Comprehensive Analysis of Mineralization in the Mankayan District Philippines

so um hello good morning to everyone welcome to the second lecture of the geoscience lecture series conducted by

the karaka state university department of geology in

partnership with csu association of mining engineering students this lecture series will cover different fields

related to geology focusing on its application to mining structural engineering for

environment and geo-informatics be related to geology application to mining specifically those related to the

different mineral deposits in the philippines we have invited resource speakers from all over the world to

share their knowledge and expertise regarding these topics i hope that you would continue on showing your support

in this and future activities of the department i also wish you would learn a lot from it and apply the learnings in

your respective professions thank you and we greatly appreciate your interest in this event once again

okay thank you very much uh thank you very much riva our very hard working chairperson and i

believe our speaker for today is already here so maybe i can

start with the introduction of our guest speaker so this speaker is a very good friend of

mine we have gone through trials and tribulations together when it comes to

our masters and even our phd dissertations and so to give a brief background on on

her academic and professional experiences so um

she obtained her bachelor's of science in chemistry in 2010 um as laude from university of the philippines

dilemma and uh she went uh straight to obtain her masters of science in geology

in 2015 at up national institute of geological sciences with with her research um

specializing uh with geophysical studies in particular her thesis title is potential field characteristics of

masbati island philippines and then

in 2016 she joined the graduate school of international

resource sciences in akita university and obtained her doctor of science degree in 2019 at akita university

with her research focusing mainly on economic geology geochemistry and mineralogy her dissertation title is

geochemical and temporal constraints on the genesis of multiple hydrothermal mineralization in the mankind district

philippines currently she is serving as an assistant professor

at the faculty of international research sciences at akita university japan and

has several experiences as a technical staff research assistant and such

and recently she was awarded the best article award in 2020 uh for the uh the for her

research geology article entitled geochemistry and fluid inclusions analysis of vein quartz in the multiple

hydrothermal systems of bangkaya mineral district as well as research encouragement award of the society of

resource geology with that uh students and participants of the second geosciences lecture series

i warmly introduce you to my good friend of mine dr perlin manalo balmater i believe she is

going to talk from akita university in japan hello can you hear me yes yes okay thank

you for having me here and thank you for that generous introduction i am

honored to be part of this initiative and reach

many students in the in the philippines so yeah let me start my

my talk this is gonna be a little lengthy so for today i'm gonna so um anytime

that my audio is uh not clear just please let me know okay because yeah

um with regard to questions how do you want it do you um if they have questions um

during your presentations do you want them to be addressed or you want to collate them at the end

i'm free you can ask anytime you want i don't mind for the participants just um

type them on the chat box and i'll be i'll be the one getting the attention of our speaker okay

okay so for today i'm going to talk about um the different uh mineralization in the

mankind district so mankind district is in northern luzon it is um one of it is my study area during my phd

and i'm still continuing studying it so there are many deposits in the area i'm

going to uh i'm going to cover

not uh just few of the deposits so i only studied a certain deposit but i'm going

to share with you some reviews based on the different published articles

there okay so today

i'm going to talk about some introduction and then most of the most of the

time will be the post they will be devoted for the geology and mineralogy of the deposit and then we'll go to some

characterization of the fluid that affected the rocks okay

so so just for an introduction so we all know that philippines is part of the

pacific ring of fire and you can see here uh the red dots are the different epithermal and periphery copper uh

deposits [Laughter] really

okay do you have it now yes mom there

really okay so this is the title slide i'm going to talk about the characteristics of the multiple

mineralization in the mankind district and then this is the outline this first uh introduction

and then the deposit geology most of the time will be spent here and some or fluid characteristics

okay okay so

i'm showing you here the map of the uh the

pacific ring of fire the philippines is the western pacific and you can see the red dots here are the

periphery copper and epithermal gold deposits the stars are the considered world-class deposit because of

according to the to lesnika in 1983 we consider world-class deposit gold deposit if the it has greater than 200

tons of code so there are different um criteria for calling uh deposit world class so different authors

have different descriptions but for now and we'll we use this okay so the

philippines here this is the map of the philippines northern luzon so the tectonic settings you must be

familiar with as the oppositely dipping subduction zones to the west and to the east so

within beneath the manila trench uh the south china sea basin is being consumed along an eastward dipping subduction

zone so to the to the east lies the east luzon trough

and the philippine trench system and so th the

the philippine sea plate is uh being consumed along the philippine trench

so because of the oblique uh convergence uh there is the philippine fault zone traversing the

