Dear Le Wang,

You have made an interesting question… To respond your to question... would was better to go the mentioned zone, make geological mapping, if the mentioned deposits can be observed on surface… Collect samples (two samples) in transition zone… to understand the region formation… needs fracture zones… How is it like the contact with granodiorite porphyry dike… Does have the granodiorite porphyry enormous REE rare earth elements?...

It is hard to give a good method if we do not have more information… I am outsider and if sent me a paper about two deposit perhaps I can give you more suggestion…

How old are the studied deposits?

Do Not forget the Granodiorite dike formation (as a plutonic rock) is longer than quartz-dacite porphyry… You have to determine the foreign rocks in quartz-dacite..

 Best Regards,

LAH

Dear Mr.  Wang,

It sounds a bit strange to try and find out what the relation is between epithermal and porphyry deposits. If you  know , that they are of IS epithermal and porphyry style, then you know that the first-mentioned ones are the "smoking guns" of the second one. You can do age dating, make use of trace elements and isotopes and so on. There are no limits but what is the goal of your study ? This is the first and foremost question to be answered.

Best regards

H.G.Dill

Dear László-Attila,

Thanks a lot for your attention. We have done the geologic mapping in the open pit of  that IS gold deposit, but not in porphyry copper deposit. The transition zone between the two deposits is covered by the Quaternary sediments and the vegetation, which made many field observation unavailable. The forming age of these two deposits are about 475-480Ma. We have collected hundreds of rock samples from IS deposit and their transition zone. The accurate rock type of the probable ore-related quartz-dacite porphyry should be dacite porphyry. I just wonder what can I do later so as to determine their original relationship.

The attachments below is the papers about these two deposits. The name of the IS is Zhengguang, while the porphyry copper is Tongshan. There are little English papers so you can read the English abstract of the papers.

Article Type，zircon U-Pb age and Paleovolcano edifice of Zhengguang ...

Dear Harald,

Thank you for your reply. The age dating samples(sericite and adularia) has been sent to the lab. Nowadays I am engaged in doing the trace elements of the IS deposit. My intention here is how can I know that the porphyry Cu deposit has the same magmatic origin and/or hydrothermal fluids with the IS deposit.

Best Regards,

Le, IGGCAS

I agree with Dr. Dill, if you could named them as epithermal and porphyry deposits, so you are already know about their origin. However, you should check the mineralization styles of the two deposits; the PCD is mainly as disseminated stockworks over a wide area around the intrusion. The latter type, the epithermal veins, is mainly sulfide-rich which in most cases localized within the vein itself, and could be as massive sulfides. I think age dating will not contribute so much in this issue, since they are very close to each others in the formation age.

regards.

Ahmed

Dear Mr. Wang,

at this stage of investigations, you have to begin with fluid inclusion and isotope studies. The fluid relics may get you a bit closer to the potential common source. I do not suggest anything further because for a detailed answer in this case you need to know directly more about local geology and mineralogy.

I wish you much success

H.G.Dill

"My intention here is how can I know that the porphyry Cu deposit has the same magmatic origin and/or hydrothermal fluids with the IS deposit". I would be concerned if this was the aim of my student - how about "My intention here is how can I know WHETHER OR NOT the porphyry Cu deposit has the same magmatic origin and/or hydrothermal fluids with the IS deposit". It is critical to philosophy and may be a language issue (and your English is so much better than my Chinese :-)

To answer your question - the best way is if you have continuity of drilling and then you can map out any continuity of zones of rock alteration. If you can do that, you can then look for systematic changes in fluid composition, separation of a vapour phase etc. If that works you then have enough control to consider things like O-H, C and S isotope studies (without fairly good control on alteration etc it is unlikely that you will get a conclusive answer).  For example, the porphyry deposit may show magmatic O-H in its hydrothermal biotite alteration and a mixture of that and meteoric water in white mica away from its potassic core (the phyllic zone) - this may grade through increasingly meteoric water O-H into the epithermal system and even give a continuous mixing/temperature evolution line. Refer to something like the "Geochemistry of hydrothermal ore deposits" (Barnes etc - latest edition)

