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Honduras Geology  January, 1997 (updated 4/27/97)
Number of Visitors since 12/12/97

The Montañas de Colón Fold and Thrust Belt, Eastern Honduras

Robert D. Rogers(1)
 
Foster Wheeler Environmental Corporation, 10900 NE 8th Street, Bellevue, WA 89004 and 334 Williams Avenue North, Renton, WA 98055. e-mail: rrogers@geology.csustan.edu 

(1) Presently at Department of Physics and Geology, California State University Stanislaus, One University Circle, Turlock, CA 95382

The citation for this report is: Rogers, R.D., (abs), 1995, The Montañas de Colón Fold and Thrust Belt, Eastern Honduras. GSA Annual Meeting p. A-122 (Condensed from the material presented in a poster session at the Geological Society of America annual meeting in New Orleans, November 1995).

Contents

ABSTRACT
The Montañas de Colón Fold and Thrust Belt, Eastern Honduras
Physical Description
Morphological Expression of Stratigraphic Units
STRATIGRAPHY Honduras Group, Yojoa Group-Atima Formation, Krausirpi beds, Valle de Angeles Group, Mafic volcanic rocks, Tabacón beds
STRATIGRAPHIC IMPLICATIONS
COMPRESSIONAL FEATURES Northwest Verging Reverse Faults Folding Tear Faults Timing of Compressional Deformation
POST COMPRESSION STRIKE-SLIP FAULTS
STRUCTURAL IMPLICATIONS

 

 


 
Location Map
Geology Map
Stratigraphic Column
Geological Cross Section
EPS print file of geology map at true size (1:50,000) is available by e-mail request to rrogers@utig.ig.utexas.edu. This will print at size of standard Honduras geology sheet.
Poles to bedding of stratigraphic units (added 4/27/97)


Honduras Group
Yojoa Group
Krausirpi beds
Valle de Angeles Group
Volcanic beds
Tabacón beds

ABSTRACT Recent geologic mapping centered near the confluence of the Río Patuca and the Río Wampú in eastern Honduras, reveals for the first time that the Montañas de Colón form a prominent northeast trending regional fold and thrust belt approximately 30 km wide and 150 km in length. The high degree of differential erosion indicates a long period of surficial exposure that clearly reveals northeast trending, southeast dipping lithologies and exposes the compressional features of this regionally significant and previously unknown fold and thrust belt. The compressional event affected all Mesozoic units, indicating a Cenozoic age of deformation. The spatial continuity of compressional features indicates that the area has been relatively unaffected by the documented strike-slip events expressed to the west of the Montañas de Colón Fold and Thrust Belt and that the compressional deformation predates the strike-slip deformation.

Large northwest verging reverse faults place Lower Cretaceous Atima limestone over Upper Cretaceous Valle de Angeles redbeds and repeats the Atima strata in the Montañas de Colón. The lithologic units exhibit a predominately northeast strike and southeast dip. Mapping at Siquiapisne on the Río Patuca and along Quebrada Kahkatingni shows interleaved Atima and Valle de Angeles strata maintaining consistent southeast dips across lithologic contacts and with the older Atima strata thrust over the younger Valle de Angeles strata. The northeast trending metamorphic highlands composed of the Jurassic-Cretaceous Honduras Group form the axis of an anticline flanked by Valle de Angeles redbeds that dip away from the highlands. The Tertiary (?) Tabacón breccia cores a northeast trending syncline exposing the gradational coarsening-up contact between the Valle de Angeles redbeds and the Tabacón breccia on both limbs of the fold. These large folds appear north of the Río Patuca and in front of the Montañas de Colón reverse faults. Small intraformational folds, thrust faults, and tear faults within the sandstone and shale of the Valle de Angeles redbeds and overlying Krausirpi beds, and a large northwest trending sinistral tear fault with 1.5 km displacement, are all consistent with northwest-southeast compression.

Aerial photography and satellite imagery show the folded strata of the Montañas de Colón extending northeast past Wampusirpi and Sierra Warunta where the strata disappear beneath the alluvium of the Mosquitia plains. The folded strata also extend to the southwest through the Cordillera Entre Ríos. North-northeast trending dextral strike-slip faults cut the northeast trending fold and thrust belt indicating a later episode of deformation. These younger faults show displacements of about 1 km on aerial photography.

The Montañas de Colón Fold and Thrust Belt provides the only known area in Honduras where the compressional event can clearly be studied without the confounding influence of the later extensive strike-slip deformation that affects much of Honduras.

