Discussion of the paper

Brogi, Andrea & Giorgetti, Giovanna (2012): Tectono-metamorphic evolution of the siliciclastic units in the Middle Tuscan Range (inner Northern Apennines): Mg-carpholite bearing quartz veins related to syn-metamorphic syn-orogenic foliation.- Tectonophysics 526-529: 167-184, Elsevier, Amsterdam.

I thank for the information published in Tectonophysics 526-529: 167-184 (2012) about the geology of the Monticiano-Roccastrada Range, the new findings there of Mg-Carpholite and a more precise documentation and reconstruction of the HP-LT metamorphic evolution of that area characterized by middle-late Tertiary subduction-related tectonic burial and exhumation. This is important work.

In advance to the following lines, I want to declare one general point of academic interest and importance: an intellectual model can't be better than the quality of the facts on which it stands on or from which it is derived of. This means in the case here: a reliable, high-quality model of the tectono-metamorphic evolution of the Monticiano-Roccastrada Area can only be setup, if the basics, which can here only be thorough mapping work, has as carefully and accurately as possible been accomplished. I am well aware that the realization of this compellingly high demand means hardest work.

The reason for discussing the paper is as follows: some years ago, I mapped an area of ca. 7 km² between Ferriera (P 263m) in the Farma Valley and the village Monticiano at scale 1:10.000. During that private post-doc-activity on my own account and my own costs, I studied and analyzed the geological relations between the Risanguigno Formation present at the type locality Rio Risanguigno close to Monticiano and lithologic equivalents of that Formation present at Ferriera (P 263m) in the Farma Valley ca. 5,3 km to the south. It was - as I already experienced in the Farma Valley - a time-consuming and exhausting step by step mapping work, where the detectability and interpretation of geological boundaries is hampered and complicated, because nearly all of them are covered beneath late Quaternary detritus.
A visual comparison revealed that the northern part of my map - not yet published - is geographically identic with a part in the western section of the map of Broghi & Giorgetti (2012) in Fig. 5 on page 172 of their paper. So it is possible to compare and to comment the geological results. This common area contains geographically the northern part of Rio Risanguigno Valley, Poggio Camerata, Romitorio, Poggio Scalari 434m, Fosso Rifregaio and a small part of the Torrente la Gonna Valley. The complexity-grade of the geomorphologic pattern of the common map-part is rather high; this indicates a difficult geological situation and the information found needs sensible geological interpretation.

First of all, I refer to the common map-part. The geological mapping results - these of Broghi & Giorgetti is Figure 1 and my one is Figure 2 - differ essentially. This may be partly explained, if it is the case that Broghi & Giorgetti and Engelbrecht worked at different map-scales.

Figure 1
(Broghi & Giorgetti)

Figure 2

The lithostratigraphy in Figure 1 consists of the Poggio al Carpino Formation (Late Permian - early Triassic) (part of the Phyllite-Quartzite-Group) at the base, which is overlain by the Verrucano Group, composed of the Civitella Marittima Formation (Induan - Anisian) and the Monte Quoio Formation (Anisian - Ladinian). In the chapter Stratigraphy (p.170) of Broghi & Giorgetti (2012) no single word is written about the type locality of the Risanguigno Formation - which occurs in the northern part of the Risanguigno Valley present in Figure 1 - and about the problematic age attributions of the Poggio al Carpino Formation, the Civitella Marittima Formation and the Verrucano Group; see my detailed discussion on the site http://www.umweltgeol-he.de/discussion1.htm .

In Figure 1, the general tectonic situation consists essentially of two superimposed Tertiary folding events: the first event DE1 produced an isoclinal antiform with the Poggio al Carpino Formation in the fold-core, which was refolded by a second event DE2. The fold axes entered in Figure 1 persist on km-scale. The sequence plotted east of the isoclinal DE2-antiform is tectonically overturned on km-scale; but the tectonic overturning is not supported by data in Figure 1: they are missing or lack ascertained sedimentary polarity. The tectonic concept presented in Figure 1 is in logical conflict with the citations in the chapter Geological Outlines on page 169-170 in the paper of Broghi & Giorgetti (2012), where the facts of "superimposed generations of normal faults" and "internal thrusting, which affected the Verrucano Group and the Phyllite-Quartzite Group" are cited, which of course also occur in the area under consideration. So it is astonishing that no tectonic thrust and only one single normal fault is present in Figure 1. In addition: neither the tectonic concept nor the heterogenous lithologies of the Formations can account for the geomorphological complexity-grade of the area.

