Glory and Hellene in the Field

Glory and Hellene

Conditions necessary for the formation of hydrothermal mineral deposits

Conditions necessary for the formation of hydrothermal mineral deposits include:
(1) Presence of hot water to dissolve and transport minerals,
(2) Presence of interconnected openings in the rock to allow the solutions to move,
(3) Availability of sites for the deposits, and
(4) Chemical reaction that will result in deposition.

What are the five most common rock-forming mineral groups?

What are the five most common rock-forming mineral groups?
1. Silicates
2. Oxides
3. Sulphides
4. Carbonates
5. Sulphate
6. Halides
7. Phosphates e.t.c

What factors controls the shape of a well formed crystal?

The following are major factors that influence the shape of a well formed crystal:
 

•   Symmetry properties of the underlying lattice
•  Rates of growth; - the overall shape of the crystal is determined by the relative rates of growth of the various faces. Thus the slower the growth rate, the larger the face. 
• The conditions under which a crystal is grown can affect its habit. The Temperature, degree of super-saturation, nature of the solvent all have their effects, and these may affect the growth of different faces in different ways. 
• The presence of impurities in the solution can radically alter the habit of a crystal, as seen in the following table for the growth of sodium chloride: 

no impurity           Fe(CN)64–         formamide Pb2+,             Cd2+          polyvinyl alcohol
cubes                     dendrites                octahedra              large crystals          needles

These effects presumably come about because these substances preferentially adsorb to certain faces, impeding their growth.

List down at least five examples of sulphide minerals.

List down at least five examples of sulphide minerals.
Sulfide ores/minerals
i. argentite (silver sulfide),
ii. cinnabar (mercury),
iii. galena (lead sulfide),
iv. molybdenite (molybdenum sulfide),
v. pentlandite (nickelsulfide]),
vi. realgar (arsenic sulfide),
vii. stibnite (antimony),
viii. sphalerite (zinc sulfide),
ix. pyrite (iron disulfide), and
x. chalcopyrite (iron-copper sulfide).

Five types of fossils

Five types of fossils are:
1. Mold (imprint) fossils
When a leaf, feather, bone or even a body of an organism leaves an imprint on sediment, which hardens and becomes rock
2. Cast fossils
When minerals fill in the hollows of an animal track, a mollusk shell, or another part of an organism
3. Fossil fuels
Fuels formed by the remains of dead plants and animals
4. Actual remains
It is the body of an organism, with all the parts intact, usually preserved in ice, amber, or tar.
5. Petrified wood
 When minerals replace wood or stone to create either petrified wood or a mineralized fossil

List the five stages in the formation of sedimentary rocks

List the five stages in the formation of sedimentary rocks
i. Weathering
ii. Erosion
iii. Transportation
iv. Deposition
v. Lithification (compaction & cementation)

What is magmatic differentiation?

What is magmatic differentiation?
This is a complex process whereby a single melt can produce a wide variety of different rocks.
Various processes have been suggested to explain the variation of magma compositions observed within small regions. Among the processes are:
1. Distinct melting events from distinct sources.
2. Various degrees of partial melting from the same source.
3. Crystal fractionation.
4. Mixing of 2 or more magmas.
5. Assimilation/contamination of magmas by crustal rocks.
6. Liquid Immiscibility.

Why sandstone and limestone do not show foliation when metamorphosed?

Why sandstone and limestone do not show foliation when metamorphosed?
Sandstone and limestone rocks are usually uniform in composition. Also rock made up of all one mineral (e.g. quartz = Quartzite, calcite = Marble; exception = Hornfels) so the minerals do not segregate into layers.

Foliated textures result when the new metamorphic minerals (many of which are platy micas such as Biotite and Muscovite) line up producing a distinct layering in the rock. The layering produces three distinctly different looking rocks; those with slaty cleavage (e.g. Slate), schistosity (e.g. Schist), and mineral banding (or Gneiss Texture). Minerals (e.g., quartz sandstone or limestone), produces rocks that are characterized by fine or coarse interlocking crystals that do not display foliation.

What is sedimentary Facies?

What is sedimentary Facies?
This is the characteristics of a rock or series of rocks reflecting their appearance, composition, and conditions of formation or characteristics of stratified sedimentary body/rock distinguished from others by its appearance, composition and conditions of formation.

