We found that the style of deformation in the Chihuahua trough is variable. Required fields are marked *.

It currently has two offices, one located in Ciudad Universitaria in Mexico City, which houses, among other buildings, the National Laboratory of Geochemistry and Mineralogy, and the Regional Northwest Station (ERNO) located in Hermosillo, Sonora. Stubborn Academy Signee Tom DFrick Drops A Hit Song Zadi Featuring Medikal, A Dangerous Street Trade by People and Places Africa. For terms and use, please refer to our Terms and Conditions Deformation in the TM and areas to the north connects the ESTS from the Garlock fault to the central Mojave region indicating a region in which mid-crustal levels of the arc and cratonal basement experienced contractional tectonism during mid-Jurassic time. The age (1,097.5 Ma) for gabbro in the Poersch [number sign]1 well in northern Kansas, as well as the general petrographic characteristics of the sedimentary rocks throughout the area favors a correlation with established Keweenawan stratigraphy in the Lake Superior region. The upper most (youngest) formations within the Thunderbird Group are volcaniclastic (trachytes, ignimbrites, and rhyolites) and have dates ranging around ~950 m.y.o. Consequently, these topics should certainly be of major interest to our readers, our Society, and society in general. This feature appears to predate formation of the mafic body in the CBP (1163 Ma) and is most likely related to Pre-Grenville tectonics, possibly representing a continental margin arc batholith. This area also shows depositional features related to an island of Precambrian rock exposed during deposition of the lower Paleozoic rocks. This is indicative of currents that shift direction. Atop this is the Bliss Formation, a Cambrian quartz arenite (quartz sandstone). A texturally and compositionally heterogeneous amphibolite-facies monzonitic complex which intrudes the basement and metasediments yields a mid-Jurassic age. AbstractIn this article we studied the northern part of the Laramide foreland of the Chihuahua Trough. region. Undeformed granite cross-cuts the foliated monzonite; some granitic rocks cut dikes of the IDs and are likely to be Cretaceous in age. Furthermore, the Boletn has been published since 1904; that makes it one of the oldest scientific journals currently active in Mexico and, most notably, its entire contents, from the first issue on, are available online. Site. of Texas, El Paso, TX (United States). Critical areamore three contains numerous small faults which generally trend NNE. 2) In this section, the contact between the Precambrian Red Bluff Granite/Thunderbird Group and the Bliss Sandstone (~500 m.y.o. xZs8~L%[Fh\0K_(Xm67Ph"Gv.DUwA-LsoS=gkfek/|1=IZM("l 2) Is the contact between the conglomerate and the sandstone exposed at this location? They appear to be splays off of one of the major faults bounding the area.

