The ancestral Mississippi drainage archived in the late Wisconsin Mississippi deep-sea fan

Clark³

et al. 2017

Tectonics

South central Pyrenean foreland basin fill preserves the eroded remnants of the early stages of fold‐thrust belt evolution and topographic growth. Specifically, the Eocene Hecho Group in the Ainsa Basin contains a succession of turbiditic channels and levees deposited in the transition zone between the fluvial‐deltaic and deep marine depozones. Detailed isotopic provenance analyses allow for the reconstruction of sediment sources of the ancient sediment routing systems. This study presents 2332 new detrital zircon (DZ) U‐Pb ages and 246 new DZ double‐dated (U‐Th)/(He‐Pb) ages from 19 turbiditic and fluvio‐deltatic sandstones in the Ainsa Basin. These data indicate a progressive provenance shift from Cadomian/Caledonian plutonic and metamorphic rocks of the eastern Pyrenees to Variscan plutonic rocks in the central Pyrenees. Minor sediment contributions from sources located to the S and SE of the basin are seen throughout the section. New DZ (U‐Th)/He results identify four main cooling events: Pyrenean orogenesis (~56 Ma), initial basin inversion (~80 Ma), Cretaceous rifting (~100 Ma), and pre‐Mesozoic cooling ages related to earlier tectonic phases. This study imposes new constraints on the paleogeographic evolution of the Pyrenees and illustrates that high‐frequency fluctuations in sediment delivery processes and sediment routing introduce superimposed noise upon the basin‐scale long‐term provenance evolution during orogenesis.

Section: Discussionmentioning

confidence: 98%

Detrital zircon (U‐Th)/(He‐Pb) double‐dating constraints on provenance and foreland basin evolution of the Ainsa Basin, south‐central Pyrenees, Spain

Thomson

Clark³

et al. 2017

Tectonics

“…In contrast, late Pleistocene sand has a DZ signature like that observed for coeval (ca. 0.04-0.07 Ma) sand in the distal Mississippi Fan at Site 615, with prominent Granite-Rhyolite, Yavapai, and Superior Province components derived from northern North American terranes (Fildani et al, 2016) and lacking components unique to the Chiapas region. The change in DZ ages at Site 3 aligns with the petrographic trends ( Figs.…”

Section: Late Cenozoic Sediment Delivery To the Wgommentioning

confidence: 99%

Late Cenozoic cooling favored glacial over tectonic controls on sediment supply to the western Gulf of Mexico

Hessler¹,

Covault

et al. 2018

Geology

Terrigenous marine sediment records the landscape response to climate and tectonic perturbations. Here, we determined the source of Miocene-Pleistocene debris in the western Gulf of Mexico (WGOM) to understand changes in sediment supply during a greenhouse-glacial transition. Sediment composition at Deep Sea Drilling Project (DSDP) Sites 3, 87, and 89-91 shows a reversal in provenance following the onset of Pleistocene glaciation. During Miocene time, sediment was supplied to the deep WGOM from tectonically active, tropical highlands of southern Mexico, accumulating as sediment-gravity-flow deposits across broad deep-water fan systems. Then, following the mid-Pleistocene transition (ca. 0.7 Ma), the WGOM saw sustained (10 5 yr) influx of sediment from the north due to glacial erosion, high discharge, and expanded drainages across the Mississippi catchment. This major provenance shift points to the importance of glacial controls on marine sediment supply during late Cenozoic cooling.

“…The Amazon River and deep-sea fan represent a globally important end-member system for understanding land-to-sea sediment dynamics. Submarine fans have been shown to archive histories of output fluxes and onshore environmental change (Normark and Reid, 2003;Fildani et al, 2016;Hessler et al, 2018), and have been used to invert up-system climate forcings in glaciated continent-scale rivers (Clift et al, 2008;Fildani et al, 2016Fildani et al, , 2018Mason et al, 2017;Li et al, 2019). The Amazon catchment straddles equatorial latitudes and has dis-tinct sediment and detrital zircon (DZ) source terranes and physiography ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Detrital zircons reveal sea-level and hydroclimate controls on Amazon River to deep-sea fan sediment transfer

Mason

Romans

et al. 2019

Geology

We use new U-Pb detrital zircon (DZ) geochronology from the Pleistocene Amazon submarine fan (n = 1352 grains), integrated with onshore DZ age data, to propose a sedimentary model for sea level-modulated and hydroclimate-modulated sediment transfer in Earth's largest source-to-sink system. DZ ages from the modern Amazon River sediment display a progressive downstream dilution by older cratonic zircons, leading to the expectation of a submarine fan with high proportions of craton-derived sediment. Our new DZ age data from the submarine fan and mixture modeling suggest that higher proportions of sediment were supplied from the distant central Andes to the Amazon fan during the last two glacioeustatic lowstands, and thus the observed DZ age spectra of the modern lower Amazon River indicate a relative increase in craton-derived sediment during the Holocene. We interpret that during interglacials, when sea level was high and the submarine fan inactive, the lower Amazon River did not efficiently transfer sand-sized sediment to the margin and thus became enriched in craton-derived sediment. During sea-level lowstands, increased gradients and incision in the lower Amazon River due to base-level lowering resulted in enhanced connectivity and transfer of Andes-sourced zircons to the deep sea. These results are also consistent with interpreted patterns of Andean-Amazon hydroclimate anti-phasing (enhanced precipitation in the central Andes and increased aridity in the northern Amazon Basin) during the Last Glacial Maximum. Our results suggest that sand-sized sediment in the Amazon submarine fan records multi-millennial patterns of sea level and South American hydroclimate.