Terranes, early faults, and pre-Late Jurassic amalgamation of the western Sierra Nevada metamorphic belt, California

Differing interpretations of geophysical and geologic data have led to debate regarding continent-scale plate configuration, subduction polarity, and timing of collisional events on the western North American plate margin in pre–mid-Cretaceous time. One set of models involves collision and accretion of far-traveled “exotic” terranes against the continental margin along a west-dipping subduction zone, whereas a second set of models involves long-lived, east-dipping subduction under the continental margin and a fringing or “endemic” origin for many Mesozoic terranes on the western North American plate margin. Here, we present new detrital zircon U-Pb ages from clastic rocks of the Rattlesnake Creek and Western Klamath terranes in the Klamath Mountains of northern California and southern Oregon that provide a test of these contrasting models. Our data show that portions of the Rattlesnake Creek terrane cover sequence (Salt Creek assemblage) are no older than ca. 170–161 Ma (Middle–early Late Jurassic) and contain 62–83% Precambrian detrital zircon grains. Turbidite sandstone samples of the Galice Formation are no older than ca. 158–153 Ma (middle Late Jurassic) and contain 15–55% Precambrian detrital zircon grains. Based on a comparison of our data to published magmatic and detrital ages representing provenance scenarios predicted by the exotic and endemic models (a crucial geologic test), we show that our samples were likely sourced from the previously accreted, older terranes of the Klamath Mountains and Sierra Nevada, as well as active-arc sources, with some degree of contribution from recycled sources in the continental interior. Our observations are inconsistent with paleogeographic reconstructions that are based on exotic, intra-oceanic arcs formed far offshore of North America. In contrast, the incorporation of recycled detritus from older terranes of the Klamath Mountains and Sierra Nevada, as well as North America, into the Rattlesnake Creek and Western Klamath terranes prior to Late Jurassic deformation adds substantial support to endemic models. Our results suggest that during long-lived, east-dipping subduction, the opening and subsequent closing of the marginal Galice/Josephine basin occurred as a result of in situ extension and subsequent contraction. Our results show that tectonic models invoking exotic, intra-oceanic archipelagos composed of Cordilleran arc terranes fail a crucial geologic test of the terranes’ proposed exotic origin and support the occurrence of east-dipping, pre–mid-Cretaceous subduction beneath the North American continental margin.

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Pressure-temperature-time paths from the Funeral Mountains, California, reveal Jurassic retroarc underthrusting during early Sevier orogenesis

Geological Society of America Bulletin ◽

10.1130/b35095.1 ◽

2019 ◽

Vol 132 (5-6) ◽

pp. 1047-1065 ◽

Cited By ~ 2

Author(s):

Suzanne Craddock Affinati ◽

Thomas D. Hoisch ◽

Michael L. Wells ◽

Jeffrey D. Vervoort

Keyword(s):

Sierra Nevada ◽

Pressure Increase ◽

Garnet Growth ◽

Lower Grade ◽

High Flux ◽

Thrust Belt ◽

Burial History ◽

Metamorphic Belt ◽

Pressure Decrease ◽

T Path

Abstract New metamorphic pressure-temperature (P-T) paths and Lu-Hf garnet ages reveal a temporal correlation between Middle to Late Jurassic retroarc underthrusting and arc magmatism in southwestern North America. P-T paths were determined for 12 garnet porphyroblasts from six samples from the Chloride Cliff area of the Funeral Mountains in southeastern California. The composite path shows a pressure increase from 4.2 to 6.5 kbar as temperature increased from 550 to 575 °C, followed by a pressure decrease to 5.1 kbar during a further increase in temperature to 590 °C. Lu-Hf garnet ages from a pelitic schist (167.3 ± 0.7 Ma) and a garnet amphibolite (165.1 ± 9.2 Ma) place these P-T paths in the Middle Jurassic. We interpret the near-isothermal pressure increase portion of the P-T path to have developed during thrust-related burial, similar to lower grade rocks at Indian Pass, 8 km to the southeast, where garnet P-T paths show a pressure increase dated by the Lu-Hf method at 158.2 ± 2.6 Ma. We interpret the pressure decrease portion of the composite P-T path from the Chloride Cliff area to reflect exhumation contemporaneous with cooling in the Indian Pass area documented from muscovite 40Ar/39Ar step-heating ages of 152.6 ± 1.4 and 146 ± 1.1 Ma. The conditions and timing of metamorphism determined for the Indian Pass and Chloride Cliff areas, and isogradic surfaces that cut across stratigraphy, support the interpretation that the strata were dipping moderately NW during metamorphism, parallel to the thrust ramp that buried the rocks. Burial likely resulted from top-SE motion along the Funeral thrust, which was later reactivated as a low-angle normal fault with opposite motion to become the currently exposed Boundary Canyon detachment that was responsible for Miocene and possibly older exhumation. The part of the burial history captured by garnet growth occurred ∼6 m.y. before the 161 Ma peak of high-flux magmatism in the arc. Burial was contemporaneous with metamorphic ages from the western Sierra Nevada metamorphic belt, with the possible timing of accretion of arc terranes in northern California, and with the initiation of Franciscan subduction. Burial ages are also similar in timing with generally E-W crustal shortening in the retroarc that produced the East Sierra thrust system, the Luning-Fencemaker fold and thrust belt, the possible early history of the Central Nevada thrust belt, and the western thrusts of the southern Sevier belt. The timing of tectonic burial documented in this study and of high-flux magmatism in the arc supports the interpretation that the development of a coherent arc-trench system in the Early Jurassic resulted in the underthrusting of melt-fertile material beneath the arc along west- to northwest-dipping faults such as the Funeral thrust in the Jurassic, which penetrated the basement to the west as well as the roots of the magmatic arc, leading to increased magmatism.