What is a porphyritic rock and how is formed?

What is a porphyritic rock and how is formed?
Rocks having large crystals in a fine groundmass of minerals/Containing relatively large isolated crystals in a mass of fine texture. Porphyritic textures develop when conditions during cooling of a magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a fine grained (aphanitic) matrix. The result is an aphanitic rock with some larger crystals (phenocrysts) imbedded within its matrix. Porphyritic texture also occurs when magma crystallizes below a volcano but is erupted before completing crystallization thus forcing the remaining lava to crystallize more rapidly with much smaller crystals.

SUPERGENE ENRICHMENT AND REACTION EQUATIONS

GOSSAN FORMATION AND SUPERGENE ENRICHMENT
Reaction Equations
1. 2FeS2 + 15/2O2 + 4H2O Fe2O3 + 4SO42- +8H+
Pyrite
Sulphuric acid enhances the breakdown of accompanying sulphides:
2. 2 CuFeS2 +17/2O2 +2H2O ---> Fe2O3 +2Cu2+ + 4 SO42- + 4H+
Chalcopyrite
Copper is leached downwards and may reprecipitate as Cu sulphates (or carbonates)
above the water table or copper sulphides (esp. chalcocite Cu2S) below the water table
(by replacement of pyrite). This can result in substantial increase in metal content.

Factors for hydrothermal alteration

Factors for hydro-thermal alteration
a) Temperature;
b) Pressure; - low pressure favors alteration
c) Rock type; - rock composition, and texture control alteration and hence permeability.
d) Permeability;
e) Fluid composition;
f) Duration of activity.

Conditions for secondary enrichment (prerequisite conditions for the secondary sulfide enrichment)

Conditions for secondary enrichment (prerequisite conditions for the secondary sulphide enrichment)

•  The climate, (temperature, rainfalls)

A warm climate, in so far as it favors chemical action, is favorable to sulphide enrichment. Deposits in high latitudes are not so likely to show extensive migration .of the metals, because low temperature decreases chemical activity, and freezing prevents solution.
Since water is the agent of ore enrichment, abundant rainfall is favorable to the formation of secondary ores.

•  Altitude

As a rule, the relief is great in areas of high altitudes, and erosion is consequently more rapid. Moreover, in such areas temperatures are lower and conditions are less favorable to solution.
Deposits located at very high altitudes, where rocks are disintegrated by frost and carried away
un-weathered as talus and boulders, are not so likely to be extensively enriched as are deposits
that lie at lower altitudes.

•  Relief;

In so far as strong relief supplies head, it is favorable to deep and rapid circulation of
underground water, and it is likewise favorable to relatively deep enrichment. In base-leveled
(flat land) regions underground circulation is sluggish and the nearly stagnant waters cannot
descend far into the zone of primary sulphides without losing the valuable metals which they
dissolve higher up.

•  Permeability of the deposits is an essential condition, for if solutions cannot find access

to the lower horizons the metals dissolved near the surface may be scattered.
Permeability is essential for sulphide enrichment. If the primary deposits are not permeable the
solutions that pass downward through the oxidized zones will move laterally along the contact
between oxidized and sulphide ores and ultimately will escape into fractures in the wall rock or
reissue as springs at some level below the points of entry. If they do not encounter a reducing
environment the metals may be scattered.

•  The duration of the period of weathering as well as time taken to concentrate the deposit

Mineral resource and mineral reserve

Mineral resource vs mineral reserve Mineral resource of a country (or an area) means the total available economically viable mineral stored in that country (or in the area). Mineral Reserve is the availability of a particular mineral in an occurrence that can be economically exploited. Please remember, reserve can be of proved, estimated or probable category, depending on the degree of the intensity of geological investigation carried out to assess the potentiality of that occurrence. But mineral resources are usually tentative. In other words, Reserve pertains to a particular mineral while the Resource is the sum total of all the economic minerals.
Mineral resources are defined as natural concentrations of minerals or, bodies of rock that are, or may become, of potential economic interest due to their inherent properties.
The classification includes the more important groups of primary ores:

•  Syngenetic deposits; contemporaneous with the inclosing rocks:

