| dc.contributor.advisor |
Muehlberger , William R . |
|
| dc.creator |
Witebsky , Susan |
|
| dc.date.accessioned |
2011 -06 -23T20 :33 :52Z |
|
| dc.date.accessioned |
2011 -08 -17T14 :37 :07Z |
|
| dc.date.available |
2011 -06 -23T20 :33 :52Z |
|
| dc.date.available |
2011 -08 -17T14 :37 :07Z |
|
| dc.date.created |
1987 -08 |
|
| dc.date.issued |
2011 -06 -23 |
|
| dc.identifier.uri |
http : / /hdl .handle .net /2152 /11931 |
|
| dc.description.abstract |
A boulder bed unit in the upper Haymond Formation (Pennsylvanian ) , generally believed to be olistostromes , is exposed in the eastern Marathon Basin , west Texas . Two localities of this unit (Housetop Mountain and Clark Butte ) contain clasts derived from several formations found within the basin , as well as exotic Devonian metamorphic and volcanic rocks . This report describes a third previously unstudied site (Martin Ranch locality ) that contains clasts of exotic Middle Cambrian shelf limestones . These limestones provide a key to the Early Paleozoic history of the Marathon region . The boulder beds lie in the upper part of the Haymond Formation . At the Martin Ranch locality they form a zone that is traceable for 6 .6 km along strike and is up to 230 m thick . These boulder beds contain interbedded units of massive , unstratified , pebble - to boulder -bearing mudstone , thickly bedded , massive sandstone , lenses of pebbly sandstone , and deformed flysch beds . About 80 percent of the clasts found in the boulder beds at Martin Ranch are chert derived from several basin formations . Unique displaced slabs of bedded chert pebble conglomerate comprise about 10 percent of the clasts . Theses conglomerates were probably derived from upper fan -channel deposits within the lower Haymond Formation . Pennsylvanian limestone clasts redeposited from the basin facies of the Dimple Formation and clasts of exotic , late Middle Cambrian limestones each comprise about 5 percent of the clasts . These Cambrian limestones , older than any formation in the Marathon Basin , contain a fauna characteristic of the seaward edge of the cratonic carbonate shelf . The presence of the Cambrian clasts constrains the location of the North American shelf edge during the Cambrian , placing it at least 120 km southeast of the present day Marathon Basin . Both the Martin Ranch and Housetop Mountain boulder beds are composed mainly of clast -bearing , matrix -supported mudstone which have pebbly sandstone , massive sandstone , and flysch beds interstratified with the mudstone and represent periodic deposition of debris flows , slumps , slides , and turbidites interspersed with normal basin deposition of flysch facies rocks . However , different clast types are found at the two localities . The Martin Ranch locality has clasts of Cambrian limestone and chert pebble conglomerate , the latter up to 90 m in length , that are absent at the other localities . Exotic Pennsylvanian limestone clasts and exotic Devonian metamorphic and volcanic rocks , common at Housetop Mountain , are rare or missing at Martin Ranch . The Clark Butte locality is unique because it lacks the mudstone which dominates the other two localities . Instead , the matrix is composed of a pebbly sandstone and conglomerate associated with thick sandstone beds . The boulder beds at this locality may represent upper fan channels and channel -lag deposits . The turbidites and olistostromes resulted from recycling of the southern edge of the tectonic basin as the advancing Ouachita thrusts uplifted the pre Haymond strata . Most of the clasts were from older basin formations exposed by these faults ; however one of these thrusts also uplifted slivers of exotic Middle Cambrian limestone . Earthquakes probably triggered slumps and rock falls off the fault scarps . As the boulders travelled downslope plowing through the slope sediments , they accumulated more material . This combination of slide debris and slope mud turned the slumps and slides into debris flows . Between episodes of debris flows and turbidity currents , normal basin deposition of thinly bedded turbiditic sandstone and pelagic shale occurred . |
en_US |
| dc.format.medium |
electronic |
|
| dc.language.iso |
eng |
en_US |
| dc.rights |
Copyright © is held by the author . Presentation of this material on the Libraries' web site by University Libraries , The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works . |
|
| dc.subject |
Sedimentation and deposition - -Texas - -Brewster County |
en_US |
| dc.subject |
Paleontology - -Texas - -Brewster County |
en_US |
| dc.subject |
Geology , Stratigraphic - -Paleozoic |
en_US |
| dc.subject |
Boulders - -Texas - -Brewster County |
en_US |
| dc.subject |
Geology - -Texas - -Brewster County |
en_US |
| dc.title |
Paleontology and sedimentology of the Haymond boulder beds (Martin Ranch ) , Marathon Basin , Trans -Pecos Texas |
en_US |
| dc.description.department |
Geological Sciences |
en_US |
| dc.type.genre |
Thesis |
|
| dc.type.material |
text |
|
| thesis.degree.name |
Master of Arts |
en_US |
| thesis.degree.level |
Masters |
en_US |
| thesis.degree.discipline |
Geology /Geological Sciences |
en_US |
| thesis.degree.grantor |
The University of Texas at Austin |
|
| thesis.degree.department |
Geological Sciences |
en_US |