The Montañas de Colón Fold and Thrust Belt, Eastern Honduras

  • Northeast trending sequence of folded and reverse faulted Mesozoic and Early Tertiary strata.
  • Exposed most prominently in the Montañas de Colón massif of folded and faulted Cretaceous limestone.
  • Isolated from intense and pervasive Late-Tertiary strike-slip deformation and volcanism in Honduras west of the Guayape Fault zone.
  • Preservation of Early-Tertiary compressional deformation that affected much of the Chortís block.

Physical Description

  • Sequence of compressionally deformed strata extends at least 185 Km from near Awaus, where the Awaus 1 well of True Oil penetrated 7000 feet of Jurassic shale of the Honduras Group before encountering Cretaceous Valle de Angeles sandstone, to near the Honduras-Nicaragua border in the Cordillera Entre Ríos.
  • LANDSAT imagery, aerial photography, and reconnaissance mapping indicates that the compressionally deformed strata is at least 55 Km in width.

Morphological Expression of Stratigraphic Units

  • Differential weathering of the deformed strata provides a clear image of the extent of the deformed strata.
  • Cretaceous limestone of the Yojoa Group forms well defined karst mountains and hills, as well as exposing folding.
  • Tertiary breccias of the Tabacón beds form prominent ridges.
  • The weakly metamorphosed sedimentary strata of the Honduras Group form the western highlands, where erosion has stripped off the younger strata.
  • The sandstone and shale of the Cretaceous Valle de Angeles Group and Krausirpi beds generally form the strike valleys of the fold and thrust belt.
  • Late Cretaceous volcanic flow rocks weather to form the low relief terrain to the south of the Montañas de Colón and along strike of the fold and thrust belt.

STRATIGRAPHY

JURASSIC-CRETACEOUS HONDURAS GROUP (JKhg)

  • Dark to light gray, pink and tan phyllite, tan to gray quartzite, minor black graphitic schist, and gray slate with quartz veins.
  • Weakly metamorphosed sedimentary strata.
  • Forms the rugged northeast trending highlands.
  • Likely equivalent to the Jurassic Agua Fría strata of the Honduras Group east of the Guayape fault.
  • Contact between the Honduras Group strata and the overlying redbeds (Valle de Angeles Group) is unconformable and only locally faulted.
  • Honduras Group strata were noted in unconformable contact below the Tertiary Tabacón beds and below mafic volcanic flows along tributaries to the Río Wampú.

CRETACEOUS YOJOA GROUP-Atima Formation (Ky)

  • Dark to medium gray, thick-bedded micrites with a few sparry and biomicrite beds.
  • Forms the Montañas de Colón karst highlands south of the Río Patuca.
  • Correlated with the Atima Formation (Albian-Aptian) of central Honduras by its general appearance, thickness, and the mapped stratigraphic relations.
  • Stratigraphic contact with underlying beds was not found.
  • The upper contact conformable with the thin-bedded sandstone and shale of the Krausirpi beds in the Sutawala valley.
  • Along the Quebrada Kahkatingni south of Cerro Wampú, Atima limestone with epikarst development was found immediately below Valle de Angeles redbeds.
  • Paleontological studies released by the Dirreción General de Minas e Hidrocarburos support this interpretation and indicates an upward shoaling from Albian to lowermost Cenomanian (IBI, 1985).
  • Likely continued deposition of Atima limestone in eastern Honduras following cessation of Atima deposition in central Honduras.
  • The Yojoa Group carbonate rock are absent north of the Río Patuca in the region.

CRETACEOUS KRAUSIRPI BEDS (Kk)

  • Predominately light gray to tan shale and gray thin and planar-bedded arkosic, lithic arenite, and graywacke. Sandstone and shale are calcareous in places. Clastic rocks contain alternating coarse-fine layers and occasional fossil wood fragments.
  • Minor thin limestone beds. Limestone breccia near the contact with the Atima limestone and a minor lithic pebble conglomerate was found. Alga stromatolites contained in one limestone bed.
  • Exposed within the strike valleys of the Montañas de Colón and along the Río Patuca during low flow in dry season.
  • Conformable contact with the underlying Atima limestone in the Sutawala valley. At Krausirpi, these beds are separated from the overlying Valle de Angeles redbeds by a minor unconformity.
  • Contains upper Albian-lower Cenomanian marine fossils (IBI, 1985). The change from marine carbonate deposition (Yojoa Group) to marine clastic deposition (Krausirpi beds), with terrestrial carbonaceous material unconformably below terrestrial redbeds (Valle de Angeles Group), indicates a marine regression.
  • Krausirpi beds were distinguished by their mappable occurrence and stratigraphic position below the Valle de Angels redbeds at Krausirpi and above the Atima limestone in the Sutawala valley.

