# No evidence for a 10-m historical tectonic uplift at Mangalia, (Romanian Black Sea coast): comment on Drăguşin et al. (2025)

Alfred Vespremeanu-Stroe, Luminiţa Preoteasa, Laurenţiu Tuţuianu, Mihaela Dobre, Florin Zăinescu, Anca Dan, Edward Anthony

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Alfred Vespremeanu-Stroe, Luminiţa Preoteasa, Laurenţiu Tuţuianu, Mihaela Dobre, Florin Zăinescu, et al. No evidence for a 10-m historical tectonic uplift at Mangalia, (Romanian Black Sea coast): comment on Drăguşin et al. (2025). Geoscience Letters, 2025, 12, pp.61. 10.1186/s40562-025-00438-x. [https://hal.science/hal-05463273](https://hal.science/hal-05463273)

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# No evidence for a 10-m historical tectonic uplift at Mangalia, (Romanian Black Sea coast): comment on Drăguşin et al. (2025)

Alfred Vespremeanu-Stroe<fnref n="1" />,<fnref n="2" />*, Luminița Preoteasa<fnref n="1" />,<fnref n="3" />, Laurențiu Țuțuianu<fnref n="1" />, Mihaela Dobre<fnref n="1" />, Florin Zăinescu<fnref n="1" />,<fnref n="4" />, Anca Dan<fnref n="5" /> and Edward Anthony<fnref n="4" />

**Abstract**

Drăguşin et al. (2025) interpreted deposits at Mangalia (Romania) as evidence of a two-phase tectonic event (~14 m subsidence and uplift) during the 18th–19th centuries. Based on multi-proxy data from the same site, we show that this scenario is inconsistent with regional tectonics, stratigraphy, and archaeology. The deposits instead record the gradual infill of a coastal depression episodically affected by extreme marine incursions.

**Introduction**

Drăguşin et al. (2025) interpret deposits now ~3–8 m above sea level (asl) at Mangalia (ancient Callatis) as evidence for an abrupt, two-phase tectonic episode in the 18th–19th centuries: ~4 m subsidence permitting marine sedimentation followed by ~10 m uplift. An earlier EGU-sphere version of this study (Drăguşin et al. 2024) was rejected after peer review; the published paper does not address the reviewers' main criticism. We argue this scenario conflicts with regional tectonics, stratigraphy, sedimentology, chronology, and the archaeological record, and that the deposits reflect episodic marine incursions

infilling a pre-existing coastal depression (likely a sinkhole).

**Regional and site-scale evidence do not support recent large tectonic motions**

Southern Dobrogea is a stable platform province at least since the Miocene (e.g., Dinu et al. 2005; Konerding et al. 2010). At Mangalia, neither field observations nor the geophysical profiles in Drăguşin et al. show offsets, fault planes, or folds indicative of recent deformation, despite the amplitude their model requires.

Analogies invoked elsewhere are inappropriate: the New Madrid sequence produced vertical steps of order ~2 m (Mueller et al. 2004), and the 1819 Kutch event created a regional scarp up to ~4.3 m over ~90 km (Rajendran and Rajendran 2011). Extrapolating such cases to a localized ~10 m uplift in an intraplate, structurally quiescent area is not tenable.

Archaeological and historical evidence also weigh against the hypothesized 18th–19th century bi-directional movement. Roman and Late Roman walls at Callatis, including several square towers, preserve consistent elevations with no warping or displacement (Alexandru 2024; Mărgineanu-Cârstoiu 2024). Ottoman-era remains

<figure><img src="image_3.png" /></figure>

<footnote>*Correspondence:</footnote>

<footnote>Alfred Vespremeanu-Stroe</footnote>

<footnote>fredi@geo.unibuc.ro</footnote>

<footnote n="1">¹GEODAR Research Center for Geomorphology, Gearchaeanology, and Paleo-Environments, ICUB Research Institute of the University of Bucharest, Bucharest, Romania</footnote>

<footnote n="2">²Faculty of Geography, University of Bucharest, Bucharest, Romania</footnote>

<footnote n="3">³Sfăntu Gheorghe Marine and Fluvial Research Station, University of Bucharest, Sf. Gheorghe, Romania</footnote>

<footnote n="4">⁴Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, CEREGE, Aix-en-Provence, France</footnote>

<footnote n="5">⁵CNRS, École Normale Supérieure, Paris 75005, France</footnote>
and documentary records lack any mention of sudden
vertical shifts (Radu and Radu-Iorguș 2022). Even the
well-documented 1901 earthquake (M 7.2) left no com-
parable imprint.

Implied rates and timescales are geodynamically implausible

Accepting the proposed chronology would require ~10 m
uplift in <200 year, on the order of 10 cm yr⁻¹ or several
multi-metre steps, neither credible here. Even in active
orogens, sustained rock-uplift of this magnitude is excep-
tional; coseismic vertical displacements typically fall near
1–2 m per event (Burbank and Anderson 2011).

