The variation of geomagnetic field intensity in Central Anatolia during the Neogene-Quaternary period

A detailed palaeointensity study was performed using the modified Thellier method on 18 Quaternary and Neogene volcanic units, ages ranging from 0.08 to 5.98 Ma, in Central Anatolia, Turkey. Robust data, which were estimated from 12 lava units in the study area, significantly increase the database of palaeomagnetic data, directions and absolute palaeointensity for the Anatolian region covering the time window back to similar to 6 Ma. Previous studies sensitively dated the samples, except for one site dated in this study. The palaeointensity (VDM) value from the upper Miocene site estimated as 48.6 +/- 9.2 mu T (10.1 x 10(22) +/- 1.9 Am-2) fits well into the Neogene VDM range in the data archives. For Pliocene samples with an age of 4.7 Ma, the palaeointensity was calculated to be 21.0 +/- 4.7 mu T. For these samples, an inclination of +42.9 degrees was determined, and together with the results of low palaeointensity and normal polarity, this corresponds to the Nunivak or Sidufjall subchrons. These are normal polarity chrons within the Gilbert Chron which predominantly has reversed polarity. Palaeodirectional data and field strength with age between 0.08 and 2.57 Ma clearly showed the Brunhes and Matuyama Chrons in the Pleistocene. Three new data with 25.0 +/- 7.9 mu T (age 1.84 Ma), 59.7 +/- 8.2 mu T (age 2.15 Ma) and 79.6 +/- 19.3 mu T (age 2.57 Ma) from the early Pleistocene period significantly contribute to global data archives, which lack palaeointensity data from similar latitude range. The average VDM values for nine Pleistocene sites were calculated to be 51.5 +/- 16.4 mu T (10.3 x 10(22) +/- 3.7 Am-2). According to the comparison of our data with the palaeointensity database, field model record and previous studies of the Pleistocene, significantly high field strength obtained from Central Anatolia, located in the Northern Hemisphere, could have occurred due to asymmetry between the Northern and Southern Hemispheres during the Pleistocene.

Automated summary

A detailed palaeointensity study was conducted in Central Anatolia, Turkey, using the modified Thellier method. The study significantly increased the database of palaeomagnetic data for the Anatolian region, covering a time window back to approximately 6 Ma. The results also revealed the presence of the Brunhes and Matuyama Chrons, as well as high field strength in the Pleistocene.