Peter W. Lipman

• PhD, Stanford U, 1962
• Professor Emeritus at United States Geological Survey

This contribution provides in-situ LA-ICP-MS U-Pb ages and trace element determinations of zircons from dacitic to rhyolitic lavas, ignimbrites and intrusions in the Southern Rocky Mountain Volcanic Field (SRMVF) in Colorado, USA. The data record a period of intense magmatic activity in the Oligocene-early Miocene (∼37-22 Ma) which gave rise to som...

Clusters of early central volcanoes in the mid-Cenozoic Southern Rocky Mountain volcanic field (SRMVF; southwestern Colorado, USA) record sites of initial magmatic focusing that led to assembly of sizable upper-crustal magma bodies capable of generating large ignimbrites. Peak growth at precursor andesitic volcanoes was followed by extended periods...

The Oligocene Platoro caldera complex of the San Juan volcanic locus in Colorado (USA) features numerous exposed plutons both within the caldera and outside its margins, enabling investigation of the timing and evolution of postcaldera magmatism. Intrusion whole-rock geochemistry and phenocryst and/or mineral trace element compositions coupled with...

The last four caldera-forming ignimbrites in the central San Juan caldera cluster, Colorado, erupted 1,400 km3 in ≤ 80 k.y. and alternated between zoned crystal-poor rhyolite to crystal-rich dacite and unzoned, crystal-rich dacite. The zoned 150 km3 Rat Creek Tuff (26.91 Ma), unzoned 250 km3 Cebolla Creek Tuff, and zoned 500 km3 Nelson Mountain Tuf...

Many eroded calderas expose associated postcollapse plutons, but detailed fieldwork-supported studies have rarely focused on the internal structure that can contribute to understanding of emplacement dynamics. The Alamosa River monzonite pluton is a postcollapse intrusion at the Platoro caldera complex that erupted six large ignimbrites between 30....

Large-volume silicic volcanism poses global hazards in the form of proximal pyroclastic density currents, distal ash fall and short-term climate perturbations, which altogether warrant the study of how silicic magma bodies evolve and assemble. The southern rocky mountain volcanic field (SRMVF) is home to some of the largest super-eruptions in the g...

Radial and linear dike swarms in the eroded roots of volcanoes and along rift zones are sensitive structural indicators of conduit and eruption geometry that can record regional paleostress orientations. Compositionally diverse dikes and larger intrusions that radiate westward from the polycyclic Platoro caldera complex in the Southern Rocky Mounta...

Diverse welding, crystallization, and structural features develop when a hot ignimbrite encounters external water, depending largely on volatile-rock ratios. Such processes are spectacularly documented by a regional ignimbrite where it ponded within an older caldera in the San Juan Mountains, Colorado (USA). Interaction of hot pyroclastic flows wit...

The multicyclic Platoro caldera complex (~30.1–28.4 Ma) located in the Southern Rocky Mountain volcanic field (Colorado) hosts several post-collapse intrusions. The largest intrusion, the ~9 × 4 km, ~NE–SW trending subvolcanic Alamosa River pluton, was emplaced into lavas and ignimbrites of the Platoro complex. We combine field mapping, petrography...

This presentation focused on new trace element zircon data.

This presentation focused on the cross correlation of cathodoluminescence zonation profiles in zircon.

Determining the mechanisms involved in generating large-volume eruptions (>100 km³) of silicic magma with crystallinities approaching rheological lock-up (~50 vol% crystals) remains a challenge for volcanologists. The Cenozoic Southern Rocky Mountain volcanic field, in Colorado and northernmost New Mexico, USA, produced ten such crystal-rich ignimb...

In continental-margin subduction zones, basalt magmas spawned in the mantle interact with the crust to produce a broad spectrum of volcanic arc associations. A distinct style of very voluminous arc volcanism develops far inland on thick crust over periods of 10-20 m.y. and involves relatively infrequent caldera-forming explosive eruptions of domina...

Among large ignimbrites, the Bonanza Tuff and its source caldera in the Southern Rocky Mountain volcanic field display diverse depositional and structural features that provide special insights concerning eruptive processes and caldera development. In contrast to the nested loci for successive ignimbrite eruptions at many large multicyclic calderas...

Multistage histories of incremental accumulation, fractionation, and solidification during construction of large subvolcanic magma bodies that remained sufficiently liquidto erupt are recorded by Tertiary ignimbrites, source calderas, and granitoid intrusions associated with large gravity lows at the Southern Rocky Mountain volcanic field (SRMVF)....

The *1,000 km 3 Carpenter Ridge Tuff (CRT), erupted at 27.55 Ma during the mid-tertiary ignimbrite flare-up in the western USA, is among the largest known strongly zoned ash-flow tuffs. It consists primarily of densely welded crystal-poor rhyolite with a pronounced, highly evolved chemical signature (high Rb/Sr, low Ba, Zr, Eu), but thickly ponded...