CRETACEOUS VALLE DE ANGELES GROUP (Kva)

  • Maroon to red fine-grained sandstone, matrix- and clast-supported pebble to boulder subangular to subrounded poorly sorted conglomerate of quartz, limestone, and minor volcanic fragments.
  • Generally planar bedding, with a few fluvial cross-beds.
  • Exposed in the lowlands along the Río Patuca, as the moderate topography flanking the Honduras Group highlands, in the valleys north of the highlands, and as fault slivers among Atima limestone in the Sutawala valley.
  • Lower contact of the Valle de Angeles redbeds is unconformable with the Honduras Group and the Krausirpi beds.
  • Southeast of Cerro Wampú, along Quebrada Kahkatingni, redbeds rest unconformably on epikarst developed on the Atima limestone.
  • The upper contact with the extremely coarse Tabacón beds is transitional, gradually coarsening up section, and displaying a loss of sand in the Tabacón beds (the matrix changes from sand to silt).
  • In places, mafic volcanic flows occur at the upper contact separating the Valle de Angeles redbeds from the Tabacón beds.
  • The age of the Valle de Angeles redbeds is constrained by lower Cenomanian limestone clasts (Atima- see above) found within the conglomerates and ages between 80.7±4.3 to 70.4±4.3 Ma for the mafic volcanic flows above the redbeds (Weiland et al. 1993).
  • The Valle de Angeles strata have planar beds, lack basal scour, contain few channels, and have matrix supported clasts; features indicating deposition by hi- viscosity and hyper-concentrated fluid flows. Deposition occurred as debris flows with minor fluvial facies on a tropical alluvial fan.

MAFIC VOLCANIC ROCKS (Kv)

  • Dark gray, green, and reddish basalt and andesite flow rock containing plagioclase phenocrysts and a biotite rich groundmass. Flow banding, scoria and autobrecciated flows. Calcite and zeolote filled cavities.
  • Found extensively in the low relief north of the Río Wampú between the Ríos Pao and Aner, and as isolated flows interbedded with the Valle de Angeles redbeds.
  • K-AR whole rock and plagioclase dating obtained ages of 80.7±4.3 to 70.4±4.3 Ma for the flow rock (Weiland et al. 1993).
  • Isotopic ages and the volcanic rock interbedded with Valle de Angeles redbeds are the reasons for assigning both the mafic volcanic rock and the generally underlying redbeds a Cretaceous age.
  • The mafic flows separate the Tabacón beds and the Valle de Angels redbeds on Crique Malawás. Mafic flows unconformably overlie the Honduras Group metasedimentary strata to the north of the Río Wampú.

TABACON BEDS (Tt)

  • Maroon to green, cobble to boulder, subangular to angular breccia and conglomerate of quartzite, volcanic rock, quartz, and minor red sandstone clasts.
  • Angular clasts are generally supported in a fissile mud matrix, and the sand size fraction of the matrix is minor. Bedding is exclusively planar with excellent exposure along the Quebrada Tabacón.
  • Tabacón beds flank the southeast side of the Honduras Group highlands and appear as a rugged ridge-former (with numerous waterfalls) to the northwest of the highlands.
  • The lower contact with the Valle de Angeles redbeds is gradational. Minor fluvial cross-beds occur within this transitional zone. The lower contact with the mafic volcanic rocks and the Honduras Group is unconformable.
  • Tabacón beds assigned an Early Tertiary age based on the Late Cretaceous ages obtained for the underlying volcanic rock and, presumably, the clasts which comprise the Tabacón deposit.
  • The Tabacón beds were deposited in hi-viscosity debris flows rich in fines. The angularity of the clasts indicates proximity to its source, presumably a fault bounded uplift.

