Geochemical Behavior and Emplacement Conditions of the Ibagué Batholith: Regional Implications

GEOCHEMICAL BEHAVIOR AND EMPLACEMENT CONDITIONS OF THE IBAGUÉ BATHOLITH: REGIONAL IMPLICATIONS

EDGAR ALEJANDRO CORTÉS CALDERÓN

UNIVERSIDAD DE LOS ANDES FACULTAD DE CIENCIAS DEPARTAMENTO DE GEOCIENCIAS BOGOTÁ D.C – 2015

2 GEOCHEMICAL BEHAVIOR AND EMPLACEMENT CONDITIONS OF THE IBAGUÉ BATHOLITH: REGIONAL IMPLICATIONS

EDGAR ALEJANDRO CORTÉS CALDERÓN

Trabajo de grado para optar al título de: Geocientífico

Director: IDAEL FRANCISCO BLANCO QUINTERO, PhD.

UNIVERSIDAD DE LOS ANDES FACULTAD DE CIENCIAS DEPARTAMENTO DE GEOCIENCIAS BOGOTÁ D.C - 2015

4 Agradecimientos

En primer lugar, quiero agradecer a mi director de tesis Dr. Idael Francisco Blanco Quintero por su apoyo, consejos y enseñanzas durante el tiempo que lo conozco, por las oportunidades que me ha dado, por mostrarme que con esfuerzo y dedicación se pueden lograr los objetivos que uno se propone, obviamente sin olvidar las risas y los buenos momentos. También, quiero agradecer al profesor Dr. Camilo Montes Rodríguez, un excelente investigador, por motivarme a querer estudiar esta carrera y tener pasión por la ciencia.

A la Beca para tesis de pregrado financiada por el Fondo Corrigan-ACGGP- ARES y al fondo FAPA del Dr. Idael Blanco otorgado por la Vicerrectoría de Investigación de la Universidad de los Andes, cuyo apoyo económico permitió la realización de esta investigación.

A mis padres, quienes me han apoyado y acompañado en todos mis objetivos. Gracias por el esfuerzo que han realizado para darme todas las comodidades y oportunidades que he tenido hasta ahora. A mis viejitos, Julio y Blanca por sus cariños, sus cuidados y ser mi ejemplo de vida. A mi hermano Santiago y a toda mi familia, por los buenos momentos y las enseñanzas que me han dejado hasta ahora. A mis amigos y compañeros con los que he compartido buenas experiencias, logros personales y académicos. Gracias por la compañía y consejos tanto en los buenos momentos como en los difíciles, por las retroalimentaciones y ayudas a este proyecto.

Muchas gracias a todos.

6 INDEX

1. Abstract ...... 9

2. Introduction ...... 13 2.1 The origin of granitoid magmas ...... 13 2.2 Emplacement of large volumes of magma ...... 14 2.3 Jurassic Subduction at northern Andes ...... 15

3. Regional geology ...... 16

4. Methodology and Analytical techniques ...... 20 4.1 Whole-rock chemistry ...... 21 4.2 Microprobe analyses ...... 23 4.3 Thermobarometric analyses ...... 24 4.4 Crystallization modelling ...... 25

5. Results ...... 25 5.1 Whole rock composition ...... 25 5.2 Petrology ...... 29 5.2.1 Petrography ...... 29 5.2.2 Mineral chemistry ...... 30 5.2.3 X-ray maps ...... 38 5.2.4 P-T crystallization conditions ...... 40 5.2.5 MELTS modelling ...... 41

6. Discussion ...... 42 6.1 Origin of the magma ...... 42 6.2 Regional implications ...... 44

7. Conclusions ...... 45

8. References ...... 46

8 1. Abstract

The Ibagué batholith is a heterogeneous I-type granitoid located along the Cordillera

Central of Colombia. It consists of many magmatic pulses that crystallized along Jurassic times (150-188 Ma). This work reports new geochemical and petrologic features from the

Ibagué batholith in an area next to Coello river west of the town of Ibagué. The petrography and mineral chemistry of the samples show a mineral assemblage that consists of plagioclase (Oligoclase to Andesine) + quartz + amphibole (Edenite and Mg-

Hornblende) + biotite (Fe-Biotite) as the main minerals, K-feldspar (Sanidine) + pyroxene

(Diopside) as minor phases, and chlorite (Ripidolite-Pycnochlorite) + epidote as alteration products. Whole-rock geochemistry indicates a volcanic arc affinity that suggests melting of a metasomatized mantle wedge and assimilation of continental crust based on Y =

12.76-20.03 ppm, Yb = 1.15-1.78 ppm, Nb = 6.25-8.74 ppm, and Ba/Nb ratios = 73.11-

160.41. The Edenite-Andesine pair suggests maximum emplacement depth at 8.2-10.5 km

(i.e. 2.5-3.2 Kbar and 750-850ºC). Therefore, Cajamarca and Tierradentro metamorphic complexes, and Payande limestones were located at this depth in order to be intruded when the batholith was emplaced. Furthermore, liquidus was found at 1074 ºC and 15 kbar using Rhyolite-Melts software. The thermodynamic models show that diopsidic pyroxenes should be xenocrystals and the order of crystallization was horblende-feldspars-biotite- quartz.

Key words: Mineral Chemistry, Thermobarometry, X-ray maps, Ibagué batholith.

10 Resumen

El batolito de Ibagué es un granitoide heterogéneo tipo-I ubicado a lo largo de la Cordillera

Central de Colombia, el cual es el resultado de varios pulsos magmáticos que cristalizaron durante el Jurásico (150-188 Ma). Este trabajo reporta nuevos datos geoquímicos y petrológicos para el batolito de Ibagué en un área cerca al rio Coello (i.e. al oeste de la ciudad de Ibagué). La petrografía y química mineral de las muestras analizadas muestran una asociación de fases que consiste de plagioclasa (oligoclase-andesina) + cuarzo + anfíbol (edenite – Mg-Hornblenda) + biotita (Fe-Biotita) como minerales princiaples, feldespato potásico (Sanidina) + piroxeno (Diópsido) como fases secundarias, y clorita

(ripidolite-picnoclorita) + epidota como productos de alteración. La geoquímica de roca total indica una afinidad de arco volcánico, lo cual sugiere un magma proveniente de una cuña mantélica metasomatizada por la infiltración de fluidos de la losa oceánica que subduce debajo de esta y una asimilación de corteza continental, basándose en Y =

12.76-20.03 ppm, Yb = 1.15-1.78 ppm, Nb = 6.25-8.74 ppm, and Ba/Nb ratios = 73.11-

160.41. Adicionalmente, parejas minerals de edenita-andesina sugieren una profundidad de emplazamiento máxima a 8.2-10.5 km (i.e. 2.5-3.2 kbar y 750-850ºC), donde se encontrarían los cuerpos intruidos por el batolito durante su emplazamiento. El liquidus fue encontrado a 1074 ºC y 15 kbar asumiendo la composición de roca total como parámetro de entrada para el fundido y solo las fases minerals observadas en las secciones delgadas como posibles productos de la cristalización. Como consecuencia, el modelo obtenido en el software Rhyolite-Melts sugiere que los piroxénos diopsídicos encontrados no proceden de la cristalización del magma, sino que deberían ser xenocristales.

Palabras clave: Química mineral, Termobarometría, Mapas de rayos X, batolito de Ibagué.

12 2. Introduction

Batholiths are the result of crystallization of large magma volumes emplaced in the crust. Although batholiths can be viewed as monotonous bodies, the origin and evolution of these rocks are still a matter of debate (Castro, 2014). Nowadays, the application of advanced tools within petrology, structural geology and geophysics give more information about batholiths, then the thermal structure of the mantle and tectonic settings can be improved (i.e. Castro, 2014; Taylor and McLennan, 1995). These batholith bodies have variable composition, predominantly intermediate to acid values in silica content and thus they are called granitoids.

2.1 The origin of granitoid magmas

There are both on- and off- crust models to I-type granitoid batholiths origin. On-crust models suggest magma generation from partial melting of lower crust rocks. Among these models, the most common are (1) basaltic underplating and crustal delamination, (2) magma mixing, (3) crustal assimilation by basaltic magmas and (4) melting of the lower crust by intrusion of basalts (Castro, 2014). On the other hand, off-crust models postulate the production of andesite magmas by processes within the mantle (Castro, 2014), and later incorporation of these magma in the crust.

On-crust models have problems mainly in phase equilibria and temperature of magma generation. For example, at lower crust conditions olivine is not stable then pyroxene should increase the silica content of the residual melt, but pyroxene slighty modifies the silica content based on crystallization models (Castro et al., 2013; Castro, 2014). Recent works about the origin of I-type granitoid batholiths combine experimental petrology and thermomechanical numerical models in order to address the problem described above (Castro et al., 2010). The results (Figure 1) are slab melting derived- cold plumes that produce melts totally compatible with the geochemical features of granitoid batholiths (Castro et al., 2010)

Figure 1. Thermomechanical numeric model results from Castro et al. (2010). The model shows the origin of slab melting derived- cold plumes in a off-crust model. The melt obtained by experiments are related with the geochemistry features of granodioritic batholiths.

2.2 Emplacement of large volumes of magma

The emplacement of high volumes of magma (≥ 1x105 km3) in the crust is the final phase in the batholith growing process. In a general level, the mechanism consists in the shift from an upward direction flow of magma to a horizontal trend (Petford et al., 2000). Nevertheless, it is not easy to understand how large volume intrusions accommodate if no open space exists in the crust (Pitcher, 1993). Therefore, complex and regional mechanisms are nedded to make large spaces in the crust, thus knowing the mechanism of emplacement of magmas is a critical point in the reconstruction of regional geology.

