The article of Vérard et al. (2015) proposed an important academic problem “to reconstruct the altitude of oldlands and the water depth of palaeo-oceans of anywhere on the globe and at any geological time”. Their heuristic method and model stimulated my deep thinking of this problem. I have written an editorial “Hope to be from model to practice” in Vol. 4, No. 1, p. 63 of JoP. These two papers, especially the Vérard et al.’s paper, attracted enthusiastic discussions. Up to now, we have received 2 discussion articles and the reply article of Dr. Christian Vérard. This paper is a preliminary review of the above papers. Criticisms and further discussions are heartily welcome.

Vérard et al. (2015, Journal of Palaeogeography, 4(1): 64-84) claim that their global geodynamic model allows one to reconstruct the surface features of topography on land and in adjacent oceans (i.e., paleobathymetry) anywhere on the globe and at any geological time during the past 600 million years (Ma). Such a grand model requires a rigorous scrutiny. The purpose of this discussion is to illustrate that the model 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without revealing their original sources or without citing relevant peer-reviewed publications, (3) the emphasis on ‘unpublished’ internal company datasets that disallow open access to the international scientific community, and (4) the use of poorly understood concepts without providing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.

Vérard and co-workers proposed in an earlier issue of this journal a method to reconstruct the 3D palaeogeography “anywhere in the world at any time”. The present contribution is a discussion of some of the assumptions on which the method of Vérard et al. is based. The reason for this discussion is that the method will give, at least seemingly, illogical outcomes for numerous situations. Moreover, some assumptions used by Vérard and his team pose theoretical problems. It is deduced that the method developed by Vérard and co-workers may occasionally help, indeed, to obtain a rough picture of the altitude of the sedimentary surface on the continents and of the depth of the sedimentary surface in the oceans in the geological past. The outcomes should, however, be treated with utmost care as several of the assumptions on which the interpretative 3D method is based have no solid basis, so that even the rough outcomes of the method must be considered questionable.

I use to say that in science, one cannot say what is right, but one can say what is wrong. And a model is, by definition, wrong, otherwise it is not a model, it is the truth. Being aware that a model aims to mimic the truth but will never be the truth, the only worth questions asking to a model are: (1) How wrong are we? And (2) Why are we wrong? The latter questions the foundations of the model, and is mainly the concerns of A. J. (Tom) van Loon’s comments (2015, this issue). The first questions the accuracy of the outcomes, and corresponds more to G. Shanmugam’s comments (2015, this issue). I am glad that our paper has aroused so rapidly as much feedbacks and comments, sometimes even before the manuscript is definitely published. We hope this paper will keep on inspiring various axes of research and opening new avenues in geosciences. Detailed answers to the comments raised by A. J. (Tom) van Loon and G. Shanmugam among others would certainly deserve a book, so my reply will just focus herein around the two aforementioned questions.

The Oxfordian (Late Jurassic) carbonate-dominated platform outcropping in the Swiss Jura Mountains offers a good biostratigraphic, sequence-stratigraphic, and cyclostratigraphic framework to reconstruct changes in facies distribution at a time-resolution of 100 ka. It thus allows interpreting the dynamic evolution of this platform in much more detail than conventional palaeogeographic maps permit. As an example, a Middle to Late Oxfordian time slice is presented, spanning an interval of about 1.6 Ma. The study is based on 12 sections logged at cm-scale. The interpreted depositional environments include marginal-marine emerged lands, fresh-water lakes, tidal flats, shallow lagoons, ooid shoals, and coral reefs. Although limestones dominate, marly intervals and dolomites occur sporadically. Major facies shifts are related to m-scale sea-level changes linked to the orbital short eccentricity cycle (100 ka). The 20-ka precession cycle caused minor facies changes but cannot always be resolved. Synsedimentary tectonics induced additional accommodation changes by creating shallow basins where clays accumulated or highs on which shoals or islands formed. Autocyclic processes such as lateral migration of ooid and bioclastic shoals added to the sedimentary record. Climate changes intervened to control terrestrial run-off and, consequently, siliciclastic and nutrient input. Coral reefs reacted to such input by becoming dominated by microbialites and eventually by being smothered. Concomitant occurrence of siliciclastics and dolomite in certain intervals further suggests that, at times, it was relatively arid in the study area but there was rainfall in more northern latitudes, eroding the Hercynian substrate. These examples from the Swiss Jura demonstrate the highly dynamic and (geologically speaking) rapid evolution of sedimentary systems, in which tectonically controlled basin morphology, orbitally induced climate and sea-level changes, currents, and the ecology of the carbonate-producing organisms interacted to form the observed stratigraphic record. However, the interpretations have to be treated with caution because the km-wide spacing between the studied sections is too large to monitor the small-scale facies mosaics as they can be observed on modern platforms and as they certainly also occurred in the past.