whole lens of the archipelago so you can see here the

red lines of the philippine fold zone so mankind this drink this is what we're going now

is the marked here by the star so it's in

located to the western flank of the luzon cordillera so the the north-south trending

mountain range here so let's zoom in to the geology

so uh mankind district has one of the most reviewed geology and uh

here in the philippines so uh work as early as the 1990s um

have already constrained what rocks are in here so the the oldest basement rocks are the late

cretaceous to esc in le pantha meta volcanics and then it's overlaid by several neogene volcanic plastic

sequences we call the balili and the pawawan volcanic plastics exposed here in the right hand corner of the map

so and then the oldest um magma evidence of magmatism is the amidomyosin bagon intrusive

this is in full contact with the metavolcanic basement and then applies seen to pleistocene

uh magmatism has been recorded uh by the imbanguilla dayside and battle day site so these days sites occur as pyroclastic

deposits and perfury the acetic domes so there are different mineralization in

the area as a whole suite of mineralization

looking here the as you can see here the blue outlines polygons those are the periphery copper

called prospects and deposits so the biggest largest of which is the world class far southeast deposit here

so to the south you can see the teresa and victoria carbonate base metal gold silver veins veins and then

to the north lies the energized gold ore bodies here this is the largest one of which is the lepanto main

energy gold or body and recently uh they have the the le panto mining company

delineated another set of veins which these are newly delineated veins located to the east and south of the

lepanto main energetic body which is the quartz pyrite gold veins the that's what they termed the newly

discovered veins so this qpg veins as we call it this is the main topic of my uh

study and yeah so most of the

data and slides that i'm going to show you today

will deal with the qpg veins okay so uh

at the surface there are different alteration patterns and you can see uh associated with the

different deposits so the most extensive uh alteration zone is the quartz alumni

pyrite zone here and then along also this

unconformity between the basement and the diacetic rocks you can see the decayed kaolinite pyrite

and above the victoria teresa veins you can see

e-lights mactite and pirate okay so this is the original view of the

of the geology alteration and mineralization okay so in cross section this is how uh

it looks like so the section runs from a to a a prime and a double prime here

okay so the basement rocks the metal volcanics is unconformably overlaid by the embankment cyperclastics the lepanto

main energized ore body of course cutting through the lepanto metal

volcanics and then it uh spreads along the unconformity so most of the deposit is along the

unconformity especially when the levant fault intersects the unconformity so that's

where the energized code uh mostly deposited so the there are qpg veins the yellow

veins here that are uh only hosted by the le panto meta

volcanics what some some other qpg veins cuts through the younger embankment dayside

pyroclastic so um here is the far south east for free uh system and these are the

uh intermediate sulfidation veins of the victoria and teresa shown here in red so that's a schematic relationship of

the deposit so a recent drilling they delineated

several concealed intrusive bodies in the subsurface it's concealed so they only

discovered it in by drilling okay so uh this is just to highlight the alteration

in the area so this is the mineral the lepantomy energetic gold ore body and the most extensive

uh quartz alumni pyrite alteration zone okay so we'll review first what no what was known for the uh

for this area so along this dashed line this is the cross section in

the previous studies we most cross sections

depicts the far southeast or body and the lepanto energized cold surrounded mostly by

silicic alteration and quartz alumni pyrite alteration in this section you can this is the

dotted section here from northeast to southwest you can see uh

the this is the main energy

or body this section illustrates the mushroom nature of the alteration so most of the

deposits are along the folds and then it spreads when it when the fault intersects the

unconformity between the embankment day site volcanic so

the unconformity and the faults are play a big role in that in the deposition of the main energy or gold or body

so the ore is hosted in procedural quartz and uh advanced uh argelic alteration zone so residual quartz means

uh the rocks suffered

very acidic leeching so only quartz which is very resistant was left and while the advanced algalic

alteration zones uh are composed mainly of the minerals that are stable in acidic

conditions the alumni quartz decayed kaolinite so from the geology we know that it is

uh the conditions are acidic in nature so this is the example of this is a

photo of the spanish tunnels outcrop in the mankind district and yes you know this is the

type locality of the mineral luzonite so this

brownish grayish mineral you can see here in filling the

fractures these are delusionite in the as they occur in the outcrop

okay so what are the minerals in the lepanto main energetic code or body so according to the previous source there

are three main mineralization stages the energized flusonite pyrite so you can see this is early