STRATIGRAPHIC IMPLICATIONS

  • The Yojoa and Valle de Angeles Groups appears to be younger (10-15 my) than in Central Honduras. This indicates a depositional basin that is younger to the east.
  • The mafic volcanic rock and Tabacón beds define a local Late Cretaceous-Early Tertiary basin fill and is evidence for tectonic activity.
  • A limestone boulder breccia and mafic volcanic rock occur along the Río Coco between Tilba and Awasbila south of the Montañas de Colón . These may correlated genetically with the Tabacón beds found north of the Montañas de Colón , defining the southern margin of a depositional basin during the Late Cretaceous-Early Tertiary.
  • Krausirpi beds thin and disappear to the southwest along the Río Patuca. This may define the margin of the marine depositional basin (Yojoa Group) during Albian/Cenomanian.
  • The Valle de Angeles strata and the basal transitional Tabacón redbeds appear to have a northern source, based on the few paleocurrent indicators found.
  • The limestone clast conglomerate of the Valle de Angeles Group always occurred south of and distal from the exposed Honduras Group highlands. No Yojoa Group limestone was found east of the Río Patuca in the map area. It is questionable whether Yojoa Group limestone was deposited east of the Río Patuca.

COMPRESSIONAL FEATURES

Northwest Verging Reverse Faults

  • Predominate northeast strikes and southeast dips are maintained across lithologic boundaries south of the metamorphic highlands.
  • Presence of Lower Cretaceous Atima limestone over Upper Cretaceous Valle de Angeles redbeds.
  • At Siquiapisne on the Río Patuca and along Quebrada Kahkatingni, interleaved Atima and Valle de Angeles strata were observed with bedding attitudes consistent across contacts and with the older Atima over the younger Valle de Angeles. This relation was seen along the northwest front of the Montañas de Colón and interpreted as southeast dipping reverse faults.
  • Valle de Angeles strata occurs as fault slivers within the Atima limestone at three localities along the Río Sutawala, indicating fault repetition of the thick Atima limestone in the Montañas de Colón. Aerial photography displays lineaments supporting this interpretation.
  • The prominent Cerro Wampú appears to have a thrust contact on its northwest face while the southeast face is a demonstrable dip slope evidenced by epikarst at the contact between the Atima limestone and the overlying Valle de Angeles redbeds. Cerro Wampú is interpreted as an isolated splay.
  • Small thrusts faults in thin-bedded Valle de Angeles and Krausirpi beds are consistent with northwest-southeast compression.

Folding

  • Small folds in thin-bedded Valle de Angeles and Krausirpi beds are consistent with northwest-southeast compression.
  • A northeast trending fold-belt is exposed across the detailed map area northwest of the Río Patuca. The northeast trending Honduras Group highland has Valle de Angeles strata exposed and dipping away from the highland on its northwest and southeast sides defining a large anticline. Indicates Honduras Group involvement in the compression.
  • Synclinal folding of the Tabacón beds southeast of the Honduras Group highlands is less well defined by bedding attitudes. However, the gradational contact between the Valle de Angeles and the Tabacón strata on both margins of the Tabacón exposure supports a syncline.
  • Northeast trending folds within Atima limestone are seen on aerial photography and Landsat imagery of the Montañas de Colón, and one small fold was mapped in the Sutawala drainage.

Tear Faults

  • Small northwest trending right and left lateral shears appear in the Valle de Angeles and Krausirpi beds in association with compressive features and are interpreted as compression related tear faults.

Timing of Compressional Deformation

  • Compressional folding and faulting affects all units mapped in detail, indicating the compression occurred during the Cenozoic.
  • Poles to bedding for the Tabacón beds show slightly less deformation than older units, suggesting the Tabacón beds may be coevel with the deformation.

POST COMPRESSION STRIKE-SLIP FAULTS

  • A series of north-northeast trending dextral strike-slip faults cut the older compressional features of the Montañas de Colón.
  • Faults have displacements up to 1 km based on aerial photography interpretation.
  • Several small faults were found showing both dextral and sinistral slip indicators that do not match orientations expected for compressional induced tear faults.

STRUCTURAL IMPLICATIONS

  • The Montañas de Colón thrust and fold-belt with associated folds to the northwest are a regional northeast trending feature extending at least 185 km in length. These features can be seen from aerial photography and Landsat imagery to the southwest through the Cordillera Entre Ríos. To the northeast, compressional features can be seen on the surface to Wampusirpi and Sierra Warunta. A well drilled near Awaus, 50 km to the northeast of the surface exposure of deformation, passed through 7000 thousand feet of Honduras Group strata before encountering Valle de Angeles strata below a thrust structure.
  • North-northeast trending dextral strike-slip faults that cut the compressional features of the Montañas de Colón may relate to deformation from the Guayape Fault 40 km to the northwest. Further work is needed to determine the relation of northeast trending structures in La Mosquitia with structures to the west.

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