The Franklin Mountains record the transition from thick- to thin skinned deformation. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. three contains numerous small faults which generally trend NNE. We also favor the publication of papers on relatively unfamiliar subjects and objectives in mainstream journals, e.g., papers devoted to new methodologies or their improvement, and areas of knowledge that in the past had relatively little attention paid them in Mexican journals, such as urban geology, water management, environmental geology, and ore deposits, among others. In similar manner, a second dated diabase dike suggests that the greatest extensional strain in the Lower Devonian was NNE--SSW. A dated trachyte dike suggests that the axis of maximum extensional strain by Middle Devonian time was NS. 4sXhYiiCT$`\TvqT/`9V%:!+9[6` 7=4>ab:kR_ '3[1>A`'yw="6hGmzU6ZYIO*uhWi~Lif&r18kkep kA/6=pJ. Depending upon the tectonic history of the individual basin all or part of the Keweenawan, Field and U-Pb zircon geochronological data from the Tiefort Mts. of Geosciences. Undeformed pegmatite, granite, and microdiorite appear as dikes throughout the region. These processes were wide spread affecting the 300 km long eastern margin of the Chihuahua trough between El Paso and the Big Bend region of west Texas. Thermal maturation within the rift probably ranges from within the oil window to over maturity. Your email address will not be published. and is the oldest of the Thunderbird Group. middle Proterozoic extension in this area. The basement rock exposed here is the Red Bluff Granite, a 1.1 Ga felsic magma that intruded the columnar basalts of the Mundy Breccia and the Castner Marble. Evidence of middle Proterozoic extension is found in the form of igneous bodies in the CBP, the Van Horn uplift, the Franklin Mountains, and the Sacramento Mountains. Sociedad Geolgica Mexicana Cenozoic kaolinite sills and mafic intrusion have filled many of the fault zones. which also contains arkosic sandstones further up in the section. As for the letters that are unseen some of you remember and dont even know at all. Thin sections and rock slabs were used to describe and identify many of the lithologic units. The Coast PMC records dynamothermal and regional contact metamorphic events related to regional plutonism within several juxtaposed terranes; its lengthy and complicated history is related to the Late Cretaceous collision of the Alexander and Wrangellia terranes and the Gravina overlap assemblage to the west against the Yukon prong and Stikine terrane to the east. Geologists refer to them as tilted-block fault mountains, and in them can be found billion-year-old Precambrian rocks, the oldest in Texas. Along strike variations in shortening direction and kinematics are controlled by the curved northeast margin of the trough and reflect stress reorientation along the weak interface between the strong platform and weak basin interior. The classic Great Nonconformity that we show in El Paso is in Mckelligon Canyon where the Red Bluff Granite lies directly below the Bliss Sandstone, to the point where you can place your hand on both units (http://www.geo.utep.edu/pub/aapg/pictures/oct04/oct23.JPG)! With a personal account, you can read up to 100 articles each month for free. The AGM is an east-northeast-trending, 600 km long, gravity low, which extends from the Texas-Oklahoma border through the central basin platform (CBP) to the Delaware basin. Geology has no boundaries so we may publish papers on any area of knowledge that is interesting to our readers. We have used gravity modeling and the comparison of gravity and magnetic anomalies with rock types reported from wells penetrating Precambrian basement to study the AGM and, A sequence of rift-related mafic volcanic rocks, volcanoclastic-, and clastic sedimentary rocks are recognized in cuttings and cores from about seventy wells in Kansas. Their trends are between N 60/sup 0/ E and N 77/sup 0/ E, suggesting that the greatest extensional strain in the area at that time was NNW--SSE.

If NE and NNE dikes are IDS-equivalent, this implies clockwise, vertical-axis rotation of 30[degree]--90[degree] by younger structures. The schools that used to have their letters on the Franklin Mountains are Bowie, Burgess, and Cathedral. Critical area two contains multiple NNW-trending faults, three sills and a possible landslide. #DKE./ R; a!6Ta$2A'6/AXrfe}60)vSrWrFI%4In]zq^;#u#*`aU+bt_.T _ Gt18xni$Hc\Om9?q9s%M Pre-Grenville tectonics, Grenville tectonics, and mid-continent rifting are represented in this area by the Abilene gravity minimum (AGM) and bimodal igneous rocks, which are probably younger. (TM) and surrounding areas in the NE Mojave Desert provide new constraints on Precambrian to Paleozoic paleogeography and Mesozoic intra-arc tectonics. intruded the columnar basalts of the Mundy Breccia, http://www.geo.utep.edu/pub/aapg/pictures/oct04/oct23.JPG, The Puzzling Geology of Northern Slim Buttes, Variabilidad microestructural de huevos de titanosaurio en el XIX Annual Meeting de la EAVP, Plan for Planting with the HMNS Museum Store, The Bridge: Connecting Science and Policy, Friday fold: Kinked Lynchburg metasediments near a soapstone body, Accretionary wedge turbidites from the Lost Coast. Joshua Villalobos, who led the hike, knows much more than I do. It has Skolithos trace fossils in it, just like Virginias Antietam Formation (which is of the same age): Though these arent the most impressive Skolithos Ive ever seen, they are at least diagnostic of vascularized body plans, and therefore of the Cambrian period of geologic time.

