First published use as a term in the Medicine Bow Mountains, Carbon Co, WY, Northern Rocky Mountain region. Rocks called Phantom Lake in this report were included as part of Deep Lake Formation in earlier reports. Is best exposed south of Phantom Lake, T16N, R79W, and along North Fork of Rock Creek, T17N, R79W. Intent to name not stated. Designation of type locality not stated. Named presumably for Phantom Creek. Unconformably overlies Archean granitic rock. Unconformably underlies quartz pebble conglomerate of Magnolia Formation (named) of Deep Lake Group (revised). Divisible into: 1) lower Phantom Lake which includes metabasalt, mafic agglomerate, felsic tuff, felsic agglomerate, garnet schist, paraconglomerate and quartzite more than 2,600 ft thick; and 2) upper Phantom Lake which includes radioactive quartz-pebble conglomerate (oldest), arkosic quartzite, pebbly quartzite, pyritic black phyllite, micaceous quartzite, and metavolcanic rocks (4,921 to 6,562 ft thick). Is 6,600 ft thick in west part of area. In north part of area, may be 10,000 ft thick. Source area is to northeast. Tabular crossbeds in upper part. Some small scale crossbeds. Subaerial, fluvial, shallow- and quiet-water marine, volcanic deposit. Geologic map; stratigraphic table. Early Proterozoic age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Revised in that Phantom Lake Metamorphic Suite underlies the newly named Magnolia Formation of the Deep Lake Group in the Medicine Bow Mountains of Carbon Co, WY in the Northern Rocky Mountain region. Name changed from Phantom Lake Group (Karlstrom, unpub thesis, 19__?) to Phantom Lake Suite. Divided into two informally designated parts because of lack of continuous marker beds and complex deformation. Lower part rests on Archean basement and consists of metabasalt, felsic tuff, agglomerate, garnet schist, quartzite, and paraconglomerate. The overlying upper part has a basal arkosic conglomerate that is overlain by quartzite, phyllite, metabasalt, and volcaniclastics. Upper and lower contacts of suite not well understood. Upper contact with Magnolia may be an unconformity. Stratigraphic chart. Geologic map. Assigned to the interval between 2500 and 2000 m.y. or Proterozoic.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Archean rocks were deformed and metamorphosed near the end of the Archean. F1 folding in metasedimentary rocks of the Phantom Lake Metamorphic Suite appears to have been penecontemporaneous with intrusion of "Late" Archean granites in the northern Medicine Bow Mountains of Carbon Co, WY in the Northern Rocky Mountain region. A regional unconformity which separates the Phantom Lake from the overlying Proterozoic Deep Lake Group is well exposed in the cirque walls of Crater Lake in the Medicine Bows. Also basal conglomerate in the Magnolia Formation, basal formation of the overlying Deep Lake, contains clasts of the Phantom Lake. Age of suite is Archean, rather than Proterozoic, the age assigned in some earlier publications. Is more than 3 km thick, and contains about 40 percent volcanic and volcaniclastic rocks, and 40 percent mature siliciclastic rocks. Overlies Overland Creek Gneiss (to be defined). Divided into Stud Creek Volcaniclastics (base), Rock Mountain Conglomerate, Bow Quartzite, Colberg Metavolcanics, and Conical Peak Quartzite (top); all of these formations to be defined. Stratigraphic charts; geologic map.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Is crosscut by granitic plutons. Mapped in the Medicine Bow Mountains and Sierra Madre, Carbon Co, WY in the Northern Rocky Mountain region. In the Medicine Bow Mountains, Phantom Lake: 1) is in fault contact with the Late Archean Overland Creek Gneiss (new); 2) unconformably underlies Magnolia Formation of Deep Lake Group; 3) is divided into the newly named Stud Creek Metavolcaniclastics, Rock Mountain Conglomerate, Bow Quartzite, Colberg Metavolcanics, Conical Peak Quartzite; 4) is 2,400 to 5,180 m thick. Isoclinically folded. Metamorphosed to amphibolite facies. In the Sierra Madre, Phantom Lake: 1) unconformably above Late Archean Vulcan Mountain Metavolcanics; 2) unconformably underlies Magnolia Formation of Deep Creek Group; 3) is divided into the newly named Jack Creek Quartzite, Silver Lake Metavolcanics, Bridger Peak Quartzite; 4) is 1,410 to 2,610 m thick; 5) is tectonically thinned; similar to rocks of Medicine Bows except that metabasalts and tuffs are less abundant and metagraywacke and volcaniclastic rocks are more abundant. Geologic map; stratigraphic table. Sequence of formations in suite uncertain because of structural complexities. Late Archean age.

Source: GNU records (USGS DDS-6; Denver GNULEX).