Middle Jurassic to Early Cretaceous tectonic evolution of the western Klamath Mountains and outboard Franciscan assemblages, northern California–southern Oregon, USA

2021 ◽  
pp. 73-130
Author(s):  
Alan D. Chapman* ◽  
Doug Yule ◽  
William Schmidt ◽  
Todd LaMaskin

ABSTRACT The Klamath Mountains province and adjacent Franciscan subduction complex (northern California–southern Oregon) together contain a world-class archive of subduction-related growth and stabilization of continental lithosphere. These key elements of the North American Cordillera expanded significantly from Middle Jurassic to Early Cretaceous time, apparently by a combination of tectonic accretion and continental arc– plus rift-related magmatic additions. The purpose of this field trip is twofold: to showcase the rock record of continental growth in this region and to discuss unresolved regional geologic problems. The latter include: (1) the extent to which Mesozoic orogenesis (e.g., Siskiyou and Nevadan events plus the onset of Franciscan accretion) was driven by collision of continental or oceanic fragments versus changes in plate motion, (2) whether growth involved “accordion tectonics” whereby marginal basins (and associated fringing arcs) repeatedly opened and closed or was driven by the accretion of significant volumes of material exotic to North America, and (3) the origin of the Condrey Mountain schist, a composite low-grade unit occupying an enigmatic structural window in the central Klamaths—at odds with the east-dipping thrust sheet regional structural “rule.” Respectively, we assert that (1) if collision drove orogenesis, the requisite exotic materials are missing (we cannot rule out the possibility that such materials were removed via subduction and/or strike slip faulting); (2) opening and closure of the Josephine ophiolite-floored and Galice Formation–filled basin demonstrably occurred adjacent to North America; and (3) the inner Condrey Mountain schist domain is equivalent to the oldest clastic Franciscan subunit (the South Fork Mountain schist) and therefore represents trench assemblages underplated >100 km inboard of the subduction margin, presumably during a previously unrecognized phase of shallow-angle subduction. In aggregate, these relations suggest that the Klamath Mountains and adjacent Franciscan complex represent telescoped arc and forearc upper plate domains of a dynamic Mesozoic subduction zone, wherein the downgoing oceanic plate took a variety of trajectories into the mantle. We speculate that the downgoing plate contained alternating tracts of smooth and dense versus rough and buoyant lithosphere—the former gliding into the mantle (facilitating slab rollback and upper plate extension) and the latter enhancing basal traction (driving upper plate compression and slab-shallowing). Modern snapshots of similarly complex convergent settings are abundant in the western Pacific Ocean, with subduction of the Australian plate beneath New Guinea and adjacent island groups providing perhaps the best analog.

2021 ◽  
Vol 2 (4) ◽  
Author(s):  
Xin Wang

Angiosperms are the single most important plant group in the current ecosystem. However, little is known about the origin and early evolution of angiosperms. Jurassic and earlier traces of angiosperms have been claimed multiple times from Europe and Asia, but reluctance to accept these records remains. To test the truthfulness of these claims, palaeobotanical records from continents other than Europe and Asia constitute a crucial test. Here I document a new angiosperm fruit, Dilcherifructus mexicana gen. et sp. nov, from the Middle Jurassic of Mexico. Its Jurassic age suggests that origin of angiosperms is much earlier than widely accepted, while its occurrence in the North America indicates that angiosperms were already widespread in the Jurassic, although they were still far away from their ecological radiation, which started in the Early Cretaceous.


2013 ◽  
Vol 50 (3) ◽  
pp. 315-323 ◽  
Author(s):  
Richard L. Cifelli ◽  
Cynthia L. Gordon ◽  
Thomas R. Lipka

Multituberculates, though among the most commonly encountered mammalian fossils of the Mesozoic, are poorly known from the North American Early Cretaceous, with only one taxon named to date. Herein we describe Argillomys marylandensis, gen. et sp. nov., from the Early Cretaceous of Maryland, based on an isolated M2. Argillomys represents the second mammal known from the Arundel Clay facies of the Patuxent Formation (Lower Cretaceous: Aptian). Though distinctive in its combination of characters (e.g., enamel ornamentation consisting of ribs and grooves only, cusp formula 2:4, presence of distinct cusp on anterobuccal ridge, enlargement of second cusp on buccal row, central position of ultimate cusp in lingual row, great relative length), the broader affinities of Argillomys cannot be established because of non-representation of the antemolar dentition. Based on lack of apomorphies commonly seen among Cimolodonta (e.g., three or more cusps present in buccal row, fusion of cusps in lingual row, cusps strongly pyramidal and separated by narrow grooves), we provisionally regard Argillomys as a multituberculate of “plagiaulacidan” grade. Intriguingly, it is comparable in certain respects to some unnamed Paulchoffatiidae, a family otherwise known from the Late Jurassic – Early Cretaceous of the Iberian Peninsula.


