Paradox Basin

37.866666666667 - 109.16666666667Koordinaten: 37 ° 52 '0 "N, 109 ° 10' 0 " W

The Paradox Basin is an asymmetric foreland basin, which is mainly located in the southeast of the U.S. state of Utah, but also on the southwestern Colorado, northwestern New Mexico and the extreme northeastern Arizona overlaps. This approximately 40,000 square kilometers of sedimentary basins formed during the late Paleozoic; the basin -forming processes were active from Upper Carboniferous to the output of the Permian.

In contrast to other sedimentary basins in the Rocky Mountains, the Paradox Basin is composed mainly of evaporites. The sediments were deposited in alternating flat water / cold water cycles. Because of the powerful salt sequences salt tectonics plays (rock salt is even at relatively low temperatures plastic deformation ) at the onset after the Pennsylvanian structural deformations a major role.

Stratigraphy

The Paradox Basin contains the following sedimentary sequence ( from young to old):

• Mesozoic layers
• Hiatus
• Cutler Formation - Gzhelium - Cisuralium (Lower Permian) - 299-270 million years
• Hiatus
• Honaker Trail Formation - Kasimovian / Gzhelium - 306-299 million years
• Paradox Formation - Moscovian / Kasimovian - 310-306 million years
• Pinkerton Trail Formation - Bashkirian / Moscovian
• Molas Formation - Bashkirian
• Large hiatus - Karst formation
• Leadville Limestone - Tournaisium
• Unconformity

In the underground of the actual Paradox basin, the following rock units found at:

• Ouray Limestone - Upper Devonian / Tournaisium
• Unconformity
• Elbert lineup - Devon
• Large hiatus
• Lynch Dolomite - Upper Cambrian
• Maxfield Limestone or Muav Limestone - Upper Cambrian
• Ophir Shale and Bright Angel Shale - Middle Cambrian
• Tintic Quartzite and Tapeats Sandstone - Middle Cambrian
• Unconformity
• Präkambrisches basement - high-grade metamorphic rocks and granitoids

The Pinkerton Trail Formation, Paradox Formation and Honaker Trail Formation are summarized for Hermosa Group.

Widths

The vorkarbonischen deposits show a marked asymmetry in their widths. Southeast of the Paradox Basin they stood at only 180 meters, in the North West, however, up to 750 meters.

During the actual basin formation Mississippian to Lower Permian have accumulated over 6700 meters of sediments in the period.

With 1800 to 2100 meters in thickness the Paradox Formation is undoubtedly the meaning Fullest. It is composed of 33 cycles of salt - thick rock salt layers, which are interrupted by intermediate layers of anhydrite, silty dolomites and black, carbon-rich shales. The rock salt layers show thickness changes from 7 to 270 meters and can contain sylvite.

However, the Triassic and Jurassic sediments achieve together in the Book Cliffs, a maximum thickness of 1450 meters, in the pelvic center, only about 750 meters.

From the later Tertiary ( Oligocene ) prevailed in the pelvic area erosion, existing sediments of Cretaceous and Tertiary were removed again. Received Cretaceous sediments in adjacent Sedimentationsräumen be up to 1850 meters thick, early Tertiary sediments and volcanics reach there more than 750 meters. In similar training of the sediments in the Paradox Basin (which is likely ) can therefore be assumed that at least 2,600 meters of erosion.

Sedimentary development

With the onset of sedimentation of the Paradox Formation in the Upper Carboniferous before about 310 million years ago there was a very strong reduction of the Paradox Basin. The subsidence held even during the deposition of the Cutler formation unabated, but slowed down after the end of the Permian. Towards the end of the Permian, all lowering movements had come to a standstill. It transgredierten then Mesozoic layers over the basin away. The top layers were subject ihrerseit again from the beginning of the Upper Cretaceous a strong reduction, which persisted until the Maastrichtian ( period 100-70 million years ago ). For about 35 million years ( Oligocene ) learns of the sedimentation of the Paradox Basin in connection with the lara mix orogeny a steady uplift, the minimum is at around 2000 meters.

Structure

The Paradox Basin is constructed in cross-section very asymmetric, its deepest point is located in the immediate vicinity of the Uncompahgre Plateau, a prominent steeply standing, generally southeast-northwest trending thrust faults Precambrian basement block. On the surface it shows an elliptical shape in its main extension direction SE-NW it reaches 305 km in NE-SW direction, only about 150 kilometers. The basin is girded by different structural high areas: the already mentioned, tectonically steep pressed out Uncompahgre Plateau in the north-east and the adjoining San Juan dome in the southeast as well as several relatively shallow Grundbegirgsaufbeulungen lara mix origin, such as the San Rafael Swell to the north west, the Circle Cliffs Uplift in the west, the monument upwarp in the southwest and the Defiance Uplift to the south. To the southeast it passes over into the subsequent San Juan Basin of the high-lying Four Corners Platform. The transition to the southern Black Mesa Basin via the Tyende Saddle. To the north it borders directly on the Uinta Basin. In the southwest of White Canyon Slope mediates the transition to the Henry Basin.

The Paradox Basin can be broken down as follows:

• Paradox Fold and Fault Belt
• Blanding Basin

Furthermore, close to some structural areas, but these are no longer counted as actual Paradox Basin:

• Henry Basin
• White Canyon Slope
• Tyende Saddle
• Red Rock Bench
• Four Corners Platform

The very profound pelvic region of the Paradox Fold and Fault Belt is located in the immediate vicinity of the Uncompahgre uplifts. It is crossed by four major Antiklinalzügen in SE-NW direction, two of these trains will be doing underlain by " salt walls " of the Paradox Formation. The Blanding Basin, however, is a much ungestörteres, shallow sub-basins. From it derives the bulk of the oil production.

Mineral resources

Important, found in the Paradox Basin natural resources are petroleum, uranium, copper and potassium salts.

The oil production comes mostly from Upper Carboniferous porous Karbonatanhäufungen such as algae mats. Additional petroleum reservoirs are tied to structural and stratigraphic oil traps (eg raised to distortions clumps and discontinuous clastic layers ). Main memory horizons are the unterkarbonische Leadville Limestone, the Upper Carboniferous Hermosa Group and the Permian Cutler formation.