Dear LE,

I have not become smarter… With time I have read dr. Harald G. Dill second advice… Agree with him-  in plus you need to verify Chemical REE elements which are presents in Granodiorite (try to find marker element  if you have luck you will find one of them and can use it like a marker element)… There is a sentence:” Its copper orebodies are mainly hosted in Caledonian granodiorite and Middle Ordovician Dubaoshan Formation andesite and tuff.” From this seems a formation of its Its copper ore bodies seems younger (?).

another: The forming age of these two deposits are about 475-480Ma “-five MA years is long…  The key is granodiorite porphyry dike and quartz-dacite porphyry relation between them..

 You need more knowledge about

Give me a reference (geographical) Position of Tongshian…

Best Regards, LA H

My understanding is that Le Wang wants to know if a specific porphyry deposit is genetically related to a specific epithermal deposit? That is why I mentioned looking first at rock alteration zoning. Things like dating can tell you that they might have both formed at roughly the same time, things like intrusive composition including REE can support that (perhaps they tell you that they formed in the same regional intrusive event, but they cannot really tell you if they formed from a single fluid system related to a single volcanic centre, which I assumed to be the question). Rock alteration gives the boundaries of fluid circulation and is one of the first things that can give clues to these things - then one can look at the spatial and compositional evolution of the fluid within the limits of these alteration boundaries.

Laszlo, you question 475-480 Ma as being long. I doubt that the error bars on this dating are less than a million years. With rock dating, a deposit dated at 475 Ma may have formed at exactly the same age as one formed at 480 Ma. It depends on your variance, not just the mean, and that is usually a function of the dating method used. Also a few million years is not necessarily a long time for the life of a single volcanic field (eg the San Juan Mountains). However the cooling time of a specific intrusion that the ore deposits are related to is more likely to be more like a few hundred thousand years at most (especially a small intrusion at shallow depth), and the duration of a single hydrothermal fluid flow system that formed ore bodies is more likely to be of the order of 50,000 years (I am just throwing around generalisations here, as seen in many mineral fields, I don't know this specific example).

Thank you very much again for all your warm-hearted guides,  László-Attila,   Ahmed, Harald, and Martin.

Dear Martin, your capacity of comprehension is awesome, the revised  sentence you offered is just what I want to express. Sorry for my poor written English.  My purpose is exactly whether they formed from a single fluid system related to a single magmatic activity. In fact, the zircon U-Pb age of the granodiorite porphyry in Tongshan PCD is 474.1± 1.28Ma( concordant age), while the zircon U-Pb age of dacite porphyry of Zhengguang IS is 480.3±2.1Ma(weighted mean age), which is a little earlier. The widespread intrusion in Tongshan PCD granodiorite has a  zircon U-Pb age of 475.9±0.8, which is absent in Zhengguang. The molybdenite Re-Os isochron age is 473±4(Hao et al., 2015).

The ideas that looking at the rock alteration zonings in PCD and IS mentioned by Martin and mineralization styles recommended by Ahmed, doing the fluid inclusion and stable isotope studies by both Harald and Martin really bring me  plenty of enlightenment on my PhD research. Thanks a lot for your unselfish help.

The attachment is a paper about the magmatic activity and tectonic settings in Tongshan and an adjacent Duobaoshan PCD. Hope it will do some help.

Thanks Le Wang - it is a pleasure to see someone posting such questions and feel free to do so at any time, there are obviously lots of experienced people willing to assist. A person who speaks another language as well as you do should not feel obliged to apologise. you are doing fine.

Thank you Martin for response and correction… !

Le, you have sent a very interesting paper:… If I have understood well… “ My response to your question after first reading “seems”  “NO” (?)  For this I will reread put another questions for to know if I understood well…

One question (again): How you got the forming age for : IS epithermal deposit?

