Zeng-Zhao Feng*

China University of Petroleum (Beijing), Beijing 100083, China

1 Introduction

Vérardet al.’s article 3D palaeogeographic reconstruc?tions of the Phanerozoic versus sea-level and Sr-ratio vari?ations(2015,Journal of Palaeogeography, 4(1): 64-84),and my editorialHope to be from model to practice—Words of the Editor-in-Chief(2015,Journal of Palaeoge?ography, 4(1): 63), have attracted enthusiastic discussion and contending.

Up to now, we have received 3 articles,i.e., discussion articles of Prof. G. Shanmugam and Prof. A. J. (Tom) van Loon, and the reply article of Dr. Christian Vérard. In the near future, more discussion articles may be submitted to theJournal of Palaeogeography.

This paper is a preliminary review of the above papers.Criticisms and further discussions from readers worldwide are heartily welcomed.

2 Discussion by Prof. G. Shanmugam

Prof. G. Shanmugam firstly submitted an article, with the title 3Dpalaeogeographic reconstructions of the Phan?erozoic versus sea-level and Sr-ratio variations:Discussion.

Prof. Shanmugam (2015) pointed out that the model of Vérardet al.suffers from: (1) the selective omission of real-world datasets that do not fit the model; (2) the inclusion of datasets without revealing their original sources or without citing relevant peer-reviewed publications; (3) the emphasis on “unpublished” internal company datasets that disallow open access to international scientific community; and (4) the use of poorly understood concepts without providing the basic conceptual clarity. These deficiencies undermine the credibility of the heuristic model.

The discussion of Prof. Shanmugam includes 7 topics: (1)submarine fans and other depositional systems; (2) masstransport deposits; (3) submarine canyons; (4) sea-level changes; (5) glacial isostasy; (6) Sr-ratio curve; (7) tectonics and palaeobathymetry.

After discussion and review of the Vérardet al.’s article(2015), Prof. Shanmugam summarized: (1) reconstructing palaeobathymetry of the Early Paleozoic sequences, such as the Ordovician of the Appalachians, is a daunting task;(2) the proposed geodynamic model of Vérardet al., without imputs from the real-world datasets on sedimentation,erosion, glacial isostasy,etc., is inherently flawed. Therefore, the universal applicability of the model is dubious.

3 Discussion by Prof. A. J. (Tom) van Loon

Prof. A. J. (Tom) van Loon also submitted an article, with the titleThe Vérardet al.(2015)method for3D paleogeo?graphic reconstruction:how solid is its base?

Prof. van Loon (2015) pointed out: (1) the paper of Vérardet al.is lacking information,i.e., lacking hypsometric and bathymetric data for any place on Earth for any time;(2) the method of statistics of their paper is unexposed,although different types of statistics may lead to different outcomes; (3) the authors of this paper only deal with clastic rocks, not with other rocks, such as chemical, biogenic,organic, pyroclastic rocks; (4) as long as no more convincing details are provided, Vérardet al.is too early to state that their model has the advantage of being applicable anywhere on the globe and at any geological time.

Therefore, Prof. van Loon is not yet convinced of the reliable applicability of the heuristic method on which the model of Vérardet al.(2015) is based.

4 Reply by Dr. Christian Vérard

Dr. Christian Vérard submitted an article, with the titleReply to comments by G. Shanmugam(2015)and A.J. (Tom) van Loon(2015)on“3D palaeogeographic recon?structions of the Phanerozoic versus sea-level and Sr-ratio variations”.

Dr. Vérard (2015) stated that: (1) In science, one cannot say what is right, but one can say what is wrong. (2) How wrong are we? (3) Why are we wrong? (4) The synthetic topography seems, to date, relative wrong at local scale, but probably fair-good at global to regional scale.

I do not agree with his viewpoints.

