Variable Quaternary Uplift Along the Southern Margin of the Central Anatolian Plateau Inferred From Modeling Marine Terrace Sequences

Daniel Melnick,Julius Jara‐Muñoz,Simone Racano,Domenico Cosentino

doi:10.1029/2019tc005921

Abstract

AbstractThe southern margin of the Central Anatolian Plateau (CAP) records a strong uplift phase after the early Middle Pleistocene, which has been related to the slab break‐off of the subducting Arabian plate beneath the Anatolian microplate. During the last 450 kyr the area underwent an uplift phase at a mean rate of ~3.2 m/kyr, as suggested by Middle Pleistocene marine sediments exposed at ~1,500 m above sea level. These values are significantly higher than the 1.0–1.5 m/kyr estimated since the Late Pleistocene, suggesting temporal variations in uplift rate. To estimate changes in uplift rate during the Pleistocene we studied the marine terraces along the CAP southern margin, mapping the remnants of the platforms and their associated deposits in the field, and used the TerraceM software to identify the position and elevation of associated shoreline angles. We used shoreline angles and the timing of Quaternary marine sedimentation as constrains for a Landscape Evolution Model that simulates wave erosion of an uplifting coast. We applied random optimization algorithms and minimization statistics to find the input parameters that better reproduce the morphology of CAP marine terraces. The best‐fitting uplift rate history suggests a significative increase from 1.9 to 3.5 m/kyr between 500 and 200 kyr, followed by an abrupt decrease to 1.4 m/kyr until the present. Our results agree with slab break‐off models, which suggest a strong uplift pulse during slab rupture followed by a smoother decrease.

Highlights

Orogenic plateaus, defined by widespread low‐relief landscapes, strongly elevated in comparison with their surrounding areas, represent singular features of the main orogenic belts
We defined a maximum threshold of 17° and 12 for slope and roughness for the study area, respectively, based on the morphometric characteristics of valleys, gullies, and other erosional features, to map the planar and sub‐planar surfaces, and we used a threefold criteria to define these surfaces as marine terraces: (1) geomorphic criteria: characteristic staircase morphology; (2) morphometric criteria: Due to the temporally pulsed nature of marine terrace formation, the platform surfaces should concentrate into discrete elevation bands if they are marine terraces (Bowles & Cowgill, 2012) (Figure 4d); (3) paleontologic criteria: the presence of remnants of marine organisms representing markers of past sea level
The distribution of marine terraces follows as SW‐NE orientation, the width of the terrace levels decrease from top to bottom; for instance, the lower T7 level is represented by small remnants of abrasion surfaces set on the Tauride units near the city of Aydıncık, with an elevation of about 50 m a.s.l. (Figure 3b)

Summary

Introduction

Orogenic plateaus, defined by widespread low‐relief landscapes, strongly elevated in comparison with their surrounding areas, represent singular features of the main orogenic belts. These low‐relief elevated areas are responsible for both local and global climate changes. In Asia Minor, the Central Anatolian region is defined by a high topography area known as the Central Anatolian Plateau (CAP). It marks the western portion of the largest collisional belt on Earth, the Turkish‐Iranian‐Caucasian‐Himalayan‐Tibetan orogen, resulting from collision between the Arabian and Indian plates with Eurasia, which in eastern Anatolia started at ca. It marks the western portion of the largest collisional belt on Earth, the Turkish‐Iranian‐Caucasian‐Himalayan‐Tibetan orogen, resulting from collision between the Arabian and Indian plates with Eurasia, which in eastern Anatolia started at ca. 20 Ma along the Bitlis‐Zagros thrust zone (e.g., Ballato et al, 2011; Okay et al, 2010)

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