The traditional mechanisms proposed for batholith emplacement include stoping, diapirism, dyking, and ballooning (Hutton, 1996). However, these

14 processes have been seriously questioned, because they do not solve the space problem in terms of stress rate and number of magmatic pulses that are involved in the emplacement. Nowadays, the models of emplacement take into account more data and factors. For example, the opening along strike-slip major faults that may solve space and the stress rates problems, and the introduction of discrete pulses of magma that emplaced in less than 102-104 years as a more realistic interpretation compared with a unique pulse (Petford et al., 2000).

2.3 Jurassic Subduction at northern Andes

The northern Andes Cordillera is a consequence of the subduction of paleo Pacific oceanic plates beneath the northwestern margin of South America. Accretion, extensive magmatism and continental margin growth are procceses associated with the tectonic setting described above, that occurred since late Paleozoic amalgamation and Jurassic fragmentation of Pangea (Blanco-Quintero et al., 2014; Restrepo and Toussaint, 1982; Vinasco et al., 2011).

The Ibagué batholith is one of the largest Jurassic products of the subduction of the paleo Pacific plate, characterized as a heterogeneous I-type elongated intrusive body along the Cordillera Central of Colombia (Nelson, 1959). It consists of many magmatic pulses (150-188 Ma) and comprises diorites, quartz diorites, granodiorites and quartz monzonites (Aspden et al., 1987; Villagómez et al., 2011). Previous studies were mainly developed in order to establish the age of the pulses, the petrography and basic geochemistry of the batholith; however, more advanced petrological features have not been studied so far (e.g. magma genesis, magma crystallization, like emplacement conditions). This work describes six samples from Ibagué batholith collected next to Coello river (west of Ibagué town) by classical petrography and geochemistry, and improves the information obtained with mineral chemistry analyses, amphibole-plagioclase thermobarometry, X-Ray composition maps and thermodynamic modelling on a representative sample in order to support field observations and to construct a better magma evolution model of the Ibagué batholith.

15 3. Regional geology

The northern Andes consist of three independent North-South-trending ranges that show processes of subduction, collision and accretion since Late Paleozoic (Restrepo and Toussaint, 1982; Vinasco et al., 2006; Villagómez et al., 2011; Cochrane, et al., 2014). From east to west, these ranges are named Eastern Cordillera, Central Cordillera and Western Cordillera, separated by the Cauca and Magdalena valleys (Figure 2).

The Eastern Cordillera is a polydeformed continental mountain range that consists of a Precambrian to Paleozoic metamorphic and igneous core overlain by Paleozoic to Cenozoic volcanic and sedimentary sequences (Aspden et al., 1987; Gonzáles et al., 1988). The Western Cordillera consists of an allochthonous oceanic plateau, volcanic arc sequences of basic igneous rocks and marine sediments of Upper Cretaceous age (Aspden et al., 1987; Gonzáles et al., 1988; Villagómez et al., 2011). The Central Cordillera comprises a pre–Mesozoic polymetamorphic basement intruded by several Meso-Cenozoic plutonic rocks (Restrepo and Toussaint, 1982; Aspden et al., 1987; Vinasco et al., 2006).

The Central Cordillera is limited by the Otú-Pericos fault to the east, and the Cauca-Almanger fault to the west (Figure 2). The basement of the Central Cordillera is represented by low to medium grade metamorphic rocks of the Cajamarca Complex (Maya and Gonzáles, 1995; Nelson, 1959) and high-grade metamorphic rocks of the El Retiro Group and Las Palmas gneiss. The Cajamarca Complex comprises pelitic schists, quartzites, marbles and amphibolites (Blanco- Quintero et al., 2014; Gonzáles, 2001; Maya and Gonzáles, 1995). The metamorphism for this complex was first dated as Permian, but it was later established of Middle to Late Triassic age (ca. 240-230 Ma; Ordoñez-Carmona, 2001; Vinasco et al., 2006; Restrepo et al., 2011; Cochrane, et al., 2014). Younger Late Jurassic to Early Cretaceous ages (ca. 157-146 Ma) for the metamorphism have been determined recently, interpreted as continental terrane collision (Blanco- Quintero et al., 2014).

Figure 2. A) Simplified geologic map of Colombia showing the location of Permian-Triassic Cajamarca Metamorphic Complex and Jurassic Ibagué Batholith. The inset shows the study area. B) Geological map of the study area (modified after Mosquera et al., 1982) showing the main geologic units with location sample sites.

Undeformed Meso-Cenozoic plutonic rocks intrude the Cajamarca complex, in some cases with not clear intrusive relationship but tectonic contacts with the metamorphic rocks. One of these plutonic rocks is the Ibagué batholith (Nelson, 1959), a medium to coarse grained quartzdioritic I-type granitoid (Toussaint and

17 Restrepo, 1994; Villagómez et al., 2011) that outcrops in the eastern flank of the Central Cordillera. The plutonic body extends from the northern part of the Tolima province to the La Plata, Huila (Cediel et al., 1976).

Proceding from the village of Calarca to Ibagué, three bodies have been described using both structural and geophysical analyses (Figure 3). First, the Anaime Complex is located in the village of Calarca and has reverse faults dipping to the east and to the west (i.e. The Romeral fault zone; Restrepo-Pace, 1992). Second, the Cajamarca Complex has foliations that vary along the complex and is located between the Anaime complex and the Ibagué batholith that is the third body (Restrepo-Pace, 1992).

The faults that limit the Cajamarca complex are the Palestina fault (i.e. The Romeral fault zone) to the west and the Otú-Pericos fault (The Chapeton-Pericos fault zone) to the east. The Chapetón-Pericos fault zone is 1.5 km wide and comprises high angle reverse and strike-slip faults (Restrepo-Pace, 1992). The Ibagué batholith is located west of the Cajamarca complex and is less faulted than the Anaime and the Cajamarca complexes. The Ibagué fault is dextral ENE-WNW high angle fault through the Ibagué batholith (Diedrix, 1987) with a predominantly brittle deformation that consists of brecciated and fractured zone. It is important to mention that more tectonic blocks have been currently recognized west of the Cajamarca Complex by petrologic studies but they are not differentiated in the structural and the geophysical studies (Figure 3).

To the west, the Ibagué Batholith intruded pre-Cambrian metamorphic rocks grouped as Tierradentro complex composed of gneisses and amphibolites (Barrero and Vesga, 1976; Esquivel et al., 1991), but in the study area the is tectonic(Figure 2D). It also intrudes metamorphic rocks from the so-called Cajamarca Complex (Nelson, 1959; Maya and Gonzáles, 1995), although in many occasions this contact is of tectonic character (Barrero and Vesga, 1976; Esquivel et al., 1991; Blanco-Quintero, et al., 2014; Mosquera et al., 1982; Gomez-Tapia and Bocanegra-Gomez, 1999).

Figure 3. A) Structural cross section along Calarca-Ibagué road (see Figure 2; modified after Restrepo-Pace (1992)), and B) Bouger gravity anomaly profile model for the Calarca-Ibagué cross section (modified after Bermúdez et al. (1985)). A) and B) have different lengths

The Ibagué batholith represents the largest Mesozoic granitoid of Colombia, and it is interpreted as an exhumed root of a Jurassic magmatic arc (Toussaint and Restrepo, 1994). This magmatic belt records at least three major magmatic peaks of ca. 195-180 Ma, 167-160 Ma, and 151-142 Ma (Aspden et al., 1987; Villagómez et al., 2011). Geochronological considerations reveal that the Ibagué Batholith also records these available ages: (1) U-Pb zircon crystallization ages for the Ibagué Batholith are 166-169 Ma and 189 Ma (Villagómez et al., 2011). (2) Published 40Ar- 39Ar hornblende cooling ages of 182 Ma and 148 Ma overlap with this crystallization whereas (3) 40Ar-39Ar biotite cooling ages of 151 and 147 Ma and (4) 40K/40Ar hornblende and biotite ages of 150–140 Ma are younger (Aspden et al., 1987; Altenberger and Concha, 2005; Brook, 1984).

19 4. Methodology and Analytical techniques

In this work, an area next to Coello River (west of Ibagué town, Colombia) was studied (Figure 2 and 4). This zone was selected because there are good outcrops of the Ibague Batholith and it is close to the contact with the Cajamarca and Tierradentro metamorphic complexes. Thus, structural relations among these bodies and the Ibague Batholith can be related to the petrologic results of the samples.

Figure 4. Ibagué Batholith in sampling area. A) Coello River B) Granodiorite cut by mafic fine grain dike. C) Diaclases in granodioritic rocks. D) Foliated Ibagué Batholith in the Chapetón-Pericos fault zone showing alignment of minerals. E-F) Enclaves of mafic (former) rocks within batholith

20 Eight samples of the Ibagué batholith (Figure 2) were collected to make polished thin sections for petrography analysis. Six fresh and unaltered samples were grinded for whole-rock geochemistry analyses by X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) (Table 1). For specific mineral chemistry and X-Ray composition maps, a representative sample (BI-08) was selected and analyzed in two zones with electron microprobe analyses (EPMA). The data obtained from mineral chemistry was used to obtain the conditions of emplacement of the Ibagué batholith using the Ridolfi et al. (2010) amphibole thermometer and Molina et al. (2015) amphibole-plagioclase barometer. Finally, a thermodynamic modelling with the Rhyolite-Melts software was developed using whole-rock composition of the sample BI-08 in order to obtain the crystallization order of the minerals and the P-T conditions of the liquidus.