for olivine diabases, 536 +- 11 m.y. 1 0 obj<>/ProcSet[/PDF/Text]>>>> endobj 2 0 obj<>stream locally contain the mylonitic fabric and appear to be syn-late kinematic. Amphibolite facies metasediments appear to correlate with lower Paleozoic miogeoclinal sequences. Map scale relationships indicate that motion on high angle basement involved thrusts post dates low angle thrusting. Prior to deposition of Paleozoic rocks the area was peneplaned. and 392 +- 8 m.y. 1) The conglomerate is part of just one of the formations that is part of what is collectively called the Thunderbird Group.This conglomerate layer is part of the Coronado Hills Fm. at the very least between the conglomerate and the sandstone: straight from K-spar to quartzarenite with no arkose(!). Learn how your comment data is processed. Are the Franklin Mountains part of the Rocky Mountains? 4 Comments/Trackbacks , 1) You dont mention how old the conglomerate is, so Im wondering exactly where the Great Unconformity lies: between the granite and the conglomerate, or between the conglomerate and the quartzarenite? Coarse-grained K-feldspar augen gneiss occurs in sharp contact with the metasedimentary rocks; U-Pb dating yields a 1393[+-]12 Ma age. inferring a relationship between the Red Bluff being the source of the Thunderbirds volcaniclastics. Felsite and biotite granite that intrude the foliated monzonitic complex. FACTS! Cretaceous and Jurassic intrusive rocks occur in five major belts and two minor belts in the region and Paleozoic intrusive rocks occur in four major and two minor belts. As part of a larger study, dikes intrusive into Proterozoic (Helikian), granulite-facies rocks near Rand Hill in the northern Adirondack Mountains were investigated.

This blog In the core from the Poersch [number sign]1 well sulfides are recognized in gabbroic sills or dikes.

