Geology topics

Joseph M. Licciardi

Publications and source records attributed to Joseph M. Licciardi.

9 recordsLinked to original sources

USGS2018

Pleistocene glaciation of the Jackson Hole area, Wyoming

Pleistocene glaciations and late Cenozoic offset on the Teton fault have played central roles in shaping the scenic landscapes of the Teton Range and Jackson Hole area in Wyoming. The Teton Range harbored a system of mountain-valley glaciers that produced the striking geomorphic features in these mountains. However, the comparatively much larger southern sector of the Greater Yellowstone glacial system (GYGS) is responsible for creating the more expansive glacial landforms and deposits that dominate Jackson Hole. The glacial history is also inextricably associated with the Yellowstone hotspot, which caused two conditions that have fostered extensive glaciation: (1) uplift and consequent cold temperatures in greater Yellowstone; and (2) the lowland track of the hotspot (eastern Snake River Plain) that funneled moisture to the Yellowstone Plateau and the Yellowstone Crescent of High Terrain (YCHT). The penultimate (Bull Lake) glaciation filled all of Jackson Hole with glacial ice. Granitic boulders on moraines beyond the south end of Jackson Hole have cosmogenic 10Be exposure ages of ~150 thousand years ago (ka) and correlate with Marine Isotope Stage 6. A thick loess mantle subdues the topography of Bull Lake moraines and caps Bull Lake outwash terraces with a reddish buried soil near the base of the loess having a Bk horizon that extends down into the outwash gravel. The Bull Lake glaciation of Jackson Hole extended 48 kilometers (km) farther south than the Pinedale, representing the largest separation of these two glacial positions in the Western United States. The Bull Lake is also more extensive than the Pinedale on the west (22 km) and southwest (23 km) margins of the GYGS but not on the north and east. This pattern is explained by uplift and subsidence on the leading and trailing “bow-wave” of the YCHT, respectively. During the last (Pinedale) glaciation, mountain-valley glaciers of the Teton Range extended to the western edge of Jackson Hole and built bouldery moraines that commonly enclose lakes. On the southern margin of the GYGS, prominent glacial outwash terraces define three phases of the Pinedale glaciation in Jackson Hole: Pinedale-1 (Pd-1) by Antelope Flats with subdued channel patterns on the east side of Jackson Hole; Pinedale-2 (Pd-2) by a large outwash fan that includes Baseline Flat on the west side of Jackson Hole with well-defined channel patterns; and Pinedale-3 (Pd-3) by The Potholes and other outwash fans farther up the Snake River in central Jackson Hole. During Pinedale glaciation, three glacial lobes of the GYGS fed into Jackson Hole, and the relative importance of these lobes changed dramatically through time. During the Pd-1 glaciation, the eastern Buffalo Fork lobe dominated whereas in Pd-2 and Pd-3 time the northern Snake River lobe dominated. This is consistent with migration of the GYGS center of ice mass westward and southward as glaciers built up towards the moisture source provided by storms moving northeastward up the eastern Snake River Plain. The recession of the eastern Buffalo Fork lobe in Pd-2 and Pd-3 times is consistent with an enlarged ice mass on the Yellowstone Plateau that placed the eastern part of the GYGS in a precipitation or snow shadow. In Pd-1 time, the Buffalo Fork lobe reached its maximum extent and was joined by the Pacific Creek lobe. This culmination may correlate with the ~21–18 ka ages of moraines in the Teton Range and nearby ranges. Three subdivisions of Pd-1 glaciation built moraines that are nearly or entirely covered by outwash almost 100 meters thick. In Pd-2 time, the Snake River lobe joined with the Pacific Creek lobe and built a large outwash fan south of the present-day Jackson Lake. Boulders on a moraine at the head of this fan are dated to 15.5 ± 0.5 ka. The relation between Teton glaciers and those of the GYGS is indicated by outwash from these Pd-2 moraines that partly buries outer Jenny Lake moraines dated to 15.2 ± 0.7 ka. East of the large outwash fan, Pd-2 ice advanced across the glacial-age Triangle X-2 lake sediments, perhaps in a surge. The Buffalo Fork lobe retreated more than 20 km up valley from its Pd-1 position and Pd-2 ice of the Snake River and Pacific Creek lobes advanced into the area previously occupied by the Buffalo Fork lobe. The Pd-3 position flanks the margin of Jackson Lake and represents a retreat to a stable position after the Pd-2 7-km advance that may have been a surge across the Triangle X-2 lake sediments. The Potholes and South Landing outwash fans were built in the area deglaciated by the retreat from Pd-2 to Pd-3 time. The Spalding Bay outwash fan continued to incise and a meltwater stream flowed just outside the Teton glacier that filled the present Jenny Lake and deposited the 14.4 ± 0.8 ka inner Jenny Lake moraines. Glacial outwash terraces increase in slope toward their respective moraines of the GYGS and are complex in both north-south and east-west directions. The Pd-1 terrace slopes to the west where it is buried by the Pd-2 outwash. The post-depositional tilting of the Pd-1 outwash terrace is an order of magnitude smaller than the original westward depositional slope. The Pd-1, 2, and 3 terraces have a shingle-like geometry such that the highest terrace decreases in age down valley, and in southern Jackson Hole, the Pd-3 terrace is only 3–5 m above the Snake River. In Pd-1 time the combined Buffalo Fork and Pacific Creek lobes scoured out four basins: (1) Emma Matilda Lake; (2) Two Ocean Lake; (3) a deep basin from lower Pacific Creek to beneath the Oxbows and Jackson Lake Dam; and (4) the largest basin from the lower Buffalo Fork to Deadmans Bar of the Snake River. These basins are largely filled with fine-grained sediment and are now marked by moist lowlands or lakes. In Pd-2 and Pd-3 time the Snake River lobe scoured the present 120-m deep Jackson Lake and possibly the 120-m deeper sediment-filled basin. Subglacial erosion of the Jackson Lake basin by confined water jets is supported by eskers that climb up to the head of the South Landing outwash fan.

