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Detrital zircon age spectra of middle and upper Eocene outcrop belts, U.S. Gulf Coast region
Basin Research ( IF 3.2 ) Pub Date : 2020-05-09 , DOI: 10.1111/bre.12464
William H. Craddock 1 , James L. Coleman 2 , Andrew R. C. Kylander‐Clark 3
Affiliation  

Recently reported detrital zircon (DZ) data help to associate the Paleogene strata of the Gulf of Mexico region to various provenance areas. By far, recent work has emphasised upper Paleocene‐lower Eocene and upper Oligocene strata that were deposited during the two episodes of the highest sediment supply in the Paleogene. The data reveal a dynamic drainage history, including (1) initial routing of western Cordilleran drainages towards the Gulf of Mexico in the Paleocene, (2) an eastward shift of the western continental divide, from the Jura‐Cretaceous cordilleran arc to the eastern edge of the Laramide province after the Paleocene and (3) a southward shift, along the eastern Laramide province, of the headwaters of river systems draining to the Mississippi and Houston embayments at some time between the early Eocene and Oligocene. However, DZ characterisation of most (~20 Myr) of the middle Eocene‐lower Oligocene section remains limited. We present 60 DZ age spectra, most of which are from the middle or upper Eocene outcrop belts, with 50–200‐km spacing. We define six to eight distinct groups of DZ age spectra for middle and upper Eocene strata. Data from this and other studies resolve at least six substantial temporal changes in age spectra at various positions along the continental margin. The evolving age spectra constrain the middle and upper Eocene drainage patterns of large parts of interior North America. The most well‐resolved aspects of these drainage patterns include (1) persistent rivers that flowed from erosional landscapes across the Paleozoic Appalachian orogen either into the low‐lying Mississippi embayment or directly into the eastern Gulf; (2) at least during marine regressions, a trunk channel that likely flowed southward along the axial part of Mississippi Embayment and integrated tributaries from the east and west; and (3) rivers that flowed to the Houston embayment in the middle Eocene that likely originated in the Laramide province in central Colorado and southern Wyoming, as Precambrian basement highs in those source areas were being unroofed.

中文翻译:

美国墨西哥湾沿岸地区中新世和上新世露头带碎屑锆石年龄谱

最近报道的碎屑锆石(DZ)数据有助于将墨西哥湾地区的古近系地层与各种物源地区联系起来。到目前为止,最近的工作强调了古新世-下新世和上渐新世上地层是在古近纪最高沉积物供应的两次事件中沉积的。数据揭示了一个动态的排水历史,包括(1)西部科迪勒山脉排水系统向古新世的墨西哥湾的初始路线,(2)西部大陆分界线的东移,从侏罗-白垩纪科迪勒山脉弧向东部边缘(3)在新世和渐新世之间的某个时期,流向密西西比河和休斯敦河道的河流水系源头沿着新的新世之后的拉拉米德省和(3)沿着拉拉米特东部向南移动。然而,始新世-下渐新世中部大部分(〜20 Myr)的DZ表征仍然有限。我们提供了60个DZ年龄谱,其中大多数来自中新世或上新世露头带,间距为50-200-km。我们为中新世和上新世地层定义了六到八个不同的DZ年龄谱。来自这项研究和其他研究的数据至少解决了沿大陆边缘不同位置的年龄谱的六个基本时间变化。不断演变的年龄谱约束了北美内部大部分地区的中新世和上新世排水模式。这些排水方式最能解决的方面包括:(1)持久性河流从侵蚀景观流过古生代阿巴拉契亚造山带,流入低层的密西西比河堤或直接流入东部海湾。(2)至少在海洋回归过程中,主干渠可能沿着密西西比河使馆的轴向部分向南流动,并从东西方向整合支流;(3)流入始新世中期休斯敦河口的河流可能起源于科罗拉多州中部的拉拉米德省和怀俄明州南部,因为这些源区的前寒武纪基底高没有被封顶。
更新日期:2020-05-09
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