Recent ocean-bottom geophysical surveys, dredging, and dives, which complement surface data and scientifi c drilling at the Island of Hawaii, document that evolutionary stages during volcano growth are more diverse than previously described. Based on combining available composition, isotopic age, and geologically constrained volume data for each of...

The Southern Rocky Mountain volcanic fi eld contains widespread andesite and dacitic lavas erupted from central volcanoes; associated with these are ~26 regional ignimbrites (each 150–5000 km3) emplaced from 37 to 23 Ma, source calderas as much as 75 km across, and subvolcanic plutons. Exposed plutons vary in composition and size from small roof-zo...

This map was first published as a printed edition in 1989. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. This map encompasses all or parts of ten 7.5 minute quadrangles in the Taos Range of the Sangre de Cristo Mountains in northern New Mexico....

Transitional-composition pillow basalts from the toe of the Hilo Ridge, collected from outcrop by submersible, have yielded the oldest ages known from the Island of Hawaii: 1138 +/- 34 to 1159 +/- 33 ka. Hilo Ridge has long been interpreted as a submarine rift zone of Mauna Kea, but the new ages validate proposals that it is the distal east rift zo...

Andesitic to rhyolitic volcanic rocks of the San Juan Mountains, along with associated epithermal ores, were studied intensively during the twentieth century (e.g., Larsen and Cross 1956), culminating with detailed study of the Creede Mining District by Steven and Ratté (1965) as well as regional field and volcanological studies (Lipman, Steven, an...

Recent geologic mapping, high-precision single-crystal sanidine 40Ar-39Ar ages, and petrologic data for eruptive products from the Southern Rocky Mountain Volcanic Field (SRMVF, 37-23 Ma) demonstrate that many individual ignimbrite caldera cycles, including precursor activity and post-caldera lavas and intrusions, were completed in notably brief ti...

In the early 1960s, new concepts and innovative techniques coalesced spectacularly to improve understanding of Tertiary pyroclastic volcanism in North America. Spotty recognition of welded tuff, among rocks mostly described as silicic lava flows, exploded with identification of individual ignimbrite sheets, some having volumes >103 km3 and extendin...

The Bonanza caldera (NE San Juan Mountains, Southern Rocky Mountain Volcanic Field), source of a compositionally complex regional ignimbrite sheet erupted at 33.19±0.04 Ma*, is a subequant resurgently domed structure of much larger size (~20 km diameter), subsidence depth (>3 km), and eruptive volume (>1,000 km3) than previously recognized. In the...

The northeastern San Juan Mountains, the least studied portion of this well-known segment of the Southern Rocky Mountains Volcanic Field are the site of several newly identified and reinterpreted ignimbrite calderas. These calderas document some unique eruptive features not described before from large volcanic systems elsewhere, as based on recent...

Granitic intrusions, ranging from small plugs coring precursor stratocones to composite batholith-scale bodies, are exceptionally exposed within and adjacent to the numerous Tertiary calderas (37-23 Ma) of the Southern Rocky Mountain volcanic field (SRMVF), as result of high regional topography, large-scale faulting associated with the Rio Grande r...

While the linkage between Cordilleran plutonism and volcanism remains debated, data for large silicic volcanic fields (LSVF) document informative space-time-composition parallels. The comparable dimensions and spacing of centers and similar petrological and geochemical characteristics support the view that, like Cordilleran batholiths, LSVF are com...

The stratigraphy of the Oligocene San Luis Caldera Complex comprises three voluminous tuffs issued from overlapping calderas and numerous, compositionally diverse pre- and post-caldera lavas. The entire complex was erupted over an amazingly short period of 50-100 k.y. From oldest to youngest, the tuffs are the Rat Creek Tuff (>150 km3) that ranges...

Recent inference that Mesozoic Cordilleran plutons grew incrementally during >106 yr intervals, without the presence of voluminous eruptible magma at any stage, minimizes close associations with large ignimbrite calderas. Alternatively, Tertiary ignimbrites in the Rocky Mountains and elsewhere, with volumes of 1-5 × 103 km3, record multistage histo...

High-resolution single-crystal laser-fusion 40Ar/39Ar age determinations on sanidine phenocrysts document sequential eruption of four multi-hundred cubic-kilometer ignimbrites and associated lavas flows from calderas in the central San Juan Mountains, Colorado within a cumulative time interval of less than 50-100 ka. The tight recurrence interval w...

The North Kona slump is an elliptical region, about 20 by 60 km (1000-km2 area), of multiple, geometrically intricate benches and scarps, mostly at water depths of 2000–4500 m, on the west flank of Hualalai Volcano. Two dives up steep scarps in the slump area were made in September 2001, using the ROV Kaiko of the Japan Marine Science and Technolog...

