zone, Ore field, Ore body;


10
Mineralization body.
2.5. Methodologies
2.5.1. Field research methods
To conduct some detailed field excursions of typical sections to study
structural and tectonic characteristics; to study morphological characteristics and
structural features of ore bodies. To sample of all kinds.
2.5.2. Laboratory study methods
a- Methods of synthesizing and systematizing related data:
An overview of the world lithium, the industrial types of deposit, LCTpegmatite model, a synthesis of research documents. To handle and interpret the
analyzing results and research documents.
b- Methods of analysis:

Using analyzing methods to study material composition, physicochemical
conditions, isotope: petrological thin section; mineragraphy, ronghen, inclusion;
microsond; Atomic Absorption Spectrophotometric; ICP; ICP-MS; stable isotope
analysis δO18 & δD to determine the ore-forming solution source; isotope age
analysis for ore (Rb /Sr) and Sa Huynh granite (U-Pb).
c- Expert method
Through the seminars and group discussions with the experts in the field
of specialized studies.
Chapter 3
GEOLOGICAL CHARACTERISTICS OF LITHIUM
MINERALIZATIONIN DUC PHO - SA HUYNH
3.1. Distribution characteristics of ore bodies
The ore bodies, mineralization bodies containing Li, Sn in the area have
been found to be concentrated in La Vi, an area of about 40km2. Here, 20 ore
bodies and 20 mineral bodies have been identified.
General characteristics of ore bodies are distributed in crystalline schist of
Kan Nack complex (A-PP kn), in the contact zone between the granitic
formations of Sa Huynh complex (γP3-T1 sh) and the mentioned above
metamorphic rocks; the ore bodies are a collection of pegmatoid veins which
tightly controlled by fracture systems, fractures in the northwest - southeast.
The ore bodies are distributed mainly in Dong Ram ore field, only some
small ore bodies are distributed in Nuoc Giap ore field.
3.1.1. Dong Ram ore field
3.1.1. Dong Ram ore field
The ore field has an area extending in the northwestern southeastern
direction of about 4km long, of 2 km wide, which is controlled by 3 parallel
systems in the northwest - southeast and the magmatic intrusive mass in the


11

northwest. The geological structure comprise mainly crystalline schist of Kan
Nack Complex, a small granite area of Sa Huynh Complex. These formations
are covered by Neogen - Pleistocene basalt.
In the ore field, 20 ore bodies and 15 mineralized bodies were identified,
including 6 Li ore bodies, 9 Li-Sn ore bodies, 5 Sn bodies, 14 Li mineralized
bodies and a Sn mineralization. These ore bodies are concentrated in three subzones: Dong Ram, La Vi river and A Kham, 300 - 500m from each other.
Dong Ram sub-area
Dong Ram sub-area is located in the center of the ore field, consisting of
18 ore bodies, mineralized bodies. The distribution area has a extended form in
the northwest - southeast about 2km, the width of 500-600m. The ore bodies are
from tens meters to 600 meters long; mainly from 240m to 480m; the thickness
of 0.4m to 2.3m, average from 0.9m to 1.5m. Stretching in the northwest southeast direction. They mainly strike to the southwest with a dip of 400 to
750, either vertical or inverted. The morphology of ore bodies is mainly vein,
flying veins and lens series.
This is the most prospective area in the region, with a total forcasting
resource of 5,100 Li2O tons, 2,700 Sn tons and 1,000 Rb tons, in additon. The
content of Li2O from 0.3-1.49%, Sn from 0.1-5.77%.
La Vi river sub-area
La Vi river sub-area is located in the southeast of the ore field, consisting
of 8 ore bodies distributed into a stretching band to subparallel of 1,2km long,
the width of 250m. Ore bodies are from 200 to 600m long; the thickness of 0.9m
to 1.5m. Extending according to subparallel. They strike mainly in the
southwestern west with a dip of 400 to 750. The morphology of ore bodies is
thin and stretching veins.
This is the second prospective area in the region, with a total resource
of 4,400 Li2 O tons, 970 Rb tons. The content of Li2O from 0,3-1,56%, Sn
from 0,1-0,92%.
A Kham sub-area
A Kham sub-area is located in the southwest of the ore field, including a
collection of 8 ore bodies, mineralized small-scale bodies, with the length from 200

to 300m, thickness of 0.6m to 1.9m. The same stretching direction of the ore bodies
is mainly northwest-southeast. They strike into the south and southwest with a dip of
500 -750. The morphology of ore bodies is mainly thin veins.
This is the small-scaled detailed evaluated area, with a total forcasting
resource of 440 Li2O tons, 495 Sn tons and 90 Rb tons. The content of Li2O
from 0,3-1,41%, Sn from 0,1-2,06%.


