Woodland Sandstone Injectes of the Park, CO Colorado Front Range: Age, regional extent, emplacement mechanism, and significance as a fluid migraon pathway

Chrisne Siddoway and W. Cody Duckworth Tava Geology Department Sandstone (intrusion) Colorado College Pikes Peak Granite

Detrital zircon probability density plot

500 1000 1500 2000 2500 3000 4000 If possible to solve this problem, could acquire a new source of informaon about terrestrial paleo- environment and tectonics … for some prior me.

1/ Injectes: When and how did these form?

Crosscung sandstone dikes, hosted by 1.08 Ga Pikes Peak Granite ; at least two injecon events, separated in me. Age of Pikes Peak Granite

Detrital zircon probability density plot

500 1000 1500 2000 2500 3000 4000 Chrystola, CO: Tabular sandstone forms hogback Tabular dike within Pikes Peak Granite (very near the ridge, 1 x 0.25 km in map dimension. Pikes Peak DX sample site). granite surrounds the sandstone. The trees are approx. 35m in height, so the vercal extent of the dike is at least 75 meters.

Images from George H. Stone Glass Plate Negaves, c. 1904 Special Collecons, Tu Library, Colorado College Outline for this talk 1/ Tava sandstone – locaon and characteriscs 2/ Colorado injectes – once an oddity, now a beacon from the Proterozoic: Age determined from Catastrophic ! detrital zircon reference spectra 3/ Parameters for emplacement, with bearing on emplacement mechanisms and triggers associaon with hydrocarbon reserves 4/ Regional extent 5/ Paleoenvironments of Rodinia superconnent

LOCATION Distribuon of Tava sandstone along the southern Ute Pass fault • mulple types of host rock • sample sites at intervals along the fault … and further afield…

Informal name: Tava sandstone Distribuon: along base of the Pikes Peak massif. Tavakaiv the indigenous name for the Peak, translates ~ as Mountain-first- touched-by-the-Sun (Tabeguache Ute).

Red line paern = Tava sandstone Bold lines = faults PPf = Pennsylv. Fountain Formaon upon simplified geological map 10 km Younger generaon of dikes (injectes) are white and very well indurated. In the image, a vercal dike forms a ‘rampart’ that is laterally connuous for 60 meters, within weathered gneiss (loosely, “Idaho Springs Formaon”). Quartz sandstone: rounded, fine- to medium- grained, poorly sorted to unsorted. Larger grains are non- touching and matrix-supported Accessory minerals: detrital zircon and detrital magnete

Williams Creek Range

all photomicrographs, 8 mm diameter: Crystola Kms-scale fault-bounded sandstones also are cut by injectes. Shared characteriscs : Isolated (“floang”) quartz granules to pebbles, 2mm to 6 cm in length Matrix-supported – uniform fine quartz sand, well rounded. Absence or paucity of clay

These point to a common age and origin in a dynamic tectonic seng that experienced rapid sedimentaon, high pore fluid pressure, and liquefacon/ injecon events. Neoproterozoic age (circa 750 Ma) established on this basis: contemporaneous rock units incorporate detrital zircon from regional reservoirs that contain diagnosc zircon age populaons.

Tava ss, dike n = 222

Nankoweap Fm n = 732

Visual and stascal comparison of normalized probability density plots, such that the area beneath the plot is the same for all samples, irrespecve of number of analyses. Neoproterozoic age, on basis of Detrital Zircon age distribuons and provenance

Paleozoic arenites

Tava sandstone

Siddoway and Gehrels, 2014, Lithosphere Sandstone hosted by Proterozioc crystalline rock, not restricted to Ute Pass fault system