4.1 Whole-rock chemistry

Powdered whole-rock samples were obtained by grinding the rocks in a tungsten carbide mill. Major element and Zr compositions were determined on glass beads, made of 0.6 g of powered sample diluted in 6 g of Li2B4O7, by a PHILIPS Magix Pro (PW-2440) X-ray fluorescence (XRF) equipment at the Centro de Instrumentación Científica (University of Granada, Spain). Precision was better than ±1.5% for concentration of 10 wt.%. Precision for Zr and LOI was better than ±4% at 100ppm concentration. The analyses were recalculated to an anhydrous 100 wt.% basis, and these data are used in the figures.

Trace element, except Zr, were determined at the University of Granada

(CIC) by ICP-Mass Spectrometry (ICP-MS) after HNO3+HF digestion of 0.1000 g of sample powder in a Teflon-lined vessel at ~180 °C and ~200 P.S.I. for 30 min. evaporation to dryness, and subsequent dissolution in 100 ml of 4 vol.% HNO3. Blanks and the international standards PMS, WSE, UBN, BEN, BR and AGV (Govindaraju, 1994) were run during analytical sessions. Accuracy was better than ±2% and ±5% for concentrations of 50 and 5 ppm.

21 Table 1. Major (wt.%) and trace (ppm.) element composition of the study samples. Sample BI-01 BI-03 BI-08 BI-02 BI-10 BI-36 Location 4º23’56’’N 4º23’58’’N 4º24’30’’N 4º24’27’’N 4º24’45’’N 4º24’56’’N 75º17’20’’W 75º17’19’’W 75º17’57’’W 75º17’32’’W 75º18’21’’ W 75º18’28’’ W

SiO2 70.9 69.85 63.64 62.71 63.93 63.56 TiO2 0.32 0.35 0.6 0.76 0.67 0.72 Al2O3 15.29 15.21 15.4 15.30 14.73 15.05 Fe2O3 2.69 3.18 5.64 5.91 5.31 5.43 MnO 0.061 0.072 0.104 0.11 0.09 0.10 MgO 1.15 1.29 2.79 2.86 2.71 2.84 CaO 2.99 3.34 4.69 4.97 4.59 4.45 Na2O 2.6 2.77 2.75 2.92 3.18 3.57 K2O 2.95 3.09 2.9 2.91 2.99 2.59 P2O5 1.00 0.101 0.186 0.18 0.18 0.19 LOI 0.00 0.32 0.66 0.84 1.06 1.05 SUM 99.951 99.573 99.36 99.47 99.45 99,54 Li 11.772 13.271 14.777 18.386 12.575 42.554 Rb 69.526 73.014 67.742 53.01 56.43 83.992 Cs 0.768 0.94 1.888 1.75 1.353 4.193 Be 1.211 1.215 1.049 1.209 1.103 1.334 Sr 410.494 436.295 564.309 511.829 513.858 424.749 Ba 639.054 683.524 817.236 646.339 1010.111 686.552 Sc 6.409 6.793 16.768 11.387 12.326 14.553 V 23.867 54.701 130.012 116.935 119.033 130.442 Cr 45.543 35.448 52.176 42.79 49.854 57.004 Co 2974.663 39.282 47.643 32.557 43.785 42.856 Ni 20.861 8.832 14.996 16.082 14.701 8.681 Cu 5.125 4.147 46.605 17.689 40.643 14.508 Zn 43.572 47.142 63.82 52.571 52.051 60.933 Ga 15.717 16.737 19.118 16.716 16.065 15.749 Y 12.76 14.105 20.834 15.924 16.346 24.465 Nb 8.741 6.251 6.426 6.067 6.297 9.055 Ta 0.722 0.731 0.705 0.657 0.692 1.052 Zr (XRF) 125.5 148.6 228.9 157,3 202,9 147,6 Mo 6.924 4.894 3.845 4.034 5.49 6.01 Sn 0.81 0.768 1.495 1.414 1.407 1.751 Tl 0.305 0.392 0.407 0.504 0.47 0.658 Pb 5.803 7.171 5.262 3.654 3.877 6.505 U 2.081 2.313 2.638 14.702 2.024 1.496 Th 14.201 14.389 6.018 9.751 6.103 8.19 La 23.172 20.703 22.091 20.528 21.723 27.477 Ce 42.304 38.278 46.486 42.903 43.97 54.115 Pr 4.388 4.24 6.078 5.115 5.285 6.37

22 Nd 15.381 15.324 24.725 20.672 21.654 25.263 Sm 2.882 3.099 4.948 4.154 4.217 5.199 Eu 0.72 0.739 1.11 1.161 1.206 1.317 Gd 2.266 2.489 4.192 3.589 3.73 4.687 Tb 0.333 0.369 0.574 0.482 0.535 0.705 Dy 1.886 2.075 3.218 2.578 2.738 3.764 Ho 0.388 0.448 0.669 0.533 0.548 0.804 Er 1.053 1.211 1.768 1.385 1.39 2.191 Tm 0.181 0.199 0.286 0.24 0.226 0.378 Yb 1.152 1.321 1.777 1.479 1.409 2.5 Lu 0.196 0.21 0.272 0.22 0.215 0.344

Table 1. (continue)

4.2 Microprobe analyses

196 point analyses were made on Electronic Probe Micro Analyzer (EPMA) distributed in two zones (i.e. Zone A and Zone B) from the BI-08 thin section. From the analyses, X-Ray composition maps were made by Imager software based on Kα-signals detected from different elements. These maps allow to identify minerals and elements distributions along the two zones.

Major element composition of minerals was obtained by wavelength dispersive spectrometers with a CAMECA SX-100 microprobe (CIC, University of Granada), operated at 15 kV and 15 nA, with a beam size of 5 μm. The standards used for element calibrations were albite (Na), quartz (Si), periclase (Mg), sanidine (K), rutile (Ti), haematite (Fe), diopside (Ca), vanadinite (Cl), barite (Ba), fluorite

(F), chromite (Cr), Al2O3 (Al), MnTiO3 (Mn) and NiO (Ni).

Amphibole composition was normalized following the scheme of Leake et al., (1997) and Fe3+ was estimated after the method of Schumacher (Leake, et al., 1997). Epidote and plagioclase were normalized to 12.5 and 8 oxygens 3+ 3+ respectively, and assuming Fe (total) = Fe . The Fe content in clinopyroxene was calculated after normalization to 4 cations and 6 oxygens (Morimoto et al., 1988). White mica and chlorite were normalized to 22 and 28 oxygens respectively, and

23 2+ assuming Fe(total) = Fe . The atomic concentration of elements per formula units is abbreviated apfu. The Mg number (#Mg) is expressed as the atomic ratio Mg/(Mg+Fe2+). Mineral and end-member abbreviations are after Whitney and Evans (2010), with the end-members of phases written in lower case.

Additional back-scattered electron (BSE) images were obtained in the Laboratorio de Caracterización Litólogica (Universidad Nacional de Bogotá). The instrument was a JEOL JXA 8230, operated at an accelerating voltage of 15 kV and 20 nA with a 3.5 nm spatial resolution.

4.3 Thermobarometric analyses

Temperature of emplacement was measured using the Ridolfi et al. (2010) amphibole thermometer (Eq.1-2). This thermomether is calculated on an Excel- spreadsheet and is based on amphibole- Aluminium mineral chemistry obtained by EPMA analyses. Pressure of emplacement was measured using the Molina et al. (2015) barometer (Eq.3) on an Excel-spreadsheet using amphibole-plagioclase pairs mineral chemistry obtained by EPMA. Mineral pairs were selected taking into account two conditions: (1) amphibole and plagioclase grains are in contact to adress mineral equilibrium, (2) Mineral pairs are Al-rich amphiboles and Ca-rich plagioclases in order to obtain peak-pressure of emplacement. The previous conditions were revised by X-ray maps and calculation of mineral chemistry.

� º� = −151.48 ∗ ��∗ + 2.041 (��. 1)

��!" ��!" ��!" ��!! ��!! �� ! ��! ��! ! ��∗ = �� + + 2 ∗ ��!" − − + + + + + + + (��. 2) 15 2 1.8 9 3.3 26 5 1.3 15 2.3

Element quantities on Eq.2 were obtained by formula recalculation for amphiboles following the scheme of Leake et al., (1997).

!" !"# !! 8.3144 ∗ � � ∗ �� !" − 8.7 ∗ � � + 23376�!" + 7578�!" − 11302 � �� = !" (��. 3) −274

24 Temperature in Eq. 3 is obtained from Ridolfi et al. (2010) thermometer and D refers to partition coefficient. All data was calculated from formula recalculation of Plagioclase and Amphibols.

4.4 Crystallization modelling

Rhyolite-Melts is a software designed to facilitate thermodynamic modelling equilibria in magmatic systems (Gualda et al., 2012; Ghiorso et al., 2015). The software permits P-T ranges from 0-2 GPa and 500-2000ºC. The models were developed through the following parameters: (1) the Whole-rock composition of sample BI-08 was established as input bulk composition of the liquidus because the P-T conditions were calculated on this sample, (2) Mineral phases able to crystallize from liquidus were only the minerals observed in the thin section, (3)

FeO and Fe2O3 contents was calculated by Ni-NiO buffer at pressures and temperature that range from 3.2-15Kbar and 750-1200ºC, (4) the temperature and pressure of granitic liquidus obtained by experimental studies (i.e. Castro et al., 2010) were used as the temperature and pressure of the liquidus in the thermodynamic modelling (5) Emplacement conditions of BI-08 were selected as boundary conditions.

