Provenance and paleogeography of the 25-17 Ma Rainbow Gardens Formation

Evidence for tectonic activity at ca. 19 Ma and internal drainage rather than throughgoing paleorivers on the southwestern Colorado Plateau

Melissa A. Lamb, L. Sue Beard, Malia Dragos, Andrew D. Hanson, Thomas A. Hickson, Mark Sitton, Paul J Umhoefer, Karl E. Karlstrom, Nelia Dunbar, William McIntosh

Research output: Contribution to journalArticle

Abstract

The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25-17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24-19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and detrital zircon data, to create a more detailed paleogeographic picture of the Lake Mead, Grand Wash Trough, and Hualapai Plateau region from 25 to 18 Ma. These data confirm that sediment was sourced primarily from Paleozoic strata exposed in surrounding Sevier and Laramide uplifts and active volcanic fields to the north. In addition, a distinctive signal of coarse sediment derived from Proterozoic crystalline basement first appeared in the southwestern corner of the basin ca. 25 Ma at the beginning of Rainbow Gardens Formation deposition and then prograded north and east ca. 19 Ma across the southern half of the basin. Regional thermochronologic data suggest that Cretaceous deposits likely blanketed the Lake Mead region by the end of Sevier thrusting. Post-Laramide northward cliffretreat offthe Kingman/Mogollon uplifts left a stepped erosion surface with progressively younger strata preserved northward, on which Rainbow Gardens Formation strata were deposited. Deposition of the Rainbow Gardens Formation in general and the 19 Ma progradational pulse in particular may reflect tectonic uplift events just prior to onset of rapid extension at 17 Ma, as supported by both thermochronology and sedimentary data. Data presented here negate the California and Arizona River hypotheses for an "old" Grand Canyon and also negate models wherein the Rainbow Gardens Formation was the depocenter for a 25-18 Ma Little Colorado paleoriver flowing west through East Kaibab paleocanyons. Instead, provenance and paleocurrent data suggest local to regional sources for deposition of the Rainbow Gardens Formation atop a stripped low-relief western Colorado Plateau surface and preclude any significant input from a regional throughgoing paleoriver entering the basin from the east or northeast.

Original languageEnglish (US)
Pages (from-to)1592-1617
Number of pages26
JournalGeosphere
Volume14
Issue number4
DOIs
StatePublished - Jan 1 2018

Fingerprint

paleogeography
rainbow
garden
provenance
plateau
drainage
tectonics
lake
uplift
conglomerate
canyon
basin
thermochronology
paleocurrent
depocenter
sediment
Proterozoic
trough
zircon
relief

ASJC Scopus subject areas

  • Geology
  • Stratigraphy

Cite this

Provenance and paleogeography of the 25-17 Ma Rainbow Gardens Formation : Evidence for tectonic activity at ca. 19 Ma and internal drainage rather than throughgoing paleorivers on the southwestern Colorado Plateau. / Lamb, Melissa A.; Beard, L. Sue; Dragos, Malia; Hanson, Andrew D.; Hickson, Thomas A.; Sitton, Mark; Umhoefer, Paul J; Karlstrom, Karl E.; Dunbar, Nelia; McIntosh, William.

In: Geosphere, Vol. 14, No. 4, 01.01.2018, p. 1592-1617.

Research output: Contribution to journalArticle

Lamb, Melissa A. ; Beard, L. Sue ; Dragos, Malia ; Hanson, Andrew D. ; Hickson, Thomas A. ; Sitton, Mark ; Umhoefer, Paul J ; Karlstrom, Karl E. ; Dunbar, Nelia ; McIntosh, William. / Provenance and paleogeography of the 25-17 Ma Rainbow Gardens Formation : Evidence for tectonic activity at ca. 19 Ma and internal drainage rather than throughgoing paleorivers on the southwestern Colorado Plateau. In: Geosphere. 2018 ; Vol. 14, No. 4. pp. 1592-1617.
@article{fae142d63b8c40fb9337a7c711443948,
title = "Provenance and paleogeography of the 25-17 Ma Rainbow Gardens Formation: Evidence for tectonic activity at ca. 19 Ma and internal drainage rather than throughgoing paleorivers on the southwestern Colorado Plateau",
abstract = "The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25-17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24-19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and detrital zircon data, to create a more detailed paleogeographic picture of the Lake Mead, Grand Wash Trough, and Hualapai Plateau region from 25 to 18 Ma. These data confirm that sediment was sourced primarily from Paleozoic strata exposed in surrounding Sevier and Laramide uplifts and active volcanic fields to the north. In addition, a distinctive signal of coarse sediment derived from Proterozoic crystalline basement first appeared in the southwestern corner of the basin ca. 25 Ma at the beginning of Rainbow Gardens Formation deposition and then prograded north and east ca. 19 Ma across the southern half of the basin. Regional thermochronologic data suggest that Cretaceous deposits likely blanketed the Lake Mead region by the end of Sevier thrusting. Post-Laramide northward cliffretreat offthe Kingman/Mogollon uplifts left a stepped erosion surface with progressively younger strata preserved northward, on which Rainbow Gardens Formation strata were deposited. Deposition of the Rainbow Gardens Formation in general and the 19 Ma progradational pulse in particular may reflect tectonic uplift events just prior to onset of rapid extension at 17 Ma, as supported by both thermochronology and sedimentary data. Data presented here negate the California and Arizona River hypotheses for an {"}old{"} Grand Canyon and also negate models wherein the Rainbow Gardens Formation was the depocenter for a 25-18 Ma Little Colorado paleoriver flowing west through East Kaibab paleocanyons. Instead, provenance and paleocurrent data suggest local to regional sources for deposition of the Rainbow Gardens Formation atop a stripped low-relief western Colorado Plateau surface and preclude any significant input from a regional throughgoing paleoriver entering the basin from the east or northeast.",
author = "Lamb, {Melissa A.} and Beard, {L. Sue} and Malia Dragos and Hanson, {Andrew D.} and Hickson, {Thomas A.} and Mark Sitton and Umhoefer, {Paul J} and Karlstrom, {Karl E.} and Nelia Dunbar and William McIntosh",
year = "2018",
month = "1",
day = "1",
doi = "10.1130/GES01127.1",
language = "English (US)",
volume = "14",
pages = "1592--1617",
journal = "Geosphere",
issn = "1553-040X",
publisher = "Geological Society of America",
number = "4",