My idea is that: (1) In geological science, what is right and what is wrong should be determined by objective geological practice, but not be determined by someone’s subjective consciousness. (2) The essential problem of the article of Vérardet al.(2015) is not what is right or what is wrong. It is that the 3D model proposed by Vérardet al.is whether effective or not to reconstract the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globle and at any geological time. (3) If the 3D model is effective to reconstract the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globe and at any geological time, this model is good; whereas, if the 3D model is not effective to do so, this model may be not a good one. (4)Therefore, the problem is that whether the 3D model is effective enough or not, or may be it good or not.

The details of my viewpoint are in the following.

5 About my viewpoint

Firstly, the article of Vérardet al.(2015) proposed a new method and a new model to reconstruct the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globe and at any geological time. This assumption is very interesting and stimulated my deep thinking.

I am unfamiliar with the Sr-isotope ratio and the new method and new model, and thus it is difficult for me to point out some concrete questions about Vérardet al.’s article. But, as a geologist and a palaeogeographer, I know exactly the difficulty of the problem “to reconstruct the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globle and at any geological time”.

I have presented my book, with the titleLithofacies Paleogeography of the Cambrian and Ordovician in Chinato Dr. Christian Vérard, and hope that Vérardet al., based on their heuristic-based approach, can reconstruct the altitude of the Cathaysian Land and North China Land and the water depth of their peripheral palaeo-oceans of the Cambrian and Ordovician in China. I hope that Vérardet al.would try to do this work and therefore they could make a great contribution to the palaeogeography of China.

Dr. Vérard replied to me that they can’t.

As mentioned in my editorialHope to be from model to practice—Words of the Editor-in-Chief(Feng, 2015), I also can’t determine the attitude of Cathaysian Land and North China Land and the water depth of their peripheral palaeo-oceans.

The Cathaysian Land was a relatively young-aged oldland with steep topography. During the Cambrian and Ordovician, it provided nearly 20,000-m-thick clastic sediments for the Southeast Clastic Platform on its western side. It was formed due to the underthrusting and compressing of the old Pacific Plate to the old Eurasian Plate. The Cathaysian Land (or Cathaysian Uplift Zone) and Southeast Clastic Platform (or Cathaysian Subsidence Zone) both belonged to the Eurasian Plate and were located at the eastern edge of Eurasian Plate. In the period of Cambrian and Ordovician, the Cathaysian Land was continually uplifted and was eroded, the Southeast Clastic Platform continually subsided and received clastics from the Cathaysian Land.Because the uplift and erosion of the Cathaysian Land and the subsidence and sedimentation of the Southeast Clastic Platform were in equilibrium, therefore the Cathaysian Land was not very high, and the water depth of the Southeast Clastic Platform was not very deep. I can neither quantitatively determine the altitude of Cathaysian Land nor quantitatively determine the water depth of Southeast Clastic Platform palaeo-ocean.

About the North China Land and its peripheral sea, I can only qualitatively state that the North China Land was an old-aged peneplained oldland, and its peripheral sea was mainly a carbonate platform sea, and I have not an effective methodology to quantitatively determine the altitude of the North China Land and the water depth of its peripheral sea.

The above two oldlands and their peripheral seas are illustrated in detail in my books and paper (Fenget al.,1990, 1991, 1998, 2001, 2004, 2014).

Somebody said that I am a conservative geologist. Yes, it is indeed. Nowadays, I can’t quantitatively determine the altitude of Cathaysian Land and North China Land and the water depth of their peripheral seas, not to mention reconstructing the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globe and at any geological time.

It is a great but very difficult task to reconstruct the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globe and at any geological time.This great task may be, or even may not be accomplished through the hard work of geologists worldwide of several generations.

Nowadays, it is obvious that a claim“to reconstruct the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globle and at any geological time” is an “overstatement”.

This “overstatement”, originally may be “self-praise”;but in fact, it may be “self-depreciation”. The result is contrary to expectation.

However, as the Editor-in-Chief of theJournal of Pal?aeogeographyand with the principle of “A hundred flowers blossom and a hundred schools of thought contend”,I have approved the article of Vérardet al.to be published in theJournal of Palaeogeography, because this article is a flower with academic significance and the words of a school of thought. We can utilize this chance to launch an academic discussion and contending, give rise to the attention of readers worldwide, encourage further discussion and contending, and thus promote the development of palaeogeography.