Wyoming↗

USGS2018

History and dynamics of the Greater Yellowstone Glacial System during the last two glaciations

The Greater Yellowstone Glacial System (GYGS) covered about 20,000 km2 at its maximum Pleistocene extent. The initiation, culmination, and ultimate decay of the GYGS involved complex interactions between several coalescent ice masses flowing from glacial source areas adjoining and including the Yellowstone Plateau. Here, we present an updated review of the history and dynamics of the GYGS during the penultimate (Bull Lake) and last (Pinedale) glaciations, drawing upon an integration of glacial-geologic mapping with >130 cosmogenic 10Be and 3He exposure ages. Bull Lake glacial deposits in greater Yellowstone are dated to ca. 150–140 ka and correlate with marine isotope stage 6. The Bull Lake glaciation extended well beyond the Pinedale along the southern and western GYGS margins, but Pinedale glaciers overrode Bull Lake ice limits on the north and east sides. The northeastward shift of the center of ice mass from Bull Lake to Pinedale time may be explained by uplift on the leading edge of the Yellowstone hotspot and subsidence on the trailing margin. In early Pinedale time (∼22–18 ka), ice buildup culminated in the high terrain of the Beartooth Uplift and High Absaroka Range. Glaciers from these source regions flowed onto the northeastern margin of the Yellowstone Plateau and advanced to terminal moraines beyond Clarks Fork Canyon and in Jackson Hole. By middle Pinedale time (∼18–16 ka), the Yellowstone Plateau ice cap surface had risen above the equilibrium-line altitude, stimulating orographic glacial buildup nourished by storms funneled eastward through the Snake River Plain. The plateau ice cap eventually thickened to >1000 m and joined glaciers from the Beartooth Uplift and Gallatin Range to form the northern Yellowstone outlet glacier. Terrain east and downwind of the ice cap crest was placed in a precipitation shadow, resulting in glacial recession in these regions. During the late Pinedale (∼16–13 ka), the plateau ice cap prograded southwestward toward the direction of moisture supply, leading to advances along the southern and western margins of the GYGS. Northern sectors of the plateau ice cap were nearly stagnant at this time. The Yellowstone region experienced widespread deglaciation ca. 15–14 ka in response to warming climate. Unloading of the ∼1 km-thick plateau ice cap and consequent release of pressure on the magmatic system beneath Yellowstone was not accompanied by volcanism, indicating that the magma chamber was not primed to erupt via decompression during the last deglaciation.

Idaho, Montana Wyoming↗

USGS2018

Geomorphic expression of rapid Holocene silicic magma reservoir growth beneath Laguna del Maule, Chile

Large rhyolitic volcanoes pose a hazard, yet the processes and signals foretelling an eruption are obscure. Satellite geodesy has revealed surface inflation signaling unrest within magma reservoirs underlying a few rhyolitic volcanoes. Although seismic, electrical, and potential field methods may illuminate the current configuration and state of these reservoirs, they cannot fully address the processes by which they grow and evolve on geologic time scales. We combine measurement of a deformed paleoshore surface, isotopic dating of volcanism and surface exposure, and modeling to determine the rate of growth of a rhyolite-producing magma reservoir. The numerical approach builds on a magma intrusion model developed to explain the current, decade-long, surface inflation at >20 cm/year. Assuming that the observed 62-m uplift reflects several non-eruptive intrusions of magma, each similar to the unrest over the past decade, we find that ~13 km 3 of magma recharged the reservoir at a depth of ~7 km during the Holocene, accompanied by the eruption of ~9 km 3 of rhyolite. The long-term rate of magma input is consistent with reservoir freezing and pluton formation. Yet, the unique set of observations considered here implies that large reservoirs can be incubated and grow at shallow depth via episodic high-flux magma injections. These replenishment episodes likely drive rapid inflation, destabilize cooling systems, propel rhyolitic eruptions, and thus should be carefully monitored.

