Partitioned tectonic shortening, with emphasis on outcrop-scale folding and flattening, Pindos fold-and-thrust belt, Peloponnese, Greece

Abstract

Shortening estimates for fold–thrust belts seldom take into consideration outcrop-scale folding, especially folding related to prethrusting layer-parallel shortening (LPS) and flattening. The Pindos belt of the Peloponnese contains products of Maastrichtian to Paleocene tectonic shortening amenable to assessing strain partitioning. Shortening there initiated with LPS, including outcrop-scale folding, which was superseded by thrusting and macrofolding, with both macromechanisms producing additional outcrop-scale folding and (or) form-modification of initial LPS outcrop-scale folds. Skourlis and Doutsos (2003. International Journal of Earth Sciences, 92: 891–903) concluded that total shortening in this region was 68%, the summation of ∼15% LPS, ∼6% fault-related macrofolding, and ∼47% thrust–slip translation. But even this degree of shortening may be underestimated when outcrop-scale folding is considered. Two limestone-dominated Cretaceous formations and one Cretaceous–Eocene formation of limestone and mudstone display spectacular outcrop-scale folding produced by true multilayer behavior, internal buckling, and disharmonic quasi-flexural folding. Fold forms vary from chevron buckling of multilayers to more rounded folding of true multilayers to disharmonic flattened folds in pseudo-bedded limestone. Ramsay analysis of layer thickness variations across individual disharmonic folds underscores the disharmonic fold forms and intense degree of pressure dissolution generated fold flattening. Line-length shortening for well exposed “packages” of LPS outcrop-scale folding is as high as 30%, but overlying and underlying panels may be more modestly folded and (or) flattened, suggesting that shortening transfer mechanisms may have caused some sections to be bypassed. Achieving more meaningful shortening estimates of the outcrop-scale folding within an entire progressive deformation will require understanding of the partitioning of distribution of this folding regionally.

Development of an intra-carbonate detachment during thrusting: The variable influence of pressure solution on deformation style, Khao Khwang Fold and Thrust Belt, Thailand

“…However, significant differences within the study area are the presence of early tectonic pressure-solution cleavage in the Pindos example (at a high angle to bedding) and the intensity of the pressure-solution-related pseudo-bedding. Ramsay's (1967) t'-α classification shows the considerable variety of fold shapes and departures from simple fold morphologies caused predominantly by the effects of mechanical stratigraphy and late flattening (see, for example, Ramsay, 1967;Hudleston and Stephansson, 1973;Hudleston and Treagus, 2010;Davis, 2019). The folds in this study show very similar variations.…”

“…In many fold and thrust belts, early layer-parallel bulk-shortening strain (LPS) by compaction and/or cleavage formation, occurs prior to the main folding and thrusting stage and can be responsible for shortening up to ~20%-30% (e.g., Gray, 1981;Mitra and Yonkee 1985;Morley, 1986;Protzman and Mitra, 1990;Cochrane et al, 1994;Mitra, 1994;Moore et al, 1995;Butler and Paton, 2010;King et al, 2010;Morley and Naghadeh, 2016;Davis, 2019). Tectonic pressure-solution cleavage can be found as widespread sub-orthogonal-to-bedding orientations indicative of early-stage deformation before significant folding Research Paper (Gray, 1981;Marshak and Engelder, 1985;Mitra and Yonkee, 1985;Morley, 1986;Mitra, 1994;Boyer and Mitra, 2019;Davis, 2019), bedding-oblique cleavage developed during folding and thrusting (e.g., Marshak and Engelder, 1985;Morley, 1986), and late-stage flattening including axial planar cleavage (e.g., Ramsay, 1962Ramsay, , 1967Dewey and McManus, 1964;Hudleston and Stephansson, 1973;Gray, 1981; see reviews in Treagus, 2010, andGratier et al, 2013). Pressure solution can also be an important process along fault zones, particularly as a deformation mechanism during aseismic creep (Gratier et al, 2013).…”

“…There are few studies in the literature that describe late flattening by pressure solution that departs from classic axial planar cleavage, but one is that of the Pindos Fold-Thrust Belt (Davis, 2014(Davis, , 2019, where flexural folds are developed in pseudo-bedding. However, significant differences within the study area are the presence of early tectonic pressure-solution cleavage in the Pindos example (at a high angle to bedding) and the intensity of the pressure-solution-related pseudo-bedding.…”

Flattening of New Media Design Based on Deep Reinforcement Learning

“…Therefore, the whole shape will also reflect a strong beauty of rules, order, and form. Flat style refers to the organic generalization, regularization, and orderly treatment of a large number of natural shapes and complex colors in life, so as to achieve formal beauty [21]. Traditional animation, represented by Disney, generally follows the creative process of summarizing complex objects into basic geometric shapes, and then artistic processing, plus various details.…”

Ali Mehmet Celâl Şengör: A geologist who unravels the histories of continents and oceans

“…Lykaion area, the author noticed that outcrop-scale folds in limestones are mainly symmetrical with respect to overall enveloping surfaces for bedding, whereas folds in cherts tend to be asymmetrical. Davis (2019) concludes that achieving meaningful regionalscale shortening estimates is difficult and requires statistical analyses of the regional distribution of outcrop-scale folds in each formation.…”