Precambrian Basement Map of Colorado PLATE 1 by P.K. Sims, Viki Bankey, and C.A. Finn 102° 109° 103° 41° 41° 108° 107° 106° 105° 104° Wr Xfh Xm Yg Xfh Xfh Xm Yg Xg Yu Cheyenne Belt Xfh Xfh .z. Xg Xg s Xfh Yg Yu Skin Gulch Xg EXPLANATION 766 ± 5 Ma, Yu Yg Description of Map Units Xfh .z. Xfh Yg Xg Surface Subsurface Soda Creek- Fish Creek s Xg Xb MESOPROTEROZOIC (1,600 -- 900 Ma) Uinta Mt. Group Xb Xg Ygp Ygp Xb Rocks of Pikes Peak batholith (~1,010 Ma) Pink, coarse-grained biotite granite intruded Yg Xg by plutons of cogenetic, fine-grained granite, Xb fayalite granite, riebeckite granite, alkali in Utah. Dehler et Xfh .z. s granite, syenites, and gabbro Yg Xg Xfh Moose Mtn. Yg Boulder Yl Las Animas Formation -- Dark slate, phyllite, al. 2012 graywacke, and chert, and, in upper part, Xg subordinate volcanic and carbonate rocks Xg Xqs 40° 40° Xg Xb Williams Range thr Xg Yu Yu s.z. Uinta Mountain Group -- Quartzite, Xqs Xfh conglomerate, and shale Xb Ralston Xb Xfh Xg Gore f ust ings - Yun Yun Yg Xfh Uncompahgre Formation -- Gray and green ault quartzite, slate, and phyllite Xg Idaho Spr Xfh Xg Ygf Xfh Yv Yv Vallecito Conglomerate -- Gray, crossbedded conglomerate and quartzite Xb Xfh Xb Xb Xb Xg Xb Yg Yg Xqs Granitic rocks of ~1.4 Ga age group -- Gray ault to pink, muscovite -- biotite or biotite granite Xg .z. e s and minor syenitic rocks Xb Ygf Yg Mosquito f Ygf Foliated granodiorite of ~1.4 Ga age group -- Homestak Xb Ygp Gray, foliated granodiorite to monzogranite

London f Xb PALEOPROTEROZOIC (2,500 -- 1,600 Ma) Xg Xb ault Xg 39° 39° Xg Xg Xb Xg Granitic rocks of ~1.7 Ga age group -- Gray, equigranular to porphyritic, foliated to massive, Ygf granodiorite and associated intermediate rocks

Xg Xm Xm Mafic rocks of ~1.7 Ga age group -- Gabbro YgpColorado and diorite Xg Xg Ygf Yg Xqs Xfh Yg Ygf Xg Xb PALEOPROTEROZOIC GNEISS COMPLEX Xb Xg Springs Xqs Xqs .z. er s Xg Xb Xb Biotite gneiss and migmatite -- largely Xb Xfh Xfh Ygf kansas Riv Yg metasedimentary Ygf Ar Xg Xqs Xqs Quartzite and mica schist facies of Xb unit Xb Cimmaron - Red Roc Xg Xg Xfh Xqs Xfh Ygf Xfh Xfh Felsic and hornblendic gneisses -- largely ks s metavolcanic .z. Xfh Xfh Xg Iron Hill ARCHEAN (2,500 Ma and older) YgYg Xb Xg Wr Late Archean rocks -- Metaquartzite, mica Yu schist, amphibolite and tectonic slivers of Xg SAN JU . lineament 38° felsic gneiss in northwest corner of state. 38° Includes Paleoproterozoic continent-margin et Mtns W metasedimentary rocks. AN Xfh Yg V Xfh OLCANIC FIELD Needle Mtns - Xfh Contact, or limit of basement at surface

Xg Boundary between geologic units inferred from Creede Regional extent: subsurface data, including aeromagnetic data caldera Xfh .z. Yu Yu Apishapa f High-angle fault -- Solid where basement is at awcita s surface; dashed in subsurface Xfh F ault Xfh Yl Thrust fault - Sawteeth on upper plate; solid where Yg Perez, 2016 basement is at surface; dashed in subsurface

Precambrian ductile shear zone -- black in exposed Yv Xg Yg Yg areas; green in covered areas Durango Yg Xfh Shaord et al. 2015 Borehole to basement (after Tweto, 1987) Caldera boundary Xfh Yg Yg s.z. Shear zone Yu .z. Xg Jemez s Volcanic field – shown only to south of Yg Xb 37° Cimarron – Red Rocks shear zone 37° 102° 103° 109° 108° 104° 107° 106° 105° Surface exposures from Tweto, 1979. Uncompahgre Quartzite 0 10 20 30 40 50 Miles 0 10 20 3040 50 ca. 1.70 Ga (Jones et al. 2008) Kilometers Regional Comparison (pmag pole posion rules out Mz and Cz)