5. Results

5.1 Whole rock composition

The rocks of Ibagué Batholith are dacitic to rhyolitic in composition in the TAS (total alkalis versus silica; Le Maitre et al., 1989) diagram, and show sub- alkaline affinity (Figure 5A). Indeed, Major-element oxide components (Table 1) such as SiO2 in the samples ranging between 64.48 to 71.58 wt.%, and alkalis

(Na2O+K2O) between 5.60 to 5.90 wt.%. Beside the samples have low values for

TiO2 that vary between 0.32 to 0.61 wt.%, medium CaO content ranging between

3.02 to 4.76 wt.% and high Al2O3 between 15.34 to 15.63 wt.% (Figure. 6B). These values were used to calculate Alkalinity index (A/NK) and Alummina index (A/CNK) (Shand. 1943), with values ranging between 1.92 to 2.04 and 0.95 to 1.18

25 respectively. These results indicate a metaluminous to peraluminous character of the magma (Figure 5B).

Figure 5. A) Composition of studied samples of the Ibagué Batholith in the TAS diagram for volcanic rocks (Le Maitre, et al., 1989). Note that this diagram were not used for classifying the rocks. B) A/NK (Al2O3/ K2O+ Na2O) vs A/CNK (Al2O3/ CaO+ K2O+ Na2O) (mol.%) discrimination diagram for metaluminous, peraluminous and peralkaline granites (Shand. 1943).

From the bulk-rock compositions the CIPW norm was calculated for each sample. Albite, anorthite and orthoclase contents obtained from CIPW were normalized and ploted in the O’connor (1965) classification diagram. As a result, all

26 the samples were classified as granodiorite, except BI-01 sample that was classified as quartz-monzonite (Figure 6A)

B) C) D)

Figure 6. A) O’connor (1965) classification diagram. B-D) Harker diagrams for Major-element oxide components of samples: B) TiO2 vs SiO2. C) CaO vs SiO2. D) Al2O3 vs SiO2 (Harker, 1909)

In the Primitive Mantle-Normalized trace element diagram (Sun and McDonough, 1989; Figure 7A), the samples show enrichment in LILEs (large ion lithophile elements) with negatives slopes, and slightly flat patterns for the HFSEs (High field strength elements). The steep negative Nb anomaly in the samples suggests that the magma was generated in a subduction-related environment (Wilson, 1989). Also, the high concentrations of Ba, Rb and U indicate release of fluids during subduction, while a high concentration in Th suggests a

27 transformation of the subducting slab or assimilation of crustal material and/or marine sediments in the slab-mantle wedge boundary (Gill, 1981; Hawkesworth et al., 1997a, 1997b; Guo et al., 2005).

Figure 7. A) Trace elements abundances of the samples normalized to the Primitive Mantle (Sun and McDonough, 1989) and B) REE elements abundances of the samples normalized to Chondrite (McDonough and Sun, 1995).

28 The chondrite normalized (McDonough and Sun, 1995) rare earth element (REE) patterns displays an enrichment in LREEs with a slight negative slope, and a relatively flat pattern in the HREEs with values close to 10 times the chondrite (Figure 7B). The samples yield a slight negative Eu anomaly (Eu/Eu * = 0.72-0.90), which is highlighted by the contents of Y = 12.76-24.46 ppm. Yb = 1.15-2.5 ppm and Nb = 6.067-9.055 ppm. As a result, these REE patterns are correlated with a continental arc volcanic activity.

5.2 Petrology

5.2.1 Petrography The samples are medium to coarse-grained granitoid rocks that can be classified as a granodiorite. The main mineralogy comprises plagioclase + quartz + hornblende + biotite + K-feldspar, and minor pyroxene, apatite and opaque mineral. The samples are slightly altered to secondary mineral like chlorite, sericite and zoicite. The modal proportions of the primary minerals are mainly 40.6% plagioclase, 27% quartz, 15% hornblende, 17% biotite and 10.4% K-feldspar.

Plagioclases have a composition that varying between oligoclase and andesine (according to the Michel-Levy Method). Plagioclase grains show zonation in most of the grains, and the most common alteration product was sericite and zoisite in the rim of the plagioclases. The amphibole grains present inclusions of quartz and plagioclase, and sometimes show a sieve texture. Amphiboles are moderate-pleochroic and present some twining. Chlorite is the principal alteration of hornblende, and occasionally hornblende overgrowths clinopyroxene (Figures 8E and 8D). Biotite grains are highly pleochroic, present inclusions, and occasionally replace hornblende.

The petrography shows that the samples are holocrystalline with phaneritic texture, and medium to coarse grained (approximately 2-3 mm; Figure 8 and 9). In terms of the shape of the grains, plagioclase, biotite and hornblende are commonly subhedral, while quartz and K-feldspars are generally anhedral and interstitial,

29 showing that they were the last phases to crystallize. Skeletal texture in amphiboles (Figure 8D), myrmekitic texture in k-feldspars (Figure 8B) and crystal zoning in plagioclase have also been identified.

BI-36 sample (Figure 6A and 6F) shows ductil deformation on minerals and a orientation of mineral grains parallel to the strike of the Otú-Pericos fault. Quartz has undulose extinction and shows a recrystallization process. Amphibole fishes were found showing a dextral shear movement similar to Otú-Pericos fault. Plagioclases show poor deformation. As consequence, the rocks can be classified as medium- grade mylonite.

5.2.2 Mineral chemistry The composition of plagioclase grains vary between oligoclase to andesine (Table 2 and Figure 9), and they are characterized by Xan (Ca/(Ca+Na)) ranging from 0.21 to 0.49 with very low contents of K (Xor <0.01). The K-feldspars are principal sanidines (Table 3 and Figure 9), have high values of Xor (Orthoclase component) ranging from 0.76 to 0.97 with low contents of Ca (Xan = <0.002).

Amphiboles are commonly calcic (CaB = 1.76-1.99 apfu) with variation in

(Na+K)A between 0.02-0.49 apfu for actinolite-magnesiohornblende- ferrohornblende and 0.50-0.58 apfu for edenite-ferroedenite compositions (Table 4, Figure 10). The grains of actinolite-magnesiohornblende-ferrohornblende have low to medium Si content ranging between 6.68-7.89 apfu, #Mg 0.45-0.73 and low to medium NaA <0.32 apfu. The grains of edenite-ferroedenite compositions have low

Si that vary between 6.67-6.82 apfu, #Mg 0.50-0.56 and high NaA 0.30-0.58 apfu.

Biotite crystals are Fe-Biotite according to Foster classification (Foster, 1960), with Si values ranging between 5.56 to 5.60 apfu and #Fe ranges 0.59 – 0.64. Mg and K vary between 1.85 – 2.11 and 1.86 – 1.90 respectively. Na values are very low ca. 0.03 apfu.

Figure 8. transmitted-light microscopy photos of the samples: A) BI36: mylonite with recrystallized quartz grains and fish-structure in hornblende showing a dextral shear, minerals are alliniated with Otú-pericos fault strike. B) BI08: Grains of plagioclase and amphiboles altered, and some interstitial quartz. C) BI10: Chlorite as retrograde mineral bounded biotite, amphibole (hornblende) grain and very anhedral quartz grains. D) BI01: Amphibole, quartz and plagioclase grains. E) BI08: Hornblende overgrowth diopside grain, biotite and interstitial quartz. (F) BI36: Amphibole, biotite, quartz and plagioclase grains aligniated with Otú-pericos fault strike. Pl (Plagioclase), Amp (Amphibole), Bt (Biotite), Px (Pyroxene), Chl (Chlorite), Qz (Quartz), Kfs (K-feldspar).

31 Table 2. Representative analyses of plagioclase grains. Sample BI-08 BI-08 BI-08 BI-08 BI-08 BI-08 Type Pl Pl Pl Pl Pl Pl

SiO2 55.76 56.55 62.06 61.41 62.68 59.46

TiO2 0.00 0.02 0.00 0.00 0.00 0.03 Al2O3 26.89 25.98 23.27 23.37 22.62 24.04 Cr2O3 0.03 0.03 0.03 0.00 0.02 0.00 FeO 0.11 0.09 0.10 0.10 0.04 0.12 MnO 0.01 0.00 0.02 0.00 0.02 0.00 MgO 0.01 0.00 0.00 0.00 0.00 0.00 NiO 0.00 0.00 0.03 0.02 0.06 0.00 CaO 9.52 8.68 4.99 4.97 4.20 6.34

Na2O 6.18 6.70 9.09 8.84 9.42 7.92

K2O 0.22 0.21 0.22 0.28 0.21 0.32 F 0.07 0.03 0.04 0.05 0.05 0.00 Cl 0.00 0.00 0.01 0.00 0.01 0.00 Sum 98.80 98.29 99.86 99.02 99.33 98.25 Si 2.54 2.58 2.76 2.76 2.80 2.70 Ti 0.00 0.00 0.00 0.00 0.00 0.00 Al 1.44 1.40 1.22 1.24 1.19 1.29 Cr 0.00 0.00 0.00 0.00 0.00 0.00 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 Fe2+ 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.00 0.00 0.00 0.00 0.00 0.00 Ca 0.46 0.42 0.24 0.24 0.20 0.31 Na 0.55 0.59 0.78 0.77 0.82 0.70 K 0.01 0.01 0.01 0.02 0.01 0.02 Ab 0.56 0.49 0.57 0.57 0.57 0.58 An 0.43 0.49 0.42 0.42 0.41 0.41 Or 0.01 0.01 0.01 0.01 0.01 0.01