12
3.1.2. Nuoc Giap ore field
Nuoc Giap tin mineralization is located in the southwest corner in La Vi with
an area of 2.0km2. The geological structure consists mainly of metamorphic rocks,
Kan Nack complex, phase 2 granite of Sa Huynh complex; The joint systems are
mainly in the northwest - southeast. Here, 6 mineralized bodies that greisenization
altered have been identified containing tin with the low content <0.3%.
3.2. Geological, morphological and structural characteristics of
ore bodies
The ore bodies are a collection of pegmatoid veins, based on the
characteristics of ore composition, can be divided into ore types such as: Li, LiSn and Sn ore. The morphological and structural characteristics, size as well as
the altered characteristics of country rocks in each ore type have their own
characteristics which differentiate from the others.
The sections showed that the ore bodies were distributed according to the
rule. The ore bodies mainly striked to the southwest, opposite to the main faults.
Li ore bodies were located in the low part of the section, followed by Li-Sn ore
bodies and on the top were Sn ore bodies. Based on the distance from the ore
bodies to granite mass (located in the north), Li ore bodies were the closest to
this mass, followed by Li-Sn ore bodies and Sn ore bodies. This indicated that
occured clear mineralization zoning with with certain rules. The zonation was
rather also quite similar to the cross-section that simulates the zonation of rare
metal pegmatite field of Cerny.

3.2.1. Lithium ore
This ore type has 10 ore bodies: TQ1, TQ6, TQ17b, TQ21a, TQ21b,
TQ22, TQ23, TQ24, TQ25, TQ26 and 13 mineralized bodies. The same
characteristics are usually 0.8-1.5m thin belts last from 230-650m. The
morphology of ore bodies is mainly vein, lens series. The ore body structure
has zoned with colorful bands, different size and mineral composition.
Typically altered albitization, the vein margin is often greisenization, little
disseminated by casiterite.
3.2.2. Li-Sn ore
This ore type has 5 ore bodies: TQ2b, TQ7, TQ8, TQ10a and TQ18. The
general characteristics are usually the large belts with the large thickness of 1.14.8m last from 400-620m. . The morphology of ore bodies is mainly vein, flying
veins and lens series. The ore body structure has zoned with the bands, lens and
pockets with different color, size and mineral composition. The Li content is
quite evenly distributed along the ore body, Sn content often concentrates highly
in the margin of veins to form pockets and lenses with the quite high content.
The typical alteration is albitization and greisenization.


13
3.2.3. Sn ore
This ore type has 6 ore bodies: TQ2a, TQ3, TQ4a, TQ4b, TQ16, TQ27
and 7 mineralized bodies. The common characteristic is usually thin, short veins
with high Sn content (highest 5.77%), typical alteration is greisenization. The
thickness of ore bodies is 0.5-1.3m, the length from 80-280m. The zonation has
not viewed yet in ore body structure.
3.3. Altered characteristic of the country rocks
3.3.1. Alkali metasomatism
Alkali metasomatism strongly occured in study area. In this process,
microclinization had been formed before it was covered and faded by
albitization.