Our OSL ages for the upper sand body (their “Unit 2”) of ~120–100 year indicate recent emplacement; the tectonic model would thus demand extremely rapid post-depositional uplift without structural signature or historical testimony.

Stratigraphy and facies argue against continuous
lagoonal submergence

At Mangalia, the contact between Sarmatian limestone
and overlying loess/red-clay cover lies typically between
-2 and +1 m asl (Constantinescu 2012); a ~10 m his-
torical uplift would more likely expose a limestone cliff
rather than an active shoreline incised in unconsolidated
loess. The internal organization of the sequence and our
analyses of the meiofauna also contradict a prolonged
lagoon:

(i) *Silts* (Unit 3) are dominantly non-marine. Meiofauna are largely absent or represented by reworked marine tests; freshwater ostracods (*Candona*) dominate, consistent with a continental wetland influenced by sulphidic springs.

(ii) *Sands* (Unit 2) are brackish-to-marine. Abundant foraminifera (*Ammonia beccarii*, *Elphidium*, *Quinqueloculina*) and marine ostracods (*Loxoconcha*, *Amnicythere*, *Cyprideis torosa*, *Cytheroma variabilis*) mark high-energy incursions, not quiet lagoon fill.

(iii) *Laterally continuous silty laminae within Unit 2* contain freshwater taxa centrally and landward but are absent seaward, a geometry and composition inconsistent with continuous marine submergence but with episodic flooding alternating with marine overwash.

The charcoal-rich “Black Layer” (Unit 3b) records slope-wash, not lagoonal settling

Unit 3b thickens toward the southern margin of the
depression, at the foot of the slopes that once hosted
ancient settlements. It contains abundant sand-sized
charcoal, roof-tile debris, pottery, and faunal fragments,
with higher sand and lower clay than the enclosing grey

silts. This composition is diagnostic of high-energy slope-
wash into a depression and incompatible with buoyant
charcoal accumulating from prolonged suspension in a
calm lagoon.

Coarse facies in the seaward sector were overlooked

Cores from the eastern (seaward) sector include poorly
sorted sands with rolled gravels, broken shell debris, and
mud aggregates, whereas these facies are absent land-
ward, indicating a clear landward decrease in energy.
These facies, overlooked by Drăgușin et al., are typical of
marine overwash during extreme events, not of a calm
loess-bounded lagoon.

Reported elevations of “marine deposits” are
overestimated

Drăgușin et al. cite 9–10 m asl for the top of natural marine sands but do not specify how these elevations were obtained. High-precision DGPS along the exposed trench and stratigraphy in our cores place the top of the natural sands (Unit 2) at ≤+8 m asl. The tectonic argument thus partly rests on an elevation datum that fails measurement control.

A plausible process sequence

A plausible reading of the evidence is:

(i) a pre-existing coastal depression, likely a sinkhole, trapped silts from runoff and springs;

(ii) marine incursions during exceptional events (i.e. storms/tsunamis) transported sands into the basin, interbedded with slope-derived silts, producing a landward decreasing energy gradient;

(iii) recent anthropogenic filling partially capped the sequence.

This model explains: the non-marine silts, marine assem-
blages in sands, lateral facies organization, the presence
of coarse clasts seaward, and the measured elevations,
without invoking undocumented neotectonics in the
18th – 19th centuries. Hydrometeorological data from
Dobrudja (sub-hourly extremes up to 21 mm/5 min;
~225 mm/24 h recorded in late August 2024 at Manga-
lia; Irașoc et al. 2024) demonstrate the capacity for high-
energy flooding to mobilize such facies.

Conclusions

The hypothesized ~14 m bi-directional vertical motion at Mangalia in the last two centuries is incompatible with regional tectonic context, the absence of structural indicators, realistic uplift rates, stratigraphic architecture, microfossil evidence, measured elevations of marine deposits, and the archaeological record. A
sinkhole-centered, event-driven infill model - episodically influenced by extreme marine incursions - accounts for the observations without extraordinary tectonics. We therefore advise caution against over-interpreting local stratigraphy as evidence of rare intraplate megadisplacements and recommend additional multi-proxy work to refine chronology and hydrodynamic drivers.

**Acknowledgements**

We thank colleagues from the GEODAR Research Center and partner institutions for their assistance in field investigations and laboratory analyses, as well as the OSL Laboratory at the University of Szeged for their support with sample dating.

**Author contributions**

All authors contributed to fieldwork, data analysis, and interpretation. The manuscript was jointly written and approved by all co-authors.

**Funding**

This research was supported by the projects ChronoCARP (Climate- and tectonics-related surface processes in the Southern Carpathians and Northern Balkan Mountains. A geochronological approach at different timescales; PNRR-III-C9-2022-18 CF253/29.11.2022) and CNFIS-FDI-2025-F-0364 (UB Research Nexus: Transforming Research through Innovation, Digitalization and Exploration at the University of Bucharest).

**Data availability**

No datasets were generated or analysed during the current study.

**Declarations**

**Competing interests**

The authors declare no competing interests.

Received: 7 October 2025 / Accepted: 3 November 2025

Published online: 12 November 2025

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