32 Table 3. Representative analyses of K-feldspar grains. Sample BI-08 BI-08 BI-08 BI-08 BI-08 BI-08 Mineral Kfs Kfs Kfs Kfs Kfs Kfs

SiO2 63.72 63.48 64.09 63.96 61.60 62.98

TiO2 0.00 0.02 0.00 0.01 0.01 0.00 Al2O3 17.93 18.16 18.02 17.97 18.34 17.93 Cr2O3 0.01 0.00 0.00 0.00 0.01 0.00 FeO 0.03 0.01 0.07 0.06 0.00 0.00 MnO 0.00 0.00 0.00 0.01 0.03 0.00 MgO 0.00 0.00 0.00 0.00 0.00 0.00 NiO 0.00 0.00 0.02 0.01 0.00 0.00 CaO 0.03 0.02 0.01 0.01 0.01 0.04

Na2O 0.98 0.54 1.28 1.28 0.29 0.32

K2O 15.10 15.71 14.66 14.74 15.65 15.89 F 0.02 0.06 0.00 0.03 0.02 0.05 Cl 0.01 0.02 0.00 0.02 0.22 0.07 Sum 97.83 98.02 98.15 98.10 96.19 97.27 Si 3.00 2.99 3.00 3.00 2.97 3.00 Ti 0.00 0.00 0.00 0.00 0.00 0.00 Al 1.00 1.01 1.00 0.99 1.04 1.01 Cr 0.00 0.00 0.00 0.00 0.00 0.00 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 Fe2+ 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.00 0.00 0.00 0.00 0.00 0.00 Ca 0.00 0.00 0.00 0.00 0.00 0.00 Na 0.09 0.05 0.12 0.12 0.03 0.03 K 0.91 0.94 0.88 0.88 0.96 0.96 Ab 0.24 0.12 0.12 0.12 0.12 0.09 An 0.00 0.00 0.00 0.00 0.00 0.00 Or 0.76 0.88 0.88 0.88 0.88 0.91

33 Table 4. Representative analyses of amphibole grains. Sample BI-08 BI-08 BI-08 BI-08 BI-08 BI-08 Mineral Amp Amp Amp Amp Amp Amp

SiO2 45.82 44.96 43.10 44.09 42.73 43.03

TiO2 1.17 1.42 2.86 1.45 1.55 1.58 Al2O3 7.01 7.78 8.08 7.53 7.75 7.80 FeO 16.47 17.90 16.56 18.46 18.68 18.15 MnO 0.41 0.40 0.36 0.41 0.40 0.36 MgO 11.51 10.23 10.10 9.93 9.80 10.03 NiO 0.01 0.02 0.05 0.00 0.00 0.00 CaO 11.40 11.26 11.83 11.28 11.22 11.38

Na2O 1.18 1.28 1.14 1.34 1.46 1.27 K2O 0.84 0.92 0.92 0.95 1.02 0.99 F 0.32 0.32 0.42 0.31 0.36 0.32 Cl 0.30 0.31 0.26 0.46 0.45 0.29 Sum 96.47 96.82 95.69 96.21 95.46 95.19 Si 6.94 6.85 6.68 6.80 6.67 6.70 Ti 0.13 0.16 0.33 0.17 0.18 0.18 Al 1.25 1.40 1.48 1.37 1.43 1.43 Fe3+ 0.24 0.22 0.03 0.24 0.35 0.34 Fe2+ 1.84 2.06 2.12 2.14 2.09 2.02 Mn 0.05 0.05 0.05 0.05 0.05 0.05 Mg 2.60 2.32 2.33 2.29 2.28 2.33 Ni 0.00 0.00 0.01 0.00 0.00 0.00 Ca 1.85 1.84 1.96 1.87 1.88 1.90 Na 0.35 0.38 0.34 0.40 0.44 0.38 K 0.16 0.18 0.18 0.19 0.20 0.20 #Mg 0.59 0.53 0.52 0.52 0.52 0.53 Si 6.94 6.85 6.68 6.80 6.67 6.70 ivAl 1.06 1.15 1.32 1.20 1.33 1.30 ivTi 0.00 0.00 0.00 0.00 0.00 0.00 Sum T 8.00 8.00 8.00 8.00 8.00 8.00 viAl 0.19 0.24 0.15 0.17 0.10 0.13 viTi 0.13 0.16 0.33 0.17 0.18 0.18 Fe3+C 0.24 0.22 0.03 0.24 0.35 0.34 MgC 2.60 2.32 2.33 2.29 2.28 2.33 Fe2+C 1.83 2.05 2.12 2.13 2.09 2.02 SumC 5.00 5.00 4.97 5.00 5.00 5.00 Fe2+B 0.02 0.01 0.00 0.01 0.00 0.00 MnB 0.05 0.05 0.00 0.05 0.05 0.05 CaB 1.85 1.84 1.96 1.87 1.88 1.90 NaB 0.08 0.10 0.04 0.07 0.07 0.05 SumB 2.00 2.00 2.00 2.00 2.00 2.00 NaA 0.27 0.28 0.31 0.33 0.38 0.33 KA 0.16 0.18 0.18 0.19 0.20 0.20 SumA 0.43 0.46 0.49 0.52 0.58 0.52

34 Table 5. Representative analyses of biotite grains. Sample BI-08 BI-08 BI-08 BI-08 BI-08 BI-08 Mineral Bt Bt Bt Bt Bt Bt

SiO2 35.08 35.50 34.77 34.95 35.33 34.45

TiO2 3.63 3.58 3.80 3.76 3.61 3.47 Al2O3 13.36 13.52 13.49 13.54 13.43 13.57 Cr2O3 0.02 0.02 0.07 0.03 0.02 0.03 FeO 23.80 23.31 24.16 23.12 23.62 24.53 MnO 0.26 0.23 0.32 0.23 0.27 0.26 MgO 8.60 8.96 8.06 8.65 8.66 7.71 NiO 0.00 0.00 0.03 0.00 0.03 0.00 CaO 0.00 0.00 0.00 0.00 0.00 0.01

Na2O 0.11 0.09 0.12 0.08 0.10 0.10

K2O 9.31 9.24 9.23 9.25 9.28 9.23 F 0.48 0.51 0.46 0.46 0.42 0.42 Cl 0.27 0.26 0.31 0.29 0.25 0.32 Sum 94.91 95.22 94.82 94.36 95.01 94.10 Si 5.58 5.60 5.56 5.57 5.60 5.56 Ti 0.43 0.43 0.46 0.45 0.43 0.42 Al 2.51 2.52 2.54 2.55 2.51 2.58 Cr 0.00 0.00 0.01 0.00 0.00 0.00 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 Fe2+ 3.17 3.08 3.23 3.08 3.13 3.31 Mn 0.03 0.03 0.04 0.03 0.04 0.04 Mg 2.04 2.11 1.92 2.06 2.05 1.85 Ni 0.00 0.00 0.00 0.00 0.00 0.00 Ca 0.00 0.00 0.00 0.00 0.00 0.00 Na 0.03 0.03 0.04 0.03 0.03 0.03 K 1.89 1.86 1.88 1.88 1.88 1.90 #Fe 0.61 0.59 0.63 0.60 0.60 0.64 #Mg 0.39 0.41 0.37 0.40 0.40 0.36

35 The pyroxene crystals are diopsidic in composition, with Ca and Mg ranging from 0.91 to 0.94 and 0.69 to 0.71 apfu, respectively (Figure 9). Total Fe is low, ranging 0.30–0.32 apfu, calculated Fe3+ is very low < 0.05 apfu and #Mg ranges 0.70–0.74 (Table 6). The Na and Al contents are very low, 0.02–0.04 and 0.02– 0.05 apfu respectively, indicating negligible contribution of jadeite substitution vector (Figure 9).