3.3.1.1. Microclinization
Microclinization metasomatism is not common in the samples, It was
almost faded by covered later metasomatism. the orthoclas was widely replaced
by microcline and was subsequently replaced by albite.
3.3.1.2. Albitization
In the area of study, albitisation strongly occurs with either granite or
pegmatite dykes. In the pegmatite veins, albitisation is presented by
replacing primary alkali feldspars with albite and injected into the country
rock. This rock is continuous altered by greisenization, quarztitation to
create the complicated structure. Albitite is bright white, the mineral
compositions are mainly albite, quarzt, pink lithium-bearing mica and topaz.
Albite grain size is rather small, most of 0,2-4mm, larger size is rare, at least
two generations of albite can be identified.
3.3.1.3. Lithium metasomatism (Lepidolitization).
Albite always comes with lepidolite in Li, Sn-Sn ore bodies, they often
create the bands, pockets and lenses with different colors.
Lepidolite replaces biotite and muscovite minerals by replacing
isomorphous method. There is Li+ abundance in the residual liquids, ionic
substitution can occur between Li+ and Al3+, Fe2+ and especially Mg2+ due to the
similarity in the ionic radius.
3.3.2. Greisenization
In the studies area, the greisenization was strongly and widely occured
within the host rock and ore veins, superposing pre-existing metasomatism. In
pegmatoid veins, greisenization often occurs in the contact margins next to the
country rock, the major mineralogical composition comprises quartz, lepidolite,
topaz, albite, casiterite. In the veins, the rays of thin vein penetrating through the
shale, the major components comprise quartz + muscovite + casiterite.


14

3.3.3. Mid-low temperature hydrothermal alterations
The altered phenomenon consits of mainly sericitization, quartzization,
chloritization related to the regional polymetallic sulfur-quarzt veins.
Chapter 4
THE MATERIAL COMPOSITION CHARATERISTICS OF LITHIUM
MINERALIZATION IN DUC PHO - SA HUYNH REGION
According to material compositions, ore types are divided into: Li, LiSn and Sn.
4.1 Mineral composition characteristics
4.1.1. Li ore
The lithium ore bodies have the petrographic compositions charaterized by
the lithium- containing albitite. The major alteration event is albitization, at
margins of the ore veins have a weak greisenization. The ore has a massive
forms, weakly banded, crystalloblast - scale grained texture.The mineral
components are mainly: quartz 10-40%, lepidolite 15-42%, albite 30-75%, topaz
0-6%; ore minerals: casiterite from several particles to <0,5%, little pyrite, little
hematite. Thereto: polylitionite, zinwaldite, taeniolite, tantalite-columbite, beryl,
cryzoberyl, amblygonite –montebrasite, goyazite, herderite, granat, monasite,
zircon, turmalin, apatite.
The typical mineralogy paragenesis assemblages (MPAS): albite + quartz +
lepidolite+topaz.
4.1.2. Li-Sn ore
The Li-Sn ore bodies have the typical lithology compositions is the
albitisation, greisenization alteration rocks containing Li and Sn. The ore has a
massive, banded forms, crystalloblast - scale grained texture, porphyritic
remnants. The mineral compositions are mainly: quartz 23-50%; lepidolite 1040%, albite 23-50%; felspar kalium 0-5%, topaz 0-3%. Besides this, there are still
hornblend, epidot, pyroxen, zircon, monazite, granat, turmalin, sphen, apatite. The
ore minerals have casiterite of several grains to >20%. The typical MPAS: albite
+ quartz + lepidolite + topaz + casiterite.
4.1.3. Sn ore
These ore bodies have the typical lithology compositions is the greisenization

alteration rocks containing Sn. The mineral compositions are mainly: quartz 20-70%;
muscovite 10-35%, felspar kalium 10-15%, plagioclase 5-30%. The ore minerals
have casiterite of little to >20%. In aditional, biotite, turmaline, zircon. The typical
MPAS: quartz + muscovite + casiterite
4.1.4. The mineral characteristics
Lepidolite: Often in the form like the petal of rose or the fan, a lower
refractive and double refraction index than muscovite. Under microscope lepidolite


