پديد آورندگان :
شمائليان، علي دانشگاه خوارزمي تهران , ده بزرگي، مريم دانشگاه خوارزمي تهران - استاديار , قرشي، منوچهر سازمان زمين شناسي و اكتشافات معدني كشور - استاد , نوزعيم، رضا دانشگاه بين المللي امام خميني قزوين - استاديار
كليدواژه :
البرز مركزي , رودخانه , گسلش فعال , مورفوتكتونيك
چكيده فارسي :
تحليل و بررسي مورفوتكتونيكي حوضه ي آبريز در شناخت تكتونيك فعال منطقه مفيد است و اطلاعات مهم و ارزشمندي در مورد شرايط زمين ساختي منطقه و ميزان فعاليت تكتونيكي منطقه ي مورد نظر، در اختيار ما قرار دهد. در اين مقاله زمين ساخت فعال دامنه ي جنوبي البرز مركزي در حوضه هاي آبريز جاجرود، ايوانكي و حبله رود (گلوشوت) با استفاده از شاخص هاي مورفومتري ناهنجاري سلسله مراتبي (Ha)، شاخص انشعابات (Bi)، انتگرال و منحني هيپسومتري (Hi)، شكل حوضه (Bs)، برجستگي حوضه (Bh) و تراكم حوضه ي زهكشي (ρ) در محيط Arc GIS 10.1 اندازه گيري شده است. نتايج به دست آمده نشان داد كه در زير حوضه هاي منطبق بر گسل هاي مشا و امام زاده داوود در ناحيه ي شمالي منطقه و گرمسار و ايوانكي و حصاربن در ناحيه ي مركزي و جنوبي منطقه و همچنين مناطق با تراكم گسلي بالا شاخص هاي اندازه گيري شده ناهنجاري هاي بالايي را نتيجه مي دهند كه اينچنين ناهنجاري اشاره به امكان تاثير گسل هاي مذكور بر منطقه و فعاليت تكتونيكي بالا در ناحيه ي مورد مطالعه مي باشند.
چكيده لاتين :
Introduction
The investigation and analysis of the morphotectonics of catchment area can be helpful in
identification of the area’s active morphotectonics. It can also provide some significant and valuable
information regarding the district's tectonic features and its tectonic activities. Rivers are of such
indicators that show extreme reactions to tectonic activities and therefore the results of investigating
their changes and alterations can be a suitable guide for analyzing and determining the amount of
tectonic activities of the study area.
As a river is shaped under active tectonic circumstances, some morphologic alterations would
take place in such structures as channels and longitudinal profiles in reaction to tectonic alterations.
Investigating the rivers' drainage system is so important especially in thrust systems since these
structures show extreme reaction to vertical tectonics and folds. The river’s bedrocks undergo
eroding on the ground and their vertical profile alterations are the most important geomorphological
components regarding the development of mountains views. In situations when the river is not
capable of removing the gradient anomalies, Knick points would be made; and if it creates a vast
area, it would be called Knick zone which would be found in the shape of a waterfall in flow-paths
with flow.
Materials and Methods
The study area is located in Southern Alborz to Varamin plain and Qom's salt lake. The controlling
factors of the area's tectonics include lithology, climate cycle, and structural factors (fold and fault).
The northern part of the area (the Southern hill of Alborz) is completely folded and faulty and has
made a totally active area tectonically. The highest part of study area is Damavand summit and its
height is 5610 m above sea level. The south area has some hills and mountains; however, they are
totally scattered and plains (Varamin plain and the surrounding areas) have occupied most of the
space of the area. This area has created a very tectonically active area since it is located in Alborz
foothill, and there are so important faults such as Mosha's thrust fault, the thrust fault of north of
Tehran, Taleghan fault, Emamzade Davood fault, and in southern areas, Garmsar, Eivanaki,
Hesarbon, and Gharbilak faults are located.
Discussion and Results
The northern half of the area, which is affected by orogenic activities of Alborz, has shown totally a
higher amount of activities comparing to the other parts of the area. In this article, the active
tectonics of the south of central Alborz in catchment areas of Jajrood, Eivanaki, and Hablerood
have been measured in ARC GIS 10.1 environment using river indexes including Hierarchical
anomaly (Ha), Bifurcation index (Bi), Hypsometric integral and curve (Hy), Basin shape (Bs),
Basin relative relief (Bh), and Drainage density index (ρ). To this end, the study area has been concentration values of Cl-, Na+, and Ca2+ in this area stems from water-rock chemical reactions,
and high HCO3
- value may be due either to solution of ascending CO2 gas in underground waters
or to dissolution of basement crystalline limestone.
- Consideration of isotopic compositions of Oxygen (δ18O) and hydrogen (δD) show that the
analyzed samples were slightly enriched in δ18O which may be related to the water-rock isotopic
exchange reactions. The water-rock interactions caused slight increase in δD as well.
- The measurement of 3H in the Sabalan geothermal fluids indicated that the circulating geothermal
fluids can be temporally divided in three groups. The first group has 3H values >10 TU and
belongs to modern waters. The second group so called sub-modern waters has 3H values within
the range of 1-10 TU. The third group which has 3H values <1 TU is regarded to be as old waters.
