Debris flows from small catchments of the Ma Ha Tuak Range, metropolitan Phoenix, Arizona

Dorn, Ronald I.

doi:10.1016/j.geomorph.2010.04.008

Cited by 14 publications

(12 citation statements)

References 72 publications

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“…Subsequent research (Liu, 1994;Liu and Dorn, 1996) developed VML as a geomorphic age determination tool in the Great Basin. The VML has now been used at various sites globally (Diaz et al, 2002;Lee and Bland, 2003;Dietzel et al, 2008;Zerboni, 2008;Dorn, 2010;Baied and Somonte, in press). The basic premise of this dating approach is that the formation of varnish microstratigraphy is mainly affected by regional and global climatic variations.…”

Section: Vml Datingmentioning

confidence: 99%

Millennial-scale varnish microlamination dating of late Pleistocene geomorphic features in the drylands of western USA

Liu

Broecker

2013

Geomorphology

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Varnish microlamination (VML) dating is a climate-based correlative age determination technique used to correlate and date various geomorphic features in deserts. In this study, we establish a generalized late Pleistocene (18-74 ka) millennial-scale microlamination sequence in fine-grained, fast-accumulating rock varnish for the drylands of western USA, radiometrically calibrate the sequence and correlate it with the δ 18 O record in the GISP2 Greenland ice core. We then use this climate-correlated varnish microstratigraphy to estimate surface exposure ages for radiometrically dated late Pleistocene geomorphic features in the study region. The VML dating of debris flow deposits on the Sehoo recessional shorelines of Lake Lahontan at the Jessup embayment of central Nevada yields a minimum-limiting age of 14.95-15.95 ka, in good agreement with a calibrated 14 C age of 15.22± 0.12 ka for the timing of the lake recession. The VML dating of a giant ejecta block on the rim of Meteor Crater in northern Arizona yields a minimum-limiting age of 49.15 ka, closely matching a thermoluminescence (TL) age of 49± 3 ka and slightly younger than a recently updated cosmogenic 36 Cl age of 56.0± 2.4 ka for the meteor impact event. The VML dating of distal Q2c fan surfaces on Hanaupah Canyon alluvial fan in Death Valley, California, yields a minimum-limiting age of 73.55 ka, in accord with cosmogenic 36 Cl depth-profile ages of 66+22/−14 ka and 72+ 24/−20 ka for the same fan deposits. The close agreement between the VML age estimates and the independently derived radiometric ages for these geomorphic features attests to the validity and reliability of millennial-scale VML dating. To further assess its potential in desert geomorphological research, we use the VML method to study alluvial-fan responses to millennial-scale climatic changes. The VML dating of a small tributary fan in Death Valley reveals two episodes of fan aggradation, one ceasing at 73.55-86.75 ka during the dry period of the last interglacial (MIS 5a) and the other finishing at 66.15 ka during the wet period of the last glacial (MIS 4). The VML and 36 Cl dating of the distal Q2c fan surfaces on Hanaupah Canyon fan reveal two episodes of large-scale fan aggradation ended at 72 + 24/− 20 ka and 73.55 ka during the wet period of MIS 4. Fanhead incision and associated within-channel or fantoe aggradation are found to take place during the relatively dry period of the glacial-to-interglacial climatic transition (12-24 ka) and the Holocene interglacial dry period (0-12 ka). These data indicate that, on the millennial to sub-Milankovitch timescale (~10 3-10 4 years), fan aggradation is a discrete sedimentational process under various climatic conditions. Because fan aggradation is ultimately controlled by the intensity and frequency of precipitation eventswhich in turn are modulated by major climatic oscillations such as Heinrich events, Dansgaard/Oeschger (DO) events, and glacial/interglacial shiftsthese major climatic changes could be the pacemaker of regionally contempor...

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Section: Vml Datingmentioning

confidence: 99%

Millennial-scale varnish microlamination dating of late Pleistocene geomorphic features in the drylands of western USA

Liu

Broecker

2013

Geomorphology

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“…Finding an abundance of lead in the uppermost varnish collected from the Four Corners region, interpreted to be from recent activity of coal-fired power plants (Wayne et al, 2006) or smelters (Spilde et al, 2007) also points to 20th century varnish accumulation. Similarly, research in metropolitan Phoenix has revealed an abundance of lead in the surface-most micron(s) of varnish (Dorn, 2010), likely from automotive pollution.…”

Section: Towards Resolving the Contradiction Of Heavy Metal Contaminamentioning

confidence: 99%

“…For at least three of these metal studies (Dorn, 1998;Fleisher et al, 1999;Dorn, 2010), the same subaerial type of rock varnish was collected and from the similar site context of surfaces exposed by erosion; these are the same sampling considerations as those studied for microlaminations . Thus, the apparent empirical contraction cannot be explained by analyzing different types of varnishes or by analyzing varnishes collected from different geomorphic contexts.…”

Section: Towards Resolving the Contradiction Of Heavy Metal Contaminamentioning

confidence: 99%

Spatial, temporal and geographic considerations of the problem of rock varnish diagenesis

Dorn

Krinsley

2011

Geomorphology

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“…Using the Holocene calibration of varnish microlaminae (Liu and Broecker, 2007), a study of varnish on debris flows in Phoenix, Arizona revealed that varnish can form one to two orders of magnitude faster in particularly mesic microenvironments; these mesic settings, however, favor acid-producing lithobionts that typically out-complete and end up eroding most of the varnish (Dorn, 2010). Fig.…”

Section: Introductionmentioning

confidence: 99%

Rock varnish in New York: An accelerated snapshot of accretionary processes

et al. 2012

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Debris flows from small catchments of the Ma Ha Tuak Range, metropolitan Phoenix, Arizona

Cited by 14 publications

References 72 publications

Millennial-scale varnish microlamination dating of late Pleistocene geomorphic features in the drylands of western USA

Millennial-scale varnish microlamination dating of late Pleistocene geomorphic features in the drylands of western USA

Spatial, temporal and geographic considerations of the problem of rock varnish diagenesis

Rock varnish in New York: An accelerated snapshot of accretionary processes

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