15
is almost colourless, lepidolite is light purple, pinkish after careful observation.
Interference colors is low, bright grey, light yellow at level 1.
Based on the associated relationship between lepidolite and quartz, albite can
identify two generations: lepidolite in a combination with quartz, a large size albite
characterized for pegmatite origin; lepidolite in a combination with quartz, small
xenomorphic albite in greisenization alteration rocks.
According to the microsond (SEM) and ICP-MS analysing results
lepidolite components are as follows: Li2O 4.65-4.96%, SiO2 47.15-57.62%;
Al2O3 25.12-32.07%; Na2O 0.27-4.1%; K2O 6.45-9.28%; MgO 0.04-0.07%; F
0.901-8,705%. Notably, rubidium content is quite high Rb2O 0.598-2.415%,
Cs2O content is 0.036-0.357% (these are very valuable and recoverable metals
during processing process of lithium ore). Mineral formula K1.8 (Li2.6Al2.9)
(Si6.7Al1.3) O20 (OH, F)4 [24].
Topaz- Al2(SiO4) (F, OH2): usually in xenomorphic form, 0.1-1.8 mm in size.
Colorless, high buoyancy, full cut, stand off, yellowish interference, level 1.
Casiterit - SnO2: usually exists in the form of xenomorphic particles,
elongated particles with size of 0.2-5 mm, sometimes larger. They are
disseminated distributed unevenly on the rock platform which is greisenization,
usually see the typical elbow-shaped twinning form. The content of casiterite
minerals (microsond analysis) is as follows: Sn2O 97.58-99.32%, MnO 0.1-1.19%,

Fe2O¬3 0.25-1.25%, Ta2O5 0.59%, Nb2O5 trace.
Tantalite-columbite (Fe, Mn) Ta2O6 - (Fe, Mn) Nb2O6: usually exists in
idiomorphic-granular forms, thin sheets, and twin plates. Dark gray, low
reflectivity, weak anisotropy. The microsond tantalite - mineral analysis results
showed that the content of components is as follows: Ta2O5 33.44-63.88%; Nb2O5
50.86-20.68%; MnO 11.3-17.24%; FeO 15-3.44%.
4.2. The chemical composition characteristics
4.2.1. Li ore
In Li ore bodies, Li is main element, the other minor ones comprise: Sn,
Ta, Nb, Be. The content of Li2O in the samples from 0,10% to 1,72%, the
average of 0,82%, high. The very valuable minor element is Rb with the
oscillation content about 798-4320ppm, the average of 2638ppm (ICP-MS).
In this ore type Li has correlated quite clearly with Rb, Be, Nb, Ta,
characterizing rare metal pegmatite ore type
4.2.2. Li-Sn ore
In Li-Sn ore bodies, Li, Sn are main minerals, the other minor ones
comprise: Rb, Ta, Nb, Be. The content of Li2O in the samples varies from 0,08%
to 2,04%, the average of 0,69%. The variation coefficient of Li content (VLi) is
64%; Sn content in samples alters unevenly from 0,04% to 4,93%, the average of


16
0,52%. Tantalum and Niobium (Ta, Nb): are relatively common elements in this
ore type, many samples reach Ta content> 100ppm and Nb> 100ppm, in particular
> 400ppm Ta. Li has an inverse correlation with Sn, Be, Nb, Ta; whereas, Sn has a
close correlation with Ta, Nb and Be.
4.2.3. Sn ore
In Sn ore bodies, the main mineral is Sn, the other minor ones comprise: Li,
Ta, Nb, Be. The content of Sn oscillated from 0,06% đến 5,77%, the average of
0,62%. In this ore type Sn has a close correlation with Nb and the correlation

with Ta, Be.
4.3. The physic-chemical conditions of lithium mineralization
4.3.1. The genesic of mineralization fluid
The samples for O-D isotope of quartz minerals were directly collected from
lithium and tin -containing pegmatoid veins in La Vi area, Duc Pho - Sa Huynh
were analyzed at China University of Geoscience - Beijing, China and were
displayed on the δO18-δD diagram (Sheppard, 1986) to identify the origin of the
water in mineralization solution. The results showed that the composition of δO18
is rather stable at about 6,5÷7,3‰, δD strongly oscillated from 70 ÷ -116‰. The
correlation chart indicated that one sample in the magmatic water field and the
others in the intermediate water field. Combined with the results of other studies,
especially the study results of regional metasomatism can suggest that the
mineralization solution has primary magmatic origins; however, the
mineralization solution has been mixed with other sources due to tectonic and
metasomatism activities which had strongly occurred in the study area.
4.3.2. Temperature conditions, formation pressure and evolution of postmagma solution
Summary of inclusion analysis results can show 3 temperature ranges as
follows: From 520-617oC; from 360-445oC; from 195-320oC. In the study of
metasomatism (Pollard 1983) has indicated that, albitisation strongly occurs in the
range of temperatures of between 400 and 800oC and at pressures of 1 kbar or
less; the greisenization was occured at the depth of 1,5 – 3 km, temperatures range
of 350-450oC. The greisenization occurred at the time when the acidity of the
post-magma solution associated with granitoid increased at the maximum level.
In the study area, related to the process of Li mineralization, there are
stages: The first if microclinization (the orthoclas was replaced by microcline),
It is subsequently albitization, K-felspat was replaced by albite. These rocks was
subsequently altered by greisenization to make complicated structure.
According to the acid and temperature evolutional diagram of
postmagmatic solution, albitization and greisenization alterations in the region