too late in terms of time and the they saw that energetic and luzonite

precipitated first followed by the tendon type chalcopyrite sphalerite and then the latest stage is

the gold telluride stage so most of the gold is occurring as the telerites like calaverite the mineral

calaverite and peptide hosted in digenite so this is a copper sulfide mineral

so from the mineral mineral assemblage uh we know that uh because there is alumni kaolinite the

kite diaspora and pyrophelite so these are uh stable in low ph condition

and energite and lusionite i are characteristic uh high sulfidation state but as you go

from energized lusunite to 10 these are

the base metal rich minerals so and then the third stage is

hope gold hosted in digenite digenite is another high sulfidation state mineral so we can see that across the stages

there is first the decreasing of sulfur fugacity to increasing again so there's

fluctuation across the stages but mostly uh everything mostly in the

high sulfidation state so according to mankind and campbell he analyzed

fluid inclusions in energy so they uh he concluded that the precipitation of the main energy gold or body is due to

the cooling of hydrothermal fluid so when because gold is transported

uh with uh sulfide complexes especially in high sulfidation state conditions the cooling or decreasing of

temperature makes the complexes unstable so they precipitate the minerals so

based on the potassium argon dates of alanite airbus

concluded that the mineralization age of the lepantomine and the red gold or body is around 1.45 million years

so yeah okay so now we'll go to the victoria veins so

in contrast to the lepanto mean ender guide code or body so these are the victoria veins here

this one okay so veins are narrower and metal content is depleted in the meta volcanic

basement than in the younger day site so uh most of the victoria veins gold are found in the

the the acetic rocks but the veins are also cutting through the metal volcanic basement

so um the the previous authors

um have have described we described that the veins uh has pinch and swell

patterns so sometimes it becomes narrow and sometimes it becomes uh broad again

okay so that's the occurrence of the victoria vein so the alteration pattern uh in the victoria veins they said that

um the alteration halo is not as extensive as the

as the lepanto main energize code or body so very narrow alteration around the

veins themselves okay so you will see here that uh there the

victoria epithermal quartz veins are very has different mineralogy than the

main energized gold or body so the first stage mineralization stage is characterized by early quartz

with interbanded with sulfides and then second stage is the

characteristic carbonate stage mainly rhodochrosite so rhodochrosite is among its carbonate

and then you can and then after that is this late sulfate

stage with anhydrite and gypsum mineral so you can see gold versus gold so here gold our electron precipitated

mainly on the carbonate stage but also starting from the late uh early stage to the sulfate stage but mostly it's

it's related to the carbonate so from this mineralogy uh you can see energize the

characteristic high sulfidation minerals energize and lusunite are absent in the paragenesis paragenesis

so they have different sulfidation state and the characteristic acidic minerals aluminide pyrophyllite

instead of those minerals victoria has elite and kaolinite and chlorite and also carbonates so these are

characteristic and near-neutral ph minerals so since gold is

was precipitated with carbonate so

it suggests that it's caused by boiling fluids and argon

argon age according to sakakibara and heading twist at all 2001 ranged from 1.31 to 1.16 ma

so not not far from the lepanto main energy or bodies

so this is the mineralization stage and conditions of mineralization for the victoria deposit

so now we will go to the newly discovered um deposit the quartz pyrite gold veins you can see

here in yellow so there are different um there are several veins they tagged it by the

number from north to south 807 826 etc

so when you compare it uh with elevation regarding elevation

this is the the pantomime ender guide gold or body the qpg in the northwest are deeper than the main energies or

body so the minerals are very are also different slightly

different so we we

documented different stages from early to late so the first stage is

characterized by abundant asphalerite choco pyrite with few magnetite and pyrite and then the

alteration in lung minerals are quartz chloride and elite so characteristic

near neutral ph assemblage and then in stage two the second stage we begin

to see carbonates along in veins and associated with

chloride chlorite alteration so you can see this is the stage two vein

cutting uh the previously altered chloride chloride altered rock

and then the main or minerals are pyrite chalcopyrite and we also found gold field diet

so here is the beginning of telluride mineralization

so uh the uh when we go to stage 3a you can see a switch in the mineralogy

we can see so we know that it took uh it's after the carbonate mineralization since

uh we saw a class this is a stage two class it has carbonate um elite alteration here inside and then

it's surrounded by um by a muscovite alteration here

so we we saw that uh it tran from from minor muscle divide to

stage three a it become uh coarse grain muscular so you can see here of course uh muscovite grains and

