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312:
284:
234:
487:
499:
216:
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The unit was first designated the Amalia
Formation in 1956 by P.F. McKinlay. As originally defined, it included basalt flows and sedimentary beds dating from before the Questa eruption. These were removed from the unit definition by Lipman in 1983, who restricted the unit to the densely welded tuff
391:
20–50 meters (66–164 feet) thick that extended as far as 45 kilometers (28 miles) to the southwest and 25 kilometers (16 miles) to the northeast. Within the caldera the tuff pooled to a depth of 1,000–2,000 meters (3,300–6,600 feet). The tuff appears to be a single cooling unit.
653:
Johnson, C.M.; Shannon, J.R.; Fridrich, C.J. (1989). "Roots of ignimbrite calderas: Batholithic plutonism, volcanism, and mineralization in the
Southern Rocky Mountains, Colorado and New Mexico".
738:
Zimmerer, M. J.; McIntosh, W. C. (May 18, 2012). "The geochronology of volcanic and plutonic rocks at the Questa caldera: Constraints on the origin of caldera-related silicic magmas".
624:
Johnson, Clark M.; Lipman, Peter W. (September 1988). "Origin of metaluminous and alkaline volcanic rocks of the Latir volcanic field, northern Rio Grande rift, New Mexico".
474:
486:
776:
498:
311:
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668:"The Miocene Questa Caldera, northern New Mexico; relation to batholith emplacement and associated molybdenum mineralization"
712:
786:
171:
178:
781:
456:
that formed the tuff was not generated in place in the upper crust. Isotope evidence suggests the original
747:
688:
633:
434:
that is nonwelded to partially welded and up to 30 meters (98 feet) thick. This contains up to 5%
505:
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136:
125:
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blocks up to 1,000 meters (0.62 miles) across. The tuff includes a lithic-rich lower
388:
239:
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29:
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content of 77-80% likely reflects some secondary silicification. It contains 10-20%
445:
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689:"Geologic map of the Latir volcanic field and adjacent areas, northern New Mexico"
439:
427:
411:
46:
119:
407:
383:), which erupted some 500–1,000 cubic kilometers (120–240 cu mi) of
221:
159:
91:
56:
713:"Geology of the Costilla and Latir Peak quadrangles, Taos County, New Mexico"
518:
outflow sheet from the Questa eruption and renamed the unit the Amalia Tuff.
193:
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96:
40:
33:
672:
The genesis of Rocky
Mountain ore deposits; changes with time and tectonics
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Exposure of intracaldera Amalia Tuff at mouth of
Cabresto Canyon
442:
rock fragments. This grades into the main bed of the formation.
372:
696:
552:
550:
548:
480:
Sample of Amalia Tuff from the type area, Amalia, New Mexico
460:
magma assimilated considerable crust material and underwent
720:
New Mexico Bureau of Mines and
Mineral Resources Bulletin
535:
533:
531:
655:
New Mexico Bureau of Mines and
Mineral Resources Memoir
426:
phenocrysts. The intracaldera tuff contains lenticular
371:
The Amalia Tuff is a weakly to densely welded ash-flow
568:
674:. Society of Exploration Geologists. pp. 133–148
579:
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356:
of 25.39 ± 0.04 million years, corresponding to the
504:A fragment of Amalia Tuff from an outcropping near
268:
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464:at a deeper level of the crust than that of the
422:, while the upper beds sometimes preserve sodic
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395:The tuff is silicic and alkaline, though its
8:
375:erupted during the formation of the Questa
539:
118:
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626:Contributions to Mineralogy and Petrology
414:tuff at the base of the main bed contain
607:
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740:Geological Society of America Bulletin
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687:Lipman, P.W.; Reed, J.C. Jr. (1989).
468:responsible for the Questa eruption.
7:
569:Johnson, Shannon & Fridrich 1989
318:
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124:Amalia Tuff at its type area, near
777:Paleogene formations of New Mexico
16:A geologic formation in New Mexico
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379:25.39 ± 0.04 million years ago (
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232:
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298:Amalia Tuff (the United States)
1:
301:Show map of the United States
557:Zimmerer & McIntosh 2012
448:of the tuffs and associated
146:2,500 m (8,200 ft)
803:
670:. In Babcock, J.W. (ed.).
387:. It originally formed an
596:Johnson & Lipman 1988
276:
117:
28:
513:History of investigation
410:. Rare occurrences of a
326:Amalia Tuff (New Mexico)
711:McKinlay, P.F. (1956).
540:Lipman & Reed 1989
348:exposed in and around
329:Show map of New Mexico
194:36.94583°N 105.46250°W
666:Lipman, P.W. (1983).
462:crystal fractionation
199:36.94583; -105.46250
787:Oligocene volcanism
752:2012GSAB..124.1394Z
638:1988CoMP..100..107J
190: /
30:Stratigraphic range
746:(7–8): 1394–1408.
646:10.1007/BF00399442
506:Petaca, New Mexico
350:Questa, New Mexico
346:geologic formation
255:Amalia Post Office
137:Geologic formation
126:Amalia, New Mexico
416:ferrohedenbergite
338:
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39:25.35–25.43
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760:10.1130/B30544.1
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632:(1): 107–128.
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389:outflow sheet
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729:November 11,
727:. Retrieved
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700:. Retrieved
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676:. Retrieved
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629:
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446:Ar-Ar dating
444:
394:
370:
341:
339:
269:Year defined
246:Type section
18:
584:Lipman 1983
440:Proterozoic
438:and sparse
428:megabreccia
412:vitrophyric
408:phenocrysts
367:Description
352:. It has a
342:Amalia Tuff
197: /
185:105°27′45″W
172:Coordinates
24:Amalia Tuff
771:Categories
661:: 275–302.
618:References
222:New Mexico
182:36°56′45″N
160:Ignimbrite
522:Footnotes
424:amphibole
358:Oligocene
251:Named for
151:Lithology
143:Thickness
34:Oligocene
702:July 26,
698:. I-1907
678:July 26,
458:basaltic
436:andesite
420:fayalite
261:Named by
166:Location
748:Bibcode
634:Bibcode
450:plutons
377:caldera
228:Country
156:Primary
108:↓
432:facies
401:quartz
397:silica
237:
219:
210:Region
716:(PDF)
692:(PDF)
454:magma
385:magma
361:epoch
344:is a
731:2020
704:2020
680:2020
418:and
403:and
373:tuff
340:The
272:1956
133:Type
47:PreꞒ
756:doi
744:124
642:doi
630:100
773::
754:.
742:.
724:42
722:.
718:.
694:.
659:46
657:.
640:.
628:.
576:^
547:^
530:^
381:Ma
363:.
97:Pg
41:Ma
32::
762:.
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636::
610:.
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571:.
559:.
542:.
102:N
92:K
87:J
82:T
77:P
72:C
67:D
62:S
57:O
52:Ꞓ
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