1. Sedimentary beds; mechanical, chemical, organic, etc.
2. Magmatic segregations; consolidated from molten magmas.

• Epigenetic deposits;, deposited later than the inclosing rocks:

1. Contact-metamorphic deposits; deposited in intruded rocks by fluids passing from consolidating intruding rocks.
2. Hydrothermal fluids;
Pegmatite veins; deposited by "aqueo-igneous" magmatic solutions.
Deposits of the deep vein zone; formed at high temperature and under great pressure, generally in and along fissures.
Deposits formed at moderate and shallow depths by ascending hot solutions.
Deposits formed at and near the surface by ascending hot solutions.
Deposits formed at moderate and shallow depths by cold meteoric solutions.

Why Placer Deposits are mined despite of their low Grade?

Answer:
In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation during sedimentary processes. The name is from the Spanish word placer, meaning "alluvial sand".  Placer mining is an important source of gold.

Minerals commercially mined from placer deposits include:

1. Gold
2. Platinum group metals
3. Tin, in the mineral cassiterite
4. Diamonds
5. Rare earth elements, from the mineral monazite
6. Thorium, from the mineral monazite
7. Titanium, from the mineral ilmenite
8. Uranium, from Precambrian paleoplacers

Types of placer deposits include:

• alluvium placer deposit, 
• eluvium placer deposit, 
• aeolian placer deposit,
• beach placers deposit, and 
• paleoplacers deposit.

Placer materials must be both dense and resistant to weathering processes. To accumulate in placers, mineral particles must be significantly denser than quartz (whose specific gravity is 2.65), as quartz is usually the largest component of sand or gravel. Placer environments typically contain black sand, a conspicuous shiny black mixture of iron oxides, mostly magnetite with variable amounts of ilmenite and hematite. Valuable mineral components often occurring with black sands are monazite, rutile, zircon, chromite, wolframite, and cassiterite.

Majority of placer deposit are small and often ephemeral as they formon the earth's surface usually at or above the local base level , so that many are removed by erosion before they can be burried.

Placer deposits are mostly of low grade but can be exploited because:

1. They are loose, easy worked on materials which require no crushing. Relatively semi-mobile separating or hydraulic mining plants can be used. Mining takes the form of dredging, about the cheapest of all mining methods
2. Placer deposit tend to concentrate minerals at a shallow depth and may contain valuable minerals such as Gold. Good example is the Witwatersrand in S. Africa.

These factors make placer deposits exploitation profitable despite the fact that they are small and of low grade

Why continental crust is older than Oceanic Crust?

Why continental crust is older than Oceanic Crust?

Answer: 

• An important difference between continental and oceanic crust is their difference in density. Continental crust has a lower average density (2.6g/cm3) than does oceanic crust (3.0g/cm3). This density difference allows the continents to float permanently on the upper mantle, persisting more or less intact billions of years. Oceanic crust in contrast, is barely able to float on the mantle (which has a density of 3.3g/cm3).
• As oceanic crust ages and cools, it accumulates a heavy under-layer of cooled mantle rocks; the resulting two-layer structure eventually sink of its own weight (because of its own weight) into the mantle, where it is melted down and recycled.

        Because of this process; no oceanic crust older than 200 million years exist on the earth.

• About 16% of mantle consists of recycled oceanic crust rocks; while only about 0.3% of mantle consists of recycled continental crust rocks. 

Events in the field

Field Studies

  Geological mapping at Dodoma

   Geological mapping at Dodoma

 at Kimani hill

 On the way up Kidofi Mountain

 Me

Me

Chimala Geological Mapping Field Report

My Geological Mapping Report

MINERAL RESOURCES INSTITUTE (MRI)

DODOMA, TANZANIA

DEPARTMENT OF GEOLOGY AND MINERAL EXPLORATION

INDUSTRIAL PRACTICAL TRAINING (IPT)

AT CHIMALA

LOCATION: MBALALI DISTRICT IN MBEYA REGION

STUDENT NAME:    PROTASE HERMAN              
REG NO:                    650 MID 12
COURSE PROGRAM:     INDUSTRIAL PRACTPCAL TRAINING (IPT)
                                            GET04206
INDUSTRIAL SUPERVISOR:   MR. NGOWI AND MR. GEORGE
DATE OF SUBMISSION:           27TH SEPTEMBER,  2013

Signature :......................