also in this stage we can see boronite chalcopyrite tendon type and hesside so this is uh because uh born night is

present already we know that this is a high sulfidation assemblage

okay and then later

so there are muscovite grains and then we saw some veins they are cutting the muscovite uh grains

and these veins are mostly quartz and alumni so we can see the transition from uh slightly acidic to more acidic

because we saw aloe knight and parts now so this is the stage 3b veins and then we also saw a pervasive

alteration of pyrophyllite so pyrophyllite indicates acidic and very high

temperature so alanite also occur along the quartz vein so this is a quartz vein you can

see the uh growth pattern and then it occurs along the halo

on the side of the vein and then this is you can see the it also occur as bug fills along the altered host rock so

most of the whole structure are highly silicified so in terms of oral minerals we saw

pyrite um with covalent inclusion so we know uh this is hypersolicidation assemblage

and then uh the stage four now these are big energized uh

veins so this uh you can see energy and lusunite here precipitating in this stage

very abundant not so much in the earlier stages but and now

abundant energy and luzonite and mostly associated with quartz so

the few pyrite are included inside the luzonite grain this is luzonite with inclusions of 10 anti-tetrahedrite and

pyrite and then some chalcopyrite also occur along the

rim of energize so you can see here

uh also include included in the energetic crystal so the last stage

almost no quartz and the previous stages have abundant quartz at the last stage there are

mostly sulfide veins and veins cutting through the stage four quartz

so mostly pyrite abundant pie right here with inclusions of lysonite and energy yeah so

that is northwest now we go to the qpg veins to the south so this is how the cross-section looks like

so this is the in in the acetic acidic rocks overlying the metabolic basement

so uh if you will remember northwest is just hosted by the lepanto meta

volcanics it doesn't cut through the acetic rocks but carmen in florence we saw the veins are cutting through the

acetic rocks the younger the acidic rocks so and the alteration assemblage is quite the

same it shows quartz the kite and alumni surrounding the veins so the

in florence we can see these are pyrite-rich qpg veins these are energite rich

qpg veins the red ones the more pyrite rich veins are surrounded by a broad quartz aldenite alteration zone

while you can see in the energi zone this is um just surrounded by

a little bit narrower uh alteration zone and then it grades immediately to uh chlorite alteration

so that's the distinct characteristic between the thyroid and energy rich veins

so in terms of paragenesis we saw that the incarnate florence both of them has

evidence of a periphery type mineralization so in the models we know that the periphery

occurs deeper and then the epithermal of course occurs are shallower so but in the carmen and florence we saw

at the same level the there are evidence of periphery type quartz uh stock works and then later

it's cut by uh qpg vein so this qpg veins contain the gold actually here

in the white very wide veins from 30 that

occurs uh until 30 meters wide

so this is a fluorine sample here you can see buggy quartz

evidence of acid leaching in epithermal environment but it surrounds a periphery type quartz vein so

we we we thought that the there is a perfect

type mineralization in the early stages and then later it is over printed by the epithermal

uh mineralization okay so the next stage is the high sulfidation stage characteristic

characterized by abundant energy and lusunite mineralization with some choco pyrite and pyrite so there is a

pervasive aluminite and pyrophyllite alteration in the rocks and then

and the late qpg veins uh this is the character is the coarse grain quartz and very coarse grained pyrite so you can

see here the grains of pyrite with some anhydride in the in the interstices so these white minerals are

anhydride so and then these rocks the host rocks they contain

porphyry type stock works but the whole thing has been uh the rest of the rocks are

are were altered by alumni and dki so yeah so evidence of acid acidic

alteration and then when you zoom in to the cubic pie right so you can see these grains when you zoom in

you can see the zoning in the pyrite grain those when you those are actually cover

light inclusions there so we can see this primary cover light so uh it suggests a high sulfidation state

okay so they have different uh different characteristics so we tried

looking at the age if to see if they were precipitated at one uh just one time or

or they were product of multiple events so i we took aloo knight from the northwest and other knight from carmen

so alanite from northwest gave an age of 2.2 million years argon organ age of 2.2 million years while carmen gave an age

of 1.6 1.62 million years so the alanite is carmen in carmen is much younger

than the alumni in northwest so this is consistent with the

cross-section that we saw earlier since northwest it's mainly in the

hosted by the le panto meta volcanic basement the credaceous to eu in rocks well carmen is hosted by the

