1) Conodont-based event stratigraphic study of mid-Late Devonian (Frasnian- Famennian, Kellwasser) mass extinction interval
Collaborative research with C.A. Sandberg, U.S. Geological Survey (USGS), W. Ziegler (deceased), E. Schindler, both Forschungsinstitut Senckenberg, and others on conodont-based event stratigraphic analysis of the mid-Late Devonian (Frasnian-Famennian, Kellwasser, ~364 Ma) biotic crisis interval, emphasizing integration of data from the western U.S. and Western Europe.  Selected publications include Morrow et al. (1995, 2004a), Morrow and Sandberg (1996), Sandberg et al. (1997, 2002), Bratton et al. (1999), and Morrow (2000).

2) Geologic history of Alamo Impact Event
Cooperative work with C.A. Sandberg, F.G. Poole, A.G. Harris, all USGS, J.E. Warme, Colorado School of Mines, and others on the conodont biostratigraphy, impact stratigraphy, and sedimentology of the mid-Frasnian (early Late Devonian, ~367 Ma), marine Alamo Impact Event, south-central Nevada and western Utah.  Recent research has focused on the offshore, deep-water, and distal effects of the impact event.  Selected publications include Sandberg et al. (1997, 2002), Morrow et al. (1998, 2001, 2002, 2003, 2004b, in press), and Morrow and Sandberg (2001, 2002, 2003a).

3) Devonian to Carboniferous depositional history and sequence stratigraphy
Collaborative research with C.A. Sandberg, F.G. Poole, W. Ziegler, and others describing and correlating Middle Devonian to Early Carboniferous depositional history and sequence and event stratigraphy, emphasizing sections in western U.S. and Western Europe.  Selected publications include Sandberg et al. (2001a, 2001b, 2002, 2003) and Morrow and Sandberg (2003b).

1) Mid-Late Devonian mass extinction publications:
Morrow, J.R., Sandberg, C.A., and Koeberl, C., 2004a, Late Devonian impacts, events, and extinctions — a paradigm for pre-Mesozoic Earth history:  Geological Society of America Abstracts with Programs, v. 36, in press.  [view]

Sandberg, C.A., Morrow, J.R., and Ziegler, W., 2002, Late Devonian sea-level changes, catastrophic events, and mass extinctions, in Koeberl, C., and MacLeod, K.G., eds., Catastrophic Events and Mass Extinctions: Impacts and Beyond:  Geological Society of America Special Paper 356, p. 473-487.  [view PDF file]

Morrow, J.R., 2000, Shelf-to-basin lithofacies and conodont paleoecology across Frasnian-Famennian (F-F, mid-Late Devonian) boundary, central Great Basin (western U.S.A.):  Courier Forschungsinstitut Senckenberg 219, Frankfurt a.M., 57 p.

Bratton, J.F., Berry, W.B.N., and Morrow, J.R., 1999, Anoxia pre-dates Frasnian-Famennian boundary mass extinction horizon in the Great Basin, USA:  Palaeogeography, Palaeoclimatology, Palaeoecology, v. 154, no. 3, p. 275-292.

Sandberg, C.A., Morrow, J.R., and Warme, J.E., 1997, Late Devonian Alamo impact event, global Kellwasser Events, and major eustatic events, eastern Great Basin, Nevada and Utah:  Brigham Young University Geology Studies, v. 42, pt. 1, p. 129-160.

Morrow, J.R., and Sandberg, C.A., 1996, Conodont faunal turnover and diversity changes through the Frasnian-Famennian (F/F) mass extinction and recovery episodes, in Repetski, J.E., ed., Sixth North American Paleontological Convention Abstracts of Papers:  The Paleontological Society Special Pub. No. 8, p. 284.

Morrow, J.R., Sandberg, C.A., and Schindler, E., 1995, Conodont diversity trends across the late Frasnian (mid-Late Devonian) mass extinction interval, Nevada and west Europe:  Geological Society of America Abstracts with Programs, v. 27, no. 4, p. 48.

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2) Alamo Impact Event publications:
Morrow, J.R., Sandberg, C.A., and Harris, A.G., Late Devonian Alamo Impact, southern Nevada, USA:  Evidence of size, marine site, and widespread effects:  Geological Society of America Special Paper 384, in press.