ACKNOWLEDGEMENT

This report is the result of the efforts of many. Firstly I would like to give my special thanks to our almighty God, he is everything to us. Also I would like to express my appreciation to the following people and organization that had contributed a lot in my field work, first of all I wish to express my deeply felt gratitude to The Principle of Mineral Resources Institute (MRI) Mr. S. A. Chiragwile for his effort, our supervisors Mr. Dickson Ngowi and Mr. George together with our bus driver Mr. Ridhiwan Msuya without forgetting Mr. Makena who was our IPT coordinator.
. 
Finally, I would like to express my sincere thanks to my parents and my relatives for their support, as well as my fellow students, especially my group members; I would like to appreciate their cooperation and understanding during field work.
 
ABSTRACT
Chimala is the area geologically composed of different lithologies of all rock types. The area we concentrated was located at the UTM of 0627000E/9024000N, 0631000E/9024000N; 0627000E/9018000N, 0631000E/9018000N.
Main purpose of conducting this field is to describe and indentify the different lithologies, rock structure, rock unit and mineralogical composition that constitute different outcrops. Mainly sedimentary rock is the type we observed in our concentrated area, sedimentary rocks observed are like shale, sandstone and conglomerate. Nevertheless the other objective was to create a geological map of the mapped area and its cross-section.
Also we had excursion at Mambi Village, Mlima Nyoka, Kongolo quarry, Isalaga and Songwe hot/warm springs were we observed vesicular basalt (olive basalt and scoriacious basalt), pyroclastic materials (bombs and lapilli tuff),  phenolite, travertine, limestone and warm springs.


 
ABBREVIATION
GPS Global Position System
UTM Universal Transverse Mercator
IPT Industrial Practical Training
E Easting’s
N Northing’s
M Meter
Mt        Mountain













 

Table of Contents

ACKNOWLEDGEMENT ii
ABSTRACT iii
ABBREVIATION iv
CHAPTER ONE 1
1.0 INTRODUCTION 1
1.1 LOCATION AND ACCESSIBLITY 1
1.1.1 LOCATION 1
1.1.2 ACCESSIBILITY 1
1.2 CLIMATE AND PHYSIOGRAPHY 1
1.2.1 CLIMATE OF THE AREA 1
1.2.2 PHYSIOGRAPHY 1
1.4. METHODOLOGY OF INVESTIGATION AND EQUIPMENTS 2
1.4.1 METHODOLOGIES 2
1.4.2 INSTRUMENTS AND EQUIPMENT 2
1.4.2.1. Compass 2
1.4.2.2. GPS (global position system) 3
1.4.2.3. Base map 3
1.4.2.4. Geological hammer 4
1.4.2.5 .Note book 5
1.4.2.6. Pencil, colored pencil, scaled rulers and maker pen 5
1.4.2.7. Sample bag 5
1.4.2.8. Hand lens 6
1.4.2.9. Tracing paper 6
1.4.2.10. HCl bottle 6
1.4.2.11 Camera 6
1.4.2.12 Magnet 6
1.4.2.13 Bush knife 6
CHAPTER TWO 7
2.0 Geology of the area/ Regional 7
2.1. The ubendian rocks 7
2.2. The ukingani rocks 7
2.3. The bukoban rocks 7
2.3.1 The lower Buanji 7
2.3.2 The Upper Buanji 8
CHAPTER THREE 9
3.0 LOCAL GEOLOGY OF THE MAPPED AREA 9
3.1.1. ROCK FORMATION 9
3.1.1.1. SEDIMENTARY ROCKS 9
3.2 NAMES OF ROCKS WHICH MAKE LITHOLOGIES OF THE MAPPED AREA ARE:- 10
3.2.1 Sandstone 10
3.2.2 Shale 10
3.2.3 Conglomerate 10
3.2.4 Alluvium 10
3.3 NATURE OF THE OUTCROP AND TOPOGRAPHIC EXPPRESSION 12
3.4 LITHOLOGICAL STRUCTURE 12
3.4.1 Bedding 12
3.4.2 Laminations 12
3.4.3 Ripple marks 13
3.4.4 Folds 13
3.4.5 Joints 13
3.4.6 Veins 13
3.5 FIELD RELATIONSHIP 15
CHAPTE FOUR 16
4.0 GEOLOGICAL HISTORY OF THE AREA 16
4.1 DESCRIPTION OF GEOLOGICAL EVENTS IN THE NATURAL SEQUENCE 16
4.2 THE MODE OF ORIGIN OF VARIOUS ROCK UNITS AND IMPORTANT STRUCTURES 16
4.2.1 Mode of origin of various rocks 17
4.2.2 Important structures 17
CHAPTER FIVE 18
5.0 CONCLUSION AND RECCOMENDATION 18
5.1 CONCLUSION 18
5.2 RECCOMENDATION 18
5.3 EXCURSION 18
REFFERENCE 24


