Central Broadtop Synclinorium and Its Implications in Appalachian Structure: ABSTRACT
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The Broadtop synclinorium is a large regional synclinorium which extends from central Pennsylvania to western Virginia. Critical study of more than 125 mi of seismic reflection surveys, 22 wells, and surface maps shows that the synclinorium is broken into a series of folded and faulted structures which reflect a precise relation of basement movement to thin-skinned tectonics. This relation indicates that Taconic and older tension-induced features have a pronounced controlling effect on structures caused by later compression. Early tension faults localize features such as decollement ramping. This ramping in turn produces many large prominent first-order structural features in both the Valley and Ridge province and the Plateau province of the Appalachian basin, such as Wil s Mountain anticline and the Allegheny front. The decollement ramping in turn induces formation of smaller second-order features such as the Whip Cove anticlines, the Whip Cove syncline, and other faults and folds within the Broadtop synclinorium. End_of_Article - Last_Page 1893------------Keywords:
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The Southern Madison Range is located in southwestern Montana. Strata range in age from Precambrian to Quaternary. Paleozoic rocks are predominantly marine carbonates, with minor units of sandstones and shales. Mesozoic rocks are predominantly fine-grained clastic rocks of nonmarine origin. All periods are represented except the Silurian. The study area lies in the zone of north-northwest-trending structures, where the Madison-Gravelly arch has moved eastward onto the Madison synclinorium. Major reverse faults, the Hilgard and Scarface faults, place Precambrian and Paleozoic strata on rocks as young as Cretaceous. These faults dip moderately to steeply west. Overturned beds occur in the lower plate. In the southern part of the study area, an east-dipping reverse fault in the upper plate is associated with the northern termination of the Hilgard fault. To the north lies the Shedhorn anticline and syncline. The Shedhorn anticline is a double plunging structure with steep dips on the northeastern limb. The Shedhorn syncline is an open structure to the west of the Shedhorn anticline. The northwestern edge of the syncline is deformed by the Scarface fault, with local overturning and an east-dipping reverse fault in the lower plate. The Taylor fault is a Cenozoic normal fault that dips steeplymore » west, with at least 2000 ft of displacement.« less
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Abstract The H elmstedt‐ S taßfurt salt wall is 70 km long, 6–8 km wide and one of the most important diapiric structures in northern G ermany, based on the economically significant lignite‐bearing rim synclines. The analysed S chöningen rim syncline, located on the southwestern side of the H elmstedt‐ S taßfurt structure, is 8 km long and 3 km wide. The basin‐fill is up to 366 m thick and characterized by 13 major lignite seams with thicknesses between 0.1 and 30 m. The key objectives of this article were to expand on the classical cross‐section based rim syncline analysis by the use of 3 D models and basin simulations. Cross‐sections perpendicular to the basin axis indicate that the basin‐fill has a pronounced lenticular shape. This shape varies from more symmetric in the NW to clearly asymmetric in the SE . Isopach maps imply a two‐fold depocentre evolution. The depocentre migrated over time towards the salt wall and also showed some distinct shifts parallel to the salt wall. The basin modelling part of the study was carried out with the software PetroMod ® , which focused on the burial history of the rim syncline. Modelling results also show the progressive migration of the rim syncline depocentre towards the salt wall. The present‐day asymmetry of the basin‐fill was already developed in the early phases of rim syncline evolution. The extracted geohistory curve shows initial rapid subsidence between 57 and 50 Ma and more moderate subsidence from 50 to 34 Ma. This pattern is interpreted to reflect salt evacuation from the source layer into the salt wall. The initial salt‐withdrawal rate was rapid, but later decreased probably due to depletion of the source layer.
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Organic geochemistry
Petroleum geology
San Joaquin
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A gravity investigation is presented of the Baraboo syncline, which is an inlier of folded pre-Cambrian igneous and metasedimentary rocks in the flat-lying Paleozoic sedimentary rocks of south-central Wisconsin. This investigation shows that gravity measurements can be useful in depicting the surface geology (lithology and structure) of a limited structural feature-the Baraboo syncline. The regional gravity anomaly consists of the southern terminus of a gravity minimum that is centered over Wisconsin. This minimum is interpreted in the light of seismic crustal studies as originating from a thickening of both the "granitic" layer and the earth's crust. A distinct gravity minimum which cannot be explained by surface geology is found associated with the Baraboo syncline. It is interpreted as originating from a local increase in thickness of the "granitic" layer. This minimum, which is quantitatively investigated, provides the clue which suggests that the Baraboo syncline does not terminate at its western end, as generally believed, but rather extends to the southwest for an additional 5 miles. Other structural and lithologic relations of the syncline are studied with the aid of the gravity data. An analysis of the complementary magnetic study of the Baraboo syncline substantiates the conclusions reached from the gravity investigation.
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Lithology
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FAUNA FROM SILURIAN GRAPTOLITIC SHALES OF THE BARDO BASIN IN THE ŚWIĘTY KRZYŻ MOUNTAINS The Bardo syncline is situated in the central part of the Świety Krzyz Mountains. south of the Kielce-Łagow (central) synclinorium from the latter, the Bardo syncline is separated by Cambrian sediments. In the central part of this syncline, especially in the region of Bardo, there appear Devonian sediments; from underneath them, in the flanks of the syncline. Silurian deposits are exposed (Fig. 1). This Silurian has here been developed in the shape form of two fundamental facies of graptolitic shales and of greywacke rocks.
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The structural form in the Yan-Liao area consists of Yanliao clinorium,Yanliao synclinorium and Qinhuangdao antiform with their sub-grade folds and faults in Yanshan-western Liaoning Province.They formed a very complicated structural system.Yanliao clinorium forms during Indosinian movement,and Yanliao synclinorium during J1-J2 period and the Qinhuangdao antiform during J3-Kperiod.The inner Mongolian axial is the northern limb of the Yanliao clinorium.The southern faults of the inner Mongolian axial is the axial longitudinal faults of Yanliao synclinorium.The sediment in the J3 period is the fracture filling.Qinhuangdao fault may cut off the Yanliao synclinorium that resulted in the different patterns of the folds and faults in Yanshan and the western Liaoning.
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