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Research paper thumbnail of Valoración De Asentamientos en Platea De Fundación De Viviendas Sociales

Research paper thumbnail of Paleosecular variation of directions from lava flows of the Xalapa Volcanic Field, Veracruz, Mexico

We collected 21 monogenetic type lava flows (316 specimens) in the Xalapa Volcanic Field, eastern... more We collected 21 monogenetic type lava flows (316 specimens) in the Xalapa Volcanic Field, eastern part of the Mexican Volcanic Belt. Geochronological results of twelve Ar-Ar determinations range from late Pleistocene to Holocene. The ages fall into three groups, those older than 2.0 Ma, those between 0.25-0.40 Ma and those less than approximately 0.1 Ma. All the samples were demagnetized by thermal and AF treatment, showing mostly a single stable component of magnetization with unblocking temperature above 530°C and/or 40-60 mT. We calculate the mean direction (D= 359.70°, I=27.4°, k=24, [U+F061]95=7.7°) and the VGP to compare and integrate with previous paleosecular variation analyses. The paleosecular variation parameter, upper and lower limit are: SF=14.6, SU=17.5 and SL=11.2, respectively. So, the VGP dispersion is consistent with the expected value of latitudedependent variation of McFadden for the last 5My.

Research paper thumbnail of Valoración De Asentamientos en Platea De Fundación De Viviendas Sociales

Research paper thumbnail of Paleosecular variation of directions from lava flows of the Xalapa Volcanic Field, Veracruz, Mexico

We collected 21 monogenetic type lava flows (316 specimens) in the Xalapa Volcanic Field, eastern... more We collected 21 monogenetic type lava flows (316 specimens) in the Xalapa Volcanic Field, eastern part of the Mexican Volcanic Belt. Geochronological results of twelve Ar-Ar determinations range from late Pleistocene to Holocene. The ages fall into three groups, those older than 2.0 Ma, those between 0.25-0.40 Ma and those less than approximately 0.1 Ma. All the samples were demagnetized by thermal and AF treatment, showing mostly a single stable component of magnetization with unblocking temperature above 530°C and/or 40-60 mT. We calculate the mean direction (D= 359.70°, I=27.4°, k=24, [U+F061]95=7.7°) and the VGP to compare and integrate with previous paleosecular variation analyses. The paleosecular variation parameter, upper and lower limit are: SF=14.6, SU=17.5 and SL=11.2, respectively. So, the VGP dispersion is consistent with the expected value of latitudedependent variation of McFadden for the last 5My.

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