Research Paper GEOSPHERE An integrated structural and GPS study of the Jalpatagua fault, southeastern Guatemala 1 1 2 1 1 1,3 4 4 GEOSPHERE, v. 17, no. 1 Bridget Garnier , Basil Tikoff , Omar Flores , Brian Jicha , Charles DeMets , Beatriz Cosenza-Muralles , Douglas Hernandez , Griselda Marroquin , Luis Mixco4, and Walter Hernandez4 https://doi.org/10.1130/GES02243.1 1Department of Geoscience, University of Wisconsin–Madison, 1215 West Dayton St., Madison, Wisconsin 53706, USA 2Centro de Estudios Superiores de Energías y Minas–Facultad de Ingeniería, Universidad de San Carlos, Ciudad Universitaria, Zona 12, Edificio T-1, tercer nivel, Ciudad de Guatemala 01012, Guatemala 3Instuto de Invesgación en Ciencias Físicas y Matemácas, Escuela de Ciencias Físicas y Matemácas, Universidad de San Carlos, Ciudad Universitaria, Zona 12, Edificio T-1, segundo nivel, Ciudad 13 figures; 6 tables; 1 supplemental file de Guatemala, Guatemala 4Dirección del Observatorio, Ministerio de Medio Ambiente y Recursos Naturales, Km. 5½ carretera a Santa Tecla, colonio y calle Las Mercedes, San Salvador, El Salvador CORRESPONDENCE: [email protected] ABSTRACT ■ INTRODUCTION Guzmán-Speziale et al., 2005; Lyon-Caen et al., 2006; CITATION: Garnier, B., Tikoff, B., Flores, O., Jicha, B., DeMets, C., Cosenza-Muralles, B., Hernandez, D., Franco et al., 2012). The dextral forearc fault system Marroquin, G., Mixco, L., and Hernandez, W., 2021, An The Jalpatagua fault in Guatemala accommodates Moving forearc slivers typically result from is the widest in Nicaragua, with NE-oriented sinistral integrated structural and GPS study of the Jalpatagua dextral movement of the Central America forearc. We strain partitioning due to oblique convergence faults that suggest bookshelf faulting may accom- fault, south eastern Guatemala: Geosphere, v. 17, no. 1, p. 201– 225, https://doi.org/10.1130/GES02243.1. present new global positioning system (GPS) data, between the subducting and overriding plates modate dextral movement rather than arc-parallel minor fault analysis, geochronological analyses, and (e.g., Fitch, 1972; Jarrard, 1986; McCaffrey, 1992). dextral faults (NFS in Fig. 1; Weinberg, 1992; La Science Editor: David E. Fastovsky analysis of lineaments to characterize deformation In these cases, strike-slip faults are typically found Femina et al., 2002). In El Salvador, the El Salvador Associate Editor: Craig H. Jones along the fault and near its terminations. Our data indi- within or adjacent to an active volcanic arc (e.g., de fault system progressively narrows to the northwest cate that the Jalpatagua fault terminates at both ends Saint Blanquat et al., 1998; Sieh and Natawidjaja, and consists of a zone of right-stepping strike-slip Received 7 February 2020 into extensional regions. The western termination 2000; Garibaldi et al., 2016). While forearc slivers faults, related pull-apart basins, active volcanoes, Revision received 21 September 2020 occurs near the Amatitlan caldera and the south- are common features around the world, the way in and calderas (ESFS in Fig. 1; Martínez-Díaz et al., Accepted 28 October 2020 ern extension of the Guatemala City graben, as no which strike-slip motion is accommodated at their 2004; Alvarado et al., 2011; Canora et al., 2014; Alon- Published online 18 December 2020 through-going structures were observed to continue boundaries varies greatly between each system. A so-Henar et al., 2014, 2015, 2017; Garibaldi et al., west into the active volcanic arc. Along the Jalpatagua singular strike-slip fault occurs in the Sumatra fault 2016; Staller et al., 2016). In southeastern Guate- fault, new and updated GPS site velocities are consis- system in Indonesia (e.g., Sieh and Natawidjaja, mala, dextral movement occurs on the Jalpatagua tent with a slip rate of 7.1 ± 1.8 mm yr–1. Minor faulting 2000), series of en echelon faults are interpreted fault, which begins near the Guatemala–El Salvador along the central section of the fault includes: (1) N-S– to occur in El Salvador (e.g., Garibaldi et al., 2016; border and continues for nearly 70 km before termi- striking normal faults accommodating E-W elongation; Martínez-Díaz et al., 2004), and a complicated fault nating at the southern extension of the Guatemala and (2) four sets of strike-slip faults (oriented 330°, 020°, network containing coeval areas of transpression City graben (JF in Fig. 1). The Jalpatagua fault is 055°, and 295°, parallel to the Jalpatagua fault trace). and transtension are present along the Andean arguably the termination of the forearc fault system, Minor fault arrays support dextral movement along a fault system in southern Chile (e.g., Grocott and as no clear evidence for discrete strike-slip faulting major fault in the orientation of the Jalpatagua fault. Taylor, 2002). It is unclear what guides the type of is apparent geologically