Relating works are excellent, only they have one problems using of subduction in tectonical interpretation… “Sankuanggou deposit were associated with the subduction of the Paleo-Pacific Plate.” (ABSTRACT)

 One thing seems good if the studied zone by you comparing with the actual zone between (China, Yellow Sea,  Korea, Sea of Japan, Japan)

Best Regards,

LAH

P.S The porphyritic granite from the Photo A is not from their formation place, to this granite we cannot connect epidermal Gold… The Epithermal Zhengguang epithermal gold deposit is related to a facture zones approximate N-S (With studying of formation of these factures (you can verify, if the they are present onto surface… And perhaps has more connection to the  Sankuanggou … (Tomorrow I will ask the questions to verify if I understood well)

Dear László, 

The latest published age of Zhengguang is deduced by the age of a diorite dike cutting the hydrothermal vein of Zhengguang, whose age is 454Ma. It means that Zhengguang formed no later than 454Ma. A diorite porphyry dike cutting the altered andesite wallrock presents me 469.4±3.9Ma in my recent dating work. This means that Zhengguang may formed earlier than 469Ma. Combined with the adjacent space relationship with Tongshan PCD, I suppose they formed under the same tectonic setting and owe a single magma origin, as for the hydrothermal system it's hard to say now.

I will think about the suggestion you give on comparing with the actual zone later. Thank you for your advice.

One question, what is the proper tectonic interpretation of Sankuanggou deposit in your opinion?

PS. The porphyritic granite of Photo A(Fig. 5) is in Duobaoshan PCD, 8km northwest in the Zhengguang deposit.

Best Regards,

Le

Dear LE,

It seems here is a tectonical key:

“The latest published age of Zhengguang is deduced by the age of a diorite dike cutting the hydrothermal vein of Zhengguang, whose age is 454Ma. It means that Zhengguang formed no later than 454Ma. A diorite porphyry dike cutting the altered andesite wallrock presents me 469.4±3.9Ma in my recent dating work. This means that Zhengguang may formed earlier than 469Ma. Combined with the adjacent space relationship with Tongshan PCD, I suppose they formed under the same tectonic setting and owe a single magma origin, as for the hydrothermal system it's hard to say now. “ You have to verify the diorite porphyry cutting ,,, (its contact to Zhengguang) Are you have clear information that this cutting is a volcanic cutting or is not a tectonic cutting (the process could happen latter)

“One question, what is the proper tectonic interpretation of Sankuanggou deposit in your opinion?”- I am using non-conventional interpretation based closed to geosyncline theory (this works well in your zone) exists two other theories (Plumes and Strench theories)  I do not have literature to study only in few small paper… you need to study them… The global tectonics does not works in your territory studied by you… (Be careful with your result and with your opponents)… Not all times the real true have to be presented as it is seems… I had felt it when I made my MSC project in territory  which has some common features with your studied area (only this area has Miocene-Maastrichtian (Cenomanian)..

Best Regards,

LAH   

Dear Le,

After a detailed reading the ”Metallogenic events and tectonic setting of the Duobaoshan ore field in Heilongjiang Province, NE China”… the next remarks seems important:

1.      Take a look onto table 2.( LA–ICP–MS U–Pb data of zircon grains of the granitoids from the Duobaoshan ore field) and examine the contain of TH and U (isotope 238 and 235)… I would like to have a data about the U isotope variations it is very important perhaps with you can deside the relation between the ores.

2.      Try to analise the presence or not presens of Zircon and Molybdenite  in the Zhengguang “epithermal gold deposit” (ore + host rock) this second point seems anormal but (try to find) information about inclusive the Re and Os quantity.

3.      That it seesms the best explanation: “The sources of metallogenic elements and the tectonic setting of the Duobaoshan and Tongshan deposits remain debated. Some researchers consider the Duobaoshan Formation as the source of metallogenic copper in the region (Zhao and Zhang, 1997; Wang et al., 2007), because it is rich in copper.” Pg (6.2. Sources of metallogenic elements, pg.453)

4.      The absent of basaltic rocks in the presented area negate subductions process!  

Best Regards.

LAH

5. In the vicinity of studied area (10-200 km) with same tectonically condition needs a map where draw up the known Hydrothermal ore with Gold (their condition of formation)… With them you can get a better explanation…