Rachel Piotraschke, Susan M. Cashman, Kevin P. Furlong, Peter J.J. Kamp, elizabeth it on Siletzia?. Lithosphere 2015;; 7 (4): 427a€“440. doi:
- Ris (Zotero)
The Klamath Mountains state of northwestern Californiaa€“southwestern Oregon is actually an anomalous take into account the Cascadia margin; these mountains possess highest typical topography, the earliest rocks, plus the only recognized instance of belated Cenozoic detachment faulting into the coastal mountains of Cascadia forearc. Low-temperature thermochronology (apatite fission-track, apatite [U-Th]/He) analyses from the central and southern Klamath Mountains state record two specific exhumation events-a Cretaceousa€“Paleocene local cooling and a southward-migrating locus of fast cooling/exhumation in the middle Tertiary. We infer this structure reflects two specific processes of exhumation: regional surface erosion (older) and migrating localized tectonic exhumation (younger). In the southern maximum sugar babies uk for this area for fast air conditioning, slickenside striations throughout the exposed La Grange mistake area record southward displacement associated with top plate along a shallowly dipping (a??20A°) detachment exterior. Thermochronologic information constrain normal dip in the mistake to some grade, upper-plate thickness to
The Klamath Mountain state (Fig. 1) straddles a fundamental changeover for the the united states plate boundary from subduction along Cascadia to interpretation across the San Andreas system, and is both geologically and topographically unique. The orogen’s Neogene to Holocene tectonic record possibly produces a window in to the development with the dish border whilst underwent the transition from a lengthy reputation of subduction (Farallon, Juan de Fuca) to encroaching translational (Pacific) dish relationships. The Klamath Mountain state presently has certain greatest geography across the convergent boundary (Fig. 1A). Max and mean elevations inside the Klamath hills become higher than those elsewhere in the coastal ranges of Cascadia (Kelsey et al., 1994), as well as the Klamath hill province, composed of Precambrian to Late Cretaceous, mainly oceanic tectonostratigraphic terranes, include the earliest (Wallin et al., 1995) and being among the most structurally intricate (cf. Irwin, 1981, 1985) models over the Cascadia margin. The period when this large geography created and also the connection between uplift and exhumation of Paleozoic and Mesozoic bedrock continue to be uncertain.
Productive distortion inside the southernmost Cascadia subduction region, during the latitude of Klamath Mountains province, additionally varies from regarding the remainder Cascadia margin.
Activities of seismicity, like the spatial and temporary circulation of episodic tremor and slip activities (Fig. 1A; Szeliga et al., 2004; Brudzinski and Allen, 2007; Gomberg et al., 2010; K. Creager, , private commun.), anticorrelation of tremor and lightweight upper-plate earthquakes (Boyarko and Brudzinski, 2010; Gomberg et al., 2010), and inferred segmentation of Cascadia subduction zone disturbance history (e.g., Wang et al., 2013), all separate the southern area of the Cascadia subduction region.
(1) do the Klamath topographic massif show relict (Late Cretaceousa€“Early Tertiary) geography, or is they a direct result younger and/or continuous uplift for this modern plate border?
(2) perform some distinctive seismologic characteristics associated with southernmost Cascadia subduction area margin echo the geologic dynamics with the regional forearc (age.g., crust with the Klamath hill state), or will they be just a purpose of the current plate-tectonic style independent of upper-plate crustal build?
Inside report, we found brand new low-temperature thermochronologic data through the central and southeastern Klamath Mountains, use these to constrain the movement history of a regionally significant error (the La Grange error), and study their ramifications your Cenozoic tectonic advancement associated with Klamath hills state. With latest thermochronometry data, we test earlier interpretations of Cenozoic reputation for the Klamath part, e.g., Neogene Condrey Mountain dome (Mortimer and Coleman, 1985) and Klamath peneplain (Diller, 1902; Aalto, 2006). We then talk about the spatial and temporal communication between mid-Cenozoic tectonic events in Klamath Mountains province and also the accretion of the Siletz terrane during the Oregon coastline Ranges (Wells et al., 2014). We deduce that Cenozoic tectonism into the Klamath hills province is linked to happenings regarding the Cascadia margin on the north.