Comparison to detrital zircon age reference spectra for sedimentary units in western USA, of known Neoproterozoic age

*For datasets having K-S probability of correlaon > 0.40

Several comparison-pairs yield values as high as 0.77 to 0.96 !! Paleogeographic ? Windemere reconstrucon ~ 750 Ma 1- Uintah Mountain group 2- Chuar-GC 3- Pahrump Group 4- Tava (this study)

Sediments transported 1 across Laurena, quartz component 2 3 4 concentrated, and ‘fines’ winnowed out, prior to incorporaon in Tava sandstone.

ca. 750 Ma reconstrucon: Blakey, cpgeosystems.org Descriptive characteristics

! Poorly sorted, very fine to medium grained sand with dispersed rounded pebbles and quartz grains

! Massive structureless to weakly graded matrix- supported granules to pebbles (3mm to 5 cm)

! 95 to 98% quartz

! Tabular bodies within granite host

! Sandstone dikes and sills within Tava sandstone host

! At least two generations – unequivocal crosscutting

! Pronounced brittle structural overprint Scale of the system?

UTE PASS FAULT

Sawatch Sandstone Cambrian

FOUNTAIN Tava sandstone FORMATION Siddoway et al. 2013

UP DOWN

Woodland Park graben

Mount Decepon quadrangle Colorado Geological Survey Temple et al. 2007 Great Valley Sequence, California (Jurassic- Cretaceous)

Panoche Hills, CA

Deep-water sediment of the North Sea: remobilizaon structures imaged seismically Hurst et al. 2003, Geofluids hydroFRACKING ON A GRAND SCALE Reviews v 106, 2011

Units: m3

A “large injecte” involves 24,000,000 to 32,000,000 cubic meters of water and 52,000,000 to 60,000,000 cubic meters of sand !!!! Sandstone injectes manifestaon of high-velocity fluid flow of sand-rich layers interbedded with clay-rich successions within the shallow subsurface, typically < 500m of burial.

Conceptual scheme for formaon Summary of world examples

Add thrust- Loading Example?

Elevated pore fluid pressure arising from lithostac load

PROCESSES: liquefacon, remobilizaon, injecon * From survey of literature, one of this number is hosted by Jolly & Lonergan 2002 crystalline rocks, and is of comparable scale & extent. modern analogs?

• Christchurch, New Zealand • 2010 2011 • M4 to 7

Christchurch, New Zealand, hp://www.kuriositas.com/2012/07/ Some of these features plainly are intrusions: dikes and sills . Once emplaced, the sandstone provides a fluid migraon pathway granite

granite

margin

Planes of shear, parallel to margins

Buffalo Creek, CO, S of US285sufficient cohesion to fracture ; permeability low enough that a Host sandstone, “redox” paerns fluid flow gradient arises Detrital zircon probability density plot Moling, indicave of Migraon of reducing fluids (overpressure)

500 1000 1500 2000 2500 3000 4000 Tava Petrology

• Mature, quartz sandstone (>90% quartz) • Poorly sorted Cross polarized light, 40X magnificaon Well sorted = high porosity Poorly sorted = Low porosity

• Matrix = fine to medium grained sandstone(0.20-0.33 mm)

• Suspended pebbles (1-4 mm) Plane polarized light, 40X magnificaon Grain sorng Strand-like interpenetrang swirls formed during fluidized injecon of Tava sandstone into Pikes Peak Granite; evident Add scale from grain size variaons and degree of cementaon And label the type of illuminaon

Transmied light and surface illuminaon, 10X magnificaon Undergrad thesis of Alec Lee, 2015 Phanerozoic Hydrocarbons With further work and funding (!), may • Reducing Fluids: Hydrocarbons and petroleum reservoir brines? be able to – (Boron in SLT-6/DUPLX) determine sources