17
are in the period 2-4 and a range of temperatures of between 400 and 600oC are
also very suitable for study results.
4.4. The mineralization process
The study results showed that Li mineralization process in the region had
undergone many phases, quite complicated, as follows:
Pegmatite period
This period has a phase (Phase I). The formation of pegmatite veins
containing lithium with the main simple components comprise: felspar quartz,
large-sized mica. The typical structure is coarse-grained, micro pegmatite. The
typical MPAS is quartz + orthoclas + muscovite. The formation temperature is
over 600oC.
Metasomatism period
This period can be devided into 3 Phases (II, III, IV)
Phase II: Alkali metasomatism (Microclinization)
The microcline replaced the large - sized orthoclas and was subsequently
replaced by albite. Banded, pocket forms; the typical structure is xenomorphic idiomorphic-granular, instead corrosion. The typical MPAS is quartz + orthoclas
+ muscovite. The formation temperature is 617-520oC.
Phase III: Na-Li metasomatism
This Phase is characterized by two Na (albitisation) and Li (lepidolitation)
metasomatism processes. These 2 metasomatism processes strongly occurred in
the pegmatite dykes containing lithium. Albite always accompanies lepidolite in
Li, Li-Sn ore bodies, they often create different colored bands, pockets and lenses.
Here, albite replaced orthoclas even albite in the previous phase. Lepidolite
replaced biotite and muscovite minerals by replacing isomorphous method. There
is Li+ abundance in the residual liquids, ionic substitution can occur between Li+
and Al3+, Fe2+ and especially Mg2+ due to the similarity in the ionic radius.
The typical forms are banded, pocket and lens; the structure is xenomorphic allotriomorphic-granular, instead corrosion. The typical MPAS is quartz + albite +
lepidolite + topaz. The formation temperature is 617-520oC.

Phase IV: Greisenization
This phase occurred when the acidity increased at the maximum level. The
typical alteration was greisenization closely related to Sn mineralization; with
them, albitization (albite of generation 2), has altered the formations in Phase I and
has recombined the albite and mica minerals containing lithium of smaller size. The
typical MPAS for greisen in pegmatite veins containing lithium is quartz + albite
(generation 2) + lepidolite (generation 2) + topaz + casiterite. For the veins, greisen
vein rays penetrating through the shale, the typical MPAS is quartz + muscovite +


18
casiterite. The typical ore forms: banded, pocket, lens, disseminated; structure:
hypautomorphic - allotriomorphic, lepidoblastic and granular.
Hydrothermal period
Phase V: Forming the polymetallic sulfur-quarzt veins.
Table 12: The forming order and the lithium mineralogy paragenesis
assemblages in Duc Pho - Sa Huynh
Period
Phase