Talchir Formation (Permo-Carboniferous) of the Gondwana Supergroup records the Late Paleozoic glaciation in Peninsular India. Talchir sedimentary succession of the Raniganj Basin, Damodar Valley Coalfields, Peninsular India, bears ten facies types grouped under three facies associations, viz., the proglacial conglomerate-sandstone facies association (CS), the foreshore-shoreface conglomerate-sandstone-mudstone facies association (CSM) and the prodelta-shelf sandstone-mudstone facies association (SM). Overall facies architecture reflects initial ice-covered terrestrial subglacial sedimentation, which was subsequently reworked and emplaced subaqueously in front of the ice-grounding line, and finally overlapped by storm-laid prodelta-shelf sediments. Repeated glacial advance-retreats with shifts in the position of the ice-grounding line during phases of climatic amelioration led to multiple deglaciation-related fining-up cycles. Decoupled ice sheet and floating icebergs contributed ice-rafted debris (IRD) to these sediments. Gradual retreat of the ice sheet, however, restricted the supply of IRD towards top of the succession. Overlap of wave-agitated shoreface-shelf sediments on the glaciogenic sediments indicates widespread marine transgression caused by glacier melting during ice-house to green-house climatic transition, and crustal downsagging related to glacioisostasy. Subsequently, complete disappearance of the ice sheet caused basinal exhumation along with crustal uplift due to isostatic rebound, leading to multiple horst-graben bounded basinal systems, which received post-Talchir coal-bearing Gondwana sediments.

Based on comprehensive analyses of seismic and log data, this study indicates that mainly four widespread angular to minor angular unconformities (Tg8, Tg51, Tg5 and Tg3) were formed during the Paleozoic. Through the interpretation of structural unconformities, calculation of eroded thickness, correction of palaeo-water depth and compaction and compilation of the Early Paleozoic structural maps, the Early Paleozoic slope break belt (geomorphologic unit) of the Tarim Basin is subdivided into uplift area, subaqueous uplift area, rift slope break belt, flexure slope break belt (slope belt), depression area and deep basin area. Palaeogeomorphology of the Cambrian-Early Ordovician was approximately in EW trend within which three tectonic units including the Tabei Palaeo-uplift, the northern Depressional Belt and the southern Palaeo-uplift developed respectively and are grouped into two slope break systems namely as the Tabei Palaeo-uplift and the southern Palaeo-uplift. These tectonic units obviously control the deposition of isolated platform, open platform, restricted platform and deep basin. Influenced by extrusion in the Mid-Late Ordovician, the southern and northern subaqueous uplifts gradually elevated and then were eroded. Resultantly two slope break systems developed, namely as the northern and central Palaeo-uplifts which obviously controlled the deposition of provenance area, isolated platform, mixed continental shelf, slope and basin facies. The intensive extrusion of the Mid-Late Ordovician leads to significant tectonic deformation of the Tarim Basin: large area of uplifting and erosion and development of EW trending anticline and syncline. Deposition of shore, tidal flat, delta, shallow marine clastics and deep marine facies is obviously controlled by the Tabei, the southern and the Tadong Palaeo-uplifts. Slope break systems control development of stratigraphic unconformity and thus truncation and onlap unconformity zones become favorable areas in a palaeo-uplift and at a palaeo-slope belt for forming important unconformity traps; Whereas slope (slope break) belt along a palaeo-uplift margin is a geomorphologic unit where high-energy sedimentary facies widely develops, such as reef, oolitic sandy clastics or bioclastic limestone beach bar facies, thus litho-structural composite hydrocarbon accumulations usually develop when tectonic condition is suitable. In addition, large-scale palaeo-uplifts are the most favourable areas for hydrocarbon accumulation development.

The Jurassic succession at Gebel Maghara, North Sinai, Egypt, represents a mixed carbonate-siliciclastic sequence. Combining information from both fossils and rocks allowed a plausible reconstruction of the depositional environments and of the basin evolution. The Jurassic succession of Gebel Maghara was deposited on a ramp, and the architecture of the ramp facies was strongly controlled not only by sea-level changes but also by extensional tectonics in connection with rifting of the Tethys, North Gondwana. Seven tectonically modified third-order sequences (DS 1-DS 7) have been recognized. The first three sequences (DS 1-DS 3), ranging from the Toarcian to the Bajocian, record sea invasion (intertidal to shallow subtidal conditions) across an intracratonic area as a result of eustatic sea-level changes during a quiescent rift stage. The remaining sequences (DS 4-DS 7) reflect open marine mid to outer ramp settings. Non-marine conditions around the Bajocian-Bathonian boundary, documented by caliche, represent the maximum regression of the sea. During an active extensional stage, horsts, which formerly acted as barriers separating the Maghara sub-basin from the main ocean, subsided. Subsequent rejuvenation and reactivation of faults shifted the homoclinal physiography of the ramp to a distally steepened ramp during the early Bathonian, creating a 200-m-thick deltaic wedge. Similar processes during the early Kimmeridgian created a calcirudite-calcarenite succession of slope origin. The diversity and the epifaunal/infaunal percentage of the macrofauna display a cyclic pattern which coincides more or less with the sequence stratigraphic architecture.