• Phanerozoic: HC from Denver Basin/Florence Oil Field? – n-alkane chains (n-C27,29,31) easily migrate/biodegrade – Gas/liquid hydrocarbons

hp://summons.mit.edu/biomarkers/biomarker-classificaon/lipids/isoprenoids/acyclic-and-cyclic-isoprenoids/

Neoproterozoic Hydrocarbons • Neoproterozoic: Remnant crystalline hydrocarbons? – Solid diamondoids (steranes, hopanes, carotenoids) » long lasng and hard to migrate – Trisnorhopane = euxinic condions in Neoproterozoic (sulfur metabolizing organisms?)

hp://summons.mit.edu/biomarkers/biomarker-classificaon/lipids/isoprenoids/polycyclic-isoprenoids-with-concatenated-ring-system/hopanoids/ Regional context, vesgial basins of Proterozoic

Las Animas Fm

Tillman Fm Debaca Fm Las Animas Fm in subsurface; Tillman in Wichita Upli (Tweto, 1976)

DeBaca Fm: Amarante et al. 2005, circa 1.26 Ga

Figure from Soreghan et 2012 Geosphere: Ancestral Rocky Mtns Dehler et al., 2010, GSAB Uinta

Tava Intraconnental deformaon, Chuar DZs (?) associated with Pahrump Rodinia breakup?

Tava, εHf -13 to -18, with few -20 to -23 (A. Hantsche, Feb. 2015)

Transport from south, from Llano? εHf for PPG, -20 to -27 (Howard 2013) εHf for Llano and Franklins, -21 to -27 (A. Hantsche, Feb. 2015) trigger mechanisms for injecon • seismic shaking • instantaneous loading • Wet-based glaciaon with glacial surges ice confined within bedrock channel Neoprot. snowball earth glaciaons • rapid migraon of pore water as a result of mineralogical phase changes (opal A to CT (Davies et al., 2006), or rapid migraon of hydrocarbon gas (Brooke et al., 1995). • decomposion of gas hydrates / instantaneous pore pressure excess

For sand remobilizaon by fluidizaon: stresses at grain-grain contacts must be low enough to be overcome by drag forces exerted by moving fluids burial depths < 500 m, ordinarily, and certainly < 1km. High strain-rate processes required, with development of overpressure (Jolly & Lonergan, 2002)

shallow (1.5 km) burial THANKS TO: W. Cross & W.O. Crosby Lizzy Fay & Sally Shaord Ma Rosales & Alec Lee Sergio Lopez & Cody Duckworth Sam Elkind Tyler Doane Mike Petronis, NMHU Jay Temple CGS - Vince Mahews Charloe Cadow Pearl & Bessie George Gehrels (intrepid Labradors) Mark Pecha David Freedman U Arizona Laserchron NMHU rock mag gang Anderson Cole Chuar and UMG authors Monty Swan

Siddoway et al. 2013, GSA Field Guides, Ch. 13 Opportunities for deeper insights - paleoenvironment

! Mature quartz sandstone / near-absence of other detritus

! Circumstances of weathering on Proterozoic vegetation-free landscape? (Dott, 2003) ! Elutriation of clay and silt component; “sanding in” of narrow fissures

! Source of fluid overpressure and cause of remobilization/injection* of inconceivable volume of sand and water ! Rodinia breakup / Fault controlled depocenter / rapid sedimentation (of supermature sandstone) ! Sturtian glaciation : warm-based glaciers to generate fluid and sediment (quartz sand possibly eroded from preexisting strata, e.g. Grand Canyon Supergroup-type)

• Variability in degree and type of interstitial cement --- variations in porosity ! Primary cement in dike array on Cheyenne Mountain: specularite More than once !! Crosscutting dikes ! Alteration, elsewhere: red/white mottling with friable texture: evidence of migration of reducing fluids ? Relationship to late Paleozoic remagnetization event ? (Geissman and Harlan 2002 - attribute to regional scale fluids migration) • Potential for atmosphere or groundwater record: Fe or sulfur isotopes