Laguna del Maule↗

USGS2017

A loess–paleosol record of climate and glacial history over the past two glacial–interglacial cycles (~ 150 ka), southern Jackson Hole, Wyoming

Loess accumulated on a Bull Lake outwash terrace of Marine Oxygen Isotope Stage 6 (MIS 6) age in southern Jackson Hole, Wyoming. The 9 m section displays eight intervals of loess deposition (Loess 1 to Loess 8, oldest), each followed by soil development. Our age-depth model is constrained by thermoluminescence, meteoric 10 Be accumulation in soils, and cosmogenic 10 Be surface exposure ages. We use particle size, geochemical, mineral-magnetic, and clay mineralogical data to interpret loess sources and pedogenesis. Deposition of MIS 6 loess was followed by a tripartite soil/thin loess complex (Soils 8, 7, and 6) apparently reflecting the large climatic oscillations of MIS 5. Soil 8 (MIS 5e) shows the strongest development. Loess 5 accumulated during a glacial interval (~ 76–69 ka; MIS 4) followed by soil development under conditions wetter and probably colder than present. Deposition of thick Loess 3 (~ 43–51 ka, MIS 3) was followed by soil development comparable with that observed in Soil 1. Loess 1 (MIS 2) accumulated during the Pinedale glaciation and was followed by development of Soil 1 under a semiarid climate. This record of alternating loess deposition and soil development is compatible with the history of Yellowstone vegetation and the glacial flour record from the Sierra Nevada.

Wyoming↗

USGS2016

Pinedale glacial history of the upper Arkansas River valley: New moraine chronologies, modeling results, and geologic mapping

This field-trip guide outlines the glacial history of the upper Arkansas River valley, Colorado, and builds on a previous GSA field trip to the area in 2010. The following will be presented: (1) new cosmogenic 10 Be exposure ages of moraine boulders from the Pinedale and Bull Lake glaciations (Marine Isotope Stages 2 and 6, respectively) located adjacent to the Twin Lakes Reservoir, (2) numerical modeling of glaciers during the Pinedale glaciation in major tributaries draining into the upper Arkansas River, (3) discharge estimates for glacial-lake outburst floods in the upper Arkansas River valley, and (4) 10 Be ages on flood boulders deposited downvalley from the moraine sequences. This research was stimulated by a new geologic map of the Granite 7.5′ quadrangle, in which the mapping of surficial deposits was revised based in part on the interpretation of newly acquired LiDAR data and field investigations. The new 10 Be ages of the Pinedale terminal moraine at Twin Lakes average 21.8 ± 0.7 ka ( n = 14), which adds to nearby Pinedale terminal moraine ages of 23.6 ± 1.4 ka ( n = 5), 20.5 ± 0.2 ka ( n = 3), and 16.6 ± 1.0 ka ( n = 7), and downvalley outburst flood terraces that date to 20.9 ± 0.9 ka ( n = 4) and 19.0 ± 0.6 ka ( n = 4). This growing chronology leads to improved understanding of the controls and timing of glaciation in the western United States, the modeling of glacial-lake outburst flooding, and the reconstruction of paleotemperature through glacier modeling.

Arkansas River valley↗

USGS2014

Glacial and Quaternary geology of the northern Yellowstone area, Montana and Wyoming