1994 ◽  
Vol 31 (6) ◽  
pp. 919-942 ◽  
Author(s):  
Giselle K. Jakobs ◽  
Paul L. Smith ◽  
Howard W. Tipper

This is the second in a series of papers intended to establish a Lower Jurassic ammonite zonation that takes into account the biostratigraphic and biogeographic peculiarities of the North American succession. In North America the lower boundary of the Toarcian is drawn at the first appearance of Dactylioceras above the last occurrence of Amaltheus and Fanninoceras. The lower Toarcian is represented by the Kanense Zone; the middle Toarcian by the Planulata and Crassicosta zones; and the upper Toarcian by the Hillebrandti and Yakounensis zones. Section 5 on the Yakoun River in the Queen Charlotte Islands is designated the stratotype for the Planulata, Crassicosta, and Hillebrandti zones; section 3 on the Yakoun River is designated the stratotype for the Yakounensis Zone; an ideal stratotype for the Kanense Zone is not presently known. Reference sections further illustrating the faunal associations that characterize the zones are designated in eastern Oregon (Snowshoe Formation) and northern British Columbia (Spatsizi Group). The Dactylioceratidae, Harpoceratinae, and Hildoceratinae provide the most important zonal indicators for the lower Toarcian; Dactylioceratidae, Phymatoceratinae, and Bouleiceratinae for the middle Toarcian; and Phymatoceratinae, Grammoceratinae, and Hammatoceratinae for the upper Toarcian. Phymatoceras hillebrandti is described as a new species.


1995 ◽  
Vol 69 (1) ◽  
pp. 89-98 ◽  
Author(s):  
G. K. Jakobs

Previous studies of the Toarcian of the North American Cordillera have mentioned the rare occurrence of Paroniceras in the Queen Charlotte Islands. Recent work has identified the presence of Leukadiella in the Middle Toarcian of the Queen Charlotte Islands, the Spatsizi area, and the Hazelton area. They occur with Rarenodia planulata, Peronoceras pacificum, Peronoceras verticosum, and Phymatoceras cf. P. pseudoerbaense. The Leukadiella specimens are well preserved and generally larger than those found in the Mediterranean region. Taxa present in North America include Paroniceras sternale, Leukadiella ionica, Leukadiella amuratica, Leukadiella aff. L. helenae, and Leukadiella aff. L. ionica. Morphologically Leukadiella is closely related to such genera as Hildaites and Hildoceras and is more suitably placed within the subfamily Hildoceratinae rather than the Bouleiceratinae. The distribution of Leukadiella and Paroniceras indicates the influence of the Hispanic Corridor linking western Tethys and the eastern Pacific during the Middle Toarcian.


2017 ◽  
Vol 188 (1-2) ◽  
pp. 9 ◽  
Author(s):  
Marc Jolivet ◽  
Anastasia Arzhannikova ◽  
Andrei Frolov ◽  
Sergei Arzhannikov ◽  
Natalia Kulagina ◽  
...  

The Late Jurassic - Early Cretaceous tectonic evolution of SE Siberia was marked by the closure of the Mongol-Okhotsk ocean. While this geodynamic event led to compressive deformation and denudation in a wide area encompassing the North-Altay, Sayan and Baikal Patom ranges, it was contemporaneous to widespread extension from the Transbaikal region situated immediately north of the suture zone to the Pacific plate, affecting eastern Mongolia and northeastern China. In this study we review the paleontological and sedimentological data available in the Russian literature and provide new macro-floral and palynological data from the Mesozoic sediments of three Transbaikal basins. These data are used to describe the paleoenvironmental and paleoclimatic evolution of the Transbaikal area in order to assess the topographic evolution of the region in relation with the closure of the Mongol-Okhotsk ocean. We establish that the Transbaikal basins evolved in a continuously extensional tectonic setting from at least the Early-Middle Jurassic to the Early Cretaceous. The associated sedimentary environments are characterized by retrogradation from alluvial fan–braided river dominated systems prevailing during the Early to Middle Jurassic initial opening of the basins to meandering river– lacustrine systems that developed during the Late Jurassic - Early Cretaceous interval. No evidence of high relief topography was found and we conclude that, while compression and denudation occurred in the North Altai, Sayan and Patom ranges, in the Transbaikal region, the docking of the Mongolia-North China continent to Siberia was a “soft collision” event, possibly involving a major strike-slip displacement that did not lead to an orogenic event implying strong compressive deformation, crustal thickening and topography building.


Geology ◽  
2021 ◽  
Vol 49 (5) ◽  
pp. 602-606 ◽  
Author(s):  
Richard O. Lease ◽  
Peter J. Haeussler ◽  
Robert C. Witter ◽  
Daniel F. Stockli ◽  
Adrian M. Bender ◽  
...  