The relatively simple Glacier Bay PC history is recorded as the roots of a Late Jurassic through late Early Cretaceous island arc that probably developed during the early stages of the above tectonic event. The Franklin Mountains are often referred to as a simple fault block mountain range related to the Rio Grande Rift. Controlled speculation on Paleozoic and Mesozoic structural events in the northern New York region may then be possible. Ages are (528 to 578) +- 11 m.y. Im guessing the former, but there would also seem to be a pretty radical shift in provenance (and flow regime!) This is what the Red Bluff looks like from the parking lot of the Wyler Aerial Tramway, which we rode to the crest of the Franklins on a very cold and windy morning. Its called the Coronado Hills Formation, and this is what it looks like: This isnt a granite. The Institute of Geology (IGI) is a unit of the National Autonomous University of Mexico (UNAM) that belongs to the Subsystem of Scientific Research (SIC). In places such as the East Potrillo Mountains and Indio Mountains is typical of the thin- skinned style, associated with the Cordilleran thrust belt, while in other places, the thick skinned deformation present is typical of the Laramide orogeny in the southern Rocky Mountains. for the trachyte. +- 10 m.y. The authors interpret this to be related to late Cenozoic strike-slip faults. According to most geographic definitions, the Franklin Mountains are not part of the Rocky Mountains Range. North Franklin Mountain Beside this, how were the Franklin Mountains formed? Final report, July 1, 1977--June 30, 1978, Magmatic and metamorphic belts and plutonic-metamorphic complexes of southeastern Alaska, Univ. Dark, fissile shale, similar to the Nonesuch Shale in the [number sign]1--4 Finn well averages 0.75% organic carbon. Sometimes, its dubbed herringbone cross-stratification. By 2015, our community is composed of 59 researchers and 43 academic technicians, an oscillating population of scholarship holders who carry out thesis work for undergraduate, master's and doctoral degrees and 117 people in the administrative area. x_o -;c65M;5VLm2a0[o?8KIq#+`wCl~pkz 46Y}:f)&vrw}o-#8GF'ai"#4{Hh%KFSfd( Heres another lovely exposure showing these primary sedimentary structures: Beds highlighted in black, cross-bedding in white, and the interpreted current flow direction shown with red arrows: A great little hike gaining 500 million years in far less than 500 vertical feet. Stratabound or stratiform deposits can occur both in the Precambrian as well as the overlying Paleozoic rocks. cambrian, granite, igneous, mesoproterozoic, primary structures, proterozoic, sediment, texas, trace fossils, unconformities, weathering Let me outline a few that I spotted, and then you can go back to the unannotated original photo and see if you can spot any others. Geologic mapping in the southern portion of the Franklin Mountains has revealed many previously unrecognized structural complexities. Moroccan Ambassador Meets Dagaarti Girl and other Influential Female Personalities In Ghana. In this region, style of deformation changes from motion on moderate to low angle thrust and reverse faults within the interior of the basin to basement involved reverse faulting on the adjacent platform. This study is in preliminary stages; as more data are accumulated on dike trends, types, and K/Ar dates, a more complete paleostrain record will emerge. The youngest magmatic features are Quaternary-age pre- and post-glacial volcanic rocks that occur in three major fields in the region, as well as in isolated locations. The major Tkope-Portland Peninsula belt of Oligocene age includes both volcanic and plutonic rocks. `I{N'g(}A{ U5#NIh'K,JP[C^p!jA|`C#+%t 22lx]>BIQ2dYii!=(W Qt"5g(?sr'e3%6PA3;c}}Ap7h;#Js5|%LOFUT1psFd)F g]JApJa.-+`U5sm9&Q'K8\rZ},^ |8D_w.T?52XWo,@#^2hZdqagbLk H.I\RjnPF@6dR`udZTLKe\JU1Ag7C Rift-related northeast-trending faults and older northwest-trending faults divide the area up into a number of orthogonal fault blocks or basins. The complicated Chugach MC history developed during and after the Late Cretaceous collision of the Chugach terrane with the Wrangellia and Alexander terranes. Three types of dike rocks were observed: olivine diabase, diabase, and trachyte. - Geological Society of America, Abstracts with Programs; (United States). Perhaps hell chime in with a response. Twenty lithologic units are present in the field area, including the southernmost Precambrian meta-sedimentary rocks in the Franklin Mountains (Lanoria Quartzite and Thunderbird group conglomerates). %PDF-1.5 % Its hard to spot where you leave the Red Bluff and enter the overlying conglomerate, which is made of Red Bluff cobbles and pebbles. The possibility of massive sulfides to occur in the mafic intrusive rocks must not be excluded. Yes, I know: the cobbles are really hard to spot. This gneiss is interpreted to represent cratonal basement of North America. There may be an additional disconformity between the conglomerate and the sandstone, with additional time missing there, but if so, I dont know about it. This item is part of a JSTOR Collection. Mexico is a land of volcanos, earthquakes, vast resources in minerals and petroleum, and a shortage of water. MTCtEF7soH![N=ScRAGhT;l |wKkH *Oi~)(Ti# 9XHm81FACo;T'Hw5OeBs &22-\ The area is dominated by Precambrian igneous rocks and lower Paleozoic carbonates, but Cenozoic ( ) intrusions are also recognized. for diabases, and 366 +- 7 m.y. section may be preserved. Proterozoic structures were reactivated during the Paleozoic, affecting both the structure and deposition in the Permian basin. Shortening directions estimated from the geometry of folds and faults and inversion of fault slip data indicate that both basement involved structures and faults within the basin record a similar Laramide deformation style.