This field guide focuses on the glacial geology and paleoecology beginning in the Paradise Valley and progressing southward into northern Yellowstone National Park. During the last (Pinedale) glaciation, the northern Yellowstone outlet glacier flowed out of Yellowstone Park and down the Yellowstone River Valley into the Paradise Valley. The field trip will traverse the following Pinedale glacial sequence: (1) deposition of the Eightmile terminal moraines and outwash 16.5 ± 1.4 10Be ka in the Paradise Valley; (2) glacial recession of ~8 km and deposition of the Chico moraines and outwash 16.1 ± 1.7 10Be ka; (3) glacial recession of 45 km to near the northern Yellowstone boundary and moraine deposition during the Deckard Flats readjustment 14.2 ± 1.2 10Be ka; and (4) glacial recession of ~37 km and deposition of the Junction Butte moraines 15.2 ± 1.3 10Be ka (this age is a little too old based on the stratigraphic sequence). Yellowstone's northern range of sagebrush-grasslands and bison, elk, wolf, and bear inhabitants is founded on glacial moraines, sub-glacial till, and outwash deposited during the last glaciation. Floods released from glacially dammed lakes and a landslide-dammed lake punctuate this record. The glacial geologic reconstruction was evaluated by calculation of basal shear stress, and yielded the following values for flow pattern in plan view: strongly converging—1.21 ± 0.12 bars (n = 15); nearly uniform—1.04 ± 0.16 bars (n = 11); and strongly diverging—0.84 ± 0.14 bars (n = 16). Reconstructed mass balance yielded accumulation and ablation each of ~3 km3/yr, with glacial movement near the equilibrium line altitude dominated by basal sliding. Pollen and charcoal records from three lakes in northern Yellowstone provide information on the postglacial vegetation and fire history. Following glacial retreat, sparsely vegetated landscapes were colonized first by spruce parkland and then by closed subalpine forests. Regional fire activity increased significantly with the development of closed subalpine forests as a result of increased fuel biomass and warmer summers. Warm dry conditions prevailed at low elevations during the early Holocene, as indicated by the presence of steppe and open mixed conifer forest. At the same time, closed subalpine forests with low fire frequency were present at higher elevations, suggesting relatively wet summer conditions. Douglas fir populations expanded throughout northern Yellowstone in the middle Holocene as a result of effectively drier conditions than before, and a decline of mesophytic plant taxa during the late Holocene imply continued drying, even though fire frequency decreased in recent millennia.

Montana;Wyoming↗

USGS2003

Quaternary geology and ecology of the Greater Yellowstone area

This field guide focuses on the glacial geology, ecology, paleoecology, caldera unrest, and archeology in Yellowstone and Grand Teton national parks and vicinity (Fig. 1). Some previous field guides of Yellowstone are Locke et al. (1995) for the Yellowstone valley, Fournier et al. (1994) for hydrothermal and volcanic geology of Yellowstone, and Pierce and Good (1992) for the Quaternary of Jackson Hole. Non–technical overviews of Yellowstone and Grand Teton National Parks are Good and Pierce (1996) and Smith and Siegel (2000). Geologic maps are: Grand Teton (Love et al., 1992), and Yellowstone (bedrock and surficial geology (USGS, 1972a; 1972b). Christiansen (2001) extensively describes Yellowstone’s volcanic geology, and Pierce (1979) describes the glacial geology of the northern Yellowstone region. We suggest that you obtain detailed maps.

Idaho, Montana, Wyoming↗

USGS2001

Freshwater forcing of abrupt climate change during the last glaciation

Large millennial-scale fluctuations of the southern margin of the North American Laurentide Ice Sheet occurred during the last deglaciation, when the margin was located between about 43° and 49°N. Fluctuations of the ice margin triggered episodic increases in the flux of freshwater to the North Atlantic by rerouting continental runoff from the Mississippi River drainage to the Hudson or St. Lawrence Rivers. We found that periods of increased freshwater flow to the North Atlantic occurred at the same time as reductions in the formation of North Atlantic Deep Water, thus providing a mechanism for observed climate variability that may be generally characteristic of times of intermediate global ice volume.

Science↗

USGS2001

Cosmogenic 3He and 10Be chronologies of the late Pinedale northern Yellowstone ice cap, Montana, USA

Cosmogenic 3 He and 10 Be ages measured on surface boulders from the moraine sequence deposited by the northern outlet glacier of the Yellowstone ice cap indicate that the outlet glacier reached its terminal position at 16.5 ± 0.4 3 He ka and 16.2 ± 0.3 10 Be ka, respectively. Concordance of these ages supports the scaled production rates used for 3 He (118.6 ± 6.6 atoms · g −1 · yr −1 ) and 10 Be (5.1 ± 0.3 atoms · g −1 · yr −1 ) (±2σ at high latitudes at sea level). Two recessional moraines upvalley from the terminal moraine have mean ages of 15.7 ± 0.5 10 Be ka and 14.0 ± 0.4 10 Be ka, respectively, and a late-glacial flood bar was deposited at 13.7 ± 0.5 10 Be ka. These cosmogenic chronologies identify a late Pinedale glacial maximum in northern Yellowstone that is significantly younger than previously thought, and they suggest deglaciation of the Yellowstone plateau by ∼14 10 Be ka.

Montana↗