Abstract The Fairweather fault (southeastern Alaska, USA) is Earth’s fastest-slipping intracontinental strike-slip fault, but its long-term role in localizing Yakutat–(Pacific–)North America plate motion is poorly constrained. This plate boundary fault transitions northward from pure strike slip to transpression where it comes onshore and undergoes a <25°, 30-km-long restraining double bend. To the east, apatite (U-Th)/He (AHe) ages indicate that North America exhumation rates increase stepwise from ∼0.7 to 1.7 km/m.y. across the bend. In contrast, to the west, AHe age-depth data indicate that extremely rapid 5–10 km/m.y. Yakutat exhumation rates are localized within the bend. Further northwest, Yakutat AHe and zircon (U-Th)/He (ZHe) ages gradually increase from 0.3 to 2.6 Ma over 150 km and depict an interval of extremely rapid >6–8 km/m.y. exhumation rates that increases in age away from the bend. We interpret this migration of rapid, transient exhumation to reflect prolonged advection of the Cenozoic–Cretaceous sedimentary cover of the eastern Yakutat microplate through a stationary restraining bend along the edge of the North America plate. Yakutat cooling ages imply a long-term strike-slip rate (54 ± 6 km/m.y.) that mimics the millennial (53 ± 5 m/k.y.) and decadal (46 mm/yr) rates. Fairweather fault slip can account for all Pacific–North America relative plate motion throughout Quaternary time and indicates stability of highly localized plate boundary strike slip on a single fault where extreme rock uplift rates are persistently localized within a restraining bend.


2002 ◽  
Vol 76 (2) ◽  
pp. 386-390 ◽  
Author(s):  
L. R. Saul ◽  
R. L. Squires

Nerineoids, so typical of the Jurassic and Early Cretaceous in Europe, are usually rare and lacking in diversity in North America north of Mexico. This is especially true of the Pacific slope faunas. Only three species of nerineoid gastropods have previously been reported from the Cretaceous of California (Saul and Squires, 1998). The oldest of these species, Aphanoptyxis andersoni Saul and Squires, 1998, is from the Early Cretaceous (Hauterivian) in northern California. The other two species are Late Cretaceous (Turonian): Aphanoptyxis californica Saul and Squires, 1998, is from northern California, and Nerinella santana Saul and Squires, 1998, is from a locality and strata in southern California near the occurrence of Nerinella califae n. sp. The description of N. califae n. sp. gives California the greatest diversity of Turonian northeastern Pacific slope nerineoids, namely, Aphanoptyxis californica and two species of Nerinella. These Turonian nerineoids are also, thus far, the geologically youngest North American Pacific slope nerineoids.


1989 ◽  
Vol 26 (12) ◽  
pp. 2645-2660 ◽  
Author(s):  
P. G. Anderson ◽  
C. Jay Hodgson

The Erickson gold mine is a typical gold quartz vein deposit. The veins are hosted by a thrust-imbricated, gently dipping, synformal allochthon of low-grade metamorphic, Devonian to Upper Triassic basalts, argillites, and peridotites of oceancrustal origin belonging to the Sylvester Group, part of the Slide Mountain assemblage. The Sylvester allochthon lies concordantly on Devonian miogeoclinal sedimentary rocks of the North American continental margin and was emplaced in the Middle Jurassic as a result of the collision of the Quesnel arc with North America. The veins in the mine are hosted mainly by a moderately dipping system of shear zones with approximately orthorhombic symmetry, indicating a triaxial bulk, inhomogeneous strain pattern superimposed on the earlier formed, gently dipping thrusts. Steeply dipping extension veinlets, rotation of schistosity, and downdip slickenlines indicate the maximum shortening axis was subvertical. The veins display complex superimposed ribbon and breccia textures, indicating incremental growth. Most of the gold occurs in association with tetrahedrite, sphalerite, and chalcopyrite in steeply dipping, late, grey quartz veinlets localized within and striking perpendicular to the main veins. The vein-forming event, dated at 130 Ma, appears to have been related to extension and high heat flow associated with the rise of the Omenica geanticline, in turn the result of crustal thickening caused by the collision of the amalgamated Quesnel arc – North America plate with Stikinia in the Middle Jurassic.


1988 ◽  
Vol 25 (3) ◽  
pp. 403-416 ◽  
Author(s):  
W. H. Fritz ◽  
Ellis L. Yochelson

In the North American Cordillera there is strong evidence that Salterella is restricted to the medial part of the Bonnia–Olenellus Zone. Reported younger and older occurrences are attributed to either stratigraphic error or misidentification. An unnamed genus with a superficial resemblance immediately postdates Salterella, but it lacks an inner laminar cone. In the Cordillera Salterella occurs in inner detrital and middle carbonate belt strata that were deposited in the upper half of Grand Cycle B and the lower half of Grand Cycle C.In and near the Appalachian Mountains of North America and in Greenland, Spitsbergen, and Scotland, occurrences of Salterella are consistent with a medial Bonnia–Olenellus Zone age; however, this cannot be as rigorously tested as in the Cordillera, because of fewer taxa associated with the genus and in super- and subjacent strata. Outer detrital (basinal) strata of the Taconic Allochthon contain Salterella, but it is uncertain whether the fossils are of local or derived origin.Speculations that Campitius titanius Firby and Durham of California belongs in the genus Salterella are doubtful, and C. titanius is clearly older. The relationship between Salterella and Volborthella and their relative ages within the Early Cambrian are still unclear.


Sign in / Sign up

Export Citation Format

Share Document