I sincerely thank Dr. Christian Vérard and his research team for contributing such a significant article to theJour?nal of Palaeogeography.

I sincerely thank Prof. G. Shanmugam for his first discussion paper submitted to theJournal of Palaeogeography,who is very familiar with studies of Sr-isotope ratio and put forward many topics for discussion.

I sincerely thank Prof. van Loon, who put forward many constructive comments.

I sincerely thank Dr. Christian Vérard, who sent back a reply paper.

I sincerely thank other readers who represented a great deal of interest for this discussion.

Let us work together to promote this discussion into further depth and the development of palaeogeography.

1. Feng, Z.Z., 2015. Hope to be from model to practice.Journal of Palaeogeography, 4(1), 63.

2. Feng, Z.Z., Bao, Z.D., Zhang, Y.S., Tan, J., Kang, Q.F., Han,Z., Wang, Y.X., Zhang, C.L., Han, Y.C., 1998. Stratigraphy Petrology Lithofacies Paleogeography of Ordovician in Ordos. Geological Publishing House, Beijing, pp. 1-144, and 8 photo plates (in Chinese with English preface, contents and abstract).

3. Feng, Z.Z., Chen, J.X., Zhang, J.S., 1991. Lithofacies Paleogeography of Early Paleozoic of Ordos. Geological Publishing House, Beijing, pp. 1-190, and 16 photo plates (in Chinese with English preface, contents and abstract).

4. Feng, Z.Z., Peng, Y.M., Jin, Z.K., Bao, Z.D., 2004. Lithofacies Paleogeography of the Cambrian and Ordovician in China.Petroleum Industry Press, Beijing, pp. 1-233, 42 color maps,and 8 color photo plates (in Chinese with English preface,contents and abstract).

5. Feng, Z.Z., Peng, Y.M., Jin, Z.K., Jiang, P.L., Bao, Z.D., Luo,Z., Ju, T.Y., Tian, H.Q., Wang, H., 2001. Lithofacies Paleogeography of the Cambrian and Ordovician in South China. Geological Publishing House, Beijing, pp. 1-221, 10 color maps,and 8 color photo plates (in Chinese with English preface,contents and abstract).

6. Feng, Z.Z., Wang, Y.H., Zhang, J.S., Zuo, W.Q., Zhang, X.L.,Hong, G.L., Chen, J.X., Wu, S.H., Chen, Y.T., Chi, Y.L., Yang,C.Y., 1990. Lithofacies Palaeogeography of Early Paleozoic of North China Platform. Geological Publishing House, Beijing,pp. 1-270 (in Chinese with English preface, contents and abstract).

7. Feng, Z.Z., Zheng, X.J., Bao, Z.D., Jin, Z.K., Wu, S.H., He,Y.B., Peng, Y.M., Yang, Y.Q., Zhang, J.Q., Zhang, Y.S., 2014.Quantitative lithofacies palaeogeography.Journal of Palaeo?geography, 3(1), 1-34.

8. Shanmugam, G., 2015. 3D palaeogeographic reconstructions of the Phanerozoic versus sea-level and Sr-ratio variations:Discussion.Journal of Palaeogeography, 4(3), 234-243.

9. Van Loon, A.J., 2015. The Vérardet al.(2015) method for 3D palaeogeographic reconstructions: How solid is its base?Journal of Palaeogeography, 4(3), 244-247.

10. Vérard, C., 2015. Reply to comments by G. Shanmugam (2015)and A. J. (Tom) van Loon (2015) on “3D palaeogeographic reconstructions of the Phanerozoic versus sea-level and Sr-ratio variations”.Journal of Palaeogeography, 4(3), 248-250.

11. Vérard, C., Hochard, C., Baumgartner, P.O., Stampfli, G.M.,2015. 3D palaeogeographic reconstructions of the Phanerozoic versus sea-level and Sr-ratio variations.Journal of Pal?aeogeography, 4(1), 64-84.