In my Figure 2, the lithostratigraphic base comprises - of course - the Risanguigno Formation, present in six scattered outcrops at the type locality - defined and published by Bagnoli & Tongiorgi (1979) - in the northern part of the Risanguigno Valley. According to my idea, this Formation is thrusted either onto the Poggio al Carpino Formation or onto the Civitella Marittima Formation. The area is intersected by normal faults and wrench faults into numerous tectonic blocks, in which the folded and/or thrusted sequence consisting of Poggio al Carpino Formation, Civitella marittima Formation and Monte Quoio Formation appears in stratigraphic order; the area seems to be megabrecciated as in the Farma Valley. The constructed b-axes are persistent on max. 350m. Isoclinal folds were found rarely in outcrop; but when present, they even occur in very competent lithologies like thick layered quartzconglomerates of the Monte Quoio Formation; isoclinal refolding of isoclinal folds was not observed. In the eastern part of Figure 2, large-scale tectonic overturning could not be ascertained. Some of the strike directions of the faults plotted in Figure 2 correlate with main directions present in the recent geomorphological pattern.
Geological misinterpretations in my Figure 2 were - of course - unavoidable and must be present due to 1) overcharge by complexity, 2) precarious outcrop situation and geographical orientation and 3) personal errors (our all fate is "errare humanum est"). If there is enough time in my life, I will control my mapping work again to improve it.

Now it is the reader's turn to decide which of the Figures 1 or 2 is more reliable and seems more realistic.

In addition to my self-critics and critics on the stratigraphy, tectonics and mapping work of Broghi & Giorgetti (2012), I do not agree with the general tectonometamorphic subdivision of the Monticiano-Roccastrada Range and the Monte Leoni Area, as given in the Fig. 4b on page 171 of Broghi & Giorgetti (2012). The reader can find my arguments in the second paragraph of the discussion on the site http://www.umweltgeol-he.de/discussion2.htm and in Engelbrecht 1997: 527 (Zeitschrift der Deutschen Geologischen Gesellschaft 148/3-4: 523-546).

Concerning the schematic lithostratigraphic column in Fig. 6 on page 173 of the paper of Broghi & Giorgetti (2012): the grade of simplification is unacceptably high and the plotted arrangements and interrelations of sedimentary textures and structures are often wrong. Although laid down under differing depositional conditions, the Civitella marittima Formation and the lower part of the Monte Quoio Formation were supplied in their graphical representations in Fig. 6 with nearly identic patterns of lines reflecting the stratification. It is astonishing that the abbreviation FF means Poggio al Carpino Formation (and not Farma Formation) and that the sedimentology entered in that Formation consists merely of the symbols for pelites and siltstones. The graphic presentation of the Anageniti minute Formation in Fig. 6 as massive, fining upward cycle can't be accepted. The abbreviations CCA and RET are not explained.

It is confusing that in Fig. 12 on page 178 of the paper of Broghi & Giorgetti (2012) some mineral-abbreviations in the figure-caption are not identic with the abbreviations for the mineral phases in the corresponding P-T-diagram immediately above (kln-Kaol, prl-Pyr, qtz-Qz, cld-Ctd) and that in this figure-caption the Alumosilicate Kyanite Al2SiO5 is mistaken with the Potassium-Magnesium-Hydrosulfate Kainite KMg(Cl/SO4)2,75H2O. In the figure-caption, two abbreviations (prl-pyr) were used for one and the same mineral phase Pyrophyllite.

Some years ago, I corresponded with Bruno Goffé - a referee of Broghi & Giorgetti's paper (2012) - to exchange ideas about the geologic and metamorphic history of the Monticiano-Roccastrada Range and I sent him my doctoral thesis containing map and profiles of the Farma Valley. It is astonishing that he did not make any use of all that information, when he evaluated the paper of Broghi & Giorgetti (2012).

In sum: according to my opinion, the mineralogical-petrogenetical information of the paper of Broghi & Giorgetti (2012) is ok, but not the geological one concerning mapping work, tectonic model, profiles, lithostratigraphy and age attribution of the geological Formations. It seems strange to me that Broghi & Giorgetti and the referees of their paper ignored my published geological work, the references of which are online. I recommend academic decartellization, democratization of citation-politics as well as appreciation and involvement of other qualitatively established opinions. Otherwise academic autism as well as academic endogamy will prevent exchange of new and good ideas and block scientific progress.

It is disappointing that such partially low quality paper was published in a high quality journal, the contributions of which I read since 1980. I think that the journal Tectonophysics needs - at least in some cases - a better quality control concerning the papers of authors, which submit there.