younger apply flies to scene they sign so if you will see the we did the compilation of the age of

magmatism and mineralization in the mankind district so the bands solid bands here

are the ages of magmatism so according to arribas potassium organ dating

so the embankila day site is around the first phase is around 3 m a and then the second phase of the

embankment decide is around 2ma and then the youngest the battery side here the green one

so the patterns shows that relative error of measurement so this is the range

of the magmatism when you consider the error or standard deviation of age determination

here so the oldest uh periphery that we know is the bowaki

here at around 5.8 million years and then comparing the qpg veins with the rest of

the with the uh with the other edges so northwest lies here it occurred

before the peak of the in bangila day site uh

second phase magmatism carmen occurred after the embankment site second phase

magmatisa so consistent with the geology that we observed that northwest is just

uh is just hosted by the meta volcanic basement carmen is hosted by the imbangi lady site so we can see here that the

mangila dayside uh already uh formed before the carmen was uh deposited or altered

okay so the youngest is the far southeast and the largest of all the deposit is

is here okay so after that that's the geolo geologic

constraint so now let's go to the or fluids and conditions so we're going to i'm going to show you the results of

our fluid inclusion micro thermometry analysis and gas analysis and then the stable

isotopes and what it can tell us about the fluids conditions

okay so these are fluid inclusions in quartz

this the host mineral is quartz and i'm going to show you so if you remember there are four five four stages

five stages in northwest but the fifth stage doesn't have quartz so we just analyzed one to four

okay so i'm showing here photo micrographs these

are fluid inclusions as viewed under the microscope and then there is

we can identify when this fluid inclusion homogenized so you can see the fluid inclusion have

are cavities they are filled with liquid aqueous liquid and then there is a vapor bubble so l

here is for liquid v is for the vapor bubble okay so

uh we call this set of fluid inclusion as fluid inclusion assemblages and

and we evaluate if they are if they are good fluid inclusion assemblages if the homogenization

temperature are closed close to each other the individual temperatures are close to

each other so we can see here that um the

range is about plus minus 20 degrees celsius and so you can see the range

here of the homogenization temperature here the x and then salinity is calculated

from the ice melting temperature of the when you freeze the fluid inclusion

because this is aqueous fluid inclusion ice will form and then we heat it up again to measure the

melting temperature of the ice that was formed so remember your colligative properties

in chemistry that when you put uh dissolve put solute in a solvent it's uh freezing there there's a colligative

property called the freezing point depression so we can calculate the

salinity from that property okay so the homogenization temperature for stage

one uh range from around 200 to 300 320 degree celsius

and using this um graph you can see here

so if you will see there are more maybe more plots here than here because

sometimes we just observe the homogenization temperature the ice melting temperature is

difficult to observe in some fluid inclusions so the salinity in the salinity versus

homogenization temperature cannot be plotted so we just record the here in the homogenization temperature and the

frequency of it its occurrence okay so and there are also minute

inclusions of polyphase uh hyper saline fluid inclusion so you can see this is liquid there's a

small vapor there and then there are transparent solid faces here three so we cannot uh identify by just looking

at it there are other methods to identify the inclusions the yeah the inclusions

but uh we can say here that uh it is uh probably formed from a very

salient fluid because one of this fluid one of these transparent phases is halite so when there is halite in your

inclusions it shows that there is a very high salinity okay so

next is uh we go to stage two now this is what uh fluid inclusions in stage two looks like uh there are vapor-rich uh

fluid inclusion and liquid-rich fluid inclusion so and then we can see

the range of the temperature uh from 240 to 380 degrees celsius and

if you plot the salinity versus the homogenization temperature there is a steep slope

of uh you can see a steep slope in the plot so this is in this indicates that co2

uh loss could have probably occurred here and

variable vapor variable size of vapor bubble indicates uh also

the the fluid was boiling so there is coexistence of liquid and

vapor so in that case when we uh use the histogram

of the homogenization temperature we always get the minimum temperature to

represent the trapping temperature of the of the fluid inclusion

okay so it's possible that since co2 is being the gas from the fluid when the crystal was

was forming it captured some of the co2 gas co2 vapor that's being the gas from the fluid so we also

calculate it and and see how it affects the calculated uh nacl

uh in the inclusion so with this not much it's just less than weight one wave percent and acl

so it doesn't affect much our measurements okay

so next we go to stage three so this is the most uh

most uh abundant samples and because the gold uh is more abundant in stage three so i

categorized it to three a and three b three a is just the a lower temperature because

it it has um muscovite transitioning to alanite stage

3b has a pyrophyllite which indicates a higher

temperature so when we looked at the fluid inclusions

so this is uh stage 3b so indeed it is a higher temperature than the rest of the of the fluid inclusions so it's

consistent with the mineralogy so as you can see here uh it

it uh from stage one to stage two to stage three it looks like the fluid the temperature

cools down and it's more apparent when you go to stage 4 so you can see here

liquid vape uh phase fluid inclusion with liquid and vapor variable vapor content

so which indicates uh boiling of the fluids and most of the fluid inclusions are in

