Facies Changes, Evolution of Biogenic Structures, and Carbon Isotope Stratigraphy of the Cambrian Series 2 to Miaolingian Transition on the Southern North China Craton
Yaghoob Lasemi
Round 1
Reviewer 1 Report
It appears that the manuscript text, figures, figure captions, descriptions, and citations of figures in the text (particularly the first 10 pages, lines 30 through 210) were prepared by someone unfamiliar or inexperience in sedimentology, sedimentary rocks, and depositional system. So, it is almost impossible to fix/correct the text, figures, figure captions, and associated text, unless the manuscript is reviewed by an expert before submission for publication.
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Reviewer 2 Report
The authors measured carbonate carbon isotopes and trace metals of successions spanning from Stage 4 to the Wuliuan. These data are combined with sedimentary structure analyses to indicate the mechanisms of carbon isotope excursion and its connection with biological evolution. I see three major issues with the paper that must be addressed before publication and the readability of this manuscript could be improved. Therefore, my suggestion for this manuscript is a moderate to minor revision.
First, the authors present an excellent work on sedimentary structure analyses. However, the significance of these structures is not fully discussed in terms of how sedimentary facies variation could have affected carbon isotope signatures. I would suggest the authors to discuss more on this.
Second, the carbon isotope excursions in the two studied sections are rather insignificant, which makes it difficult to establish a direct correlation between the studied section and the standard stratotype. Maybe more detailed fossil evidence or lithology description should be added?
Third, redox sensitive trace elements were analyzed but not really discussed in the manuscript. Furthermore, changes in redox proxies are accompanied by changes in lithology, thus the authors should explain why the changing concentrations of trace metals are not simply caused by different lithological hosts.
Minor edits
Line 11: add a space before the bracket.
Line 44: poor composition? Do you mean depletion?
Line 46: upwelling is not formed by anoxic water.
Line 47-50: this sentence is somewhat wordy. Please revise it for readability.
Line 52: the age of the Kalkarindji LIP should be noted here.
Line 60: wordy.
Line 82: the authors declare that the Miaolingian is dominantly deposited as carbonates, particularly oolitic limestones, but in the lithological column of Fig. 1, the Miaolingian mainly corresponds to mudstone deposition and oolitic limestone only occur in the uppermost portion of the section.
Line 87: the two studied sections are not clearly marked in Fig. 1.
Line 127: the standard material and analytical uncertainty should be mentioned for trace metal analysis.
Line 148: this is somewhat contradictory to Fig. 3. It looks like that the first phase corresponds to Member I and lower Member II (green color).
Lines 158, 168, and 198: this should be removed to the discussion section, and the authors should explain why these proxies can indicate ocean redox.
Line 159: it is actually the middle part of Member II.
Line 187: the cycles should be marked in the figures.
Line 210: this section should be removed to the discussion section.
Fig. 1: a/b should be changed to numbers.
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Reviewer 3 Report
First of all, thank you for considering me as a potential reviewer. I have carefully read the manuscript by Wen-Yi he et al (Facies Changes, Evolution of Biogenic Structures, and Carbon Isotope Stratigraphy of the Cambrian Series 2 to Miaolingian Transition on the Southern North China Craton). I consider it to be a good article, novel, and above all with geochemical data. I have made only some minor revisions (please carefully check the pdf file) with reference to the nomenclature and please carefully check the bibliographical references, as they do not match, for example: Zhu, 2006; Dillard et al., 2007; Álvaro et al., 2010.
My opinion is that the article be published with minor revisions.
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Reviewer 4 Report
Minerals: Review of He et al., Facies changes…
Ed Landing, my review can be acknowledged,
Overall recommendation: This is a very good paper that should be accepted for publication by Minerals following modest but mandatory revision. The ms. is very thorough and is interesting as it fuses standard lithostratigraphic description with stable isotope analyses that lead to plausible syntheses of the Lower–Middle Cambrian boundary interval in North China. Information on this region is presently limited for non-Chinese readers. This means the article will have long shelf life and will be a standard of reference.
Mandatory changes: The literature that there was no Cambrian “deep anoxic seawater” has to be cited. The authors accept the “standard paradigm” on Cambrian paleooceanography—that the World Ocean featured “deep anoxic seawater” (line 53). The problem is that this conclusion is based on stratigraphic successions that were relatively shallow successions (as ramp or upper slope successions with anoxic/dysoxic black mudstones) of the OMZ. Far deeper successions (lowest slope and rise) show persistent oxygenation of deep water and red mudtones in the Taconian allochthons of eastern New York, Quebec, and western Newfoundland. See Landing et al. (1992) for early literature on distal green and red mudstones with a mid-water OMZ represented by black, organic-rich mudstones. Also see Landing (2012, 2013a, 2013b).
I agree that there was onlap of dysoxic/anoxic water in Lower–Middle Cambrian boundary interval. Authors must note this was the initial onlap of the long-term Hatch Hill dysoxic/anoxic interval onto the shelf (Landing et al., 2002; also Landing 2012, 2013a, 2013b; Landing and Webster, 2018; see also Landing et al., in press).