Save my name, email, and website in this browser for the next time I comment. It is believed that large amounts of Keweenawan clastic sedimentary rock were eroded from the nemaha uplift east of the central graben of the rift and transported in an easterly direction. The Franklin Mountains exist as a small range running through far Western Texas (near the city of El Paso), north through Southeastern New Mexico.Click to see full answer. Igneous dikes may be looked upon as paleostrain indicators, and; hence, as aids in reconstructing the strain history (and, ideally, the stress history) of a region. The three major plutonic-metamorphic complexes (PMC), from east to west, are: the Coast PMC in the Coast Mountains; the Glacier Bay-Chichag of plutonic complex (Chugach MC) in the northern outer islands. 7 reasons KiDi deserves 2022 VGMA Artiste of the Year, Stubborn Academy Signee & Superstar Tom DFrick Releases Stay Wicked Music Video Featuring Medikal, Feli Nuna Releases Snippet Ahead Of New Song Towel, Stubborn Academy New Signee Tom DFrick Releases His First Song Featuring Medikal, Ghanaian UK-Based Artist Drogx Releases A Hit Single Dubbed Bando. Considering this, what are the mountains in El Paso called?The Franklin Mountains of Texas are a small range (23 miles long, 3 miles (4.8 km) wide) that extend from El Paso, Texas north into New Mexico. Three critical regions within the study area show that these mountains contain structural complexities. Dept. Vertical silicic dikes at southern TM trend N5-25E and are dated at 148[+-]14 Ma, coeval with the Independence dike swarm (IDS). This unit also sits above the Red Bluff Granite (radiometrically dated to ~980 m.y.o +- 20 m.y.) Three large high-angle faults define the boundaries of map.

Analysis of gravity and magnetic anomalies shows that paired gravity and magnetic highs are related to mafic intrusions in the upper crust. 7 figures, 1 table.

There were intervening glauconitic sands (also Bliss) that my camera would not cooperate in photographing. (It is unknown what substrate the Castner Marble was deposited upon.) The major calcalkalic Coast Mountains belt of early and middle Eocene age is the single largest magmatic feature of the, The geologic structure of part of the southern Franklin Mountains, El Paso County, Texas. Early Tertiary and latest Cretaceous magmatism is represented by the major calcalkalic great tonalite sill belt, a remarkable long and narrow feature along the west side of the Coast Mountains. based on fossil evidence) is not very distinct. Al 2015 nuestra comunidad est integrada por 59 investigadores y 43 tcnicos acadmicos, una poblacin oscilante de becarios que realizan trabajos de tesis de licenciatura, maestra y doctorado y 117 personas del rea administrativa. Its a conglomerate. No actual exposed contact or you know I would have photographed it. El Instituto de Geologa (IGl) es una dependencia de la Universidad Nacional Autnoma de Mxico (UNAM) que pertenece al Subsistema de la Investigacin Cientfica (SIC). Typical high-potassium granite.

Dike trends range from N 60/sup 0/ E through E--W to N 75/sup 0/ W, and dike widths vary between 0.15 and 0.80 m. Crosscutting dikes were dated at three locations by use of the conventional K/Ar whole-rock method, The Cordilleran orogen in southeastern Alaska includes 24 distinct magmatic belts, ranging in age from Cambrian to Holocene, that are defined by map relations, lithology, age, and chemical composition. On the other hand, the orientation of the shortening direction can be explained based on the geometry of the trough and especially the strike of its eastern margin. To access this article, please. Mapping of middle Proterozoic igneous rocks and the paired anomalies outlines a 530 km diameter area of distributed east-west-oriented extension. Middle proterozoic tectonic activity in west Texas and eastern New Mexico and analysis of gravity and magnetic anomalies, Mesozoic intra-arc tectonics in the NE Mojave Desert, CA, Dikes of Rand Hill, northeast Adirondacks, as paleostrain indicators. Better yet, or at least more impressively expressed, are the cross-beds: Notice how in one bed, the cross beds tilt to the left, and in the next, they tilt to the right. Your email address will not be published. Required fields are marked *. In critical area one, Precambrian granites and rhyolites are structurally juxtaposed, and several faults bisecting the area affect the Precambrian/Paleozoic fault contact. The Franklin Mountains are a west tilted fault block mountain range which extends northwards from the city of El Paso, Texas. Your email address will not be published. Similar dikes that occur at TM trend N60-80E. Posted in: Unconformity above the granite, below the conglomerate, for a nonconformity, sensu stricto. Restoration of folds and the IDS to the regional NW trend results in top to the E to NE sense of shear during Jurassic deformation. - AAPG Bulletin (American Association of Petroleum Geologists); (United States). They appear to be splays off of one of the major faults bounding the area.