200 to 240 degrees celsius the lowest of all the stages but you can see a trail here

and so this is uh evidence also of the boiling fluids because when the gases are trapped within the fluid

inclusion the observed homogenization temperature will increase

so with this we know that fluid boiling likely occurred

okay now we moved on to the carmen so for carmen and florence our approach was uh a little different because we

observed here the over printing there is a periphery type vein and cut by epithermal type vein so we

characterized we first observed the fluid inclusions in epithermal type

veins so you can see the in energize there is a very rich vape vapor inclusion while in carbon qpg we

we can see liquid rich fluid inclusion so the homogenization temperature are

within two to five degrees of each other so it's fairly reliable reliable so the energetic bearing veins are

were precipitated at higher temperature from 290 to 330 degrees celsius unlike the energized veins in northwest

they were formed 220 degrees celsius a bit lower temperature well the qpg veins are the ones formed at a lower

temperature around 220 degrees celsius so you can see from now there are different

mineral mineralizing conditions in this deposit so you can see the epithermal type veins

in florence uh we characterized it if they occur as quartz in aspects of

cement or within the energy vein so you can see

here on fluid inclusion assemblage with variable vapor um percentage in at room temperature so as

you can see the higher vapor the bigger vapor bubble it contains the higher the observed homogenization

temperature so the it is very likely that when this fluid

inclusion was trapped so some of the vapor that is being the gas out of the system has been also

trapped within the fluid so that's why it has a big vapor so

for our purposes we always see we always get the minimum temperature to represent the homogenization temperature so here

is our representative homogenization temperature

okay so as i've mentioned earlier there is an earlier periphery type veining that was

observed in carmen and florence when we looked at the when we look at the fluid inclusion so

they contained uh polyphase fluid inclusion

sometimes with hematite and halide inside so they are abundant you can see in the

background there are more fluid inclusions like this so it confirmed um

our inference that these veins were formed at a higher temperature and higher

pressure so uh when we plot the homogenization temperature versus the salinity

it uh the our results plot around 700 bars so the pressure when this was formed at 700 bars

so the interesting thing here is now it of course at the same level of the

epithermal mineralization so it means it means that there was periphery type mineralization and then somehow it was

brought up to epithermal condition and then the epithermal mineralization occurred

so yeah our current study is now how how these over printing um affects how big the gold grade should be

but yeah but that's uh ongoing study right now so we also can see the gases trapped

in fluid inclusions so not just um the temperature and the salinity we can actually analyze uh analyze

what gases are within those micro uh microscopic fluid inclusion for this uh we did this

we have a collaborator in new mexico the he he did the analysis of

the gases in fluid inclusion so what he do is get the quartz and then crush it

so when you crush when you crush the quartz the fluid inclusions break and then it liberates

the gases within within the fluid inclusion and then those gases were collected by um

by a with a pressure valve and then it's analyzed by a mass spectrometer so that's the

the theory or the instrumentation for that

so for fluids there are three main

uh components so you can see nitrogen argon and helium

okay so first argon argon is present in the atmospheric in the atmosphere so it is an

atmospheric gas so when your fluid

is meteoric means it's exposed on that to the atmosphere it tends to have high

argon so that's why the air and air saturated water plots near the argon and member

okay nitrogen nitrogen comes from subducted

sediments so if your fluids have a high nitrogen nitrogen content

so it's likely that the fluids were solved from magma that was produced in a subduction environment so

you can see the brown dots here these are philippine geothermal waters and they have a

nitrogen con a high nitrogen content um plotting near the pragmatic andesite um

n member here so yeah that's why

it has a large uh relatively large nitrogen content the because it the fluids were exhaust

from uh magmas coming from the subducting slum

and then the third one is helium so when the fluids equilibrated with the deep crustal rocks continental rocks

so it the helium tends to increases helium content within the fluid increases also

