A Geological-Geophysical Prospecting Model for Deep-Seated Gold Deposits in the Jiaodong Peninsula, China

Round 1

Reviewer 1 Report

minerals-1458554

A geological-geophysical prospecting model for deep-seated gold deposits in Jiaodong area, China

Summary
The manuscript titled "A geological-geophysical prospecting model for deep-seated gold deposits in Jiaodong Peninsula, China” integrates current geological and geophysical knowledge that has proven useful in exploring deep gold deposits. The manuscript focuses on gold deposits in the Jiaodong Peninsula, China. The manuscript highlights the importance of developing new exploration technologies to sustain new ore discoveries in the current context where ore deposits are increasingly buried and concealed. 
With this manuscript, the authors make the following contributions: 
* Gold deposits in the Jiaodong Peninsula are controlled by large-scale faults.
* These faults generally occur near the contacts between Early Precambrian metamorphic rocks and Mesozoic granitoids.
* The traditional exploration methods are adapted to deep-seated deposits by proposing to search for ore-controlling structural planes, rather than near-surface anomalies.
* A joint interpretation of gravity, magnetics, resistivity, induced polarization, and seismic reflection signals proved useful in delineating the Shuiwangzhuang gold deposit, situated at a depth of approximately 1 km. 

General comments
The manuscript is appropriate for the "New Methods and Technologies for Mineral Geological and Geophysical Exploration in China" special issue of Minerals. The themes of resource shortage, deep exploration, exploration under overburden, and geophysical methods are considered throughout the manuscript. Overall, my recommendation is that the authors revise the manuscript before it is considered acceptable for publication. I also recommend that the English language be thoroughly revised before acceptance is considered.

The manuscript is clearly structured, reasonably well-written and understandable. There is room for improvement to the English language and specific terms are sometimes used  incorrectly (see specific comments). 

The cited references are mostly current and relevant. Out of 42 references, 9 (21%) are citations of previous work by the first author, which appears abnormally high. It can be argued by the authors that these references are relevant. 

The manuscript relies on many previous works by the research group, which is not always properly cited in the text.

The manuscript is scientifically sound. However, the methods and data collected by the spectral induced polarization method are not correctly presented. The terms used to describe SIP data are not concordant with the SIP literature. As a specialist of the SIP method I could infer what was being argued. However the SIP results will be very unclear for readers who are not specialists and are trying to understand by looking at external references. Please see my specific comments below.

There is not enough information about geophysical survey parameters for the experiments to be fully reproducible. I recommend the authors address these issue before acceptance (electrode spacings, station spacings, instruments used, calibration methods, etc). Please either provide references to the surveys or add more information in the manuscript.

The figures are appropriate but should be revised due to typographical errors and incorrect terms (see specific comments).

There is a lack of quantitative data presented in the paper, as most of the geological and geophysical integration is conducted qualitatively. If this is intended, the authors should explicitly state that the aim of the paper is to make a qualitative exploration model.

The conclusions are consistent with the evidence and arguments presented in the manuscript. 

The ethics and data availability statements appear adequate. Each author's contribution is mentioned and the funding sources are acknowledged. The authors declared no conflict of interest. The authors mention that the data were obtained from previous work of the project team, however there is no statement on data availability for the reader.

Specific comments
- Line 29: magnetic field signals
- Line 142: Please provide a reference for the 2% - 5% polarizability of some ore deposits.
- Table 1: The symbols in the table header are not defined prior to Table 1 being referenced. Please define them in the table caption or in the text before referencing Table 1.
- Line 202: "c, e, f, and c types" c-type is mentioned twice. 
- Section 4.2.1: Please explain quantitatively what "weak, medium and strong" noise levels refer to in the electromagnetic prospecting methods.
- Line 384: "polarized" bodies should be "polarizable". The metallic minerals are only polarized under the application of an electric field, provided they are polarizable. 
- Line 386: Please provide references for this claim. I have not come across any examples of the SIP method being sensitive down to 2000 m depth.
- Figure 4: "metamorphosed rocks" should be "metamorphic rocks" ?
- Line 417: Please define Delta_T prior to referring to it.
- Line 420: Please define Delta_g prior to referring to it.
- Line 438: What is the traditional high-power induced polarization method? Are the authors referring to time-domain induced polarization? Also, in my experience the depth of investigation is similar between the TDIP and SIP method. And now the claim of 2500 m investigation depth is more than what was previously claimed in the manuscript (2000 m). In what frequency range is this possible? Please provide references. 
- Line 443: Please define apparent polarizability (how is it computed from the complex resistivity spectra measured by the SIP method?). Please also define apparent charging rate, time constant, and "correlation" coefficient. From my understanding these are very similar to "Chargeability (m)", "Relaxation time constant (tau)", and "Frequency-dependence coefficient (c)" as defined in the Cole-Cole relaxation model. Please provide references from the SIP literature.
- Line 450: "reflected waves of Mesozoic rock masses" or "waves reflected by Mesozoic rock masses"? This sentence is not clear.
- Line 477: The SIP method used on the Y3 section was conducted in what frequency range? 
- Figure 5a:  "hig-accuracy" should be "high-accuracy".
- Figure 5a-b: Is the x-axis the "Number of points" or the "Distance/m"? 
- Figure 5b: "Reduction of the magnetic pole" should be "Reduction to the magnetic pole"
- Figure 5e: The correlation coefficient of frequencies is a new term to me. I think the authors are referring to the Frequency-dependence coefficient (c-exponent) of the Cole-Cole relaxation model commonly used to reduce SIP data
- Figure 5: Please standardize the SIP parameters with those defined in the text. Sometimes "Charging rate" is used, sometimes "Charge rate". The proper parameter name should be "Chargeability" according to the IP literature. 
- Line 508: Same comment as above. Please standardize the SIP parameters.
- Lines 520-531: This is good, but should be part of the introduction. This paragraph is how the paper should start because it clearly indicates the main problems the manuscript is trying to solve (concealed ore deposits, pressure for ressource discoveries, deep ore deposits and how geophysical methods can help).
- Line 532: The conclusion starts here (summary of what was done to achieve the main contributions and implications for the future). 
- Line 562: "geologic tectonism" sounds like a pleonasm to me. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Journal: Minerals (ISSN 2075-163X)