Morrow, J.R., Sandberg, C.A., and Harris, A.G., 2004b, New evidence on size and marine site of Late Devonian Alamo Impact, southern Nevada:  Geological Society of America Abstracts with Programs, v. 36, in press.  [view]

Morrow, J.R., Racki, G., and Malkowski, K., 2003, Timing of Frasnian (early Late Devonian) carbon isotopic and Alamo Impact events, southern Nevada:  Geological Society of America Abstracts with Programs, v. 35, v. 6.  [view]

Morrow, J.R., and Sandberg, C.A., 2003a, Late Devonian Alamo Event, Nevada, USA; Multiple evidence of an off-platform marine impact, in Papers Presented to Third International Conference on Large Meteorite Impacts, Nördlingen, Germany, LPI Contribution No. 1167, 2 p.  [view PDF file]

Morrow, J.R., and Sandberg, C.A., 2002, Distribution and characteristics of proximal to distal ejecta from Late Devonian Alamo Impact, Nevada:  Geological Society of America Abstracts with Programs, v. 34, no. 6, p. 543-544.  [view]

Morrow, J.R., Sandberg, C.A., and Poole, F.G., 2002, Deep-water deposits of Late Devonian Alamo Impact Breccia, northern Reveille and southern Hot Creek Ranges, Nevada:  Geological Society of America Abstracts with Programs, v. 34, no. 4, p. A-52.  [view]

Sandberg, C.A., Morrow, J.R., and Ziegler, W., 2002, Late Devonian sea-level changes, catastrophic events, and mass extinctions, in Koeberl, C., and MacLeod, K.G., eds., Catastrophic Events and Mass Extinctions: Impacts and Beyond:  Geological Society of America Special Paper 356, p. 473-487.  [view PDF file]

Morrow, J.R., and Sandberg, C.A., 2001, Distribution and characteristics of multi-sourced shock-metamorphosed quartz grains, Late Devonian Alamo Impact, Nevada, in Papers Presented to the 32nd Lunar and Planetary Science Conference, Houston, Texas, LPI Contribution No. 1080, 2 p.  [view PDF file]

Morrow, J.R., Sandberg, C.A., and Poole, F.G., 2001, New evidence for deeper water site of Late Devonian Alamo Impact, Nevada, in Papers Presented to the 32nd Lunar and Planetary Science Conference, Houston, Texas, LPI Contribution No. 1080, 2 p.  [view PDF file]

Morrow, J.R., Sandberg, C.A., Warme, J.E., and Kuehner, H.-C., 1998, Regional and possible global effects of sub-critical Late Devonian Alamo Impact Event, Southern Nevada, USA:  Journal of the British Interplanetary Society, v. 51, p. 451-460.

Sandberg, C.A., Morrow, J.R., and Warme, J.E., 1997, Late Devonian Alamo impact event, global Kellwasser Events, and major eustatic events, eastern Great Basin, Nevada and Utah:  Brigham Young University Geology Studies, v. 42, pt. 1, p. 129-160.

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3) Devonian to Carboniferous depositional history publications:
Morrow, J.R., and Sandberg, C.A., 2003b, Late Devonian sequence and event stratigraphy across the Frasnian-Famennian (F-F) boundary, Utah and Nevada, Chapter 10, in Harries, P.J., ed., High-Resolution Approaches in Stratigraphic Paleontology: Kluwar Academic Publishers, Dordrecht, The Netherlands, p. 351-419.

Sandberg, C.A., Morrow, J.R., Poole, F.G., and Ziegler, W., 2003, Middle Devonian to Early Carboniferous event stratigraphy of Devils Gate and Northern Antelope Range sections, Nevada, U.S.A.:  Courier Forschungsinstitut Senckenberg, Frankfurt, a.M., p. 187-207.

Sandberg, C.A., Morrow, J.R., and Poole, F.G., 2002, Middle to Upper Devonian basin-to-shelf correlations across the proto-Antler forebulge, central Nevada:  Geological Society of America Abstracts with Programs, v. 34, no. 4, p. A-52.  [view]

Sandberg, C.A., Morrow, J.R., and Poole, F.G., 2001a, Significance of type Devils Gate Limestone on Devonian proto-Antler forebulge, west of Eureka, Nevada, in Miller, M.S., and Walker, J.P., eds., Structure & Stratigraphy of the Eureka, Nevada, area:  2001 Fieldtrip Guidebook, Nevada Petroleum Society, Inc., Reno, Nevada, p. 59-71 [reprinted 2002].