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New Insight Into Berau Sub-Basin North East Borneo: Basin Evolution and Tectonostratigraphy and Their Implication to New Exploration Play Concept

Proc. Indon. Petrol. Assoc., Digital Technical Conference, 2020 ◽

10.29118/ipa20-g-489 ◽

2020 ◽

Author(s):

A. Krisnabudhi

Keyword(s):

Late Jurassic ◽

Oil And Gas ◽

Early Jurassic ◽

Basin Evolution ◽

Metamorphic Belt ◽

Seismic Section ◽

North East ◽

Surface Data ◽

Carbonate Sequence ◽

Mahakam Delta

Understanding the evolution of the basin and tectonostratigraphy is the key role to reveal all geological aspects and potential hydrocarbon resources. Northeast Borneo has many hydrocarbon resources especially in Mahakam delta. However, Berau sub-basin remains unclear due to lack of G&G data. This paper presents a new concept of tectonostratigraphy and basin evolution based on subsurface and surface data integrated with thin section as well as radiolaria analysis to determine the age of such basin. Present-day aerogravity data shows that Berau sub-basin has two depocenters trending N-S and E-W and is bordered by Mangkalihat High (MKH) in the south and Rajang Embaluh Group (REG) in the west area. The metamorphic belt in REG area was formed in Early Jurassic (190 Ma), meanwhile in MKH, the ophiolite sequence was formed during Middle-Late Jurassic based on the presence of Holocrptocanium sp. in chert interbedded with mudstone. Based on the analysis, Berau sub-basin experienced subduction to obduction during Early Jurassic to Late Jurassic. In Cretaceous, Berau sub-basin is filled with conglomerate, shale and quartz sandstone of Telen and Benggara Fm. that has provenance from MKH and REG area. In Paleogene, major breakup unconformity can be seen on the seismic section and spread across the basin overlaid by shale with tuff of Eocene-Oligocene Sembakung Fm. The deposition of Sembakung Fm is controlled by extensional regime caused by subduction rollback in NW Borneo. The carbonate sequence has dominated this area in Late Oligocene to Early Miocene. Following the collision of Kuching high in Middle -Late Miocene, the deposition was dominated by deltaic sediment due to regional regression phase. In Plio-Pleistocene period, Berau sub-basin consists of carbonate and deltaic sediment from Domaring and Sajau Fm. In this time structural reactivation and inversion due to transpressional system with SE-NW pattern had controlled Berau sub-basin. Based on the evolution of Berau sub-basin, four hydrocarbon plays are identified in this paper, Mesozoic Play especially in Telen Fm, Paleogene Carbonate Play in Tabbalar & Birang Fm, Middle Miocene Play especially in Latih Fm and Plio-Pleistocene Play in Sajau Fm and Labanan Fm. Working petroleum system in the basin manifested by many oil seeps that can be found in surface and postmortem of several wells data shows commercial to sub-commercial and abundant oil and gas show.

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Geochronology of plutonic rocks from the Sanandaj-Sirjan zone, Iran and new zircon and titanite U-Th-Pb ages for granitoids from the Marivan pluton

Geochronometria ◽

10.2478/s13386-013-0156-z ◽

2014 ◽

Vol 41 (3) ◽

pp. 207-215 ◽

Cited By ~ 24

Author(s):

Ali Sepahi ◽

Hossein Shahbazi ◽

Wolfgang Siebel ◽

Ahmad Ranin

Keyword(s):

Continental Margin ◽

Late Jurassic ◽

Active Continental Margin ◽

Continental Collision ◽

Magmatic Activity ◽

Geochronological Data ◽

Metamorphic Belt ◽

Sanandaj Sirjan Zone ◽

Orogenic Cycle ◽

Age Constraints

Abstract The Sanandaj-Sirjan zone of Iran is a metamorphic belt consisting of rocks which were metamorphosed under different pressure and temperature conditions and intruded by various plutons ranging in composition from gabbro to granite. The majority of these granitoids formed along the ancient active continental margin of the Neo-Tethyan ocean at the southeastern edge of the central Iranian microplate. Geochronological data published in recent years indicate periodic plutonism lasting from Carboniferous through Mesozoic to late-Paleogene times (from ca. 300 to ca. 35 Ma) with climax activity during the mid- and late-Jurassic. The age constraints for plutonic complexes, such as Siah-Kouh, Kolah-Ghazi, Golpayegan (Muteh), Azna, Aligoodarz, Astaneh, Borujerd, Malayer (Samen), Alvand, Almogholagh, Ghorveh, Saqqez, Marivan, Naqadeh and Urumieh, clearly indicate the periodic nature of magmatism. Therefore, the Sanandaj-Sirjan zone preserves the record of magmatic activity of a complete orogenic cycle related to (1) Permocarboniferous(?) rifting of Gondwana and opening of the Neo-Tethyan ocean, (2) subduction of the oceanic crust, (3) continental collision and (4) post-collision/post-orogenic activities. The formation of the Marivan granitoids, northwestern Sanandaj-Sirjan zone, for which we present U-Pb zircon and titanite ages of ca. 38 Ma, can be related to the collisional and post-collisional stages of this orogenic cycle.

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