 

CHAPTER ONE

1.0 INTRODUCTION
It was Saturday, 8th June, 2013, the day I travelled from home, Dodoma to Chimala, Mbeya. My journey began earlier in the morning at 06.00a.m, by bus. It was a bit long and tiresome journey but late in evening around 07.30p.m I arrived at Chimala Village. Our IPT program started on Monday, 10th June, 2013 with about seven days of training by our supervisor.
1.1 LOCATION AND ACCESSIBLITY
1.1.1 LOCATION
Chimala is at Mbarali district found in Mbeya Region. It is located within a quarter degree sheet 024/03. Also it is found within latitude 80 45’ to 90 00’ south of the equator and longitude 340 15’E of the Greenwich or Prime Meridian and it’s about 76km from Mbeya town.
1.1.2 ACCESSIBILITY
Chimala is accessible by road transport (Tanzania–Zambia/Malawi highway) and railway (TAZARA railway). During mapping some parts were remote due to thick thorny bushes, big river and higher mountains with steep slope but were successful mapped.
1.2 CLIMATE AND PHYSIOGRAPHY
1.2.1 CLIMATE OF THE AREA 
The climatic condition of the area is wet on September up to April and then dries from May to August. Also the annual mean temperature as about 220C and the rainfall starts on November and end up to April. Daytime maximum temperature is around 27 ºC.
1.2.2 PHYSIOGRAPHY
The area is characterized by well-vegetated low hills, mountains and flat lowland. The Southern part is uplifted or elevated. It is highland consisting of hills and mountains there are two higher mountains namely Mt. Kidofi and Mt. Chaufukwe. The Northern part is lowland with shrubs and mangrove swamps, mainly composed of massive alluvial deposits (sediments) which make this part contain fertile soil hence common for large scale paddy (rice) plantations.
 The area of Chimala is well drained by many streams most of which are seasonal, and three main rivers; Chimala River (in the west), Ruaha river (in the middle of the area) and Kimani River (in the east). Chimala All Rivers are running to the north; hence provide water for irrigation in the paddy plantations. River and Kimani River join Ruaha River to form one great Ruaha River.

The area is sparsely inhabited bush country with bushes, sparse short trees and grasslands especially in low land and in most parts of the area. There are tall trees and fewer grasses in the area around the mountain slopes. Human habitation is restricted to villages along the main Dar es Salaam to Malawi/Zambia road (Tan-Zam highway). Limited agriculture is practiced along the road and in some irrigated areas in the Northern part.