Sandberg, C.A., Poole, F.G., and Morrow, J.R., 2001b, Construction and destruction of crinoidal mudmounds on Mississippian Antler forebulge, east of Eureka, Nevada, in Miller, M.S., and Walker, J.P., eds., Structure & Stratigraphy of the Eureka, Nevada, area:  2001 Fieldtrip Guidebook, Nevada Petroleum Society, Inc., Reno, Nevada, p. 25-42 [reprinted 2002].

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Conodont-based Frasnian-Famennian (mid-Late Devonian) boundary event stratigraphic framework for central Great Basin area, Nevada and Utah, showing selected important eustatic, depositional, biotic, and tectonic events (after Sandberg et al., 2002, 2003; Morrow and Sandberg, 2003b; and references therein).  KWL = interval of Kellwasser Limestone at type area in Germany.  Click image for larger view.

Late Frasnian microfossil conodont species of the pelagic genus Palmatolepis, central Great Basin, Nevada and Utah.  These specimens are 0.25-0.75 mm across (from Morrow, 2000).

Spindle diagrams showing changes of relative conodont generic abundances and sea level across the Frasnian-Famennian boundary, European and North American offshore localities (data in Morrow and Sandberg, 1996).  UKWL = interval of Upper Kellwasser Limestone at type area in Germany.  Click image for larger view.

Dark, anoxic Lower and Upper Kellwasser Limestone intervals beneath Frasnian-Famennian boundary (at 10-cm-tall photo scale), Kellwasser Valley, Germany.

10-cm-wide lens cap overlain by 1-m-thick interval of dark, anoxic siltstone underlying Frasnian-Famennian boundary, Devils Gate, Nevada.  This siltstone is equivalent in part to anoxic Upper Kellwasser Limestone of Western Europe (see Sandberg et al., 1997, 2003, for more information).

Partly restored paleotectonic map of Nevada and Utah during the early Frasnian (early Late Devonian), showing possible site of oceanic Alamo Impact (bullseye) relative to carbonate platform and distribution of resulting Alamo Breccia and related deposits.  Alamo Breccia Zones 1, 2, and 3 form semicircular pattern on ramp (Zone 1), outer carbonate platform (Zone 2), and peritidal, inner platform (Zone 3).  Also shows location of four deep-water channels of Alamo Breccia.  Selected major post-Breccia structural features: RMT, latest Devonian to Early Carboniferous Roberts Mountains thrust, and three Tertiary lineaments that affected distribution of Alamo Breccia - LVL, Las Vegas lineament; SKL, Silver King lineament; and PRL, Pancake Range lineament.  Other abbreviations indicate important measured sections (after Sandberg et al., 2002).  Click image for larger view.

Offshore, deep-water channel-fill of Alamo Breccia, which was erosively emplaced by the marine Alamo Impact Event.  Locality RMW (see map above), Hot Creek Range, Nevada.

Stratigraphic section of upper member of Fox Mountain Formation and lower part of Guilmette Formation, showing type section of Alamo Breccia Member, Hancock Summit, West Pahranagat Range, Nevada.  Also shows microfossil conodont biofacies and position of 24 conodont samples used to constrain the biostratigraphic age of the Breccia (from Sandberg et al., 1997).  Click image for larger view.

Shocked quartz grain from the Alamo Breccia, showing at least two sets of highly decorated Planar Deformation Features (PDFs).  Scale bar is 0.1 mm.

Plot of indexed PDFs in shocked quartz, based on combined data from six Alamo Breccia localities (from Morrow and Sandberg, 2001).  Click image for larger view.

University of Northern Colorado undergraduate research assistants Tom Hillman (L), Bryan Musgrave, and Kelly Jenkins (R), Alamo Impact project, 2001.

Resistant sandy, peloid-rich, allodapic limestone ledges of Fenstermaker Wash Formation within lower-slope Woodruff Formation, recording onset and development of proto-Antler forebulge, Northern Antelope Range, central Nevada (see Sandberg et al., 2001a, 2002, 2003).