they analyzed um fluids coming from mid-oceanic ridge basalts

and along the rift rift environments and they also

found that it is um has a high helium content so this is empirically uh determined

so when it plots near helium your fluids must have either

circulated deeply in the crust or uh exhale from a basaltic mill yeah so that's how we read this diagram

and so we can see here the different epithermal type veins in northwest and

carmen and florence so for northwest the stage 2 quartz carbonate are plots

along the line connecting the helium and air saturated water so

we we think that this could either be

the mineralization involves fluids that were derived from basaltic magma or it can also be um

crustal because of the evolved evolution of water within the deeper apart of the crust

so energetic mineralization involves fluid derived from antisedic magma so you can see energetic mineralization

stage four here the red ones and the um and the green ones here so you can

see both energite mineralization both in northwest and florence involve a high component from endocytic magma

while qpg mineralization in carmen so the pyrite rich qpg veins flood between the air and air saturated water so

mostly these are from meteoric water so you can see this different mineralization performed from different

sources of fluids so now we look at the sorry this is porphyry type veins quartz

so from carmen and florence and for comparison the far south east

so the most of the the far south east quartz from the serie

side chloride clay alteration involves mainly meteoric water as you can see between the air and air saturated water

while the remnant uh perfect type quartz in carbon and florence have high n2 over ar ratio indicating uh it involves

magmatic component okay from the same data set we can also look at the carbon dioxide and nitrogen

so from blamey 2012 he indicated that when there is a

negative slope of carbon dioxide over nitrogen versus the total volatile content

it means that the fluids are boiling so these are because um carbon dioxide

escapes more quickly than the nitrogen so that's why it gets

the negative slope so this is for confirmation of the the

trends that we that we observed in the micro thermometry so this is independent uh

confirmation so we know if it's really boiling or non-boiling fluids that are is that is responsible for our

mineralization so from this data we can see that boiling is a significant mechanism for

both qpg and energetic mineralization yeah but the carbon but as you can see carbonate bearing veins here has high

carbon dioxide within the fluid so it's consistent also with the mineralogy but it doesn't um the trend

is uh not it's just a scatter so we cannot say it's boiling or

not so now we looked at the oxygen and hydrogen isotopes so

the oxygen hydrogen isotopes were analyzed from d kites so you can analyze any

a mineral with oxygen and hydrogen in its um formula to see uh where

where to see its um or origin or proximity to what type of fluid so this is meteoric water here

and the box here shows the volcanic vapors and felsic magma and

the fields show the previous data of ariebus 1998 about the lepanto main energized

ore body so we can see here that the stage 4 fluids

here the energy bearing fluids in northwest have higher magmatic component because it has a

higher delta 180 and it's closer to the signature of

felsic magma of and volcanic big parts so you can see this is magmatic field this is meteoric

line so and then the place of your

the plots shows how much mixing could uh if the pla the plot will show you uh

the degree of mixing somehow to some extent uh between the magmatic contribution and

the meteoric contribution okay so we can see that the energite bridge fluids have a higher magmatic component than the

pirate ridge fluid this is consistent with the gas analysis because we

know that the the energy has have high end to a our ratio so the fluids that formed in the

northwest uh are heavier in delta 180 than the fluids that form the candidates

from the left domain energy or body so these are all the kites analyzed so when we compare it to the

main energy or body we can see that the isotopes are heavier for the northwest deposit

and then for carmen and florence also the approach was different because we

we chose d kites one is from the vein one

comes from the alteration of the rum so the heavier isotopes have where the were the sample that came

from the rocks while the lighter relatively lighter d kites are the minerals that we

separated from the veins so we know that the water rock interaction

a effect on the isotopic signature of the of the

minerals so that was the uh rationale for uh analyzing the florence and carmendi kites

okay so we also looked at the sulfur isotopes of the sulfides

so we can see here this is stage one to stage five of northwest qpg we analyze different minerals

we just um just a very quick uh

description stage 1 has the highest highest delta 34s heavy isotope and then it goes

uh down up to stage five so this decrease in the

delta 34s of sulfides parallel the decrease of temperature recorded by the microthermometry of

fluid equations in quartz so earlier i described that the the quartz the fluid inclusions in

quartz show uh decrease in general decrease in temperature and so that sulfur isotopes also

reflects that trend so and then this is uh alumni so these are all sulfites and then this is the

alumni that i analyzed the delta 34s of adenite and

this just concludes that the alumni here was formed by supergene hypogene origin so hypogene means it was