MPAS
Mineral
name

Pegmatite
I
Pegmatit
thực sự

II

KMetasomatism

Metasomatism
III
Na-Li Metasomatism

Qu+Or
+Mus

Qu+Mi
+Mus

Qu+Ab+
Lp+Tp

pocket,
mass

pocket, band,
mass

Coarsegrained,
micro
pegmatite

xenomorphic idiomorphicgranular, instead
corrosion

xenomorphic idiomorphicgranular,
lepidoblastic,

instead corrosion

hypautomorphic
allotriomorphic,
lepidoblastic
and granular

hypautomorphic
allotriomorphic
granular

microclinization

Albitization
Lepidolitation

greisenization

Sericitization,
chloritization

450-360o

320-195o

IV

Hydrothermal
VI

Greisenization

Q+Mus+Cs;
Qu+Ab+
Lp+Tp

Qu+Py+
Chp+Gal
+Spl

pocket, band,
veins,
lens
disseminated

veins,
infected

Quartz
Plagioclas
Orthoclas
Biotite
Muscovite
Microcline
Albite
Turmalin
Beryl
Topaz
Lepidolite
Montebrasite

Amblygonite
TantaliteColumbite
Cassiterite
Pyrite
Chalcopyrite
Galena
Sphalerite
Hematite
Structural
features
Typical
structure

Typical
altered
phenomenon
Formation
temperature

>600o

617-520o

Notes: Major minerals:
; minor:
; rare:
;
Abbreviations: Qu- quarzt, Or- Orthoclas, Mi- Microcline, Mus- muscovite, Ab- albite,
Lp- lepidolite, Tp- topaz, Cs- casiterrite, Py- pyrite, Chp- chalcopyrite, Gal- galena,
Spl- sphalerite.

19
4.5. The age of lithium mineralization and granitoid, Sa Huynh Complex

The mineralization age of lithium rare metal in Duc Pho - Sa Huynh
Lithium mineralization age in Duc Pho - Sa Huynh is analyzed by Rb/Sr
total-rock method. Samples were analyzed at the Department of Geology and
Physics, Ryukyu University, Okinawa, Japan, using Neptune Plus MC-ICP-MS
Multisystem Mass spectrometry machine. Results processing with Isoplot v.4.1
(Ludwig, 2014), the correlation chart 87Rb / 86Sr and 87Sr / 86Sr give the age results
of the lithium ore sample set of 264 ± 3.6 MA.
The 87Sr/86Sr isotope ratio of the lithium ore group is very high (0.8025)
compared to 0.703 to 0.707 mantle-derived material, indicating that the acid
rock group has the origin of re-molting (S-type granite).

Figure 4.15: Isotime line identifying lithium ore isotope age

The granitoid isotope age of Sa Huynh complex
The granitoid isotope age of Sa Huynh complex was analyzed by UPb isotope method in zircon. Samples were processed and analyzed at the State
Key Laboratory- China University of Geosciences (Beijing), analysis of 2 sets of
samples. The results of analysis and calculation for age values are 259.4 ± 7.9
million years (SH3 sample) and 251.6 ± 3 million years (SH4 sample)
corresponding to the Late Permian to the Early Triassic (P3-T1).
The results showed that lithium and granitoid rocks of Sa Huynh complex
had the same formation age in the Late Permian to the Early Triassic (P3-T1) .

Figure 4.16: Concordia curve representing
the value of granite isotope age, Sa Huynh complex

20
4.6. Establishing the type of Li deposits and ore in Duc Pho - Sa Huynh

4.6.1. Establishing the type of lithium deposits in Duc Pho - Sa Huynh
Based on geological conditions, distribution characteristics, structural
morphology, the relationship with granitoid magma in the region; Material
composition characteristics, physic - chemical formation conditions. In
comparison with the industrial deposit types which mentioned in Chapter 2, it is
possible to classify the lithium mineralization in Duc Pho - Sa Huynh into the
type of industrial origin deposits which is Na-Li granite pegmatite type,
lepidolite pegmatite sub-type: the main lithium mineral is lepidolite, the useful
minor minerals are casiterite, columbite, tantalite,...
4.6.2. Classification of ore types in Duc Pho - Sa Huynh area
Based on their useful composition characteristisc and their industrial values,
the ore types can be classified as: Li, Li - Sn and Sn.
4.6.2.1. Li ore: Consitsts of pegmatite ore bodies containing lithium, major
alteration is albitization. The typical MPAS is albite + quartz + lepidolite +
topaz. Major mineral is Li, attached minor minerals are Rb, Sn, Ta, Nb, Be.
4.6.2.2. Li-Sn ore: Comprises pegmatoid ore bodies containing lithium,
major alteration is albitization and greisenization. The typical MPAS is albite +
quartz + lepidolite + topaz + casiterite. Major minerals are Li and Sn, attached
minor minerals are Rb, Ta, Nb, Be.
4.6.2.3. Sn ore bodies: Consists of veins, vein system, greisen lens. The
typical MPAS is quartz + muscovite + casiterite. Major minerals are Sn, attached
minor minerals are Ta, Nb
Chapter 5
FACTORS CONTROLLING LITHIUM ORE AND LI PROSPECTING
PREMISES - SIGNS IN DUC PHO - SA HUYNH
5.1. Factors controlling Li ore

