The Malpaisillo Formation: A sequence of explosive eruptions in the mid to late Pleistocene (Nicaragua, Central America)

Abstract

The subduction-related volcanic front in Nicaragua consists of the Tertiary "Coyol" member in the eastern highlands and the Quaternary to recent volcanic arc within the Nicaraguan depression. Although the Holocene to recent explosive volcanism has been studied extensively no detailed work has been done on the products of explosive volcanism from Quaternary volcanic complexes comprising also the Malpaisillo and Monte Galán Calderas, the focus of this study. The 11 km-wide Malpaisillo Caldera and~3.5 km-wide Monte Galán Caldera, located~50 km northwest of Managua, are surrounded by tens of meters of rhyolitic tephras. These pyroclastic flow and fall deposits extend proximally at least 11 km to the southeast and 23 km to the southwest, with observed depositional thicknesses of N16 m for a single ignimbrite unit (or N25 m for the entire section). Distal deposits are found as far as 350 km offshore in the Pacific. At least twelve highly explosive large-volume eruptive phases with corresponding tephra deposits (LPT

Miocene to Holocene Marine Tephrostratigraphy Offshore Northern Central America and Southern Mexico: Pulsed Activity of Known Volcanic Complexes

“…For Nicaragua, the ~450‐ka age of La Sabanetta Tephra, correlated to layer C18 (Site 497), fits the results from the recent study of the Malpaisillo Formation by Stoppa et al (), who radiometrically dated the directly overlying Tolapa tephra (420 ± 40 ka) and the 570 ± 70‐ka‐old La Paz Centro Tephra at the base of the Malpaisillo Formation (Stoppa et al, ).…”

“…For each marine ash bed, we carried out 15–20 EMP analyses, and the majority of marine ash beds were analyzed additionally for their trace element composition by LA‐ICP‐MS. For reference fields of onshore deposits, we used published major and trace element data (Kutterolf, Freundt, Peréz, et al, ; Kutterolf et al, ; Stoppa, ; Stoppa et al, ). In many cases, major element characteristics could not discriminate well between eruptions from single volcanoes, but then the trace element compositions of volcanic glass shards provided a unique “fingerprint” for each single eruption.…”

“…Age data for the marine tephra layers initially came from the shipboard age‐depth models derived from magnetostratigraphy and biostratigraphy from each site (Aubouin et al, ; Mayer et al, ; von Huene et al, ; Watkins et al, ). Marine tephra correlations to dated terrestrial tephra deposits (e.g., Koch & McLean, ; Kutterolf, Freundt, Peréz, et al, ; Rose et al, ; Stoppa et al, ) provide additional independent time markers and modified the existing age models (Figure S1). The ages of yet undated ash layers can be estimated from their relative position between known time markers (biostratigraphic time markers, paleomagnetic time markers, and correlations to independently dated terrestrial tephra deposits) by applying linear interpolation, which assumes constant sedimentation rates across such an interval.…”

“…Correlations of ash beds to terrestrial deposits as well as between different marine sites are based on major and trace element concentrations and ratios ( Geochemistry, Geophysics, Geosystems Schindlbeck et al, 2018;Wulf et al, 2004) as well as the relative stratigraphic positions and age constraints. For each marine ash bed, we carried out 15-20 EMP analyses, and the majority of marine ash beds were analyzed additionally for their trace element composition by LA-ICP-MS. For reference fields of onshore deposits, we used published major and trace element data Kutterolf et al, 2016;Stoppa, 2015;Stoppa et al, 2018). In many cases, major element characteristics could not discriminate well between eruptions from single volcanoes, but then the trace element compositions of volcanic glass shards provided a unique "fingerprint" for each single eruption.…”

A geographical cline in craniofacial morphology across populations of Mesoamerican lake‐dwelling fishes

“…In this regard, the degree of morphological differences between Astyanax and Bramocharax morphs within each lake is likely associated with the age of the lakes. The independent origin of the Bramocharax morph could be related to both phylogenetic history of the genus and the degree of divergence associated with the geological history of the lake systems (Díaz et al, 2017;Ferrari, López-Martínez, Aguirre-Díaz, & Carrasco-Núñez, 1999;Ornelas-García et al, 2008;Stoppa et al, 2018). This would suggest that the Central American populations are the oldest lineages.…”