Table 6. Representative analyses of pyroxene grains. Sample BI-08 BI-08 BI-08 BI-08 BI-08 BI-08 Mineral Px Px Px Px Px Px

SiO2 51.94 52.18 51.62 51.87 51.32 52.26 TiO2 0.11 0.06 0.25 0.07 0.20 0.06

Al2O3 0.77 0.47 0.98 0.49 1.05 0.43

Cr2O3 0.00 0.04 0.00 0.00 0.04 0.01 FeO 10.02 9.56 9.29 9.48 9.61 9.49 MnO 0.62 0.51 0.45 0.53 0.57 0.52 MgO 12.51 12.39 12.39 12.51 12.08 12.47 NiO 0.00 0.00 0.00 0.00 0.03 0.00 CaO 22.19 22.54 22.83 22.79 22.68 23.06

Na2O 0.35 0.36 0.39 0.45 0.42 0.25 K2O 0.01 0.02 0.02 0.02 0.05 0.01 F 0.08 0.10 0.12 0.10 0.13 0.10 Cl 0.00 0.01 0.00 0.00 0.10 0.00 Sum 98.60 98.24 98.35 98.33 98.28 98.66 Si 1.98 2.00 1.97 1.98 1.97 1.99 Ti 0.00 0.00 0.01 0.00 0.01 0.00 Al 0.03 0.02 0.04 0.02 0.05 0.02 Fe3+ 0.03 0.01 0.03 0.05 0.04 0.01 Fe2+ 0.29 0.30 0.26 0.25 0.26 0.29 Mn 0.02 0.02 0.01 0.02 0.02 0.02 Mg 0.71 0.71 0.70 0.71 0.69 0.71 Ca 0.91 0.92 0.93 0.93 0.93 0.94 Na 0.03 0.03 0.03 0.03 0.03 0.02 K 0.00 0.00 0.00 0.00 0.00 0.00 #Mg 0.71 0.70 0.73 0.74 0.72 0.71 #Cr 0.00 0.05 0.00 0.00 0.03 0.02 Q(Px) 97.37 97.32 97.06 96.57 96.83 98.14 Jd(Px) 1.49 1.88 1.70 1.03 1.66 1.08 Ae 1.14 0.80 1.24 2.39 1.50 0.78 Fs 15.33 15.40 13.90 13.27 14.05 14.90 En 37.23 36.66 37.05 37.56 36.59 36.54 Wo 47.44 47.95 49.05 49.18 49.36 48.56

36 Epidote is the common composition of the epidote group minerals with high pistacite contents (Xpist = Fe3+ / (Al3++Fe3+)) ranging from 0.66 to 1.00 apfu. Chlorite has #Mg = 0.42-0.52, Si = 5.45–5.95 and Al = 4.26–5.17 apfu (Table 7). The chemical variations of chlorite are mainly due to the combination of the VI IV VI IV tschermak (Mg,Fe) Si Al-1 Al-1 and FeMg-1 exchange vectors. Chlorite is ripidolite-pycnochlorite according to the Si and #Mg contents (Hey, 1954) (Table 7).

Table 7. Representative analyses of epidote and chlorite grains. Sample BI-08 BI-08 BI-08 BI-08 BI-08 BI-08 Mineral Chl Chl Chl Ep Ep Ep

SiO2 26.38 26.56 26.16 37.44 36.21 36.91 TiO2 0.03 0.02 0.03 0.04 0.40 0.20

Al2O3 17.84 16.54 16.49 24.09 20.41 21.57

Cr2O3 0.00 0.03 0.02 0.02 0.08 0.05 FeO 29.19 28.63 28.65 10.39 13.95 13.02 MnO 0.43 0.35 0.38 0.06 0.02 0.06 MgO 12.52 13.17 12.86 0.50 0.04 0.02 NiO 0.02 0.00 0.00 0.00 0.00 0.00 CaO 0.06 0.05 0.05 22.21 22.56 22.55

Na2O 0.02 0.00 0.01 0.00 0.01 0.00 K2O 0.06 0.07 0.07 0.02 0.04 0.01 F 0.12 0.20 0.18 0.09 0.16 0.16 Cl 0.02 0.02 0.08 0.01 0.00 0.00 Sum 86.69 85.65 84.98 94.88 93.87 94.57 Si 5.77 5.88 5.85 3.02 3.00 3.02 Ti 0.00 0.00 0.00 0.00 0.03 0.01 Al 4.60 4.32 4.35 2.29 1.99 2.08 Cr 0.00 0.01 0.00 0.00 0.01 0.00 Fe3+ 0.00 0.00 0.00 0.70 0.97 0.89 Fe2+ 5.34 5.30 5.36 0.00 0.00 0.00 Mn 0.08 0.07 0.07 0.00 0.00 0.00 Mg 4.09 4.35 4.29 0.06 0.00 0.00 Ni 0.00 0.00 0.00 0.00 0.00 0.00 Ca 0.01 0.01 0.01 1.92 2.00 1.98 Na 0.01 0.00 0.01 0.00 0.00 0.00 K 0.02 0.02 0.02 0.00 0.00 0.00 #Mg 0.43 0.45 0.44 1.00 1.00 1.00

Xpist - - - 0.71 1.01 0.92

Figure 9. A) Ca-Mg-Fe clinopyroxene classification (Morimoto, 1989). B) Classification of feldspars. (Deer et al., 1966)

Figure 10. Composition of amphiboles plotted in the classification scheme of Leake et al. (1997). The atomic concentrations of elements per formula units are present as apfu.

5.2.3 X-ray maps Differences between pyroxenes and amphiboles can be observed by

Calcium (Ca)- Kα signails (Figure 11B). Pyroxenes have higher values of Ca than amphiboles in zone A of the sample BI-08. Plagioclases show element zonation of Ca, with cores of andesine composition and rims of oligoclase composition (Figure 11D). Furthermore, albitization and sausuritization processes can be observed in some plagioclases as a high decrease in Ca (violet colors in Figure 11D). Chloritization of biotite can also be observed by Silicon (Si) - Kα signails (Figure 11F) that show chlorite in the rim and biotite in the core.

Figure 11. (A),(C),(E) BSE images of thin sections in mineral chemistry areas. (B),(D),(F) X-ray maps of two zones of the sample BI08 thin section, color bars are in counts where red is highest and violet the lowest. (B) Zone A: Ca-Kα signail to differentiate pyroxenes (green) and Amphiboles (blue), (D) Zone A: Ca-Kα signail to evaluate albitic component (Violet) and anorthitic component (red) distribution in plagioclases. (F) Zone B: Si- Kα signail to differentiate biotite (yellow) from chlorite (blue). Pl (Plagioclase), Amp (Amphibole), Bt (Biotite), Px (Pyroxene), Chl (Chlorite), Qz (Quartz).

39 5.2.4 P-T crystallization conditions Chemical differences between amphibole crystals can be related to the variations in temperature, pressure and saturation in SiO2 of the melt (Johnson and Rutherford, 1989; Sato et al., 1999; Scaillet and Evans, 1999). Unpublished Excel spreadsheets from Ridolfi et al. (2010) and Molina et al. (2015) were used in order to calculate temperature and pressure of representative amphibole-plagioclase mineral pairs respectively. These two Excel spreadsheet were chosen instead of the models of Holland and Blundy (1994) because they are more robust models. Sample BI08 were selected for calculating P-T conditions because it is the most representative among samples. Table 8. Input data for Ridolfi et al., (2010) and Molina et al., (2015) spreadsheets, and pressure- temperature results. Sample BI-08A BI-08A BI-08A BI-08B Mineral Amp-116 Amp-117 Amp-118 Amp-217 SiO2 44,09 42,73 43,03 44,24 TiO2 1,45 1,55 1,58 1,38 Al2O3 7,53 7,75 7,80 7,56 Cr2O3 0,00 0,03 0,00 0,00 NiO 0,00 0,00 0,00 0,02 FeO 18,46 18,68 18,15 18,85 MnO 0,41 0,40 0,36 0,41 MgO 9,93 9,80 10,03 9,62 CaO 11,28 11,22 11,38 11,39 Na2O 1,34 1,46 1,27 1,31 K2O 0,95 1,02 0,99 0,95 F 0,31 0,36 0,32 0,30 Cl 0,46 0,45 0,29 0,40 Mineral Pl-160 Pl-160 Pl-157 Pl-234 SiO2 58,70 61,34 59,21 61,28 Al2O3 25,69 23,18 24,37 23,47 FeO 0,02 0,13 0,14 0,07 MnO 0,00 0,00 0,00 0,01 MgO 0,00 0,00 0,01 0,00 CaO 7,32 5,12 6,73 5,25 Na2O 7,46 8,51 7,86 8,76 K2O 0,04 0,40 0,32 0,21 P(kbar) 3,20 2,60 2,20 3,00 T(ºC) 835,00 850,00 852,00 831,00

40 The pressure and temperature obtained range from 2.6 to 3.2 kbar and 830- 850ºC. These conditions of emplacement suggest an upper crust emplacement depth of ca. 8-10 km. Thus, the rocks intruded by Ibagué batholith should be located at this depth when emplacement occurred.

5.2.5 MELTS modelling Four models were developed in Rhyolite-Melts software (Table 9-10): (1) Whole-rock composition of BI-08 sample was established as melt composition, and clinopyroxene, feldspar, biotite, hornblende and quartz were fixed as the unique minerals that can crystallize from the melt. (2) Same parameters of model 1 but water content was incresed to 3 wt%. (3) Same parameters of model 1 but clinopyroxene was eliminated from possible minerals that can crystallize. (4) Same parameter of model 2 but clinopyroxene was eliminated from possible minerals that can crystallize. These models were selected in order to determine the effect of water content and clinopyroxene in the final mineral association.

Table 9. Input melt compositions normalized to 100%. *FeO/Fe2O3 is established by Ni-NiO buffer Oxides Input 1 Input 2 Input 3 Input 4 SiO2 63,64 62,8854 63,64 62,8854 TiO2 0,6 0,5929 0,6 0,5929 Al2O3 15,4 15,2174 15,4 15,2174 Fe2O3 0,633 0,641 0,633 0,641 FeO* 4,536 4,4379 4,536 4,4379 MnO 0,105 0,1028 0,105 0,1028 MgO 2,822 2,7569 2,822 2,7569 CaO 4,744 4,6344 4,744 4,6344 Na2O 2,781 2,7174 2,781 2,7174 K2O 2,933 2,8656 2,933 2,8656 P2O5 0,188 0,1838 0,188 0,1838 H2O 0,6676 2,9644 0,6676 2,9644

The effect of clinopyroxene in the thermodynamic modelling was important because when this phase was allowed to crystallize the hydrous phases as micas and amphiboles did not crystallize (Table 10. Model 1 and 2). Differences between

41 models 3 and 4 are the number of hydrous phases that crystallized. Model 4 had more water content than model 3, then horblende and biotite crystallized in model 4 insted of model 3 where only biotite crystallized as hydrous phase. Finally, Model 4 is unique among all the models showing the complete mineralogy observed in thin sections. Additionally, Model 4 is more consistent with P-T conditions obtained from experimental liquidus of cordilleran granitoids (Castro et al., 2010).