5.1.1. Magmatic factors - Sa Huynh complex
The magmatic factors controlling lithium ore in La Vi area, Duc Pho - Sa
Huynh region have been defined:
Space relationship: Lithium ore bodies were distributed in the contacting
zone between the granitoid formation of Sa Huynh complex (γP3-T1 sh) and
metamorphic rocks of Kan Nack complex (A-PP kn), here albitization and
greisenization altered zones have strongly developed.
Formation time: The stydied results showed that lithium ore and granitoid
rocks of Sa Huynh complex have same formation age from Late Permi to Early
Trias (P3-T1).
Origin relationship: represents in the following relation


21
- The typical minor mineral compositions of rocks and ore are similar:
ilmenite, granat, monazite, tantalite-columbite, casiterite.
- Lithogeochemical characteristics: The granitoid formations of Sa Huynh
complex have similar geochemical characteristics to granite bearing tin and rare
metals. S-granite type, aluminum saturated, formed in the synkinematic setting, the
evolutionary level strongly occurred to fractionated. The elements have a higher
content than clark value are Sn, Li, Ta, Th, Rb, Hf, B, W, Mo, Zn, Pb.
- On the variation chart of standard trace elements with Chondrit has
showed that rare earth elements in variable lithium ore are similar to the granite
samples of phase 2 of Sa Huynh complex.
- Metallogenic potential: geochemical characteristics, from phase 1 to the
vein-stone phase and greisenization altered rocks, the clark content of Sn, Li, Be,
Ta strongly increased. The clark content of Sn in Phase 1 is 0,21, phase 2 is 1,38,
vein-stone phase (aplite, pegmatite): 9,95, in greisenization altered rocks: 48,19.
The clark content of Li in the corresponding phases as 1,04, 7,34, 10,14, 9,02, of
Be: 0,08, 0,96, 2,29, 4,37; of Ta: 0,95, 1,23.

- Metallogenic specialization: On the correlation diagrams of K+ - Na+, Mg2+ K+ and Mg2+ -Na+ classifying metallogenic specialization of granite magmatic
rocks the samples mainly fall into Mo-Sn field.
- The results of stable isotope analysis δ18O & δD showed that the
mineralization solution has primary magmatic origin but was mixed due to the
tectonic and metamorphic activities which had strongly occurred in the study area.
5.1.2.Tectonic structural factors
Tectonic structural factors have played a role as a waterway and place of
setting the ore forming materials, to decide the ore concentration and
distribution.
- Fault: The northwest - southeast fault system plays a dominant role and
controls Li, Sn mineralization veins.
- Joint: The mineralization vein systems containing tin are separated
structures of northwest - southeast, they are several centimeter-meter wide, strike
mainly to the southwest with a common dip of 50-700. They are the attached joint
systems (strike in the opposite direction to the main fault system) of the Ba TrangNui Chua fault system.
- Folding: plays a role to make complicated structure of the study area.
5.1.3. Lithological stratigraphy factors
In the region the lithium-containing pegmatoid dykes mainly encountered in
the crystallised schist intercalated marble, quartzite (f-h/A-PPkn) mixed with
gabroamphibolite assemblages distributing in the contact zone with granitoid
magmatic rocks of Sa Huynh complex.