}

TY - JOUR

T1 - Provenance and paleogeography of the 25-17 Ma Rainbow Gardens Formation

T2 - Evidence for tectonic activity at ca. 19 Ma and internal drainage rather than throughgoing paleorivers on the southwestern Colorado Plateau

AU - Lamb, Melissa A.

AU - Beard, L. Sue

AU - Dragos, Malia

AU - Hanson, Andrew D.

AU - Hickson, Thomas A.

AU - Sitton, Mark

AU - Umhoefer, Paul J

AU - Karlstrom, Karl E.

AU - Dunbar, Nelia

AU - McIntosh, William

PY - 2018/1/1

Y1 - 2018/1/1

N2 - The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25-17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24-19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and detrital zircon data, to create a more detailed paleogeographic picture of the Lake Mead, Grand Wash Trough, and Hualapai Plateau region from 25 to 18 Ma. These data confirm that sediment was sourced primarily from Paleozoic strata exposed in surrounding Sevier and Laramide uplifts and active volcanic fields to the north. In addition, a distinctive signal of coarse sediment derived from Proterozoic crystalline basement first appeared in the southwestern corner of the basin ca. 25 Ma at the beginning of Rainbow Gardens Formation deposition and then prograded north and east ca. 19 Ma across the southern half of the basin. Regional thermochronologic data suggest that Cretaceous deposits likely blanketed the Lake Mead region by the end of Sevier thrusting. Post-Laramide northward cliffretreat offthe Kingman/Mogollon uplifts left a stepped erosion surface with progressively younger strata preserved northward, on which Rainbow Gardens Formation strata were deposited. Deposition of the Rainbow Gardens Formation in general and the 19 Ma progradational pulse in particular may reflect tectonic uplift events just prior to onset of rapid extension at 17 Ma, as supported by both thermochronology and sedimentary data. Data presented here negate the California and Arizona River hypotheses for an "old" Grand Canyon and also negate models wherein the Rainbow Gardens Formation was the depocenter for a 25-18 Ma Little Colorado paleoriver flowing west through East Kaibab paleocanyons. Instead, provenance and paleocurrent data suggest local to regional sources for deposition of the Rainbow Gardens Formation atop a stripped low-relief western Colorado Plateau surface and preclude any significant input from a regional throughgoing paleoriver entering the basin from the east or northeast.

AB - The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25-17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24-19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and detrital zircon data, to create a more detailed paleogeographic picture of the Lake Mead, Grand Wash Trough, and Hualapai Plateau region from 25 to 18 Ma. These data confirm that sediment was sourced primarily from Paleozoic strata exposed in surrounding Sevier and Laramide uplifts and active volcanic fields to the north. In addition, a distinctive signal of coarse sediment derived from Proterozoic crystalline basement first appeared in the southwestern corner of the basin ca. 25 Ma at the beginning of Rainbow Gardens Formation deposition and then prograded north and east ca. 19 Ma across the southern half of the basin. Regional thermochronologic data suggest that Cretaceous deposits likely blanketed the Lake Mead region by the end of Sevier thrusting. Post-Laramide northward cliffretreat offthe Kingman/Mogollon uplifts left a stepped erosion surface with progressively younger strata preserved northward, on which Rainbow Gardens Formation strata were deposited. Deposition of the Rainbow Gardens Formation in general and the 19 Ma progradational pulse in particular may reflect tectonic uplift events just prior to onset of rapid extension at 17 Ma, as supported by both thermochronology and sedimentary data. Data presented here negate the California and Arizona River hypotheses for an "old" Grand Canyon and also negate models wherein the Rainbow Gardens Formation was the depocenter for a 25-18 Ma Little Colorado paleoriver flowing west through East Kaibab paleocanyons. Instead, provenance and paleocurrent data suggest local to regional sources for deposition of the Rainbow Gardens Formation atop a stripped low-relief western Colorado Plateau surface and preclude any significant input from a regional throughgoing paleoriver entering the basin from the east or northeast.

UR - http://www.scopus.com/inward/record.url?scp=85051110548&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85051110548&partnerID=8YFLogxK

U2 - 10.1130/GES01127.1

DO - 10.1130/GES01127.1

M3 - Article

VL - 14

SP - 1592

EP - 1617

JO - Geosphere

JF - Geosphere

SN - 1553-040X

IS - 4

ER -