or geodetically (Ellis et al., GPS and fault data indicate that the Jalpatagua fault faulting that will accommodate forearc movement 2019) west of Guatemala City. terminates to the east near the Guatemala–El Salvador in each setting, particularly in the presence of an The goal of this study was to document and border. Data delineate a pull-apart basin southeast of active volcanic arc, which complicates the rheolog- interpret deformation along and near the Jalpa- the fault termination, which is undergoing transten- ical behavior of the upper crust (Martin et al., 2014). tagua fault system. The Jalpatagua fault is relatively sion as the Jalpatagua fault transitions into the El The Central American moving forearc, which unstudied (Carr, 1974, 1976; Plafker, 1976; Duffield Salvador fault system to the east. Within the basin, may have resulted from multiple factors within an et al., 1992; Authemayou et al., 2011), likely because minor faulting and lineations trend to the NW and uncoupled subduction zone, provides an oppor- of poor exposure resulting from abundant vege- accommodate NE-directed elongation. This faulting tunity to investigate along-strike variations in the tation and tropical weathering. Here, we present differs from E-W elongation observed along the Jalpa- character of strike-slip faulting. The forearc region in new global positioning system (GPS) data and an tagua fault and is more similar to minor faults within Central America accommodates dextral movement associated elastic block model, minor fault analysis, the El Salvador fault system. and extends from Costa Rica to southern Guate- geochronological analyses, and analysis of linea- This paper is published under the terms of the mala, along the active volcanic arc, and parallels ments associated with the Jalpatagua fault. Minor CC-BY-NC license. Bridget Garnier https://orcid.org/0000-0001-9622-8269 the Middle America Trench (Fig. 1; DeMets, 2001; faulting supports dextral movement along the © 2020 The Authors GEOSPHERE | Volume 17 | Number 1 Garnier et al. | Jalpatagua fault Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/17/1/201/5217780/201.pdf 201 by guest on 25 September 2021 Research Paper 92°W 90°W 88°W 86°W 84°W 92°W 91°W 90°W 89°W 88°W N ° 8 1 A B 1 North America plate North America Plate 6 ° N Mexico Belize CA relative to NA -1 t N 19 ± 2 mm yr l ° Panel B au 6 c F 1 Guatemala hi lt loc au Honduras o F P ua PMFS tag Mo 1 Caribbean plate 5 JF ° N N ° 4 ESFS 1 GCG Caribbean Plate El Salvador Nicaragua IG CO relative to NA Fo 82 ± 3 mm yr-1 For NFS re e arc N a b ° rc oun JF 2 M da 1 A s ry T liv 1 er 4 ° CO relative to FS N 74 ± 6 mm yr-1 Fig. 3, 8, 13 ESFS N Cocos plate Panama ° 0 Costa Rica Forearc sliver 1 1 3 ° 0 100 200 300KM CR Cocos Plate Volcano 0 100 200KM N Figure 1. (A) Overview of the major tectonic plates, plate velocities, and fault systems in northern Central America. Dashed gray box indicates the area of panel B. The general boundaries of the dextral forearc fault system extend from Guatemala to Costa Rica and are based on Authemayou et al. (2011). The plate velocities and 95% uncertainties were determined using angular velocities from table 1 of Ellis et al. (2019). Plate names and boundaries of major fault systems are abbreviated as follows: CA—Caribbean plate; CO—Cocos plate; FS—Central America forearc sliver; NA—North American plate; MAT—Middle America Trench; PMFS—Polochic-Motagua fault system; JF—Jalpatagua fault; ESFS—El Salvador fault system; NFS—Nicaragua fault system; CR—Cocos Ridge. Black star represents the location of Guatemala City, within the Guatemala City graben. (B) 20 m digital elevation model of Guatemala and El Salvador (OpenStreetMap contributors, 2015) annotated with major faults and features. Black star represents Guatemala City within the Guatemala City graben (GCG). Dashed gray box indicates the area of Figures 2, 8, and 13. IG—Ipala graben. Jalpatagua fault, although with along-strike varia- 2008; Rodriguez et al., 2009; Authemayou et al., 2011; subduction zone, (2) pull from the North America tions. In southeastern Guatemala, the Jalpatagua Franco et al., 2012). The North America–Caribbean plate where the forearc is pinned and moves to fault terminates at its eastern end into a complex plate boundary is defined by the arcuate left-lateral the northwest as the Caribbean plate moves east- zone of faulting associated with a step-over in the Polochic-Motagua fault system in central Guate- ward, (3) westward push from a collision of the El Salvador fault system. The fault terminates at mala, as the North America plate moves ~18 mm Cocos Ridge beneath the Costa Rican forearc, and/ its western end near the Amatitlan caldera and the yr–1 westward relative to the Caribbean plate (Ellis or (4) a combination of pushing of the Cocos Ridge southern end of the Guatemala City graben.