Table 10. Minerals that crystallized from melt in the models calculated in Melts-Rhyolite.

Model 1 Model 2 Minerals Component mol frac Minerals Component mol frac Feldspar Albite 0,553 clinopyroxene Clinoestatite 0,859 Clinopyroxene Clinoestatite 0,877 feldspar Albite 0,529 quartz clinopyroxene hedenbergite 0,317 clinopyroxene Al -buffonite 0,583 clinopyroxene Al-buffonite 0,65 feldspar Sanidine 0,716 P(Kbar) 15 P(Kbar) 15 T(ºC) 1336,13 T(ºC) 1267,19 Model 3 Model 4 Minerals Component mol frac Minerals Component mol frac Feldspar Albite 0,508 horblende Fe-pargasite 0,634 Biotite Flogopite 0,692 feldspar Albite 0,554 quartz biotite flogopite 0,527 Feldspar Sanidine 0,802 quartz feldspar Sanidine 0,819 P(Kbar) 15 P(Kbar) 15 T(ºC) 1111,3 T(ºC) 1036,52

6. Discussion

6.1 Origin of the magma

The sub-alkaline magma that formed the Ibagué batholith has a volcanic arc-related origin according to n the REE pattern in Chondrite-normalized diagram (Figure 7B). The Nb/Y, Ta/Yb, Rb/Yb+Ta and Rb/Y+Nb discrimination diagrams (Pearce et al., 1984) for the tectonic interpretation of granitic rocks confirm the continental volcanic arc affinity of the batholith (Figure 12).

42 Enrichment of the LREE and LILE shows an interaction of magma with sediment-derived fluids and/or the crust. The Primitive Mantle-Normalized (Sun and McDonough, 1989) trace element diagram shows high Ba/Nb ratios (73.11 to 160.41) suggesting a melt produced in a metasomatized mantle wedge above a dehydrating subducting slab (Hildreth and Moorbath, 1988).

The rocks have low K2O/Na2O ratios of 1.05-1.13, Cr and Ni contents vary in the range of 35.45-57.00 ppm and 8.68-20.86 ppm, respectively. These compositions together with the metaluminous to low peraluminous character and the presence of hornblende and biotite confirm the I-type classification for the batholith. Therefore, the magma was formed by an active continental margin dominated by subduction regimen.

Figure 12. Trace element discrimination Rb/Ta+Yb (Pearce et al., 1984).

Mineral chemistry analysis and X-ray maps show that the mineral zonation of plagioclase grains and the distribution of Ca and Na elements along the rim and the core within the different grains are according to process involved in magmatic chambers (Castro, 2015). Additionally, pyroxene were classified as diopside,

43 however augitic pyroxenes would be more consistent with the SiO2 content of the samples. Thermodynamic modelling suggest that diopsidic grains did not crystallize from the magma but they are xenocrystals. Petrography, geochemistry and thermodynamic modelling are consistent with an off-crust model of magma origin (Castro et al., 2010; Castro et al., 2014) due to the low contents of water, the volcanic arc origin, and the experimental P-T boundary contions and minerals observed in thin sections confirmed by thermodynamic model 4. However, a detailed study on isotopes of the Ibagué Batholith is needed in order to ensure that assertion is valid.

6.2 Regional implications

Since Early Jurassic, the Northwestern margin of South America, including Colombia and Ecuador, was characterized by subduction of Farallon Plate and the growth of multiple continental rifting events associated with the opening of the Caribbean (e.g., Pindell and Kennan, 2009). This subduction system produced widespread Jurassic magmatism along the eastern flank of the (future) Central Cordillera (Aspden et al., 1987) and the upper Magdalena Valley (Bayona et al., 1994; 2005). The most extended magmatic rocks include the Ibagué Batholith (Pindell and Kennan, 2009; Villagomez et al., 2011) and the Saldaña volcano- sedimentary formation (Bayona et al., 1994; 2005). The geochemical character of the studied rocks (I-type and calc-alkaline affinity) confirms this tectonic setting.

The P-T emplacement conditions of the Ibagué batholith show a typical emplacement depth of I-type batholiths. It is important to compare this results with the bodies of rock that were intruded by the batholith because it helps to construct a better tectonic model. At the same age range (i.e. Jurassic) both the Cajamarca Complex and the Ibagué batholith were located at different depths, however both bodies of rock are in contact today. Then, two scenarios can be suggested: (1) the Cajamarca Complex were exposed by erosion before the batholith were emplaced and (2) the Jurassic Cajamarca Complex was formed in a different place in comparison to the Ibagué Batholith, then strike-slip faults put both bodies in contact.

44 According to paleomagnetic results, the Jurassic volcanic activity (i.e. Saldaña Formation) within Magdalena valley was formed south of its current position (Bayona et al., 2005). This tectonic model suggests a transpressional system where faults put together bodies of rock formed in different locations. The Ibagué batholith can be associated with this tectonic model because the geochemical and field affinities between the Saldaña Formation and the Ibagué batholith (Bayona et al., 1994), and the fault contacts observed in both thin sections of the Ibagué batholith and field.

7. Conclusions

At north of Coello Village, Ibagué Batholith appears in fault contact with the Cajamarca Complex (Central Cordillera of Colombia) based on the P-T (pressure and temperature) crystallization conditions for the batholith (2.6-3.2 Kbar and 830- 850ºC), the Jurassic peak condition of the Cajamarca Complex metamorphism (ca. 8 Kbar and 550-580ºC; Blanco-Quintero, et al., 2014), paleomagnetic results of the extrusive Jurassic bodies of rock (Bayona et al., 2005), textures found in petrography analysis of the Ibagué batholith samples and field observations.

The studied samples present a mineralogy that consist of oligoclase to andesine plagioclases, quartz, edenite and Mg-hornblende amphiboles, and Fe- biotite as main minerals, sanidine and diopside as minor phases, and chlorite and epidote as alteration products.

The igneous body have a volcanic arc affinity with Y = 12.76-20.03 ppm, Yb= 1.15-1.78 ppm and Nb= 6.25-8.74 ppm, and the Ba/Nb ratios = 73.11 to 160.41 indicate a melt produced in a metasomatized mantle wedge above a dehydrating subducting slab and contamination by crustal assimilation.

45 8. References

Altenberger. U.. and Concha. A. (2005). Late Lower to Early Middle Jurassic arc magmatism in the northern Ibagué-Batholith/Colombia. Geología Colombiana . 87-97.

Anderson, J. L., Barth, A. P., Wooden, J. L., et al. (2008). “Thermometers and thermobarometers in granitic systems”. Reviews in Mineralogy and Geochemistry. 69, 121-42

Anderson, J. L. and Smith, D. R. (1995). The effect of temperature and oxygen fugacity on Al-in-hornblende barometry. AM MINERAL 80, 549-59.

Annen. C. (2011). Implications of incremental emplacement of magma bodies for magma differentiation. thermal aureole dimensions and plutonism– volcanism relationships. Tectonophysics . 3-10.

Aspden. J. A.. McCourt. W. J.. and Brook. M. (1987). Geometrical Control of subduction-related magmatism: The Mesozoic Andes Cenozoic plutonic history of Western Colombia. Journal of the Geological society . 144. 893- 905.

Barrero. D.. and Vesga. C. (1976). Mapa Geológico del cuadrángulo K-9 Armero y mitad Sur del Cuadrángulo J-9 La Dorada. Escala 1:10000. Bogotá: Ingeominas.

Bayona, G., García, D., Mora, G. (1994). La Formación Saldaña: producto de la actividad de estratovolcanes continentales en un dominio de retroarco, en Etayo-Serna, F., ed., Estudios Geológicos del Valle Superior del Magdalena: Bogotá, Universidad Nacional de Colombia, Capítulo I, 21 p.

Bayona, G., Silva, C., Rapalini, A. E.; Costanzo-Álvarez, V., Aldana, M., Roncancio, J. (2005). Paleomagnetismo y Mineralogía Magnética en rocas de la Fm. Saldaña y unidades Cretácicas suprayacentes en la parte norte del Valle Superior del Magdalena. Boletín de Geología de la UIS 27 (2), 69- 85.

46 Blanco-Quintero, I.F. Garcia-Casco, A. Toro, L. Moreno, M. Ruiz, E. Vinasco, C. (2014). Late Jurassic terrane collision in the northwestern margin Gondwana (Cajamarca Complex. eastern flank of the Central Cordillera. Colombia). International Geology Review.

Blundy, J. D. and Holland, T. J. B. (1990). Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer. CONTRIB MINERAL PETROL 104, 208-24.

Castro A. (2015). Petrografía de rocas ígneas y metamórficas. Ediciones Paraninfo SA. España. Ed. 1. 260 pp.

Castro A. 2014. The off-crust origin of granite batholiths. Geoscience Frontiers 5 (1) 63-75.

Castro, A., Gerya, T., García-Casco, A., Fernández, C., Diaz-Alvarado, J., Moreno- Ventas, I., Löw. I. (2010). Melting relations of MORB-sediment melanges in underplated mantle wedge plumes. Implications for the origin of cordilleran- type batholiths. Journal of Petrology, 51, 1267-1295.