Major-element and volatile (H2O, CO2, S) compositions of glasses from the submarine flanks of Kilauea Volcano record its growth from pre-shield into tholeiite shield-stage. Pillow lavas of mildly alkalic basalt at 2600–1900 mbsl on the upper slope of the south flank are an intermediate link between deeper alkalic volcaniclastics and the modern thol...

Compositional and age data from offshore pillow lavas and volcaniclastic sediments, along with on-land geologic, seismic, and deformation data, provide broad perspectives on the early growth of Kilauea Volcano and the long-term geometric evolution of its rift zones. Sulfur-rich glass rinds on pillow lavas and volcaniclastic sediments derived from t...

Submarine lavas recovered from the Hilina bench region, offshore Kilauea, Hawaii Island provide information on ancient Kilauea volcano and the geochemical components of the Hawaiian hotspot. Alkalic lavas, including nephelinite, basanite, hawaiite, and alkali basalt, dominate the earliest stage of Kilauea magmatism. Transitional basalt pillow lavas...

To evaluate physical and chemical diversity in submarine basaltic rocks, approximately 280 deep submarine samples recovered by submersibles from the underwater flanks of the Hawaiian Islands were analyzed and compared. Based on observations from the submersibles and hand specimens, these samples were classified into three main occurrence types (lav...

Locally, voluminous andesitic volcanism both preceded and followed large eruptions of silicic ash-flow tuff from many calderas in the San Juan volcanic field. The most voluminous post-collapse lava suite of the central San Juan caldera cluster is the 28 Ma Huerto Andesite, a diverse assemblage erupted from at least 5–6 volcanic centres that were ac...

Submarine lavas recovered from the Hilina bench region, offshore Kilauea, Hawaii Island provide information on ancient Kilauea volcano and the geochemical components of the Hawaiian hotspot. Alkalic lavas, including nephelinite, basanite, hawaiite, and alkali basalt, dominate the earliest stage of Kilauea magmatism. Transitional basalt pillow lavas...

Emplacement of a giant submarine slide complex, offshore of South Kona, Hawaii Island, was investigated in 2001 by visual observation and in-situ sampling on the bench scarp and a megablock, during two dives utilizing the Remotely Operated Vehicle (ROV) Kaiko and its mother ship R/V Kairei. Topography of the bench scarp and megablocks were defined...

Emplacement of a giant submarine slide complex , offshore of South Kona, Hawaii Island, was investigated in 2001 by visual observation and in-situ sampling on the bench scarp and a megablock, during two dives utilizing the Remotely Operated Vehicle (ROV) Kaiko and its mother ship R/V Kairei. Topography of the bench scarp and megablocks were defined...

Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from JAMSTEC submersibles (Japan Marine Science and Technology Center) show that prominent benches at mid-depths on flanks of both Mauna Loa and Kilauea consist of volcanicl...

Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from submersibles show that prominent benches at middepths on flanks of Mauna Loa and Kilauea consist of volcaniclastic debris derived by landsliding from nearby shallow sub...

Submarine-flank deposits of Hawaiian volcanoes are widely recognized to have formed largely by gravitationally driven volcano spreading and associated landsliding. Observations from submersibles show that prominent benches at middepths on flanks of Mauna Loa and Kı ¯lauea consist of volcaniclastic debris derived by landsliding from nearby shallow s...

Lava samples recovered from off-shore Hawaii Island, using remote and manned submersibles during JAMSTEC cruises in 1998, 1999, and 2001, were analyzed for major and trace elements. On the scarp below the Hilina bench (~ 3000 m bmsl), clasts of alkali and transitional basalt were recovered from debris-flow breccias, but tholeiite basalt of modern K...

More than 5000 km3 of nearly compositionally homogeneous crystal-rich dacite (∼68 wt % SiO2: ∼45% Pl + Kfs + Qtz + Hbl + Bt + Spn + Mag + Ilm + Ap + Zrn + Po) erupted from the Fish Canyon magma body during three phases: (1) the pre-caldera Pagosa Peak Dacite (an unusual poorly fragmented pyroclastic deposit, ∼200 km3); (2) the syn-collapse Fish Can...

Joint Japan-USA cruises in 1998-99 explored and sampled the previously unstudied deep offshore region south of Kïlauea. Bathymetric features, dive observations, and recovered samples indicate that the 3-km-deep mid-slope bench, bounded seaward by a 2-km-high lower scarp, is underlain by massive turbidite sandstone and interbedded debris-flow brecci...