22
5.2. Premise, prospecting and forcasting signs
5.2.1. Prospecting premise
5.2.1.1- Intrusive magmatic premise
The granitoid formations of Sa Huynh complex have a close relationship with
lithium ore in the region. They are S-granite type, aluminum saturation; formed in
the tectonic collision setting, the evolutionary level strongly occurred to

fractionated. Metallogenic potential is Li, Sn, Be, Ta, Mo.
5.2.1.2- Tectonic structural premise
The geological structures such as magmatic dome positions, to contact to
metamorphic rocks, to develop folded, laminated, jointed structures to create the
convenient space for ore forming.
5.2.1.3 - Lithological stratigraphy premise
In Duc Pho-Sa Huynh, the lithium - containing pegmatite dykes intruded into
the metamorphic rocks of Kan Nack complex.
Most the lithium - containing pegmatites intruded into the metamorphic rocks,
typically low-pressure amphibolite facies to greenschist facies, eruptive
sedimentary rocks or unmodified rocks (Ĉerný, 1992), this is the survey
orientation, not condition.
5.2.2. Prospecting and forcasting signs
Pegmatite fields: Lithium-containing pegmatites in the study area have
been in pegmatite field stretching to the northwest - southeast and controlled by
the same fault system
Boulder zone: The Li-Sn containing boulder zones are directly related signs
to the original ore.
Altered rock zones: altered rocks by albitization, microclinization which
often distributed in the dome part of granitoid intrusive mass, in the margin of
pegmatite veins and in the hydrothermal veins.
Placer dispersion haloes: The Placer dispersion haloes assemblages of
casiterite, tantalite, elbait, spesartin, monazite minerals.
Secondary geochemical dispersion haloes: The dispersion haloes
assemblages of As Be, Sn elements can form a distance of 10-20km; of Nb-Ta is
1-5km; while of Li, Rb, Cs tend to highly flexible and can be found in clayriched line sediments.


23
CONCLUSION AND RECOMENDATION

1. Conclusion
1. On the basis for clarifying the geological and physic chemical conditions
of the ore formation and the relationship with magmatic and metamorphic
formations, it is possible to classify the lithium mineralization in Duc Pho - Sa
Huynh into the type of industrial origin deposits which is Na-Li granite
pegmatite type, lepidolite pegmatite sub-type: the main lithium mineral is
lepidolite, the useful minor minerals are casiterite, columbite, tantalite,... There
are types of ore: Li, Li-SN and Sn.
Lithium mineralization in the study area was formed during metasomatism
of pegmatite bodies and gresenization with overlaping tin mineralization.
2. Lithium mineralization in Duc Pho – Sa Huynh has been controled by
the geological factors: Magmatic factors: the intrusive magma of Sa Huynh
complex; Tectonic structural factors: Northwest-southeast fault system and
attached structure are both waterway and storage areas, localizing ore bodies in
the region; Lithological factors: metamorphic rocks of Kan Nack complex.
3. The study area has undergone many magmatic activity, tectonic and
metallogenic stages, so the geological formations have been metamorphosed
strongly and complexly with many stages which overlapped in the same ore
controlling structure. The study results showed that the Li-bearing
metasomatism occurred in 3 Phases: K metasomatism (microclinization), Na-Li
metasomatism (albitization), metasomatism (lepidolitation). Thereto, there were
also greisenization hydrothermal altered processes with related Sn ore.
4. The isotope age analyzing results showed that lithium ore and granitoid
rocks of Sa Huynh complex had the same formation age in the Late Permian to
the Early Triassic (P3-T1). According to U/Pb isotope analysis results in zircon,
the granite isotope age, Sa Huynh complex had the age values of 259.4 ± 7.9
million years (SH3 sample) and 251.6 ± 3 million years (SH4 sample)
corresponding to the Late Permian to the Early Triassic (P3-T1). The
mineralization age of lithium rare metal in Duc Pho – Sa Huynh region was
analysed by total-stone Rb/Sr method for the age isotope result of 264±3,6

million years.
The 87Sr/86Sr isotope ratio of the lithium ore group is very high (0.8025)
compared to 0.703 to 0.707 mantle-derived material, indicating that the acid
rock group has the origin of re-molting (S-type granite).
5. The results of stable isotope analysis δ18O & δD showed that the
mineralization solution had primary magmatic origin but was mixed due to the
tectonic, metasomatism and hydrothermal activities which had strongly occurred
in the study area.