Detrital heavy minerals, white mica and zircon geochronology in the Ordovician South Mayo Trough, western Ireland: signatures of the Laurentian basement and the Grampian orogeny

2010 ◽  
Vol 167 (6) ◽  
pp. 1147-1160 ◽  
Author(s):  
Maria Mange ◽  
Bruce Idleman ◽  
Qing-Zhu Yin ◽  
Hiroshi Hidaka ◽  
John Dewey
Keyword(s):  
White Mica ◽  
Heavy Minerals ◽  
Zircon Geochronology ◽  
Western Ireland

Heavy minerals solve structural and stratigraphic problems in Ordovician strata of the western Irish Caledonides

2003 ◽  
Vol 140 (1) ◽  
pp. 25-30 ◽  
Author(s):  
MARIA A. MANGE ◽  
JOHN F. DEWEY ◽  
DAVID T. WRIGHT
Keyword(s):  
Island Arc ◽  
Heavy Minerals ◽  
Metamorphic Complex ◽  
The South ◽  
Standard Sequence ◽  
Western Ireland ◽  
Complex Parts ◽  
Wide Horizon

Heavy minerals in Ordovician successions in western Ireland record, in the Upper Arenig Sheeffry Formation, the erosion of an ophiolite/island arc complex. The appearance of staurolite and garnet at a basin-wide horizon in the Lower Llanvirn Upper Derrylea Formation signals the unroofing of the Dalradian metamorphic complex. Parts of the Ordovician sequence on Inishturk and in two small inliers are correlated with the standard sequence with unexpected results. The garnet-, sillimanite-, and staurolite-bearing Letter Formation correlates with the Upper Derrylea Formation and, on Inishturk, heavy minerals in south-younging turbidites reveal a sinistral ramp zone, that places the Sheeffry Formation structurally above and to the south of the younger Derrylea Formation.

Guidelines for assessing the provenance of Mesozoic and Cenozoic clastic successions sourced by pre-Jurassic basement complexes in southernmost North America

2020 ◽  
Vol 90 (5) ◽  
pp. 513-532 ◽  
Author(s):  
Michelangelo Martini ◽  
Luigi Solari ◽  
Mariana Peña-Guerrero ◽  
Mildred Zepeda-MartÍnez ◽  
Chiara Montomoli
Keyword(s):  
North America ◽  
White Mica ◽  
Heavy Minerals ◽  
Geochemical Data ◽  
Provenance Analysis ◽  
Mineral Phases ◽  
The Face ◽  
Rank 2 ◽  
Available Information ◽  
Different Sources

ABSTRACT Mexico is an attractive place for provenance studies focused on reconstructing the tectonic evolution of North America. This is because Mexico hosts a well-preserved clastic record associated with some of the major Mesozoic and Cenozoic tectonic processes that shaped the face of this continent. However, the available information on Mexican pre-Mesozoic source terranes is presently insufficient for provenance analysis. With the aim of drawing the guidelines for provenance determination, we present here detrital modes, geochemical data, and zircon U-Pb ages for detritus derived from pre-Jurassic basement complexes of Mexico. Our data show that the various basement complexes produce distinctive detrital modes and supply diagnostic and compositionally different detrital heavy minerals that represent powerful provenance tracers. The Oaxacan Complex, Ayú Complex, and East Mexico Arc are the main sources of quartzo-feldspathic and feldspatho-quartzose detritus. Quartz with rutile needles, mesoperthitic K-feldspar, orthopyroxene, augitic to diopsidic clinopyroxene, and Mg- to Ca-rich almandine (Alm71–52Grs7–3Prp43–23Sps3–1Alm74–56Grs21–19Prp23–2Sps5–2) are common minerals in detritus from the Oaxacan Complex. The Ayú Complex supplies detritus marked by the occurrence of sagenitic biotite and white mica, as well as Mn-rich almandine (Alm69–66Grs4–3Prp18–11Sps19–10). Detritus from the East Mexico Arc contains any of these mineral phases ubiquitous in the Oaxacan and Ayú complexes. The Acatlán Complex is the main source of detritus dominated by metamorphic lithic grains and quartz, with minor amounts of feldspar. Lithic grains are rank 2–4 metabasitic, metapelitic, and metapsammitic–metafelsitic fragments. Diagnostic mineral phases are schorl–dravitic tourmaline, Na-amphibole, and helycitic garnet varying from a Ca- to Mn-rich almandine (Alm74–55Grs34–15Prp16–3Sps12–1-Alm70–46Grs20–15Prp3–1Sps32–12). Zircon U-Pb geochronology proves to have some virtues but also major limitations because: 1) the zircon U-Pb age signature of many different sources in Mexico is similar and 2) zircon documents a limited number of sources because of variations in zircon fertility.

scholarly journals Provenance Shift during the Plio-Pleistocene in the Vertex of Yangtze Delta and Its Geomorphological Implications

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 996
Author(s):  
Junjie Yu ◽  
Wei Yue ◽  
Ping Liu ◽  
Bo Peng ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Yangtze River ◽  
River Channel ◽  
Heavy Minerals ◽  
Tectonic Subsidence ◽  
Zircon Geochronology ◽  
The Yangtze River ◽  
Yangtze Delta ◽  
The South ◽  
Source To Sink ◽  
Regional Tectonic