The midslope bench on the submarine south flank of Kilauea volcano consists of volcaniclastic breccias and sandstones shed from Mauna Loa and Kilauea. Highly alkalic clasts (alkali basalt to nephelinite and phonotephrite), previously dated between 275 and 130 ka, record early Kilauea volcanism. High S concentrations (>750 ppm) in clasts and many sa...

The deep submarine eastern flanks of Mauna Kea, Kohala, and Haleakala vol­ canoes were mapped for the first time with a multibeam bathymetric and sidescan sonar system during joint Japan-US cruises aboard the JAMSTEC vessel R/V Yokosuka in 1999. The Pololu slump off northeast Kohala is overlain by a car­ bonate platform in the shallow region and th...

In the summer of 1963, when a group of Japanese scientists arrived at the aged building of the Hawaiian Volcano Observatory, run by the U.S. Geological Survey, there began a program of cooperation and friendship between American and Japanese volcanologists that continues to the present. The late Professor Takeshi Minakami, a top volcano-physicist l...

The submarine Hilina region exposes a succession of magma compositions spanning the juvenile "Lō'ihi" through tholeiitic shield stages of Kīlauea volcano. Early products, preserved as glass grains and clasts in volcaniclastic rocks of the 3000 m deep Hilina bench, include nephelinite, basanite, phonotephrite, hawaiite, alkali basalt, transitional b...

The deep submarine eastern flanks of Mauna Kea, Kohala, and Haleakala volcanoes were mapped for the first time with a multibeam bathymetric and sidescan sonar system during joint Japan-US cruises aboard the JAMSTEC vessel R/V Yokosuka in 1999. The Pololu slump off northeast Kohala is overlain by a carbonate platform in the shallow region and the de...

Most slopes of the Hilina slump are steep, but local small benches, mantled by volcaniclastic sand and fine sediments, were sampled in 1998-1999 with ROV KAIKO and DSRV SHINKAI 6500. Most surficial glass sands on the Hilina slump have compositions of subaerially erupted Kilauea lava, which fragmented and quenched as they entered the sea. Samples fr...

Features of subaerial pahoehoe tumuli from Kilauea and Mauna Loa Volcanoes in Hawaii and subaqueous flow lobes from Loihi Seamount off Hawaii and north of Oahu Island document the controlling factors of flow-lobe formation. Studied subaerial flow-lobe tumuli consist of uplifted pahoehoe crust, formed from coalesced flow lobes. The south rift zone o...

On the south flank of Hawai'i Island, frequent eruptions, abundant earthquakes, and rapid ground deformation mark the current locus of volcanism along the Hawaiian Ridge. Kïlauea and Mauna Loa volcanoes are in a tholeiitic shield-building stage, erupting mainly on land. South of Kïlauea, Lö'ihi Seamount has erupted alkalic and transitional basalts...

Submersible observations and samples show that the lower south flank of Hawaii, offshore from Kilauea volcano and the active Hilina slump system, consists entirely of compositionally diverse volcaniclastic rocks; pillow lavas are confined to shallow slopes. Submarine-erupted basalt clasts have strongly variable alkalic and transitional basalt compo...

Remotely operated vehicle (ROV) KAIKO dives north of Oahu Island, Hawaii, and on the lower south rift zone of Loihi Seamount revealed diverse flow morphologies of submarine lava that correlate with slope and rate of lava delivery. Steep to moderate (>10°) slopes are covered with elongate pillows and narrow pahoehoe streams; bulbous pillows and smoo...

The Pagosa Peak Dacite is an unusual pyroclastic deposit that immediately predated eruption of the enormous Fish Canyon Tuff (∼5000 km³) from the La Garita caldera at 28 Ma. The Pagosa Peak Dacite is thick (to 1 km), voluminous (>200 km³), and has a high aspect ratio (1:50) similar to those of silicic lava flows. It contains a high proportion (40–6...

Hawaiian volcanoes are exceptional examples of intraplate hotspot volcanism. Hotspot volcanoes, which frequently host large eruptions and related earthquakes, flank-failure landslides, and associated tsunamis, can present severe hazards to populated regions. Many studies have focused on subaerial parts of Hawaiian volcanoes, but the deep-water flan...

Eruption of at least 8800 km3 of dacitic-rhyolitic magma as 9 major ash-flow sheets (individually 150-5000 km 3) was accompanied by recurrent caldera subsidence between 28.3 and about 26.5 Ma in the central San Juan Mountains, Colorado. Voluminous andesitic-dacitic lavas and breccias were erupted from central volcanoes prior to the ash-flow eruptio...

 Diverse subsidence geometries and collapse processes for ash-flow calderas are inferred to reflect varying sizes, roof geometries, and depths of the source magma chambers, in combination with prior volcanic and regional tectonic influences. Based largely on a review of features at eroded pre-Quaternary calderas, a continuum of geometries and subsi...