 1.3 OBJECTIVES OF THE STUDY
The main objectives of study which was done at Chimala are:
• To determine the structure of the rock in the chosen area such as joints, fault, fold and other structures.
• To measure different structures like joints, fault and fold present in the outcrops.
• To indentify different rock type that was present within the mapped 
• To determine the mineralogical composition of different rocks.
• Identification of the nature of the environment that the rocks are formed such as stream, road cut and uplifting environment.
• To measure the orientation of the bedding plane and read the altitude of the outcrops. 
• Creation of geological map and geological section by using data gathered during field work according to collection and identification of the representation sample. 
1.4. METHODOLOGY OF INVESTIGATION AND EQUIPMENTS
1.4.1 METHODOLOGIES
Our area of interest was rectangular in shape of about 4km × 6km, and we divided it into squares of about 200M sided. Our mapping was done by traversing zigzag line from north to south and back. The line and direction of traverse was perpendicular to the strike so as to descover contacts and new lithology easily. Data were collected after every 200M and where a geological feature and structure was encountered. 
1.4.2 INSTRUMENTS AND EQUIPMENT
The instruments and equipments used during field observation were;
1.4.2.1. Compass
We had two main geological compasses namely; Brunton compass and Suünton compass. Compasses are used for determining and measuring direction as well as bearing of place, position or location. Also compasses consist of inclinometer/clinometers used for measuring dip of the outcrop. Brunton compasses consist of bubble type and Suünton compasses contain pendulum type inclinometer. Generally compasses were mainly used for measuring strike, dip and dip direction of the outcrop exposed also used in plague and trend measurements and taking bearing of the features. 
1.4.2.2. GPS (global position system)
It is used to determine location and elevation on the earth’s surface by using signals from selected satellites. It determines location coordinates in two different systems depending on the one desired. The coordinate system can be UTM or latitude and longitude system. We preferred UTM coordinate system in recording location data as it is the best for mapping. A GPS requires signals from at least four (4) satellites to record accurate information and must be in open space. For instance area covered by thick forest and the period of higher cloud cover interfere the accuracy of a GPS.
1.4.2.3. Base map
It is commonly a topographical map of the area of interest used in geological mapping as a base map as it shows various features and elevation in the area by the contour lines. The base map was used for preliminary study of the nature and structure of the area, orienting our position in the field and planning traverse lines/path during field work (mapping).
HOW TO USE A BASE MAP
Before working with the base map, the followings have to be taken into account;
1. Identifying the north part of the map,
2. Scale used on the map,
3. Recognizing and identifying symbols used on the map, by the help of a legend or a key of the map,
      4.   Coordinate system used (UTM or latitude and longitude).

WORKING WITH THE BASE MAP
• The map has to be oriented the north after identifying the north part of the map sheet, with the help of the north arrow present on the map. The compass is laid on the map sheet with its edge coinciding with the grid lines. The map sheet is rotated until its north part is the pointing in the same direction as that of the compass.
• The coordinates of our present location/position were read from the GPS i.e. 0628400E/9022980N.
• Finally we find our current location position on the base map using the coordinate obtained from the GPS (corresponding base map position) and we marked/note it.

  
Figure no. 1 d). Orienting in the field
1.4.2.4. Geological hammer
It was used to break rocks in order to get fresh sample for identification and interpretation of the observed rock. And collecting samples for further study in the off the field.
Fig. geological Hammer Fig. a GPS
Fig. Hand lenses fig. Brunton compass

 Fig. Suünton compass
Illustration of some geological tools and instruments



1.4.2.5 .Note book
It is used to record or documents all observations during field work.
1.4.2.6. Pencil, colored pencil, scaled ruler and maker pen
These were used for sketching, drawing and labeling different geological features and rock types/ name in the field and during office work. Mark pens were used for labeling samples.
1.4.2.7. Sample bag
Used for carrying rock sample after collecting them from the concentrated area and has been approved not less than 500g. A sample bag were of plastic type as it reduce contamination of samples
1.4.2.8. Hand lens
The hand lens is used for rock analysis in the field to identify lineation, mineral composition and rock texture. We had two lenses; a 10× magnification lens and a 20× magnification lens. Also Suünton compass provided has lens on it.
1.4.2.9. Tracing paper
This was used for sketching and drawing various features such as contact between lithologies, dip and strike in the field and during office work.
1.4.2.10. HCl bottle
This was used to carry diluted HCl acid, which is used for testing the presence of carbonate (calciate minerals) in the rocks. It helps especially on the identification of rock such as Dolostone, Marble, Limestone and Travertine.
1.4.2.11 Camera
This is used for taking photos of interesting features, structures and rock in the field. The GPS (fig no. 3) we had consisted of a 5M pixel camera which help on taking photos.
1.4.2.12 Magnet 
A Magnet was used to test the presence of hematite and magnetite minerals (iron content) in a rock (outcrop) 

1.4.2.13 Bush knife
Bush knife are usually for clearing some bushes, thorny and trees which are obstacle to the traversing way.

Amazing pictures

1. Amazing
2. Friendship

True Love

True Love