formed from magmatic waters and it's not a product of weathering because alanite can also be a product of

weathering but in that case if it's formed not by magmatic origin the delta 34s of alanite would be near the

sulphides but in our case it's hypogene because it has a high positive delta 34s so sulfur isotope is useful

because it if you have pairs of the sulfide and sulfate you can calculate the temperature at which it

forms so it's an independent geothermometry so

these are sulfide along pairs and these are the calculated temperature using fractionation factors

and you can see it the alumni pyrite pairs were formed from

200 to 300 degrees celsius which is similar to the homogenization temperature of fluid

inclusion so we're just compiling piling up evidence about the temperature of formation from different methods

and then if you plot the delta 34 s of sulfide and sulfate and draw a line it will

it will converge to a single point that single point represents the bulk delta 34 s so because

if you're given a fluid it has a bulk delta 34 from

that fluid sulfide and sulfate will precipitate so the

heavy isotopes will partition between the sulfide and the sulfate like they will share

the delta 34 s the

heavy isotope budget so conversely if you plot it and and

look for the converging point you will find the bulk from where it started so the bulk uh delta 34s of the fluid

for northwest qpg is around plus six uh del uh per meal

it's a little bit higher than the lepanto main energized ore body uh measured at plus two per ml

okay so you can see that the looking at the slope of the plot the sulfate has a steeper slope

than the sulfide so if the sulfate varies more so you can see that the

reduced species um buffers or it's the dominant sulfur specie in the fluid so if

if if the slope of the sulfide is more gentle it

means h2s is the dominant sulfur species in the fluid okay so the same thing for carbon and

fluorine for carmen carmen has a little uh almost the same as the

northwest qpg and the alanite uh alanite temperatures are within 220 degrees celsius

okay consistent with the homogenization temperature of fluid inclusion

so now from these all of these things from mineralogy from the fluid inclusion and the sulfur isotope

we can estimate and we can picture out how did the

the north west florence and carmen evolve through time so we know from stage in northwest

from stage one intermediate sulfidation we just we we increase a bit of sulfidation to

uh to stage two and then when the kovalight bearing

pyrite in stage three b and goes back to the energite uh varying bearing uh mineralization to stage four

while the carmen deposits show from uh a high to very high

uh sulfuridation state at the consistent with a cooling temperature so you can remember that the middle is

energized luzonite stage and then plate qpg contains the tiny cobilite inclusion so that's why

we went from high to very high okay and then well for my examples uh we can we saw that the mineralization in

florence evolved at a relatively uh constant solicitation state so this illustrates

a different evolution patterns for each

each deposit so we can also see say something about the oxidation state so this is the

oxygen fugacity and then the temperature so we calculated it using the

uh oxy from hydrogen and water fugacity measured from the gas analysis

of fluid inclusion so periphery has a higher

oxygen fugacity and then going down to the epithermal mineralization so you can see

here that the the the data our data for the far south is is consistent with previous

data from email 2000 the evolution of farsoft is

is colored here in blue arrow yeah so we can see here that the dominance of

h2s in the fluid indicated by the um oxygen fugacity supports the trends in the sulfur isotope analysis so i

mentioned that h2s was the dominant so for species and you can see the the

plots of the carmen and northwest stages here is within the h2s dominant field

so yeah that's how we read this diagram

so our highlights and these are the uh what in summary so we know for uh for fluid source

energy rich veins have more magmatic fluid component while pyrite rich veins have more meteoric water component so

the isotopic characteristics indicate influence of earlier periphery type mineralization

temperature it shows that the qpg veins in northwest carmen and florence generally develop in

progressively cooling environment and ph and redox

gold occurrence is closely related to acidic alteration and qpg veins were formed from fluids with a dominant h2s

species and then the deposition mechanism most are fluid boiling plays a significant

role in the qpg formation okay so that's the summary of my technical side i'm just going to briefly

show you um about akita university so if you're wondering akita is in the northwest

of japan it's um it's one of the suburban um areas

so this is the campus this is the main gate and we have lots of snow during winter

and so there are four faculties within our uh

within the university i belong to the faculty of international resource sciences

that is um mostly about the study of earth resources

so different geology petroleum in the faculty we also have resource policy resource economics

materials mineral processing and

mining engineering so anything both social sciences and um hard sciences on the

about resources okay so there are within the faculty of international resource science we have

the resource policy and management uh earth resource engineering and environmental science and earth resource