Manuscript ID: minerals-1458554

Type: Article

Title: A geological-geophysical prospecting model for deep-seated gold deposits in Jiaodong area, China

Authors: Mingchun Song * , Guoqiang Xue , Hongbo Liu , Chunyan He , Hongjun Wang , Bin Wang , Yingxin song , Shiyong Li

Section: Mineral Exploration Methods and Applications

Special Issue: New Methods and Technologies for Mineral Geological and Geophysical Exploration in China

 

Specific Comments:

Authors are advised to check the writing of the title of their manuscript, as the English version may not be very appropriate. The argument of the paper is more suited to a "Review" than an "Article".

Abstract: the authors do not make it clear what their true objective is. It is difficult to understand what the usefulness of this work is. The content of the abstract is ambiguous. It is not specified what type of gold deposits are to be located, nor the tonnage, nor what the host rocks are. No idea is given as to the importance of locating such deep deposits. It is recommended that the abstract be rewritten to put the ideas in the right place. Rewrite.

Line 37: Write "5.000 t" instead of "5,000 t". Rewrite.

Line 38: Please separate these two words "area(Figure 1)". Rewrite.

Line 53: Change comma to full stop "1,000 tonnes". Please revise throughout the manuscript. Rewrite.

Line 62: Why don't the authors use a more simple expression, such as "very deep deposits (VDD)", instead of "deep-seated"?

The "Materials and Methods" section is missing, so it is very difficult to find one's way through the manuscript and follow the authors' idea. I still insist that this work has more the character of a "Review" than a Scientific Article. Consider.

Figures 2, 3, 4 and 5: They are of poor quality and should be improved. Fix.

Line 300. Rock and ores are two very different things; please check the expression "rocks (ores)". Revise.

Lines 461 to 475: No citation of references ???

Line 481: No citation of references ???

Line 535: It is surprising that deep prospecting has focused only on faults. What about alteration zones and the other prospecting criteria?

Lines 520 to 543: This entire paragraph needs to be removed from the Conclusions and placed in the "Results and Discussion" Section.

Line 544 to 565: These arguments are the same ones that the authors have written several times throughout the manuscript, therefore, they cannot be considered as conclusions.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The presented study includes a detailed description of the genesis of the superficial and deep-seated gold deposits in Jiaodong Peninsula, China. The geological aspects of the peculiarities of the province are detaily considered. The mechanisms of formation of stepped patterns of gold deposits are described. A detailed description of the characteristics of major geological bodies related to gold deposits is also provided. Based on all this, the recommendation for the use of certain geophysical prospecting techniques is reasonable and logical.
In general, presented analysis is seen as detailed, and the geophysical technologies presented for searching for overburden deep-seated gold deposits are reasonable.
However, the authors indicate in the abstract that they are presenting a new multi-parameter exploration model. Moreover, all methods used in the study are standard. In industry practice, the integration of various geophysical methods is a routine task. The purpose of such integration is to increase the contrast of the search object and obtain a more confident forecast of its occurrence. In this sense, the authors' assertion about the novelty of their methodology is not obvious.
The authors should disclose in more detail the novelty of the proposed methodology: what it consists of - whether a new aspects of geophysical technologies are used or some new methods of processing and integration of survey data are used.
A greater disclosure of the novelty of new multi-parameter geological-geophysical prospecting model is needed.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have responded to all comments made by the Reviewer. 

It is proposed to the Academic Editor that this paper be considered for publication in Minerals.