One of the key issues of the Source-to-Sink process is revealing the geomorphological evolutions of large rivers from the perspective of river sink areas. This study aims to reveal the provenance change near the vertex of the Yangtze delta during the late Cenozoic and provide insight into the Yangtze channelization into the sea due to regional tectonic subsidence. Heavy minerals and zircon geochronology in the Plio-Pleistocene sediments of the vertex of the modern Yangtze delta (core RGK15) reveal that a significant provenance shift occurred at ~2.6 Ma (the beginning of the Pleistocene). During the Pliocene, ultra-stable heavy minerals and pre-Mesozoic zircon grains predominated in the sediments, probably derived from contemporary outcrops of sedimentary rock that were widely distributed in the delta and its surrounding area. They are completely different from those in the Pliocene sediments of the south delta, indicating that decentralized, local, small watersheds dominated the Yangtze delta during the Pliocene. This resulted from the relatively elevated terrain of this region due to the adjacent ancient Zhejiang–Fujian Uplift (ZFU) at that time. However, diversified heavy minerals and zircon geochronology similar to those of the modern upper Yangtze fingerprints occur in the Pleistocene sediments of core RGK15, implying that a significant provenance shift to the Yangtze River occurred here at ~2.6 Ma. The provenance shift recorded by the cores in the south delta mainly occurred at ~1.2 Ma, indicating that the Yangtze River channel was dragged southward with the further subsidence of the ancient Zhejiang–Fujian Uplift. This study reveals the southward migration process of the Yangtze River channel with the regional tectonic subsidence from the perspective of provenance evolution, which contributes to an understanding of when the Yangtze River channelized into the sea.

Long-lived granite-related molybdenite mineralization at Connemara, western Irish Caledonides

2010 ◽  
Vol 147 (6) ◽  
pp. 886-894 ◽  
Author(s):  
MARTIN FEELY ◽  
DAVID SELBY ◽  
JON HUNT ◽  
JAMES CONLIFFE
Keyword(s):  
Zircon Geochronology ◽  
Mixing Zone ◽  
Granite Emplacement ◽  
Tectonic Processes ◽  
Slab Breakoff ◽  
Caledonian Orogeny ◽  
Granite Magmatism ◽  
Western Ireland ◽  
Granite Samples ◽  
Caledonian Granite

AbstractNew Re–Os age determinations from the Galway Granite (samples: KMG = 402.2 ± 1.1 Ma, LLG = 399.5 ± 1.7 Ma and GBM = 383.3 ± 1.1 Ma) show that in south Connemara, late Caledonian granite-related molybdenite mineralization extended from c. 423 Ma to c. 380 Ma. These events overlap and are in excellent agreement with the published granite emplacement history determined by U–Pb zircon geochronology. The spatial distribution of the late-Caledonian Connemara granites indicates that initial emplacement and molybdenite mineralization occurred at c. 420 Ma (that is, the Omey Granite and probably the Inish, Leterfrack and Roundstone granites) to the N and NW of the Skird Rocks Fault, an extension of the orogen-parallel Southern Uplands Fault in western Ireland. A generally southern and eastward progression of granite emplacement (and molybdenite mineralization) sited along the Skird Rocks Fault then followed, at c. 410 Ma (Roundstone Murvey and Carna granites), at c. 400 Ma (Errisbeg Townland Granite, Megacrystic Granite, Mingling Mixing Zone Granodiorite, Lough Lurgan Granite and Kilkieran Murvey Granite) and at c. 380 Ma (Costelloe Murvey Granite, Shannapheasteen and Knock granites). The duration of granite magmatism and mineralization in Connemara is similar to other sectors of the Appalachian–Caledonian orogeny and several tectonic processes (e.g. slab-breakoff, asthenospheric flow, transtension and decompression) may account for the duration and variety of granite magmatism of the western Irish Caledonides.

scholarly journals Reconstructing drainage pathways in the North Atlantic during the Triassic utilizing heavy minerals, mineral chemistry, and detrital zircon geochronology

Geosphere ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. 479-500
Author(s):  
Steven D. Andrews ◽  
Andrew Morton ◽  
Audrey Decou ◽  
Dirk Frei
Keyword(s):  
North Atlantic ◽  
Detrital Zircon ◽  
Heavy Minerals ◽  
Zircon Geochronology ◽  
Reservoir Prediction ◽  
Transport Pathways ◽  
Detrital Zircon Geochronology ◽  
Tethys Sea ◽  
The North ◽  
The North Atlantic

Abstract In this study, single-grain mineral geochemistry, detrital zircon geochronology, and conventional heavy-mineral analysis are used to elucidate sediment transport pathways that existed in the North Atlantic region during the Triassic. The presence of lateral and axial drainage systems is identified and their source regions are constrained. Axial systems are suggested to have likely delivered sediment sourced in East Greenland (Milne Land–Renland) as far south as the south Viking Graben (>800 km). Furthermore, the data highlight the existence of lateral systems issuing from Western Norway and the Shetland Platform as well as a major east-west–aligned drainage divide positioned adjacent to the Milne Land–Renland region. This divide separated the catchments that flowed north to the Boreal Ocean from those that flowed south into a series of endoreic basins and, ultimately, the Tethys Sea. A further potential drainage divide is identified to the west of Shetland. The data presented and the conclusions reached have major implications for reservoir prediction, as well as correlation, throughout the region. Furthermore, understanding the drainage networks that existed during the Triassic can help constrain paleogeographic reconstructions and provides an important framework for the construction of facies models in the region.

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