An Active Composite Pull-apart Basin Within the Central Part of the North Anatolian Fault System: the Merzifon-Suluova Basin, Turkey


ROJAY F. B. , Kocyigit A.

TURKISH JOURNAL OF EARTH SCIENCES, cilt.21, ss.473-496, 2012 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 21 Konu: 4
  • Basım Tarihi: 2012
  • Dergi Adı: TURKISH JOURNAL OF EARTH SCIENCES
  • Sayfa Sayısı: ss.473-496

Özet

The North Anatolian Fault System (NAPS) that separates the Eurasian plate in the north from the Anatolian microplate in the south is an intracontinental transform plate boundary. Its course makes a northward convex arch-shaped pattern by flexure in its central part between Ladik in the east and Kargi in the west. A number of strike-slip basins of dissimilar type and age occur within the NAFS. One of the spatially large basins is the E-W-trending Merzifon-Suluoya basin (MS basin), about 53 km long and 22 km wide, located on the southern inner side of the northerly-convex section of the NAFS. The MS basin has two infills separated from each other by an angular unconformity. The older and folded one is exposed along the fault-controlled margins of the basin, and dominantly consists of a Miocene fluvio-lacustrine sedimentary sequence. The younger, nearly horizontal basin infill (neotectonic infill) consists mainly of Plio-Quaternary conglomerates and sandstone-mudstone alternations of fan-apron deposits, alluvial fan deposits and recent basin floor sediments. The two basin infills have an angular unconformity between them and the deformed pattern of the older infill reveals the superimposed nature of the MS basin. The MS basin is controlled by a series of strike-slip fault zones along its margins. These are the E-W-trending Merzifon dextral fault zone along its northern margin, the E-W-trending Saribugday dextral fault zone along its southern margin and the NW-trending Suluova normal fault zone along its eastern margin. The basin is cut by the E-W-trending Uzunyazi dextral fault zone, which runs parallel to the northern and southern bounding fault zones and displays a well-developed overlapping relay pattern by forming a positive flower structure. The faults of the zone cut Quaternary neotectonic infill and tectonically juxtapose the fill with older rock units. The central faults are seismically more active than the bounding faults, and are therefore relatively younger faults. The early-formed rhomboidal basin is subdivided by these E-W-trending younger faults into several coalescing sub-basins, converting it into a composite pull-apart basin. The total cumulative post-Pliocene dextral offset along the southern bounding faults is about 12.6 km.