Cediel, F., Ujueta, G., and Caceres, C. (1976). Mapa Geológico de Colombia. Nota explicativa. Bogotá: GEOTEC Ltda.

Cochrane. R.. Spikins. R. A.. Gerdes. A.. Ulianov. A.. Mora. A.. Villagómez. D.. y otros. (2014). Permo-Triassic anatexis. continental rifting and the disasembly of Pangea. Lithos . 190-191. 383-402.

Deer, W.A., Howie, R.A., Zussman, J. (1966) Introduction to the Rock-Forming Minerals. Geological society

Esquivel. J.. Flores. D.. and . A. (1991). Mapa Geológico de la plancha 301 Planadas. Escala 1:100000. Memoria Explicativa. Santa Fe de Bogotá: Ingeominas.

Foster, M. D. (1960). Interpretation of the composition of trioctahedral micas. Geological Survey Professional Paper. 354-B, 49.

47 Ghiorso M.S., Gualda, G.A.R., (2015) An H2O-CO2 mixed fluid saturation model compatible with rhyolite-MELTS. Contributions to Mineralogy and Petrology 2015, in press

Gill. J. B. (1981). Orogenic andesites and plate tectonics. Berlin: Springer.

Gomez-Tapia. J.. and Bocanegra-Gomez. A. (1999). Estudio Geológico-Estructural de la falla Otú-Pericos al W de la ciudad de Ibagué. Manizales: Universidad de Manizales.

Gonzáles, H. (2001). Mapa Geológico del departamento de Antioquia. Escala 1:400000. Memoria Explicativa. Ingeominas .

Gonzáles. H.. Núñez. A.. and Paris. G. (1988). Mapa Geológico de Colombia. Memoria explicativa. Colombia: Ingeominas.

Govindaraju. K. (1994). Compilation of working values and sample description for 383 geostandards. Geostandards and Geoanalytical Research . 18. 1-158.

Gualda G.A.R., Ghiorso M.S., Lemons R.V., Carley T.L. (2012) Rhyolite-MELTS: A modified calibration of MELTS optimized for silica-rich, fluid-bearing magmatic systems. Journal of Petrology, 53, 875-890.

Guo, Z., Hertogen, J., Liu, J., Pasteels, P., Boven, A., Punzalan, L., He, H., Luo, X., Zhang, W., 2005. Potassic magmatism in western Sichun and Yunnan provinces, SE Tibet, China: petrological and geochemical constraints on petrogenesis. J. Petrol. 46, 33–78.

Guo, Z., Wilson, M., Liu, J., Mao, Q., 2006. Post-collisional, potassic and ultrapotassic magmatism of the northern Tibetan Plateau: constraints on characteristics of the mantle source, geodynamic setting and uplift mechanisms. J. Petrol. 47, 1177–1220.

Harker, A., (1909). The Natural History of Igneous Rocks. Macmillan Company, New York, 384pp.

48 Hawkesworth, C.J., Turner, S.P., McDermott, F., Peate, D.W., van Calsteren, P., (1997a). U–Th isotopes in arc magmas: implications for element transfer from the subducted crust. Science 276, 551–555.

Hawkesworth, C., Turner, S., Peate, D., McDermott, F., van Calsteren, P., (1997b). Elemental U and Th variations in island arc rocks: implications for U-series isotopes. Chem. Geol. 139, 207–221.

Hildreth. W.. and Moorbath. S. (1988). Crustal contributions to arc magmatism in the Andes of Central Chile. Contrib. Mineral. Petrol. . 98. 455-489.

Holland, T. and Blundy, J. 1994. Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometry. CONTRIB MINERAL PETROL 116, 433-47.

Hutton. D. (1996). The 'space problem' in the emplacement of granite. Episodes. Journal of international Geoscience . 114-119.

Johnson, M.C., Rutherford, M.J., (1989). Experimental calibration of the aluminum- in hornblende geobarometer with application to Long Valley caldera (California) volcanic rocks. Geology 17, 837e841.

Le Maitre. R.. Bateman. P.. Dudek. A.. Keller. J.. Lameyre. J.. Le Bas. M.. y otros. (1989). A classification of igneous rocks and glossary of terms. Oxford: Blackwell.

Leake. B. E.. Woolley. A. R.. Birch. W. D.. Gilbert. M. C.. Grice. J. D.. Hawthorne. F. C.. y otros. (1997). Nomenclature of amphiboles: Report of the subcommittee on amphiboles of the International Mineralogical Association. Commission on new minerals and mineral names. American Mineralogist . 82. 1019-1037.

Maya, M., and Gonzáles, H. (1995). Unidades litodémicas en la cordillera central de Colombia. Boletin Geológico , 35 (2-3), 43-57.

49 McDonough, W.F. and Sun, S.S. (1995). The composition of the earth. Chemical Geology . 120 (3-4). 223-253.

Molina, J.F. Moreno, J.A. Castro, A. Rodríguez, C. Fershtater, G.B. (2015). Calcic amphibole thermobarometry in metamorphic and igneous rocks: New calibrations based on plagioclase/amphibole Al-Si partitioning and amphibole/liquid Mg partitioning. Lithos 232, 286-305.

Morimoto, N., Fabries, J., Ferguson, A.K., Ginzburg, I.V., Ross, M., Seifert, F.A., Zussman, J., Aoki, K., Gottardi, G. (1988). Nomenclature of pyroxenes. American Mineralogist 73, 1123–1133.

Mosquera. D.. Núñez. A.. and Vesga. C. (1982). Mapa Geológico preliminar de la plancha 244-Ibagué. Escala 1:100000. Bogotá: Ingeominas.

Nelson. H. W. (1959). Contribution to the geology of the central and western cordillera of colombia in the sector between Ibagué and Cali. Leidsche Geol. Meded. . 22. 1-75

Ordoñez-Carmona, O. (2001). Caracterização isotópica Rb-Sr e Sm-Nd Caracterização isotópica Rb-Sr e Sm-Nd dos principais eventos magmáticos nos Andes Colombianos principais eventos magmáticos nos Andes Colombianos. [Ph.D. Tesis] , 176.

Pearce. J. A.. Harris. N.. and Tindle. A. G. (1984). Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of petrology . 25. 956-983.

Petford. N.. Cruden. A. R.. McCaffrey. K. J.. and Vigneresse. J.-L. (2000). Granite magma formation. transport and emplacement in the Earth's crust. Nature . 669-673.

Pindell, J., and Kennan, L., 2009, Tectonic evolution of the Gulf of Mexico, Caribbean and northern South America in the mantle reference frame: an update. In: James, K.H., Lorente, M.A., Pindell, J.L. (Eds.), The origin and

50 evolution of the Caribbean Plate: Geological Society of London, Special Publications, v. 328, p. 1–55.

Pitcher. W. S. (1993). The Nature and Origin of Granite. Blackie Academic .

Restrepo. J. J.. Ordoñez-Carmona. O.. Amstrong. R.. and Pimentel. M. M. (2011). Triassic metamorphism in the northern part of the Tahami terrane of the Central Cordillera of Colombia. Journal of South American Earth Sciences . 32. 497-507.

Restrepo. J.. and Toussaint. J. (1982). Metamorfismos superpuestos en la cordillera central de colombia. Asociación geologica de Argentina. Buenos Aires: V Congreso Latinoamericano de geologia.

Sato, H., Nakada, S., Fujii, T., Nakamura, M., Suzuki-Kamata, K., (1999). Groundmass pargasite in the 1991e1995 dacite of Unzen volcano: phase stability experiments and volcanological implications. J. Volcanol. Geotherm. Res. 89, 197e 212.

Scaillet, B., Evans, B.W., (1999). The 15 June 1991 eruption of Mount Pinatubo, I, Phase equilibria and pre-eruption PeTefO2eH2O conditions of the dacite magma. J. Petrol. 40, 381e411.

Schmidt, M. W. (1992). Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer. CONTRIB MINERAL PETROL 110, 304-10.

Shand, S. J. (1943). The Eruptive Rocks, 2nd edn. (New York: John Wiley), 444p. Sun. S. S.. and McDonough. W. F. (1989). Chemical and isotopic systematics of ocean basalts; implication for mantle composition and process. (A. D. Saunders. and M. J. Norry. Edits.) Geological Society of London . 313-345.

Toussaint, J.F. and Restrepo, J.J., (1994): The ColombianAndes during Cretaceous Times. In: Salfity, J.A (ed.):Cretaceous tectonics of the Andes. Earth Evolution Sciences, 61-100. Vieweg and Sohn. Wiesbaden.

51 Villagómez. D.. Spikings. R.. Magna. T.. Krammer. A.. Winkler. W.. and Beltrán. A. (2011). Geochronology. Geochemistry and tectonic evolution of the western and central cordilleras of colombia. Lithos . 125. 875-896.

Vinasco. C. J.. Cordani. U. G.. Gonzáles. H.. Weber. M.. and Pelaez. C. (2006). Geochronological. isotopic. and geochemical data from Permo-Triassic granitic gneisses and granitoids of the Colombian Central Andes. Journal of South American Earth Sciences . 21. 355-371.

Whitney. D.. and Evans. B. (2010). Abbreviations for names of rock-forming minerals. American Mineralogist . 95. 185-187.

Wilson. M. (1989). Igneous petrogenesis. London: Unwin Hyman.