Authors must note global hyperwarming model. 1) The rising temperature in Lower–Middle Cambrian boundary interval is possibly related to Kalkarindji Igneous Province activity, but sea-level rise across continents with high albedo means transgression by shallow sea water with high insolation and high heat capacity. This means that a global Lower–Middle Cambrian boundary interval onlap leads to higher global temps and means transgression by warming epeiric sea water with reduced oxygen solubility. (e.g., Landing 2012).
Similarly, high organic sediment deposition with onlap means high carbon-13 carbonates, but increased rate of aragonite formation in warm epeiric seas also means high carbon-13 in pristine carbonates! Similarly, high carbon 13 values in shallowest sedimentary rocks as a result of riverine influx is nonsense (line 309), as these facies would be most oxidized and muds would have lost carbon-12.
Explanation needed: Why does an anoxia/paleoredox fall with onlap then lead to extinction?? Biotas and oxic lithofacies should simply migrate into the interior of a paleocontinent. Yes? The reason may be persistence of anoxia/dysoxia even to the shoreline (see Landing et al., in press, Bakken model).
Why would a “sharp decline in biomass” take place with this Lower–Middle Cambrian boundary interval sea-level rise? How was this measured in existing literature? Surely increased deposition of organic-rich muds with sea-level rise shows continued biomass formation (and preservation), with local loss in metazoan abundance, obviously, in low-oxygen facies.
Line editing throughout ms.
1) Write “upper Stage 4” etc. (not Upper, line 35 etc.) throughout ms. Lower level chronostrat. units (formal & informal series, stages, zones) do not have capitalized divisions.
2) Write “Genus Zone” or “Genus species Zone” with capitalalized word Zone throughout ms.
3) Write Shandong Province (line 102 and elsewhere) with capitalized word Province.
4) Write “Wuliuan Stage” (line 40 and elsewhere) with capitalized word Stage.
5) It is convention to write the plural of capitalized nouns in lower case: write “Zhangxia and Gushan formations” (line 91 and plurals elsewhere) as “formations” not “Formations.”
6) In many places in ms., word “dolomite” (the mineral, line 176 and elsewhere) is written when the authors should write “dolostone” (the rock).
7) In places in ms., authors write “sediment” (line 137 and elsewhere) when “sedimentary rock” is appropriate—these are lithified rocks not loose sediment.
Section 4.1: Misspelling of many trace fossil genera names.
Table 1: not “rain drop impressions” in current literature, likely gas bubble escape structures.
Yes, you have “birds eye structures,” but larger (4 cm diameter) likely filled vugs.
“Conglomerate limestone” as illustrated is an “edgewise conglomerate” showing wave-imbrication of clasts.
The following references cited above can be down-loaded from researchgate ed landing:
LANDING, E., 2012. Time-specific black mudstones and global hyperwarming on the Cambrian–Ordovician slope and shelf of the Laurentia palaeocontinent. Palaeogeography, Palaeoclimatology, Palaeoecology, 367–368, 256–272.
LANDING, E. 2013a. Extended Abstract—The Great American Carbonate Bank in northeast Laurentia: its births, deaths, and linkage to continental slope oxygenation (Early Cambrian–Late Ordovician), pp. 253a–260a, Figs. 1, 2. In J. R. Derby, R. D. Fritz, S. A. Longacre, W. A. Morgan, and C. A. Sternbach (eds.), The Great American Carbonate Bank, essays in honor of James Lee Wilson. American Association of Petroleum Geologists Bulletin, 1733 p. [Published January 2013]
LANDING, E. 2013b. The Great American Carbonate Bank in northeast Laurentia: its births, deaths, and linkage to continental slope oxygenation (Early Cambrian–Late Ordovician), pp. 451–492, Figs. 1–7, Appendices 1, 2. In J. R. Derby, R. D. Fritz, S. A. Longacre, W. A. Morgan, and C. A. Sternbach (eds.), The Great American Carbonate Bank, essays in honor of James Lee Wilson. American Association of Petroleum Geologists Bulletin, 1733 p. [Published January 2013]
Landing, E., and M. Webster. 2018. Iapetan rift‒passive margin transition in NE Laurentia and eustatic control on continental slope oxygenation, Taconic slate colors, and Early Paleozoic climate. In T.W. Grover and H. Mango (eds.), 110th New England Intercollegiate Geological Conference and 90th New York Geological Association, October 12‒14, Lake George, NY, pp. A5-1‒A5-41, Figures 1‒12.
Landing, E., Benus, A. P., and Whitney, P. R. 1992. Early and early Middle Ordovician continental slope deposition: shale cycles and sandstones in the New York Promontory and Quebec Reentrant region. New York State Museum Bulletin, 474, 40 p, 11 figs.
LANDING, E., G. GEYER, AND K.E. BARTOWSKI. 2002. Latest Early Cambrian small shelly fossils, trilobites, and Hatch Hill dysaerobic interval on the east Laurentian continental slope. Journal of Paleontology, 76:285–303, 9 Figs. 1–9, 2 Tables).
LANDING, E., S.R. WESTROP, AND G. GEYER. In press. Trans-Avalonian green–black boundary (early Middle Cambrian): transform fault-driven epeirogeny and onset of 26 m.y. of shallow marine anoxia in Avalonia (Rhode Island–Belgium) and Baltica. Canadian Journal of Earth Sciences (2023), 113 pp., 10 figs.
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Round 2
Reviewer 1 Report
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